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 #include "packfile.h"
  30
  31 /**
  32  * Parses the value of --rebase. If value is a false value, returns
  33  * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is
  34  * "merges", returns REBASE_MERGES. If value is a invalid value, dies with
  35  * a fatal error if 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 static int recurse_submodules_cli = RECURSE_SUBMODULES_DEFAULT;
  76
  77 /* Options passed to git-merge or git-rebase */
  78 static enum rebase_type opt_rebase = -1;
  79 static char *opt_diffstat;
  80 static char *opt_log;
  81 static char *opt_signoff;
  82 static char *opt_squash;
  83 static char *opt_commit;
  84 static char *opt_edit;
  85 static char *cleanup_arg;
  86 static char *opt_ff;
  87 static char *opt_verify_signatures;
  88 static char *opt_verify;
  89 static int opt_autostash = -1;
  90 static int config_autostash;
  91 static int check_trust_level = 1;
  92 static struct strvec opt_strategies = STRVEC_INIT;
  93 static struct strvec opt_strategy_opts = STRVEC_INIT;
  94 static char *opt_gpg_sign;
  95 static int opt_allow_unrelated_histories;
  96
  97 /* Options passed to git-fetch */
  98 static char *opt_all;
  99 static char *opt_append;
 100 static char *opt_upload_pack;
 101 static int opt_force;
 102 static char *opt_tags;
 103 static char *opt_prune;
 104 static char *max_children;
 105 static int opt_dry_run;
 106 static char *opt_keep;
 107 static char *opt_depth;
 108 static char *opt_unshallow;
 109 static char *opt_update_shallow;
 110 static char *opt_refmap;
 111 static char *opt_ipv4;
 112 static char *opt_ipv6;
 113 static int opt_show_forced_updates = -1;
 114 static char *set_upstream;
 115 static struct strvec opt_fetch = STRVEC_INIT;
 116
 117 static struct option pull_options[] = {
 118         /* Shared options */
 119         OPT__VERBOSITY(&opt_verbosity),
 120         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 121                 N_("force progress reporting"),
 122                 PARSE_OPT_NOARG),
 123         OPT_CALLBACK_F(0, "recurse-submodules",
 124                    &recurse_submodules_cli, N_("on-demand"),
 125                    N_("control for recursive fetching of submodules"),
 126                    PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules),
 127
 128         /* Options passed to git-merge or git-rebase */
 129         OPT_GROUP(N_("Options related to merging")),
 130         OPT_CALLBACK_F('r', "rebase", &opt_rebase,
 131                 "(false|true|merges|interactive)",
 132                 N_("incorporate changes by rebasing rather than merging"),
 133                 PARSE_OPT_OPTARG, parse_opt_rebase),
 134         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 135                 N_("do not show a diffstat at the end of the merge"),
 136                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 137         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 138                 N_("show a diffstat at the end of the merge"),
 139                 PARSE_OPT_NOARG),
 140         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 141                 N_("(synonym to --stat)"),
 142                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 143         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 144                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 145                 PARSE_OPT_OPTARG),
 146         OPT_PASSTHRU(0, "signoff", &opt_signoff, NULL,
 147                 N_("add a Signed-off-by trailer"),
 148                 PARSE_OPT_OPTARG),
 149         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 150                 N_("create a single commit instead of doing a merge"),
 151                 PARSE_OPT_NOARG),
 152         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 153                 N_("perform a commit if the merge succeeds (default)"),
 154                 PARSE_OPT_NOARG),
 155         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 156                 N_("edit message before committing"),
 157                 PARSE_OPT_NOARG),
 158         OPT_CLEANUP(&cleanup_arg),
 159         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 160                 N_("allow fast-forward"),
 161                 PARSE_OPT_NOARG),
 162         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 163                 N_("abort if fast-forward is not possible"),
 164                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 165         OPT_PASSTHRU(0, "verify", &opt_verify, NULL,
 166                 N_("control use of pre-merge-commit and commit-msg hooks"),
 167                 PARSE_OPT_NOARG),
 168         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 169                 N_("verify that the named commit has a valid GPG signature"),
 170                 PARSE_OPT_NOARG),
 171         OPT_BOOL(0, "autostash", &opt_autostash,
 172                 N_("automatically stash/stash pop before and after")),
 173         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 174                 N_("merge strategy to use"),
 175                 0),
 176         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 177                 N_("option=value"),
 178                 N_("option for selected merge strategy"),
 179                 0),
 180         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 181                 N_("GPG sign commit"),
 182                 PARSE_OPT_OPTARG),
 183         OPT_SET_INT(0, "allow-unrelated-histories",
 184                     &opt_allow_unrelated_histories,
 185                     N_("allow merging unrelated histories"), 1),
 186
 187         /* Options passed to git-fetch */
 188         OPT_GROUP(N_("Options related to fetching")),
