builtin/pull.c

   1 /*
   2  * Builtin "git pull"
   3  *
   4  * Based on git-pull.sh by Junio C Hamano
   5  *
   6  * Fetch one or more remote refs and merge it/them into the current HEAD.
   7  */
   8 #include "cache.h"
   9 #include "config.h"
  10 #include "builtin.h"
  11 #include "parse-options.h"
  12 #include "exec-cmd.h"
  13 #include "run-command.h"
  14 #include "sha1-array.h"
  15 #include "remote.h"
  16 #include "dir.h"
  17 #include "refs.h"
  18 #include "refspec.h"
  19 #include "revision.h"
  20 #include "submodule.h"
  21 #include "submodule-config.h"
  22 #include "tempfile.h"
  23 #include "lockfile.h"
  24 #include "wt-status.h"
  25
  26 enum rebase_type {
  27         REBASE_INVALID = -1,
  28         REBASE_FALSE = 0,
  29         REBASE_TRUE,
  30         REBASE_PRESERVE,
  31         REBASE_INTERACTIVE
  32 };
  33
  34 /**
  35  * Parses the value of --rebase. If value is a false value, returns
  36  * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is
  37  * "preserve", returns REBASE_PRESERVE. If value is a invalid value, dies with
  38  * a fatal error if fatal is true, otherwise returns REBASE_INVALID.
  39  */
  40 static enum rebase_type parse_config_rebase(const char *key, const char *value,
  41                 int fatal)
  42 {
  43         int v = git_parse_maybe_bool(value);
  44
  45         if (!v)
  46                 return REBASE_FALSE;
  47         else if (v > 0)
  48                 return REBASE_TRUE;
  49         else if (!strcmp(value, "preserve"))
  50                 return REBASE_PRESERVE;
  51         else if (!strcmp(value, "interactive"))
  52                 return REBASE_INTERACTIVE;
  53
  54         if (fatal)
  55                 die(_("Invalid value for %s: %s"), key, value);
  56         else
  57                 error(_("Invalid value for %s: %s"), key, value);
  58
  59         return REBASE_INVALID;
  60 }
  61
  62 /**
  63  * Callback for --rebase, which parses arg with parse_config_rebase().
  64  */
  65 static int parse_opt_rebase(const struct option *opt, const char *arg, int unset)
  66 {
  67         enum rebase_type *value = opt->value;
  68
  69         if (arg)
  70                 *value = parse_config_rebase("--rebase", arg, 0);
  71         else
  72                 *value = unset ? REBASE_FALSE : REBASE_TRUE;
  73         return *value == REBASE_INVALID ? -1 : 0;
  74 }
  75
  76 static const char * const pull_usage[] = {
  77         N_("git pull [<options>] [<repository> [<refspec>...]]"),
  78         NULL
  79 };
  80
  81 /* Shared options */
  82 static int opt_verbosity;
  83 static char *opt_progress;
  84 static int recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
  85
  86 /* Options passed to git-merge or git-rebase */
  87 static enum rebase_type opt_rebase = -1;
  88 static char *opt_diffstat;
  89 static char *opt_log;
  90 static char *opt_signoff;
  91 static char *opt_squash;
  92 static char *opt_commit;
  93 static char *opt_edit;
  94 static char *opt_ff;
  95 static char *opt_verify_signatures;
  96 static int opt_autostash = -1;
  97 static int config_autostash;
  98 static struct argv_array opt_strategies = ARGV_ARRAY_INIT;
  99 static struct argv_array opt_strategy_opts = ARGV_ARRAY_INIT;
 100 static char *opt_gpg_sign;
 101 static int opt_allow_unrelated_histories;
 102
 103 /* Options passed to git-fetch */
 104 static char *opt_all;
 105 static char *opt_append;
 106 static char *opt_upload_pack;
 107 static int opt_force;
 108 static char *opt_tags;
 109 static char *opt_prune;
 110 static char *max_children;
 111 static int opt_dry_run;
 112 static char *opt_keep;
 113 static char *opt_depth;
 114 static char *opt_unshallow;
 115 static char *opt_update_shallow;
 116 static char *opt_refmap;
 117 static char *opt_ipv4;
 118 static char *opt_ipv6;
 119
 120 static struct option pull_options[] = {
 121         /* Shared options */
 122         OPT__VERBOSITY(&opt_verbosity),
 123         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 124                 N_("force progress reporting"),
 125                 PARSE_OPT_NOARG),
 126         { OPTION_CALLBACK, 0, "recurse-submodules",
 127                    &recurse_submodules, N_("on-demand"),
 128                    N_("control for recursive fetching of submodules"),
 129                    PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules },
 130
 131         /* Options passed to git-merge or git-rebase */
 132         OPT_GROUP(N_("Options related to merging")),
 133         { OPTION_CALLBACK, 'r', "rebase", &opt_rebase,
 134           "false|true|preserve|interactive",
 135           N_("incorporate changes by rebasing rather than merging"),
 136           PARSE_OPT_OPTARG, parse_opt_rebase },
 137         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 138                 N_("do not show a diffstat at the end of the merge"),
 139                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 140         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 141                 N_("show a diffstat at the end of the merge"),
 142                 PARSE_OPT_NOARG),
 143         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 144                 N_("(synonym to --stat)"),
