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 "revision.h"
  19 #include "submodule.h"
  20 #include "submodule-config.h"
  21 #include "tempfile.h"
  22 #include "lockfile.h"
  23 #include "wt-status.h"
  24
  25 enum rebase_type {
  26         REBASE_INVALID = -1,
  27         REBASE_FALSE = 0,
  28         REBASE_TRUE,
  29         REBASE_PRESERVE,
  30         REBASE_MERGES,
  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  * "merges", returns REBASE_MERGES. If value is "preserve", returns
  38  * REBASE_PRESERVE. If value is a invalid value, dies with a fatal error if
  39  * 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         int v = git_parse_maybe_bool(value);
  45
  46         if (!v)
  47                 return REBASE_FALSE;
  48         else if (v > 0)
  49                 return REBASE_TRUE;
  50         else if (!strcmp(value, "preserve"))
  51                 return REBASE_PRESERVE;
  52         else if (!strcmp(value, "merges"))
  53                 return REBASE_MERGES;
  54         else if (!strcmp(value, "interactive"))
  55                 return REBASE_INTERACTIVE;
  56
  57         if (fatal)
  58                 die(_("Invalid value for %s: %s"), key, value);
  59         else
  60                 error(_("Invalid value for %s: %s"), key, value);
  61
  62         return REBASE_INVALID;
  63 }
  64
  65 /**
  66  * Callback for --rebase, which parses arg with parse_config_rebase().
  67  */
  68 static int parse_opt_rebase(const struct option *opt, const char *arg, int unset)
  69 {
  70         enum rebase_type *value = opt->value;
  71
  72         if (arg)
  73                 *value = parse_config_rebase("--rebase", arg, 0);
  74         else
  75                 *value = unset ? REBASE_FALSE : REBASE_TRUE;
  76         return *value == REBASE_INVALID ? -1 : 0;
  77 }
  78
  79 static const char * const pull_usage[] = {
  80         N_("git pull [<options>] [<repository> [<refspec>...]]"),
  81         NULL
  82 };
  83
  84 /* Shared options */
  85 static int opt_verbosity;
  86 static char *opt_progress;
  87 static int recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
  88
  89 /* Options passed to git-merge or git-rebase */
  90 static enum rebase_type opt_rebase = -1;
  91 static char *opt_diffstat;
  92 static char *opt_log;
  93 static char *opt_signoff;
  94 static char *opt_squash;
  95 static char *opt_commit;
  96 static char *opt_edit;
  97 static char *opt_ff;
  98 static char *opt_verify_signatures;
  99 static int opt_autostash = -1;
 100 static int config_autostash;
 101 static struct argv_array opt_strategies = ARGV_ARRAY_INIT;
 102 static struct argv_array opt_strategy_opts = ARGV_ARRAY_INIT;
 103 static char *opt_gpg_sign;
 104 static int opt_allow_unrelated_histories;
 105
 106 /* Options passed to git-fetch */
 107 static char *opt_all;
 108 static char *opt_append;
 109 static char *opt_upload_pack;
 110 static int opt_force;
 111 static char *opt_tags;
 112 static char *opt_prune;
 113 static char *max_children;
 114 static int opt_dry_run;
 115 static char *opt_keep;
 116 static char *opt_depth;
 117 static char *opt_unshallow;
 118 static char *opt_update_shallow;
 119 static char *opt_refmap;
 120 static char *opt_ipv4;
 121 static char *opt_ipv6;
 122
 123 static struct option pull_options[] = {
 124         /* Shared options */
 125         OPT__VERBOSITY(&opt_verbosity),
 126         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 127                 N_("force progress reporting"),
 128                 PARSE_OPT_NOARG),
 129         { OPTION_CALLBACK, 0, "recurse-submodules",
 130                    &recurse_submodules, N_("on-demand"),
 131                    N_("control for recursive fetching of submodules"),
 132                    PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules },
 133
 134         /* Options passed to git-merge or git-rebase */
 135         OPT_GROUP(N_("Options related to merging")),
 136         { OPTION_CALLBACK, 'r', "rebase", &opt_rebase,
 137           "false|true|merges|preserve|interactive",
 138           N_("incorporate changes by rebasing rather than merging"),
 139           PARSE_OPT_OPTARG, parse_opt_rebase },
 140         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 141                 N_("do not show a diffstat at the end of the merge"),
 142                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 143         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 144                 N_("show a diffstat at the end of the merge"),
 145                 PARSE_OPT_NOARG),
 146         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 147                 N_("(synonym to --stat)"),
 148                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 149         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 150                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 151                 PARSE_OPT_OPTARG),