 189         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 190                 N_("fetch from all remotes"),
 191                 PARSE_OPT_NOARG),
 192         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 193                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 194                 PARSE_OPT_NOARG),
 195         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 196                 N_("path to upload pack on remote end"),
 197                 0),
 198         OPT__FORCE(&opt_force, N_("force overwrite of local branch"), 0),
 199         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 200                 N_("fetch all tags and associated objects"),
 201                 PARSE_OPT_NOARG),
 202         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 203                 N_("prune remote-tracking branches no longer on remote"),
 204                 PARSE_OPT_NOARG),
 205         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 206                 N_("number of submodules pulled in parallel"),
 207                 PARSE_OPT_OPTARG),
 208         OPT_BOOL(0, "dry-run", &opt_dry_run,
 209                 N_("dry run")),
 210         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 211                 N_("keep downloaded pack"),
 212                 PARSE_OPT_NOARG),
 213         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 214                 N_("deepen history of shallow clone"),
 215                 0),
 216         OPT_PASSTHRU_ARGV(0, "shallow-since", &opt_fetch, N_("time"),
 217                 N_("deepen history of shallow repository based on time"),
 218                 0),
 219         OPT_PASSTHRU_ARGV(0, "shallow-exclude", &opt_fetch, N_("revision"),
 220                 N_("deepen history of shallow clone, excluding rev"),
 221                 0),
 222         OPT_PASSTHRU_ARGV(0, "deepen", &opt_fetch, N_("n"),
 223                 N_("deepen history of shallow clone"),
 224                 0),
 225         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 226                 N_("convert to a complete repository"),
 227                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 228         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 229                 N_("accept refs that update .git/shallow"),
 230                 PARSE_OPT_NOARG),
 231         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 232                 N_("specify fetch refmap"),
 233                 PARSE_OPT_NONEG),
 234         OPT_PASSTHRU_ARGV('o', "server-option", &opt_fetch,
 235                 N_("server-specific"),
 236                 N_("option to transmit"),
 237                 0),
 238         OPT_PASSTHRU('4',  "ipv4", &opt_ipv4, NULL,
 239                 N_("use IPv4 addresses only"),
 240                 PARSE_OPT_NOARG),
 241         OPT_PASSTHRU('6',  "ipv6", &opt_ipv6, NULL,
 242                 N_("use IPv6 addresses only"),
 243                 PARSE_OPT_NOARG),
 244         OPT_PASSTHRU_ARGV(0, "negotiation-tip", &opt_fetch, N_("revision"),
 245                 N_("report that we have only objects reachable from this object"),
 246                 0),
 247         OPT_BOOL(0, "show-forced-updates", &opt_show_forced_updates,
 248                  N_("check for forced-updates on all updated branches")),
 249         OPT_PASSTHRU(0, "set-upstream", &set_upstream, NULL,
 250                 N_("set upstream for git pull/fetch"),
 251                 PARSE_OPT_NOARG),
 252
 253         OPT_END()
 254 };
 255
 256 /**
 257  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 258  */
 259 static void argv_push_verbosity(struct strvec *arr)
 260 {
 261         int verbosity;
 262
 263         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 264                 strvec_push(arr, "-v");
 265
 266         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 267                 strvec_push(arr, "-q");
 268 }
 269
 270 /**
 271  * Pushes "-f" switches into arr to match the opt_force level.
 272  */
 273 static void argv_push_force(struct strvec *arr)
 274 {
 275         int force = opt_force;
 276         while (force-- > 0)
 277                 strvec_push(arr, "-f");
 278 }
 279
 280 /**
 281  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 282  */
 283 static void set_reflog_message(int argc, const char **argv)
 284 {
 285         int i;
 286         struct strbuf msg = STRBUF_INIT;
 287
 288         for (i = 0; i < argc; i++) {
 289                 if (i)
 290                         strbuf_addch(&msg, ' ');
 291                 strbuf_addstr(&msg, argv[i]);
 292         }
 293
 294         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 295
 296         strbuf_release(&msg);
 297 }
 298
 299 /**
 300  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 301  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 302  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 303  * error.
 304  */
 305 static const char *config_get_ff(void)
 306 {
 307         const char *value;
 308
 309         if (git_config_get_value("pull.ff", &value))
 310                 return NULL;
 311
 312         switch (git_parse_maybe_bool(value)) {
 313         case 0:
 314                 return "--no-ff";
 315         case 1:
 316                 return "--ff";
 317         }
 318
 319         if (!strcmp(value, "only"))
 320                 return "--ff-only";
 321
 322         die(_("invalid value for '%s': '%s'"), "pull.ff", value);
 323 }
 324
 325 /**
 326  * Returns the default configured value for --rebase. It first looks for the
 327  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 328  * branch, and if HEAD is detached or the configuration key does not exist,
 329  * looks for the value of "pull.rebase". If both configuration keys do not
 330  * exist, returns REBASE_FALSE.