 145                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 146         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 147                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 148                 PARSE_OPT_OPTARG),
 149         OPT_PASSTHRU(0, "signoff", &opt_signoff, NULL,
 150                 N_("add Signed-off-by:"),
 151                 PARSE_OPT_OPTARG),
 152         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 153                 N_("create a single commit instead of doing a merge"),
 154                 PARSE_OPT_NOARG),
 155         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 156                 N_("perform a commit if the merge succeeds (default)"),
 157                 PARSE_OPT_NOARG),
 158         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 159                 N_("edit message before committing"),
 160                 PARSE_OPT_NOARG),
 161         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 162                 N_("allow fast-forward"),
 163                 PARSE_OPT_NOARG),
 164         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 165                 N_("abort if fast-forward is not possible"),
 166                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 167         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 168                 N_("verify that the named commit has a valid GPG signature"),
 169                 PARSE_OPT_NOARG),
 170         OPT_BOOL(0, "autostash", &opt_autostash,
 171                 N_("automatically stash/stash pop before and after rebase")),
 172         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 173                 N_("merge strategy to use"),
 174                 0),
 175         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 176                 N_("option=value"),
 177                 N_("option for selected merge strategy"),
 178                 0),
 179         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 180                 N_("GPG sign commit"),
 181                 PARSE_OPT_OPTARG),
 182         OPT_SET_INT(0, "allow-unrelated-histories",
 183                     &opt_allow_unrelated_histories,
 184                     N_("allow merging unrelated histories"), 1),
 185
 186         /* Options passed to git-fetch */
 187         OPT_GROUP(N_("Options related to fetching")),
 188         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 189                 N_("fetch from all remotes"),
 190                 PARSE_OPT_NOARG),
 191         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 192                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 193                 PARSE_OPT_NOARG),
 194         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 195                 N_("path to upload pack on remote end"),
 196                 0),
 197         OPT__FORCE(&opt_force, N_("force overwrite of local branch"), 0),
 198         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 199                 N_("fetch all tags and associated objects"),
 200                 PARSE_OPT_NOARG),
 201         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 202                 N_("prune remote-tracking branches no longer on remote"),
 203                 PARSE_OPT_NOARG),
 204         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 205                 N_("number of submodules pulled in parallel"),
 206                 PARSE_OPT_OPTARG),
 207         OPT_BOOL(0, "dry-run", &opt_dry_run,
 208                 N_("dry run")),
 209         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 210                 N_("keep downloaded pack"),
 211                 PARSE_OPT_NOARG),
 212         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 213                 N_("deepen history of shallow clone"),
 214                 0),
 215         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 216                 N_("convert to a complete repository"),
 217                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 218         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 219                 N_("accept refs that update .git/shallow"),
 220                 PARSE_OPT_NOARG),
 221         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 222                 N_("specify fetch refmap"),
 223                 PARSE_OPT_NONEG),
 224         OPT_PASSTHRU('4',  "ipv4", &opt_ipv4, NULL,
 225                 N_("use IPv4 addresses only"),
 226                 PARSE_OPT_NOARG),
 227         OPT_PASSTHRU('6',  "ipv6", &opt_ipv6, NULL,
 228                 N_("use IPv6 addresses only"),
 229                 PARSE_OPT_NOARG),
 230
 231         OPT_END()
 232 };
 233
 234 /**
 235  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 236  */
 237 static void argv_push_verbosity(struct argv_array *arr)
 238 {
 239         int verbosity;
 240
 241         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 242                 argv_array_push(arr, "-v");
 243
 244         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 245                 argv_array_push(arr, "-q");
 246 }
 247
 248 /**
 249  * Pushes "-f" switches into arr to match the opt_force level.