 152         OPT_PASSTHRU(0, "signoff", &opt_signoff, NULL,
 153                 N_("add Signed-off-by:"),
 154                 PARSE_OPT_OPTARG),
 155         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 156                 N_("create a single commit instead of doing a merge"),
 157                 PARSE_OPT_NOARG),
 158         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 159                 N_("perform a commit if the merge succeeds (default)"),
 160                 PARSE_OPT_NOARG),
 161         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 162                 N_("edit message before committing"),
 163                 PARSE_OPT_NOARG),
 164         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 165                 N_("allow fast-forward"),
 166                 PARSE_OPT_NOARG),
 167         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 168                 N_("abort if fast-forward is not possible"),
 169                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 170         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 171                 N_("verify that the named commit has a valid GPG signature"),
 172                 PARSE_OPT_NOARG),
 173         OPT_BOOL(0, "autostash", &opt_autostash,
 174                 N_("automatically stash/stash pop before and after rebase")),
 175         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 176                 N_("merge strategy to use"),
 177                 0),
 178         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 179                 N_("option=value"),
 180                 N_("option for selected merge strategy"),
 181                 0),
 182         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 183                 N_("GPG sign commit"),
 184                 PARSE_OPT_OPTARG),
 185         OPT_SET_INT(0, "allow-unrelated-histories",
 186                     &opt_allow_unrelated_histories,
 187                     N_("allow merging unrelated histories"), 1),
 188
 189         /* Options passed to git-fetch */
 190         OPT_GROUP(N_("Options related to fetching")),
 191         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 192                 N_("fetch from all remotes"),
 193                 PARSE_OPT_NOARG),
 194         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 195                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 196                 PARSE_OPT_NOARG),
 197         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 198                 N_("path to upload pack on remote end"),
 199                 0),
 200         OPT__FORCE(&opt_force, N_("force overwrite of local branch"), 0),
 201         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 202                 N_("fetch all tags and associated objects"),
 203                 PARSE_OPT_NOARG),
 204         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 205                 N_("prune remote-tracking branches no longer on remote"),
 206                 PARSE_OPT_NOARG),
 207         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 208                 N_("number of submodules pulled in parallel"),
 209                 PARSE_OPT_OPTARG),
 210         OPT_BOOL(0, "dry-run", &opt_dry_run,
 211                 N_("dry run")),
 212         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 213                 N_("keep downloaded pack"),
 214                 PARSE_OPT_NOARG),
 215         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 216                 N_("deepen history of shallow clone"),
 217                 0),
 218         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 219                 N_("convert to a complete repository"),
 220                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 221         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 222                 N_("accept refs that update .git/shallow"),
 223                 PARSE_OPT_NOARG),
 224         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 225                 N_("specify fetch refmap"),
 226                 PARSE_OPT_NONEG),
 227         OPT_PASSTHRU('4',  "ipv4", &opt_ipv4, NULL,
 228                 N_("use IPv4 addresses only"),
 229                 PARSE_OPT_NOARG),
 230         OPT_PASSTHRU('6',  "ipv6", &opt_ipv6, NULL,
 231                 N_("use IPv6 addresses only"),
 232                 PARSE_OPT_NOARG),
 233
 234         OPT_END()
 235 };
 236
 237 /**
 238  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 239  */
 240 static void argv_push_verbosity(struct argv_array *arr)
 241 {
 242         int verbosity;
 243
 244         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 245                 argv_array_push(arr, "-v");
 246
 247         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 248                 argv_array_push(arr, "-q");
 249 }
 250
 251 /**
 252  * Pushes "-f" switches into arr to match the opt_force level.