 331  */
 332 static enum rebase_type config_get_rebase(int *rebase_unspecified)
 333 {
 334         struct branch *curr_branch = branch_get("HEAD");
 335         const char *value;
 336
 337         if (curr_branch) {
 338                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 339
 340                 if (!git_config_get_value(key, &value)) {
 341                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 342                         free(key);
 343                         return ret;
 344                 }
 345
 346                 free(key);
 347         }
 348
 349         if (!git_config_get_value("pull.rebase", &value))
 350                 return parse_config_rebase("pull.rebase", value, 1);
 351
 352         *rebase_unspecified = 1;
 353
 354         return REBASE_FALSE;
 355 }
 356
 357 /**
 358  * Read config variables.
 359  */
 360 static int git_pull_config(const char *var, const char *value, void *cb)
 361 {
 362         int status;
 363
 364         if (!strcmp(var, "rebase.autostash")) {
 365                 config_autostash = git_config_bool(var, value);
 366                 return 0;
 367         } else if (!strcmp(var, "submodule.recurse")) {
 368                 recurse_submodules = git_config_bool(var, value) ?
 369                         RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
 370                 return 0;
 371         } else if (!strcmp(var, "gpg.mintrustlevel")) {
 372                 check_trust_level = 0;
 373         }
 374
 375         status = git_gpg_config(var, value, cb);
 376         if (status)
 377                 return status;
 378
 379         return git_default_config(var, value, cb);
 380 }
 381
 382 /**
 383  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 384  * into merge_heads.
 385  */
 386 static void get_merge_heads(struct oid_array *merge_heads)
 387 {
 388         const char *filename = git_path_fetch_head(the_repository);
 389         FILE *fp;
 390         struct strbuf sb = STRBUF_INIT;
 391         struct object_id oid;
 392
 393         fp = xfopen(filename, "r");
 394         while (strbuf_getline_lf(&sb, fp) != EOF) {
 395                 const char *p;
 396                 if (parse_oid_hex(sb.buf, &oid, &p))
 397                         continue;  /* invalid line: does not start with object ID */
 398                 if (starts_with(p, "\tnot-for-merge\t"))
 399                         continue;  /* ref is not-for-merge */
 400                 oid_array_append(merge_heads, &oid);
 401         }
 402         fclose(fp);
 403         strbuf_release(&sb);
 404 }
 405
 406 /**
 407  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 408  * retrieve the name of the remote if the repository only has one remote.
 409  */
 410 static int get_only_remote(struct remote *remote, void *cb_data)
 411 {
 412         const char **remote_name = cb_data;
 413
 414         if (*remote_name)
 415                 return -1;
 416
 417         *remote_name = remote->name;
 418         return 0;
 419 }
 420
 421 /**
 422  * Dies with the appropriate reason for why there are no merge candidates:
 423  *
 424  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 425  *    up not fetching anything. This is usually because the user provided a
 426  *    wildcard refspec which had no matches on the remote end.
 427  *
 428  * 2. We fetched from a non-default remote, but didn't specify a branch to
 429  *    merge. We can't use the configured one because it applies to the default
 430  *    remote, thus the user must specify the branches to merge.
 431  *
 432  * 3. We fetched from the branch's or repo's default remote, but:
 433  *
 434  *    a. We are not on a branch, so there will never be a configured branch to
 435  *       merge with.
 436  *
 437  *    b. We are on a branch, but there is no configured branch to merge with.
 438  *
 439  * 4. We fetched from the branch's or repo's default remote, but the configured
 440  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 441  *    part of the configured fetch refspec.)
 442  */
 443 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 444 {
 445         struct branch *curr_branch = branch_get("HEAD");
 446         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 447
 448         if (*refspecs) {
 449                 if (opt_rebase)
 450                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 451                 else
 452                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 453                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 454                                         "matches on the remote end."));
 455         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 456                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 457                         "a branch. Because this is not the default configured remote\n"
 458                         "for your current branch, you must specify a branch on the command line."),
 459                         repo);
 460         } else if (!curr_branch) {
 461                 fprintf_ln(stderr, _("You are not currently on a branch."));
 462                 if (opt_rebase)
 463                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 464                 else
 465                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 466                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 467                 fprintf(stderr, "\n");
 468                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 469                 fprintf(stderr, "\n");
 470         } else if (!curr_branch->merge_nr) {
 471                 const char *remote_name = NULL;
 472
 473                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 474                         remote_name = _("<remote>");
 475
 476                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 477                 if (opt_rebase)
 478                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 479                 else
 480                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 481                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 482                 fprintf(stderr, "\n");
 483                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 484                 fprintf(stderr, "\n");
 485                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));
 486                 fprintf(stderr, "\n");
 487                 fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",
 488                                 remote_name, _("<branch>"), curr_branch->name);
 489         } else
 490                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 491                         "from the remote, but no such ref was fetched."),
 492                         *curr_branch->merge_name);
 493         exit(1);
 494 }
 495
 496 /**
 497  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 498  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 499  * is not provided in argv, it is set to NULL.