 250  */
 251 static void argv_push_force(struct argv_array *arr)
 252 {
 253         int force = opt_force;
 254         while (force-- > 0)
 255                 argv_array_push(arr, "-f");
 256 }
 257
 258 /**
 259  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 260  */
 261 static void set_reflog_message(int argc, const char **argv)
 262 {
 263         int i;
 264         struct strbuf msg = STRBUF_INIT;
 265
 266         for (i = 0; i < argc; i++) {
 267                 if (i)
 268                         strbuf_addch(&msg, ' ');
 269                 strbuf_addstr(&msg, argv[i]);
 270         }
 271
 272         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 273
 274         strbuf_release(&msg);
 275 }
 276
 277 /**
 278  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 279  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 280  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 281  * error.
 282  */
 283 static const char *config_get_ff(void)
 284 {
 285         const char *value;
 286
 287         if (git_config_get_value("pull.ff", &value))
 288                 return NULL;
 289
 290         switch (git_parse_maybe_bool(value)) {
 291         case 0:
 292                 return "--no-ff";
 293         case 1:
 294                 return "--ff";
 295         }
 296
 297         if (!strcmp(value, "only"))
 298                 return "--ff-only";
 299
 300         die(_("Invalid value for pull.ff: %s"), value);
 301 }
 302
 303 /**
 304  * Returns the default configured value for --rebase. It first looks for the
 305  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 306  * branch, and if HEAD is detached or the configuration key does not exist,
 307  * looks for the value of "pull.rebase". If both configuration keys do not
 308  * exist, returns REBASE_FALSE.
 309  */
 310 static enum rebase_type config_get_rebase(void)
 311 {
 312         struct branch *curr_branch = branch_get("HEAD");
 313         const char *value;
 314
 315         if (curr_branch) {
 316                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 317
 318                 if (!git_config_get_value(key, &value)) {
 319                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 320                         free(key);
 321                         return ret;
 322                 }
 323
 324                 free(key);
 325         }
 326
 327         if (!git_config_get_value("pull.rebase", &value))
 328                 return parse_config_rebase("pull.rebase", value, 1);
 329
 330         return REBASE_FALSE;
 331 }
 332
 333 /**
 334  * Read config variables.
 335  */
 336 static int git_pull_config(const char *var, const char *value, void *cb)
 337 {
 338         if (!strcmp(var, "rebase.autostash")) {
 339                 config_autostash = git_config_bool(var, value);
 340                 return 0;
 341         } else if (!strcmp(var, "submodule.recurse")) {
 342                 recurse_submodules = git_config_bool(var, value) ?
 343                         RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
 344                 return 0;
 345         }
 346         return git_default_config(var, value, cb);
 347 }
 348
 349 /**
 350  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 351  * into merge_heads.
 352  */
 353 static void get_merge_heads(struct oid_array *merge_heads)
 354 {
 355         const char *filename = git_path_fetch_head();
 356         FILE *fp;
 357         struct strbuf sb = STRBUF_INIT;
 358         struct object_id oid;
 359
 360         fp = xfopen(filename, "r");
 361         while (strbuf_getline_lf(&sb, fp) != EOF) {
 362                 if (get_oid_hex(sb.buf, &oid))
 363                         continue;  /* invalid line: does not start with SHA1 */
 364                 if (starts_with(sb.buf + GIT_SHA1_HEXSZ, "\tnot-for-merge\t"))
 365                         continue;  /* ref is not-for-merge */
 366                 oid_array_append(merge_heads, &oid);
 367         }
 368         fclose(fp);
 369         strbuf_release(&sb);
 370 }
 371
 372 /**
 373  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 374  * retrieve the name of the remote if the repository only has one remote.