 253  */
 254 static void argv_push_force(struct argv_array *arr)
 255 {
 256         int force = opt_force;
 257         while (force-- > 0)
 258                 argv_array_push(arr, "-f");
 259 }
 260
 261 /**
 262  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 263  */
 264 static void set_reflog_message(int argc, const char **argv)
 265 {
 266         int i;
 267         struct strbuf msg = STRBUF_INIT;
 268
 269         for (i = 0; i < argc; i++) {
 270                 if (i)
 271                         strbuf_addch(&msg, ' ');
 272                 strbuf_addstr(&msg, argv[i]);
 273         }
 274
 275         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 276
 277         strbuf_release(&msg);
 278 }
 279
 280 /**
 281  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 282  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 283  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 284  * error.
 285  */
 286 static const char *config_get_ff(void)
 287 {
 288         const char *value;
 289
 290         if (git_config_get_value("pull.ff", &value))
 291                 return NULL;
 292
 293         switch (git_parse_maybe_bool(value)) {
 294         case 0:
 295                 return "--no-ff";
 296         case 1:
 297                 return "--ff";
 298         }
 299
 300         if (!strcmp(value, "only"))
 301                 return "--ff-only";
 302
 303         die(_("Invalid value for pull.ff: %s"), value);
 304 }
 305
 306 /**
 307  * Returns the default configured value for --rebase. It first looks for the
 308  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 309  * branch, and if HEAD is detached or the configuration key does not exist,
 310  * looks for the value of "pull.rebase". If both configuration keys do not
 311  * exist, returns REBASE_FALSE.
 312  */
 313 static enum rebase_type config_get_rebase(void)
 314 {
 315         struct branch *curr_branch = branch_get("HEAD");
 316         const char *value;
 317
 318         if (curr_branch) {
 319                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 320
 321                 if (!git_config_get_value(key, &value)) {
 322                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 323                         free(key);
 324                         return ret;
 325                 }
 326
 327                 free(key);
 328         }
 329
 330         if (!git_config_get_value("pull.rebase", &value))
 331                 return parse_config_rebase("pull.rebase", value, 1);
 332
 333         return REBASE_FALSE;
 334 }
 335
 336 /**
 337  * Read config variables.
 338  */
 339 static int git_pull_config(const char *var, const char *value, void *cb)
 340 {
 341         if (!strcmp(var, "rebase.autostash")) {
 342                 config_autostash = git_config_bool(var, value);
 343                 return 0;
 344         } else if (!strcmp(var, "submodule.recurse")) {
 345                 recurse_submodules = git_config_bool(var, value) ?
 346                         RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
 347                 return 0;
 348         }
 349         return git_default_config(var, value, cb);
 350 }
 351
 352 /**
 353  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 354  * into merge_heads.
 355  */
 356 static void get_merge_heads(struct oid_array *merge_heads)
 357 {
 358         const char *filename = git_path_fetch_head();
 359         FILE *fp;
 360         struct strbuf sb = STRBUF_INIT;
 361         struct object_id oid;
 362
 363         fp = xfopen(filename, "r");
 364         while (strbuf_getline_lf(&sb, fp) != EOF) {
 365                 if (get_oid_hex(sb.buf, &oid))
 366                         continue;  /* invalid line: does not start with SHA1 */
 367                 if (starts_with(sb.buf + GIT_SHA1_HEXSZ, "\tnot-for-merge\t"))
 368                         continue;  /* ref is not-for-merge */
 369                 oid_array_append(merge_heads, &oid);
 370         }
 371         fclose(fp);
 372         strbuf_release(&sb);
 373 }
 374
 375 /**
 376  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 377  * retrieve the name of the remote if the repository only has one remote.
 378  */
 379 static int get_only_remote(struct remote *remote, void *cb_data)
 380 {
 381         const char **remote_name = cb_data;
 382
 383         if (*remote_name)
 384                 return -1;
 385
 386         *remote_name = remote->name;
 387         return 0;
 388 }
 389
 390 /**
 391  * Dies with the appropriate reason for why there are no merge candidates:
 392  *
 393  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 394  *    up not fetching anything. This is usually because the user provided a
 395  *    wildcard refspec which had no matches on the remote end.