 500  */
 501 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 502                 const char ***refspecs)
 503 {
 504         if (argc > 0) {
 505                 *repo = *argv++;
 506                 argc--;
 507         } else
 508                 *repo = NULL;
 509         *refspecs = argv;
 510 }
 511
 512 /**
 513  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 514  * repository and refspecs to fetch, or NULL if they are not provided.
 515  */
 516 static int run_fetch(const char *repo, const char **refspecs)
 517 {
 518         struct strvec args = STRVEC_INIT;
 519         int ret;
 520
 521         strvec_pushl(&args, "fetch", "--update-head-ok", NULL);
 522
 523         /* Shared options */
 524         argv_push_verbosity(&args);
 525         if (opt_progress)
 526                 strvec_push(&args, opt_progress);
 527
 528         /* Options passed to git-fetch */
 529         if (opt_all)
 530                 strvec_push(&args, opt_all);
 531         if (opt_append)
 532                 strvec_push(&args, opt_append);
 533         if (opt_upload_pack)
 534                 strvec_push(&args, opt_upload_pack);
 535         argv_push_force(&args);
 536         if (opt_tags)
 537                 strvec_push(&args, opt_tags);
 538         if (opt_prune)
 539                 strvec_push(&args, opt_prune);
 540         if (recurse_submodules_cli != RECURSE_SUBMODULES_DEFAULT)
 541                 switch (recurse_submodules_cli) {
 542                 case RECURSE_SUBMODULES_ON:
 543                         strvec_push(&args, "--recurse-submodules=on");
 544                         break;
 545                 case RECURSE_SUBMODULES_OFF:
 546                         strvec_push(&args, "--recurse-submodules=no");
 547                         break;
 548                 case RECURSE_SUBMODULES_ON_DEMAND:
 549                         strvec_push(&args, "--recurse-submodules=on-demand");
 550                         break;
 551                 default:
 552                         BUG("submodule recursion option not understood");
 553                 }
 554         if (max_children)
 555                 strvec_push(&args, max_children);
 556         if (opt_dry_run)
 557                 strvec_push(&args, "--dry-run");
 558         if (opt_keep)
 559                 strvec_push(&args, opt_keep);
 560         if (opt_depth)
 561                 strvec_push(&args, opt_depth);
 562         if (opt_unshallow)
 563                 strvec_push(&args, opt_unshallow);
 564         if (opt_update_shallow)
 565                 strvec_push(&args, opt_update_shallow);
 566         if (opt_refmap)
 567                 strvec_push(&args, opt_refmap);
 568         if (opt_ipv4)
 569                 strvec_push(&args, opt_ipv4);
 570         if (opt_ipv6)
 571                 strvec_push(&args, opt_ipv6);
 572         if (opt_show_forced_updates > 0)
 573                 strvec_push(&args, "--show-forced-updates");
 574         else if (opt_show_forced_updates == 0)
 575                 strvec_push(&args, "--no-show-forced-updates");
 576         if (set_upstream)
 577                 strvec_push(&args, set_upstream);
 578         strvec_pushv(&args, opt_fetch.v);
 579
 580         if (repo) {
 581                 strvec_push(&args, repo);
 582                 strvec_pushv(&args, refspecs);
 583         } else if (*refspecs)
 584                 BUG("refspecs without repo?");
 585         ret = run_command_v_opt(args.v, RUN_GIT_CMD | RUN_CLOSE_OBJECT_STORE);
 586         strvec_clear(&args);
 587         return ret;
 588 }
 589
 590 /**
 591  * "Pulls into void" by branching off merge_head.
 592  */
 593 static int pull_into_void(const struct object_id *merge_head,
 594                 const struct object_id *curr_head)
 595 {
 596         if (opt_verify_signatures) {
 597                 struct commit *commit;
 598
 599                 commit = lookup_commit(the_repository, merge_head);
 600                 if (!commit)
 601                         die(_("unable to access commit %s"),
 602                             oid_to_hex(merge_head));
 603
 604                 verify_merge_signature(commit, opt_verbosity,
 605                                        check_trust_level);
 606         }
 607
 608         /*
 609          * Two-way merge: we treat the index as based on an empty tree,
 610          * and try to fast-forward to HEAD. This ensures we will not lose
 611          * index/worktree changes that the user already made on the unborn
 612          * branch.