 375  */
 376 static int get_only_remote(struct remote *remote, void *cb_data)
 377 {
 378         const char **remote_name = cb_data;
 379
 380         if (*remote_name)
 381                 return -1;
 382
 383         *remote_name = remote->name;
 384         return 0;
 385 }
 386
 387 /**
 388  * Dies with the appropriate reason for why there are no merge candidates:
 389  *
 390  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 391  *    up not fetching anything. This is usually because the user provided a
 392  *    wildcard refspec which had no matches on the remote end.
 393  *
 394  * 2. We fetched from a non-default remote, but didn't specify a branch to
 395  *    merge. We can't use the configured one because it applies to the default
 396  *    remote, thus the user must specify the branches to merge.
 397  *
 398  * 3. We fetched from the branch's or repo's default remote, but:
 399  *
 400  *    a. We are not on a branch, so there will never be a configured branch to
 401  *       merge with.
 402  *
 403  *    b. We are on a branch, but there is no configured branch to merge with.
 404  *
 405  * 4. We fetched from the branch's or repo's default remote, but the configured
 406  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 407  *    part of the configured fetch refspec.)
 408  */
 409 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 410 {
 411         struct branch *curr_branch = branch_get("HEAD");
 412         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 413
 414         if (*refspecs) {
 415                 if (opt_rebase)
 416                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 417                 else
 418                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 419                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 420                                         "matches on the remote end."));
 421         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 422                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 423                         "a branch. Because this is not the default configured remote\n"
 424                         "for your current branch, you must specify a branch on the command line."),
 425                         repo);
 426         } else if (!curr_branch) {
 427                 fprintf_ln(stderr, _("You are not currently on a branch."));
 428                 if (opt_rebase)
 429                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 430                 else
 431                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 432                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 433                 fprintf(stderr, "\n");
 434                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 435                 fprintf(stderr, "\n");
 436         } else if (!curr_branch->merge_nr) {
 437                 const char *remote_name = NULL;
 438
 439                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 440                         remote_name = _("<remote>");
 441
 442                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 443                 if (opt_rebase)
 444                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 445                 else
 446                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 447                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 448                 fprintf(stderr, "\n");
 449                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 450                 fprintf(stderr, "\n");
 451                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));
 452                 fprintf(stderr, "\n");
 453                 fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",
 454                                 remote_name, _("<branch>"), curr_branch->name);
 455         } else
 456                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 457                         "from the remote, but no such ref was fetched."),
 458                         *curr_branch->merge_name);
 459         exit(1);
 460 }
 461
 462 /**
 463  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 464  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 465  * is not provided in argv, it is set to NULL.
 466  */
 467 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 468                 const char ***refspecs)
 469 {
 470         if (argc > 0) {
 471                 *repo = *argv++;
 472                 argc--;
 473         } else
 474                 *repo = NULL;
 475         *refspecs = argv;
 476 }
 477
 478 /**
 479  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 480  * repository and refspecs to fetch, or NULL if they are not provided.