 396  *
 397  * 2. We fetched from a non-default remote, but didn't specify a branch to
 398  *    merge. We can't use the configured one because it applies to the default
 399  *    remote, thus the user must specify the branches to merge.
 400  *
 401  * 3. We fetched from the branch's or repo's default remote, but:
 402  *
 403  *    a. We are not on a branch, so there will never be a configured branch to
 404  *       merge with.
 405  *
 406  *    b. We are on a branch, but there is no configured branch to merge with.
 407  *
 408  * 4. We fetched from the branch's or repo's default remote, but the configured
 409  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 410  *    part of the configured fetch refspec.)
 411  */
 412 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 413 {
 414         struct branch *curr_branch = branch_get("HEAD");
 415         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 416
 417         if (*refspecs) {
 418                 if (opt_rebase)
 419                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 420                 else
 421                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 422                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 423                                         "matches on the remote end."));
 424         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 425                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 426                         "a branch. Because this is not the default configured remote\n"
 427                         "for your current branch, you must specify a branch on the command line."),
 428                         repo);
 429         } else if (!curr_branch) {
 430                 fprintf_ln(stderr, _("You are not currently on a branch."));
 431                 if (opt_rebase)
 432                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 433                 else
 434                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 435                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 436                 fprintf(stderr, "\n");
 437                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 438                 fprintf(stderr, "\n");
 439         } else if (!curr_branch->merge_nr) {
 440                 const char *remote_name = NULL;
 441
 442                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 443                         remote_name = _("<remote>");
 444
 445                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 446                 if (opt_rebase)
 447                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 448                 else
 449                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 450                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 451                 fprintf(stderr, "\n");
 452                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 453                 fprintf(stderr, "\n");
 454                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));
 455                 fprintf(stderr, "\n");
 456                 fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",
 457                                 remote_name, _("<branch>"), curr_branch->name);
 458         } else
 459                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 460                         "from the remote, but no such ref was fetched."),
 461                         *curr_branch->merge_name);
 462         exit(1);
 463 }
 464
 465 /**
 466  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 467  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 468  * is not provided in argv, it is set to NULL.
 469  */
 470 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 471                 const char ***refspecs)
 472 {
 473         if (argc > 0) {
 474                 *repo = *argv++;
 475                 argc--;
 476         } else
 477                 *repo = NULL;
 478         *refspecs = argv;
 479 }
 480
 481 /**
 482  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 483  * repository and refspecs to fetch, or NULL if they are not provided.
 484  */
 485 static int run_fetch(const char *repo, const char **refspecs)
 486 {
 487         struct argv_array args = ARGV_ARRAY_INIT;
 488         int ret;
 489
 490         argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
 491
 492         /* Shared options */
 493         argv_push_verbosity(&args);
 494         if (opt_progress)
 495                 argv_array_push(&args, opt_progress);
 496
 497         /* Options passed to git-fetch */
 498         if (opt_all)
 499                 argv_array_push(&args, opt_all);
 500         if (opt_append)
 501                 argv_array_push(&args, opt_append);
 502         if (opt_upload_pack)
 503                 argv_array_push(&args, opt_upload_pack);
 504         argv_push_force(&args);
 505         if (opt_tags)
 506                 argv_array_push(&args, opt_tags);
 507         if (opt_prune)
 508                 argv_array_push(&args, opt_prune);
 509         if (recurse_submodules != RECURSE_SUBMODULES_DEFAULT)
 510                 switch (recurse_submodules) {
 511                 case RECURSE_SUBMODULES_ON:
 512                         argv_array_push(&args, "--recurse-submodules=on");