 613          */
 614         if (checkout_fast_forward(the_repository,
 615                                   the_hash_algo->empty_tree,
 616                                   merge_head, 0))
 617                 return 1;
 618
 619         if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 620                 return 1;
 621
 622         return 0;
 623 }
 624
 625 static int rebase_submodules(void)
 626 {
 627         struct child_process cp = CHILD_PROCESS_INIT;
 628
 629         cp.git_cmd = 1;
 630         cp.no_stdin = 1;
 631         strvec_pushl(&cp.args, "submodule", "update",
 632                      "--recursive", "--rebase", NULL);
 633         argv_push_verbosity(&cp.args);
 634
 635         return run_command(&cp);
 636 }
 637
 638 static int update_submodules(void)
 639 {
 640         struct child_process cp = CHILD_PROCESS_INIT;
 641
 642         cp.git_cmd = 1;
 643         cp.no_stdin = 1;
 644         strvec_pushl(&cp.args, "submodule", "update",
 645                      "--recursive", "--checkout", NULL);
 646         argv_push_verbosity(&cp.args);
 647
 648         return run_command(&cp);
 649 }
 650
 651 /**
 652  * Runs git-merge, returning its exit status.
 653  */
 654 static int run_merge(void)
 655 {
 656         int ret;
 657         struct strvec args = STRVEC_INIT;
 658
 659         strvec_pushl(&args, "merge", NULL);
 660
 661         /* Shared options */
 662         argv_push_verbosity(&args);
 663         if (opt_progress)
 664                 strvec_push(&args, opt_progress);
 665
 666         /* Options passed to git-merge */
 667         if (opt_diffstat)
 668                 strvec_push(&args, opt_diffstat);
 669         if (opt_log)
 670                 strvec_push(&args, opt_log);
 671         if (opt_signoff)
 672                 strvec_push(&args, opt_signoff);
 673         if (opt_squash)
 674                 strvec_push(&args, opt_squash);
 675         if (opt_commit)
 676                 strvec_push(&args, opt_commit);
 677         if (opt_edit)
 678                 strvec_push(&args, opt_edit);
 679         if (cleanup_arg)
 680                 strvec_pushf(&args, "--cleanup=%s", cleanup_arg);
 681         if (opt_ff)
 682                 strvec_push(&args, opt_ff);
 683         if (opt_verify)
 684                 strvec_push(&args, opt_verify);
 685         if (opt_verify_signatures)
 686                 strvec_push(&args, opt_verify_signatures);
 687         strvec_pushv(&args, opt_strategies.v);
 688         strvec_pushv(&args, opt_strategy_opts.v);
 689         if (opt_gpg_sign)
 690                 strvec_push(&args, opt_gpg_sign);
 691         if (opt_autostash == 0)
 692                 strvec_push(&args, "--no-autostash");
 693         else if (opt_autostash == 1)
 694                 strvec_push(&args, "--autostash");
 695         if (opt_allow_unrelated_histories > 0)
 696                 strvec_push(&args, "--allow-unrelated-histories");
 697
 698         strvec_push(&args, "FETCH_HEAD");
 699         ret = run_command_v_opt(args.v, RUN_GIT_CMD);
 700         strvec_clear(&args);
 701         return ret;
 702 }
 703
 704 /**
 705  * Returns remote's upstream branch for the current branch. If remote is NULL,
 706  * the current branch's configured default remote is used. Returns NULL if
 707  * `remote` does not name a valid remote, HEAD does not point to a branch,
 708  * remote is not the branch's configured remote or the branch does not have any
 709  * configured upstream branch.
 710  */
 711 static const char *get_upstream_branch(const char *remote)
 712 {
 713         struct remote *rm;
 714         struct branch *curr_branch;
 715         const char *curr_branch_remote;
 716
 717         rm = remote_get(remote);
 718         if (!rm)
 719                 return NULL;
 720
 721         curr_branch = branch_get("HEAD");
 722         if (!curr_branch)
 723                 return NULL;
 724
 725         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 726         assert(curr_branch_remote);
 727
 728         if (strcmp(curr_branch_remote, rm->name))
 729                 return NULL;
 730
 731         return branch_get_upstream(curr_branch, NULL);
 732 }
 733
 734 /**
 735  * Derives the remote-tracking branch from the remote and refspec.
 736  *
 737  * FIXME: The current implementation assumes the default mapping of
 738  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 739  */
 740 static const char *get_tracking_branch(const char *remote, const char *refspec)
 741 {
 742         struct refspec_item spec;
 743         const char *spec_src;
 744         const char *merge_branch;
 745
 746         refspec_item_init_or_die(&spec, refspec, REFSPEC_FETCH);
 747         spec_src = spec.src;
 748         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 749                 spec_src = "HEAD";
 750         else if (skip_prefix(spec_src, "heads/", &spec_src))
 751                 ;
 752         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 753                 ;
 754         else if (starts_with(spec_src, "refs/") ||
 755                 starts_with(spec_src, "tags/") ||
 756                 starts_with(spec_src, "remotes/"))
 757                 spec_src = "";
 758
 759         if (*spec_src) {
 760                 if (!strcmp(remote, "."))
 761                         merge_branch = mkpath("refs/heads/%s", spec_src);
 762                 else
 763                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 764         } else
 765                 merge_branch = NULL;
 766
 767         refspec_item_clear(&spec);
 768         return merge_branch;
 769 }
 770
 771 /**
 772  * Given the repo and refspecs, sets fork_point to the point at which the
 773  * current branch forked from its remote-tracking branch. Returns 0 on success,
 774  * -1 on failure.