 481  */
 482 static int run_fetch(const char *repo, const char **refspecs)
 483 {
 484         struct argv_array args = ARGV_ARRAY_INIT;
 485         int ret;
 486
 487         argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
 488
 489         /* Shared options */
 490         argv_push_verbosity(&args);
 491         if (opt_progress)
 492                 argv_array_push(&args, opt_progress);
 493
 494         /* Options passed to git-fetch */
 495         if (opt_all)
 496                 argv_array_push(&args, opt_all);
 497         if (opt_append)
 498                 argv_array_push(&args, opt_append);
 499         if (opt_upload_pack)
 500                 argv_array_push(&args, opt_upload_pack);
 501         argv_push_force(&args);
 502         if (opt_tags)
 503                 argv_array_push(&args, opt_tags);
 504         if (opt_prune)
 505                 argv_array_push(&args, opt_prune);
 506         if (recurse_submodules != RECURSE_SUBMODULES_DEFAULT)
 507                 switch (recurse_submodules) {
 508                 case RECURSE_SUBMODULES_ON:
 509                         argv_array_push(&args, "--recurse-submodules=on");
 510                         break;
 511                 case RECURSE_SUBMODULES_OFF:
 512                         argv_array_push(&args, "--recurse-submodules=no");
 513                         break;
 514                 case RECURSE_SUBMODULES_ON_DEMAND:
 515                         argv_array_push(&args, "--recurse-submodules=on-demand");
 516                         break;
 517                 default:
 518                         BUG("submodule recursion option not understood");
 519                 }
 520         if (max_children)
 521                 argv_array_push(&args, max_children);
 522         if (opt_dry_run)
 523                 argv_array_push(&args, "--dry-run");
 524         if (opt_keep)
 525                 argv_array_push(&args, opt_keep);
 526         if (opt_depth)
 527                 argv_array_push(&args, opt_depth);
 528         if (opt_unshallow)
 529                 argv_array_push(&args, opt_unshallow);
 530         if (opt_update_shallow)
 531                 argv_array_push(&args, opt_update_shallow);
 532         if (opt_refmap)
 533                 argv_array_push(&args, opt_refmap);
 534         if (opt_ipv4)
 535                 argv_array_push(&args, opt_ipv4);
 536         if (opt_ipv6)
 537                 argv_array_push(&args, opt_ipv6);
 538
 539         if (repo) {
 540                 argv_array_push(&args, repo);
 541                 argv_array_pushv(&args, refspecs);
 542         } else if (*refspecs)
 543                 die("BUG: refspecs without repo?");
 544         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 545         argv_array_clear(&args);
 546         return ret;
 547 }
 548
 549 /**
 550  * "Pulls into void" by branching off merge_head.
 551  */
 552 static int pull_into_void(const struct object_id *merge_head,
 553                 const struct object_id *curr_head)
 554 {
 555         /*
 556          * Two-way merge: we treat the index as based on an empty tree,
 557          * and try to fast-forward to HEAD. This ensures we will not lose
 558          * index/worktree changes that the user already made on the unborn
 559          * branch.
 560          */
 561         if (checkout_fast_forward(the_hash_algo->empty_tree, merge_head, 0))
 562                 return 1;
 563
 564         if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 565                 return 1;
 566
 567         return 0;
 568 }
 569
 570 static int rebase_submodules(void)
 571 {
 572         struct child_process cp = CHILD_PROCESS_INIT;
 573
 574         cp.git_cmd = 1;
 575         cp.no_stdin = 1;
 576         argv_array_pushl(&cp.args, "submodule", "update",
 577                                    "--recursive", "--rebase", NULL);
 578         argv_push_verbosity(&cp.args);
 579
 580         return run_command(&cp);
 581 }
 582
 583 static int update_submodules(void)
 584 {
 585         struct child_process cp = CHILD_PROCESS_INIT;
 586
 587         cp.git_cmd = 1;
 588         cp.no_stdin = 1;
 589         argv_array_pushl(&cp.args, "submodule", "update",
 590                                    "--recursive", "--checkout", NULL);
 591         argv_push_verbosity(&cp.args);
 592
 593         return run_command(&cp);
 594 }
 595
 596 /**
 597  * Runs git-merge, returning its exit status.