 513                         break;
 514                 case RECURSE_SUBMODULES_OFF:
 515                         argv_array_push(&args, "--recurse-submodules=no");
 516                         break;
 517                 case RECURSE_SUBMODULES_ON_DEMAND:
 518                         argv_array_push(&args, "--recurse-submodules=on-demand");
 519                         break;
 520                 default:
 521                         BUG("submodule recursion option not understood");
 522                 }
 523         if (max_children)
 524                 argv_array_push(&args, max_children);
 525         if (opt_dry_run)
 526                 argv_array_push(&args, "--dry-run");
 527         if (opt_keep)
 528                 argv_array_push(&args, opt_keep);
 529         if (opt_depth)
 530                 argv_array_push(&args, opt_depth);
 531         if (opt_unshallow)
 532                 argv_array_push(&args, opt_unshallow);
 533         if (opt_update_shallow)
 534                 argv_array_push(&args, opt_update_shallow);
 535         if (opt_refmap)
 536                 argv_array_push(&args, opt_refmap);
 537         if (opt_ipv4)
 538                 argv_array_push(&args, opt_ipv4);
 539         if (opt_ipv6)
 540                 argv_array_push(&args, opt_ipv6);
 541
 542         if (repo) {
 543                 argv_array_push(&args, repo);
 544                 argv_array_pushv(&args, refspecs);
 545         } else if (*refspecs)
 546                 BUG("refspecs without repo?");
 547         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 548         argv_array_clear(&args);
 549         return ret;
 550 }
 551
 552 /**
 553  * "Pulls into void" by branching off merge_head.
 554  */
 555 static int pull_into_void(const struct object_id *merge_head,
 556                 const struct object_id *curr_head)
 557 {
 558         /*
 559          * Two-way merge: we treat the index as based on an empty tree,
 560          * and try to fast-forward to HEAD. This ensures we will not lose
 561          * index/worktree changes that the user already made on the unborn
 562          * branch.
 563          */
 564         if (checkout_fast_forward(the_hash_algo->empty_tree, merge_head, 0))
 565                 return 1;
 566
 567         if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 568                 return 1;
 569
 570         return 0;
 571 }
 572
 573 static int rebase_submodules(void)
 574 {
 575         struct child_process cp = CHILD_PROCESS_INIT;
 576
 577         cp.git_cmd = 1;
 578         cp.no_stdin = 1;
 579         argv_array_pushl(&cp.args, "submodule", "update",
 580                                    "--recursive", "--rebase", NULL);
 581         argv_push_verbosity(&cp.args);
 582
 583         return run_command(&cp);
 584 }
 585
 586 static int update_submodules(void)
 587 {
 588         struct child_process cp = CHILD_PROCESS_INIT;
 589
 590         cp.git_cmd = 1;
 591         cp.no_stdin = 1;
 592         argv_array_pushl(&cp.args, "submodule", "update",
 593                                    "--recursive", "--checkout", NULL);
 594         argv_push_verbosity(&cp.args);
 595
 596         return run_command(&cp);
 597 }
 598
 599 /**
 600  * Runs git-merge, returning its exit status.
 601  */
 602 static int run_merge(void)
 603 {
 604         int ret;
 605         struct argv_array args = ARGV_ARRAY_INIT;
 606
 607         argv_array_pushl(&args, "merge", NULL);
 608
 609         /* Shared options */
 610         argv_push_verbosity(&args);
 611         if (opt_progress)
 612                 argv_array_push(&args, opt_progress);
 613
 614         /* Options passed to git-merge */
 615         if (opt_diffstat)
 616                 argv_array_push(&args, opt_diffstat);
 617         if (opt_log)
 618                 argv_array_push(&args, opt_log);
 619         if (opt_signoff)
 620                 argv_array_push(&args, opt_signoff);
 621         if (opt_squash)
 622                 argv_array_push(&args, opt_squash);
 623         if (opt_commit)
 624                 argv_array_push(&args, opt_commit);
 625         if (opt_edit)
 626                 argv_array_push(&args, opt_edit);
 627         if (opt_ff)
 628                 argv_array_push(&args, opt_ff);
 629         if (opt_verify_signatures)
 630                 argv_array_push(&args, opt_verify_signatures);
 631         argv_array_pushv(&args, opt_strategies.argv);
 632         argv_array_pushv(&args, opt_strategy_opts.argv);
 633         if (opt_gpg_sign)
 634                 argv_array_push(&args, opt_gpg_sign);
 635         if (opt_allow_unrelated_histories > 0)
 636                 argv_array_push(&args, "--allow-unrelated-histories");
 637
 638         argv_array_push(&args, "FETCH_HEAD");
 639         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 640         argv_array_clear(&args);
 641         return ret;
 642 }
 643
 644 /**
 645  * Returns remote's upstream branch for the current branch. If remote is NULL,
 646  * the current branch's configured default remote is used. Returns NULL if
 647  * `remote` does not name a valid remote, HEAD does not point to a branch,
 648  * remote is not the branch's configured remote or the branch does not have any
 649  * configured upstream branch.