 775  */
 776 static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,
 777                 const char *refspec)
 778 {
 779         int ret;
 780         struct branch *curr_branch;
 781         const char *remote_branch;
 782         struct child_process cp = CHILD_PROCESS_INIT;
 783         struct strbuf sb = STRBUF_INIT;
 784
 785         curr_branch = branch_get("HEAD");
 786         if (!curr_branch)
 787                 return -1;
 788
 789         if (refspec)
 790                 remote_branch = get_tracking_branch(repo, refspec);
 791         else
 792                 remote_branch = get_upstream_branch(repo);
 793
 794         if (!remote_branch)
 795                 return -1;
 796
 797         strvec_pushl(&cp.args, "merge-base", "--fork-point",
 798                      remote_branch, curr_branch->name, NULL);
 799         cp.no_stdin = 1;
 800         cp.no_stderr = 1;
 801         cp.git_cmd = 1;
 802
 803         ret = capture_command(&cp, &sb, GIT_MAX_HEXSZ);
 804         if (ret)
 805                 goto cleanup;
 806
 807         ret = get_oid_hex(sb.buf, fork_point);
 808         if (ret)
 809                 goto cleanup;
 810
 811 cleanup:
 812         strbuf_release(&sb);
 813         return ret ? -1 : 0;
 814 }
 815
 816 /**
 817  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 818  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 819  */
 820 static int get_octopus_merge_base(struct object_id *merge_base,
 821                 const struct object_id *curr_head,
 822                 const struct object_id *merge_head,
 823                 const struct object_id *fork_point)
 824 {
 825         struct commit_list *revs = NULL, *result;
 826
 827         commit_list_insert(lookup_commit_reference(the_repository, curr_head),
 828                            &revs);
 829         commit_list_insert(lookup_commit_reference(the_repository, merge_head),
 830                            &revs);
 831         if (!is_null_oid(fork_point))
 832                 commit_list_insert(lookup_commit_reference(the_repository, fork_point),
 833                                    &revs);
 834
 835         result = get_octopus_merge_bases(revs);
 836         free_commit_list(revs);
 837         reduce_heads_replace(&result);
 838
 839         if (!result)
 840                 return 1;
 841
 842         oidcpy(merge_base, &result->item->object.oid);
 843         free_commit_list(result);
 844         return 0;
 845 }
 846
 847 /**
 848  * Given the current HEAD oid, the merge head returned from git-fetch and the
 849  * fork point calculated by get_rebase_fork_point(), compute the <newbase> and
 850  * <upstream> arguments to use for the upcoming git-rebase invocation.
 851  */
 852 static int get_rebase_newbase_and_upstream(struct object_id *newbase,
 853                 struct object_id *upstream,
 854                 const struct object_id *curr_head,
 855                 const struct object_id *merge_head,
 856                 const struct object_id *fork_point)
 857 {
 858         struct object_id oct_merge_base;
 859
 860         if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))
 861                 if (!is_null_oid(fork_point) && oideq(&oct_merge_base, fork_point))
 862                         fork_point = NULL;
 863
 864         if (fork_point && !is_null_oid(fork_point))
 865                 oidcpy(upstream, fork_point);
 866         else
 867                 oidcpy(upstream, merge_head);
 868
 869         oidcpy(newbase, merge_head);
 870
 871         return 0;
 872 }
 873
 874 /**
 875  * Given the <newbase> and <upstream> calculated by
 876  * get_rebase_newbase_and_upstream(), runs git-rebase with the
 877  * appropriate arguments and returns its exit status.
 878  */
 879 static int run_rebase(const struct object_id *newbase,
 880                 const struct object_id *upstream)
 881 {
 882         int ret;
 883         struct strvec args = STRVEC_INIT;
 884
 885         strvec_push(&args, "rebase");
 886
 887         /* Shared options */
 888         argv_push_verbosity(&args);
 889
 890         /* Options passed to git-rebase */
 891         if (opt_rebase == REBASE_MERGES)
 892                 strvec_push(&args, "--rebase-merges");
 893         else if (opt_rebase == REBASE_INTERACTIVE)
 894                 strvec_push(&args, "--interactive");
 895         if (opt_diffstat)
 896                 strvec_push(&args, opt_diffstat);
 897         strvec_pushv(&args, opt_strategies.v);
 898         strvec_pushv(&args, opt_strategy_opts.v);
 899         if (opt_gpg_sign)
 900                 strvec_push(&args, opt_gpg_sign);
 901         if (opt_signoff)
 902                 strvec_push(&args, opt_signoff);
 903         if (opt_autostash == 0)
 904                 strvec_push(&args, "--no-autostash");
 905         else if (opt_autostash == 1)
 906                 strvec_push(&args, "--autostash");
 907         if (opt_verify_signatures &&
 908             !strcmp(opt_verify_signatures, "--verify-signatures"))
 909                 warning(_("ignoring --verify-signatures for rebase"));
 910
 911         strvec_push(&args, "--onto");
 912         strvec_push(&args, oid_to_hex(newbase));
 913
 914         strvec_push(&args, oid_to_hex(upstream));
 915
 916         ret = run_command_v_opt(args.v, RUN_GIT_CMD);
 917         strvec_clear(&args);
 918         return ret;
 919 }
 920
 921 static int get_can_ff(struct object_id *orig_head,
 922                       struct oid_array *merge_heads)
 923 {
 924         int ret;
 925         struct commit_list *list = NULL;
 926         struct commit *merge_head, *head;
 927         struct object_id *orig_merge_head;
 928
 929         if (merge_heads->nr > 1)
 930                 return 0;
 931
 932         orig_merge_head = &merge_heads->oid[0];
 933         head = lookup_commit_reference(the_repository, orig_head);
 934         commit_list_insert(head, &list);
 935         merge_head = lookup_commit_reference(the_repository, orig_merge_head);
 936         ret = repo_is_descendant_of(the_repository, merge_head, list);
 937         free_commit_list(list);
 938         return ret;
 939 }
 940
 941 /*
 942  * Is orig_head a descendant of _all_ merge_heads?