 598  */
 599 static int run_merge(void)
 600 {
 601         int ret;
 602         struct argv_array args = ARGV_ARRAY_INIT;
 603
 604         argv_array_pushl(&args, "merge", NULL);
 605
 606         /* Shared options */
 607         argv_push_verbosity(&args);
 608         if (opt_progress)
 609                 argv_array_push(&args, opt_progress);
 610
 611         /* Options passed to git-merge */
 612         if (opt_diffstat)
 613                 argv_array_push(&args, opt_diffstat);
 614         if (opt_log)
 615                 argv_array_push(&args, opt_log);
 616         if (opt_signoff)
 617                 argv_array_push(&args, opt_signoff);
 618         if (opt_squash)
 619                 argv_array_push(&args, opt_squash);
 620         if (opt_commit)
 621                 argv_array_push(&args, opt_commit);
 622         if (opt_edit)
 623                 argv_array_push(&args, opt_edit);
 624         if (opt_ff)
 625                 argv_array_push(&args, opt_ff);
 626         if (opt_verify_signatures)
 627                 argv_array_push(&args, opt_verify_signatures);
 628         argv_array_pushv(&args, opt_strategies.argv);
 629         argv_array_pushv(&args, opt_strategy_opts.argv);
 630         if (opt_gpg_sign)
 631                 argv_array_push(&args, opt_gpg_sign);
 632         if (opt_allow_unrelated_histories > 0)
 633                 argv_array_push(&args, "--allow-unrelated-histories");
 634
 635         argv_array_push(&args, "FETCH_HEAD");
 636         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 637         argv_array_clear(&args);
 638         return ret;
 639 }
 640
 641 /**
 642  * Returns remote's upstream branch for the current branch. If remote is NULL,
 643  * the current branch's configured default remote is used. Returns NULL if
 644  * `remote` does not name a valid remote, HEAD does not point to a branch,
 645  * remote is not the branch's configured remote or the branch does not have any
 646  * configured upstream branch.
 647  */
 648 static const char *get_upstream_branch(const char *remote)
 649 {
 650         struct remote *rm;
 651         struct branch *curr_branch;
 652         const char *curr_branch_remote;
 653
 654         rm = remote_get(remote);
 655         if (!rm)
 656                 return NULL;
 657
 658         curr_branch = branch_get("HEAD");
 659         if (!curr_branch)
 660                 return NULL;
 661
 662         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 663         assert(curr_branch_remote);
 664
 665         if (strcmp(curr_branch_remote, rm->name))
 666                 return NULL;
 667
 668         return branch_get_upstream(curr_branch, NULL);
 669 }
 670
 671 /**
 672  * Derives the remote tracking branch from the remote and refspec.
 673  *
 674  * FIXME: The current implementation assumes the default mapping of
 675  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 676  */
 677 static const char *get_tracking_branch(const char *remote, const char *refspec)
 678 {
 679         struct refspec_item spec;
 680         const char *spec_src;
 681         const char *merge_branch;
 682
 683         refspec_item_init_or_die(&spec, refspec, REFSPEC_FETCH);
 684         spec_src = spec.src;
 685         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 686                 spec_src = "HEAD";
 687         else if (skip_prefix(spec_src, "heads/", &spec_src))
 688                 ;
 689         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 690                 ;
 691         else if (starts_with(spec_src, "refs/") ||
 692                 starts_with(spec_src, "tags/") ||
 693                 starts_with(spec_src, "remotes/"))
 694                 spec_src = "";
 695
 696         if (*spec_src) {
 697                 if (!strcmp(remote, "."))
 698                         merge_branch = mkpath("refs/heads/%s", spec_src);
 699                 else
 700                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 701         } else
 702                 merge_branch = NULL;
 703
 704         refspec_item_clear(&spec);
 705         return merge_branch;
 706 }
 707
 708 /**
 709  * Given the repo and refspecs, sets fork_point to the point at which the
 710  * current branch forked from its remote tracking branch. Returns 0 on success,
 711  * -1 on failure.