 650  */
 651 static const char *get_upstream_branch(const char *remote)
 652 {
 653         struct remote *rm;
 654         struct branch *curr_branch;
 655         const char *curr_branch_remote;
 656
 657         rm = remote_get(remote);
 658         if (!rm)
 659                 return NULL;
 660
 661         curr_branch = branch_get("HEAD");
 662         if (!curr_branch)
 663                 return NULL;
 664
 665         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 666         assert(curr_branch_remote);
 667
 668         if (strcmp(curr_branch_remote, rm->name))
 669                 return NULL;
 670
 671         return branch_get_upstream(curr_branch, NULL);
 672 }
 673
 674 /**
 675  * Derives the remote tracking branch from the remote and refspec.
 676  *
 677  * FIXME: The current implementation assumes the default mapping of
 678  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 679  */
 680 static const char *get_tracking_branch(const char *remote, const char *refspec)
 681 {
 682         struct refspec *spec;
 683         const char *spec_src;
 684         const char *merge_branch;
 685
 686         spec = parse_fetch_refspec(1, &refspec);
 687         spec_src = spec->src;
 688         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 689                 spec_src = "HEAD";
 690         else if (skip_prefix(spec_src, "heads/", &spec_src))
 691                 ;
 692         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 693                 ;
 694         else if (starts_with(spec_src, "refs/") ||
 695                 starts_with(spec_src, "tags/") ||
 696                 starts_with(spec_src, "remotes/"))
 697                 spec_src = "";
 698
 699         if (*spec_src) {
 700                 if (!strcmp(remote, "."))
 701                         merge_branch = mkpath("refs/heads/%s", spec_src);
 702                 else
 703                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 704         } else
 705                 merge_branch = NULL;
 706
 707         free_refspec(1, spec);
 708         return merge_branch;
 709 }
 710
 711 /**
 712  * Given the repo and refspecs, sets fork_point to the point at which the
 713  * current branch forked from its remote tracking branch. Returns 0 on success,
 714  * -1 on failure.
 715  */
 716 static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,
 717                 const char *refspec)
 718 {
 719         int ret;
 720         struct branch *curr_branch;
 721         const char *remote_branch;
 722         struct child_process cp = CHILD_PROCESS_INIT;
 723         struct strbuf sb = STRBUF_INIT;
 724
 725         curr_branch = branch_get("HEAD");
 726         if (!curr_branch)
 727                 return -1;
 728
 729         if (refspec)
 730                 remote_branch = get_tracking_branch(repo, refspec);
 731         else
 732                 remote_branch = get_upstream_branch(repo);
 733
 734         if (!remote_branch)
 735                 return -1;
 736
 737         argv_array_pushl(&cp.args, "merge-base", "--fork-point",
 738                         remote_branch, curr_branch->name, NULL);
 739         cp.no_stdin = 1;
 740         cp.no_stderr = 1;
 741         cp.git_cmd = 1;
 742
 743         ret = capture_command(&cp, &sb, GIT_SHA1_HEXSZ);
 744         if (ret)
 745                 goto cleanup;
 746
 747         ret = get_oid_hex(sb.buf, fork_point);
 748         if (ret)
 749                 goto cleanup;
 750
 751 cleanup:
 752         strbuf_release(&sb);
 753         return ret ? -1 : 0;
 754 }
 755
 756 /**
 757  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 758  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 759  */
 760 static int get_octopus_merge_base(struct object_id *merge_base,
 761                 const struct object_id *curr_head,
 762                 const struct object_id *merge_head,
 763                 const struct object_id *fork_point)
 764 {
 765         struct commit_list *revs = NULL, *result;
 766
 767         commit_list_insert(lookup_commit_reference(curr_head), &revs);
 768         commit_list_insert(lookup_commit_reference(merge_head), &revs);
 769         if (!is_null_oid(fork_point))
 770                 commit_list_insert(lookup_commit_reference(fork_point), &revs);
 771
 772         result = get_octopus_merge_bases(revs);
 773         free_commit_list(revs);
 774         reduce_heads_replace(&result);
 775
 776         if (!result)
 777                 return 1;
 778
 779         oidcpy(merge_base, &result->item->object.oid);
 780         free_commit_list(result);
 781         return 0;
 782 }
 783
 784 /**
 785  * Given the current HEAD SHA1, the merge head returned from git-fetch and the
 786  * fork point calculated by get_rebase_fork_point(), runs git-rebase with the
 787  * appropriate arguments and returns its exit status.