 943  * Unfortunately is_descendant_of() cannot be used as it asks
 944  * if orig_head is a descendant of at least one of them.
 945  */
 946 static int already_up_to_date(struct object_id *orig_head,
 947                               struct oid_array *merge_heads)
 948 {
 949         int i;
 950         struct commit *ours;
 951
 952         ours = lookup_commit_reference(the_repository, orig_head);
 953         for (i = 0; i < merge_heads->nr; i++) {
 954                 struct commit_list *list = NULL;
 955                 struct commit *theirs;
 956                 int ok;
 957
 958                 theirs = lookup_commit_reference(the_repository, &merge_heads->oid[i]);
 959                 commit_list_insert(theirs, &list);
 960                 ok = repo_is_descendant_of(the_repository, ours, list);
 961                 free_commit_list(list);
 962                 if (!ok)
 963                         return 0;
 964         }
 965         return 1;
 966 }
 967
 968 static void show_advice_pull_non_ff(void)
 969 {
 970         advise(_("You have divergent branches and need to specify how to reconcile them.\n"
 971                  "You can do so by running one of the following commands sometime before\n"
 972                  "your next pull:\n"
 973                  "\n"
 974                  "  git config pull.rebase false  # merge\n"
 975                  "  git config pull.rebase true   # rebase\n"
 976                  "  git config pull.ff only       # fast-forward only\n"
 977                  "\n"
 978                  "You can replace \"git config\" with \"git config --global\" to set a default\n"
 979                  "preference for all repositories. You can also pass --rebase, --no-rebase,\n"
 980                  "or --ff-only on the command line to override the configured default per\n"
 981                  "invocation.\n"));
 982 }
 983
 984 int cmd_pull(int argc, const char **argv, const char *prefix)
 985 {
 986         const char *repo, **refspecs;
 987         struct oid_array merge_heads = OID_ARRAY_INIT;
 988         struct object_id orig_head, curr_head;
 989         struct object_id rebase_fork_point;
 990         int rebase_unspecified = 0;
 991         int can_ff;
 992         int divergent;
 993
 994         if (!getenv("GIT_REFLOG_ACTION"))
 995                 set_reflog_message(argc, argv);
 996
 997         git_config(git_pull_config, NULL);
 998         if (the_repository->gitdir) {
 999                 prepare_repo_settings(the_repository);
1000                 the_repository->settings.command_requires_full_index = 0;
1001         }
1002
1003         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
1004
1005         if (recurse_submodules_cli != RECURSE_SUBMODULES_DEFAULT)
1006                 recurse_submodules = recurse_submodules_cli;
1007
1008         if (cleanup_arg)
1009                 /*
1010                  * this only checks the validity of cleanup_arg; we don't need
1011                  * a valid value for use_editor
1012                  */
1013                 get_cleanup_mode(cleanup_arg, 0);
1014
1015         parse_repo_refspecs(argc, argv, &repo, &refspecs);
1016
1017         if (!opt_ff) {
1018                 opt_ff = xstrdup_or_null(config_get_ff());
1019                 /*
1020                  * A subtle point: opt_ff was set on the line above via
1021                  * reading from config.  opt_rebase, in contrast, is set
1022                  * before this point via command line options.  The setting
1023                  * of opt_rebase via reading from config (using
1024                  * config_get_rebase()) does not happen until later.  We
1025                  * are relying on the next if-condition happening before
1026                  * the config_get_rebase() call so that an explicit
1027                  * "--rebase" can override a config setting of
1028                  * pull.ff=only.