 712  */
 713 static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,
 714                 const char *refspec)
 715 {
 716         int ret;
 717         struct branch *curr_branch;
 718         const char *remote_branch;
 719         struct child_process cp = CHILD_PROCESS_INIT;
 720         struct strbuf sb = STRBUF_INIT;
 721
 722         curr_branch = branch_get("HEAD");
 723         if (!curr_branch)
 724                 return -1;
 725
 726         if (refspec)
 727                 remote_branch = get_tracking_branch(repo, refspec);
 728         else
 729                 remote_branch = get_upstream_branch(repo);
 730
 731         if (!remote_branch)
 732                 return -1;
 733
 734         argv_array_pushl(&cp.args, "merge-base", "--fork-point",
 735                         remote_branch, curr_branch->name, NULL);
 736         cp.no_stdin = 1;
 737         cp.no_stderr = 1;
 738         cp.git_cmd = 1;
 739
 740         ret = capture_command(&cp, &sb, GIT_SHA1_HEXSZ);
 741         if (ret)
 742                 goto cleanup;
 743
 744         ret = get_oid_hex(sb.buf, fork_point);
 745         if (ret)
 746                 goto cleanup;
 747
 748 cleanup:
 749         strbuf_release(&sb);
 750         return ret ? -1 : 0;
 751 }
 752
 753 /**
 754  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 755  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 756  */
 757 static int get_octopus_merge_base(struct object_id *merge_base,
 758                 const struct object_id *curr_head,
 759                 const struct object_id *merge_head,
 760                 const struct object_id *fork_point)
 761 {
 762         struct commit_list *revs = NULL, *result;
 763
 764         commit_list_insert(lookup_commit_reference(curr_head), &revs);
 765         commit_list_insert(lookup_commit_reference(merge_head), &revs);
 766         if (!is_null_oid(fork_point))
 767                 commit_list_insert(lookup_commit_reference(fork_point), &revs);
 768
 769         result = get_octopus_merge_bases(revs);
 770         free_commit_list(revs);
 771         reduce_heads_replace(&result);
 772
 773         if (!result)
 774                 return 1;
 775
 776         oidcpy(merge_base, &result->item->object.oid);
 777         free_commit_list(result);
 778         return 0;
 779 }
 780
 781 /**
 782  * Given the current HEAD SHA1, the merge head returned from git-fetch and the
 783  * fork point calculated by get_rebase_fork_point(), runs git-rebase with the
 784  * appropriate arguments and returns its exit status.
 785  */
 786 static int run_rebase(const struct object_id *curr_head,
 787                 const struct object_id *merge_head,
 788                 const struct object_id *fork_point)
 789 {
 790         int ret;
 791         struct object_id oct_merge_base;
 792         struct argv_array args = ARGV_ARRAY_INIT;
 793
 794         if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))
 795                 if (!is_null_oid(fork_point) && !oidcmp(&oct_merge_base, fork_point))
 796                         fork_point = NULL;
 797
 798         argv_array_push(&args, "rebase");
 799
 800         /* Shared options */
 801         argv_push_verbosity(&args);
 802
 803         /* Options passed to git-rebase */
 804         if (opt_rebase == REBASE_PRESERVE)
 805                 argv_array_push(&args, "--preserve-merges");
 806         else if (opt_rebase == REBASE_INTERACTIVE)
 807                 argv_array_push(&args, "--interactive");
 808         if (opt_diffstat)
 809                 argv_array_push(&args, opt_diffstat);
 810         argv_array_pushv(&args, opt_strategies.argv);
 811         argv_array_pushv(&args, opt_strategy_opts.argv);
 812         if (opt_gpg_sign)
 813                 argv_array_push(&args, opt_gpg_sign);
 814         if (opt_autostash == 0)
 815                 argv_array_push(&args, "--no-autostash");
 816         else if (opt_autostash == 1)
 817                 argv_array_push(&args, "--autostash");
 818         if (opt_verify_signatures &&
 819             !strcmp(opt_verify_signatures, "--verify-signatures"))
 820                 warning(_("ignoring --verify-signatures for rebase"));
 821
 822         argv_array_push(&args, "--onto");
 823         argv_array_push(&args, oid_to_hex(merge_head));
 824
 825         if (fork_point && !is_null_oid(fork_point))
 826                 argv_array_push(&args, oid_to_hex(fork_point));
 827         else
 828                 argv_array_push(&args, oid_to_hex(merge_head));
 829
 830         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 831         argv_array_clear(&args);
 832         return ret;
 833 }
 834
 835 int cmd_pull(int argc, const char **argv, const char *prefix)
 836 {
 837         const char *repo, **refspecs;
 838         struct oid_array merge_heads = OID_ARRAY_INIT;
 839         struct object_id orig_head, curr_head;
 840         struct object_id rebase_fork_point;
 841         int autostash;
 842
 843         if (!getenv("GIT_REFLOG_ACTION"))
 844                 set_reflog_message(argc, argv);
 845
 846         git_config(git_pull_config, NULL);
 847
 848         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 849