 788  */
 789 static int run_rebase(const struct object_id *curr_head,
 790                 const struct object_id *merge_head,
 791                 const struct object_id *fork_point)
 792 {
 793         int ret;
 794         struct object_id oct_merge_base;
 795         struct argv_array args = ARGV_ARRAY_INIT;
 796
 797         if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))
 798                 if (!is_null_oid(fork_point) && !oidcmp(&oct_merge_base, fork_point))
 799                         fork_point = NULL;
 800
 801         argv_array_push(&args, "rebase");
 802
 803         /* Shared options */
 804         argv_push_verbosity(&args);
 805
 806         /* Options passed to git-rebase */
 807         if (opt_rebase == REBASE_MERGES)
 808                 argv_array_push(&args, "--rebase-merges");
 809         else if (opt_rebase == REBASE_PRESERVE)
 810                 argv_array_push(&args, "--preserve-merges");
 811         else if (opt_rebase == REBASE_INTERACTIVE)
 812                 argv_array_push(&args, "--interactive");
 813         if (opt_diffstat)
 814                 argv_array_push(&args, opt_diffstat);
 815         argv_array_pushv(&args, opt_strategies.argv);
 816         argv_array_pushv(&args, opt_strategy_opts.argv);
 817         if (opt_gpg_sign)
 818                 argv_array_push(&args, opt_gpg_sign);
 819         if (opt_autostash == 0)
 820                 argv_array_push(&args, "--no-autostash");
 821         else if (opt_autostash == 1)
 822                 argv_array_push(&args, "--autostash");
 823         if (opt_verify_signatures &&
 824             !strcmp(opt_verify_signatures, "--verify-signatures"))
 825                 warning(_("ignoring --verify-signatures for rebase"));
 826
 827         argv_array_push(&args, "--onto");
 828         argv_array_push(&args, oid_to_hex(merge_head));
 829
 830         if (fork_point && !is_null_oid(fork_point))
 831                 argv_array_push(&args, oid_to_hex(fork_point));
 832         else
 833                 argv_array_push(&args, oid_to_hex(merge_head));
 834
 835         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 836         argv_array_clear(&args);
 837         return ret;
 838 }
 839
 840 int cmd_pull(int argc, const char **argv, const char *prefix)
 841 {
 842         const char *repo, **refspecs;
 843         struct oid_array merge_heads = OID_ARRAY_INIT;
 844         struct object_id orig_head, curr_head;
 845         struct object_id rebase_fork_point;
 846         int autostash;
 847
 848         if (!getenv("GIT_REFLOG_ACTION"))
 849                 set_reflog_message(argc, argv);
 850
 851         git_config(git_pull_config, NULL);
 852
 853         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 854
 855         parse_repo_refspecs(argc, argv, &repo, &refspecs);
 856
 857         if (!opt_ff)
 858                 opt_ff = xstrdup_or_null(config_get_ff());
 859
 860         if (opt_rebase < 0)
 861                 opt_rebase = config_get_rebase();
 862
 863         if (read_cache_unmerged())
 864                 die_resolve_conflict("pull");
 865
 866         if (file_exists(git_path_merge_head()))
 867                 die_conclude_merge();
 868
 869         if (get_oid("HEAD", &orig_head))
 870                 oidclr(&orig_head);
 871
 872         if (!opt_rebase && opt_autostash != -1)
 873                 die(_("--[no-]autostash option is only valid with --rebase."));
 874
 875         autostash = config_autostash;
 876         if (opt_rebase) {
 877                 if (opt_autostash != -1)
 878                         autostash = opt_autostash;
 879
 880                 if (is_null_oid(&orig_head) && !is_cache_unborn())
 881                         die(_("Updating an unborn branch with changes added to the index."));
 882
 883                 if (!autostash)
 884                         require_clean_work_tree(N_("pull with rebase"),
 885                                 _("please commit or stash them."), 1, 0);