1029                  */
1030                 if (opt_rebase >= 0 && opt_ff && !strcmp(opt_ff, "--ff-only"))
1031                         opt_ff = "--ff";
1032         }
1033
1034         if (opt_rebase < 0)
1035                 opt_rebase = config_get_rebase(&rebase_unspecified);
1036
1037         if (read_cache_unmerged())
1038                 die_resolve_conflict("pull");
1039
1040         if (file_exists(git_path_merge_head(the_repository)))
1041                 die_conclude_merge();
1042
1043         if (get_oid("HEAD", &orig_head))
1044                 oidclr(&orig_head);
1045
1046         if (opt_rebase) {
1047                 if (opt_autostash == -1)
1048                         opt_autostash = config_autostash;
1049
1050                 if (is_null_oid(&orig_head) && !is_cache_unborn())
1051                         die(_("Updating an unborn branch with changes added to the index."));
1052
1053                 if (!opt_autostash)
1054                         require_clean_work_tree(the_repository,
1055                                 N_("pull with rebase"),
1056                                 _("please commit or stash them."), 1, 0);
1057
1058                 if (get_rebase_fork_point(&rebase_fork_point, repo, *refspecs))
1059                         oidclr(&rebase_fork_point);
1060         }
1061
1062         if (run_fetch(repo, refspecs))
1063                 return 1;
1064
1065         if (opt_dry_run)
1066                 return 0;
1067
1068         if (get_oid("HEAD", &curr_head))
1069                 oidclr(&curr_head);
1070
1071         if (!is_null_oid(&orig_head) && !is_null_oid(&curr_head) &&
1072                         !oideq(&orig_head, &curr_head)) {
1073                 /*
1074                  * The fetch involved updating the current branch.
1075                  *
1076                  * The working tree and the index file are still based on
1077                  * orig_head commit, but we are merging into curr_head.
1078                  * Update the working tree to match curr_head.
1079                  */
1080
1081                 warning(_("fetch updated the current branch head.\n"
1082                         "fast-forwarding your working tree from\n"
1083                         "commit %s."), oid_to_hex(&orig_head));
1084
1085                 if (checkout_fast_forward(the_repository, &orig_head,
1086                                           &curr_head, 0))
1087                         die(_("Cannot fast-forward your working tree.\n"
1088                                 "After making sure that you saved anything precious from\n"
1089                                 "$ git diff %s\n"
1090                                 "output, run\n"
1091                                 "$ git reset --hard\n"
1092                                 "to recover."), oid_to_hex(&orig_head));
1093         }
1094
1095         get_merge_heads(&merge_heads);
1096
1097         if (!merge_heads.nr)
1098                 die_no_merge_candidates(repo, refspecs);
1099
1100         if (is_null_oid(&orig_head)) {
1101                 if (merge_heads.nr > 1)
1102                         die(_("Cannot merge multiple branches into empty head."));
1103                 return pull_into_void(merge_heads.oid, &curr_head);
1104         }
1105         if (merge_heads.nr > 1) {
1106                 if (opt_rebase)
1107                         die(_("Cannot rebase onto multiple branches."));
1108                 if (opt_ff && !strcmp(opt_ff, "--ff-only"))
1109                         die(_("Cannot fast-forward to multiple branches."));
1110         }
1111
1112         can_ff = get_can_ff(&orig_head, &merge_heads);
1113         divergent = !can_ff && !already_up_to_date(&orig_head, &merge_heads);
1114
1115         /* ff-only takes precedence over rebase */
1116         if (opt_ff && !strcmp(opt_ff, "--ff-only")) {
1117                 if (divergent)
1118                         die_ff_impossible();
1119                 opt_rebase = REBASE_FALSE;
1120         }
1121         /* If no action specified and we can't fast forward, then warn. */
1122         if (!opt_ff && rebase_unspecified && divergent) {
1123                 show_advice_pull_non_ff();
1124                 die(_("Need to specify how to reconcile divergent branches."));
1125         }
1126
1127         if (opt_rebase) {
1128                 int ret = 0;
1129
1130                 struct object_id newbase;
1131                 struct object_id upstream;
1132                 get_rebase_newbase_and_upstream(&newbase, &upstream, &curr_head,
1133                                                 merge_heads.oid, &rebase_fork_point);
1134
1135                 if ((recurse_submodules == RECURSE_SUBMODULES_ON ||
1136                      recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) &&
1137                     submodule_touches_in_range(the_repository, &upstream, &curr_head))
1138                         die(_("cannot rebase with locally recorded submodule modifications"));
1139
1140                 if (can_ff) {
1141                         /* we can fast-forward this without invoking rebase */
1142                         opt_ff = "--ff-only";
1143                         ret = run_merge();
1144                 } else {
1145                         ret = run_rebase(&newbase, &upstream);
1146                 }
1147
1148                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
1149                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
1150                         ret = rebase_submodules();
1151
1152                 return ret;
1153         } else {
1154                 int ret = run_merge();
1155                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
1156                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
1157                         ret = update_submodules();
1158                 return ret;
1159         }
1160 }