 850         parse_repo_refspecs(argc, argv, &repo, &refspecs);
 851
 852         if (!opt_ff)
 853                 opt_ff = xstrdup_or_null(config_get_ff());
 854
 855         if (opt_rebase < 0)
 856                 opt_rebase = config_get_rebase();
 857
 858         if (read_cache_unmerged())
 859                 die_resolve_conflict("pull");
 860
 861         if (file_exists(git_path_merge_head()))
 862                 die_conclude_merge();
 863
 864         if (get_oid("HEAD", &orig_head))
 865                 oidclr(&orig_head);
 866
 867         if (!opt_rebase && opt_autostash != -1)
 868                 die(_("--[no-]autostash option is only valid with --rebase."));
 869
 870         autostash = config_autostash;
 871         if (opt_rebase) {
 872                 if (opt_autostash != -1)
 873                         autostash = opt_autostash;
 874
 875                 if (is_null_oid(&orig_head) && !is_cache_unborn())
 876                         die(_("Updating an unborn branch with changes added to the index."));
 877
 878                 if (!autostash)
 879                         require_clean_work_tree(N_("pull with rebase"),
 880                                 _("please commit or stash them."), 1, 0);
 881
 882                 if (get_rebase_fork_point(&rebase_fork_point, repo, *refspecs))
 883                         oidclr(&rebase_fork_point);
 884         }
 885
 886         if (run_fetch(repo, refspecs))
 887                 return 1;
 888
 889         if (opt_dry_run)
 890                 return 0;
 891
 892         if (get_oid("HEAD", &curr_head))
 893                 oidclr(&curr_head);
 894
 895         if (!is_null_oid(&orig_head) && !is_null_oid(&curr_head) &&
 896                         oidcmp(&orig_head, &curr_head)) {
 897                 /*
 898                  * The fetch involved updating the current branch.
 899                  *
 900                  * The working tree and the index file are still based on
 901                  * orig_head commit, but we are merging into curr_head.
 902                  * Update the working tree to match curr_head.
 903                  */
 904
 905                 warning(_("fetch updated the current branch head.\n"
 906                         "fast-forwarding your working tree from\n"
 907                         "commit %s."), oid_to_hex(&orig_head));
 908
 909                 if (checkout_fast_forward(&orig_head, &curr_head, 0))
 910                         die(_("Cannot fast-forward your working tree.\n"
 911                                 "After making sure that you saved anything precious from\n"
 912                                 "$ git diff %s\n"
 913                                 "output, run\n"
 914                                 "$ git reset --hard\n"
 915                                 "to recover."), oid_to_hex(&orig_head));
 916         }
 917
 918         get_merge_heads(&merge_heads);
 919
 920         if (!merge_heads.nr)
 921                 die_no_merge_candidates(repo, refspecs);
 922
 923         if (is_null_oid(&orig_head)) {
 924                 if (merge_heads.nr > 1)
 925                         die(_("Cannot merge multiple branches into empty head."));
 926                 return pull_into_void(merge_heads.oid, &curr_head);
 927         }
 928         if (opt_rebase && merge_heads.nr > 1)
 929                 die(_("Cannot rebase onto multiple branches."));
 930
 931         if (opt_rebase) {
 932                 int ret = 0;
 933                 if ((recurse_submodules == RECURSE_SUBMODULES_ON ||
 934                      recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) &&
 935                     submodule_touches_in_range(&rebase_fork_point, &curr_head))
 936                         die(_("cannot rebase with locally recorded submodule modifications"));
 937                 if (!autostash) {
 938                         struct commit_list *list = NULL;
 939                         struct commit *merge_head, *head;
 940
 941                         head = lookup_commit_reference(&orig_head);
 942                         commit_list_insert(head, &list);
 943                         merge_head = lookup_commit_reference(&merge_heads.oid[0]);
 944                         if (is_descendant_of(merge_head, list)) {
 945                                 /* we can fast-forward this without invoking rebase */
 946                                 opt_ff = "--ff-only";
 947                                 ret = run_merge();
 948                         }
 949                 }
 950                 ret = run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
 951
 952                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
 953                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
 954                         ret = rebase_submodules();
 955
 956                 return ret;
 957         } else {
 958                 int ret = run_merge();
 959                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
 960                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
 961                         ret = update_submodules();
 962                 return ret;
 963         }
 964 }