 886
 887                 if (get_rebase_fork_point(&rebase_fork_point, repo, *refspecs))
 888                         oidclr(&rebase_fork_point);
 889         }
 890
 891         if (run_fetch(repo, refspecs))
 892                 return 1;
 893
 894         if (opt_dry_run)
 895                 return 0;
 896
 897         if (get_oid("HEAD", &curr_head))
 898                 oidclr(&curr_head);
 899
 900         if (!is_null_oid(&orig_head) && !is_null_oid(&curr_head) &&
 901                         oidcmp(&orig_head, &curr_head)) {
 902                 /*
 903                  * The fetch involved updating the current branch.
 904                  *
 905                  * The working tree and the index file are still based on
 906                  * orig_head commit, but we are merging into curr_head.
 907                  * Update the working tree to match curr_head.
 908                  */
 909
 910                 warning(_("fetch updated the current branch head.\n"
 911                         "fast-forwarding your working tree from\n"
 912                         "commit %s."), oid_to_hex(&orig_head));
 913
 914                 if (checkout_fast_forward(&orig_head, &curr_head, 0))
 915                         die(_("Cannot fast-forward your working tree.\n"
 916                                 "After making sure that you saved anything precious from\n"
 917                                 "$ git diff %s\n"
 918                                 "output, run\n"
 919                                 "$ git reset --hard\n"
 920                                 "to recover."), oid_to_hex(&orig_head));
 921         }
 922
 923         get_merge_heads(&merge_heads);
 924
 925         if (!merge_heads.nr)
 926                 die_no_merge_candidates(repo, refspecs);
 927
 928         if (is_null_oid(&orig_head)) {
 929                 if (merge_heads.nr > 1)
 930                         die(_("Cannot merge multiple branches into empty head."));
 931                 return pull_into_void(merge_heads.oid, &curr_head);
 932         }
 933         if (opt_rebase && merge_heads.nr > 1)
 934                 die(_("Cannot rebase onto multiple branches."));
 935
 936         if (opt_rebase) {
 937                 int ret = 0;
 938                 if ((recurse_submodules == RECURSE_SUBMODULES_ON ||
 939                      recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) &&
 940                     submodule_touches_in_range(&rebase_fork_point, &curr_head))
 941                         die(_("cannot rebase with locally recorded submodule modifications"));
 942                 if (!autostash) {
 943                         struct commit_list *list = NULL;
 944                         struct commit *merge_head, *head;
 945
 946                         head = lookup_commit_reference(&orig_head);
 947                         commit_list_insert(head, &list);
 948                         merge_head = lookup_commit_reference(&merge_heads.oid[0]);
 949                         if (is_descendant_of(merge_head, list)) {
 950                                 /* we can fast-forward this without invoking rebase */
 951                                 opt_ff = "--ff-only";
 952                                 ret = run_merge();
 953                         }
 954                 }
 955                 ret = run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
 956
 957                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
 958                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
 959                         ret = rebase_submodules();
 960
 961                 return ret;
 962         } else {
 963                 int ret = run_merge();
 964                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
 965                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
 966                         ret = update_submodules();
 967                 return ret;
 968         }
 969 }