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 "sha1-array.h"
  16 #include "remote.h"
  17 #include "dir.h"
  18 #include "refs.h"
  19 #include "refspec.h"
  20 #include "revision.h"
  21 #include "submodule.h"
  22 #include "submodule-config.h"
  23 #include "tempfile.h"
  24 #include "lockfile.h"
  25 #include "wt-status.h"
  26 #include "commit-reach.h"
  27
  28 enum rebase_type {
  29         REBASE_INVALID = -1,
  30         REBASE_FALSE = 0,
  31         REBASE_TRUE,
  32         REBASE_PRESERVE,
  33         REBASE_MERGES,
  34         REBASE_INTERACTIVE
  35 };
  36
  37 /**
  38  * Parses the value of --rebase. If value is a false value, returns
  39  * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is
  40  * "merges", returns REBASE_MERGES. If value is "preserve", returns
  41  * REBASE_PRESERVE. If value is a invalid value, dies with a fatal error if
  42  * fatal is true, otherwise returns REBASE_INVALID.
  43  */
  44 static enum rebase_type parse_config_rebase(const char *key, const char *value,
  45                 int fatal)
  46 {
  47         int v = git_parse_maybe_bool(value);
  48
  49         if (!v)
  50                 return REBASE_FALSE;
  51         else if (v > 0)
  52                 return REBASE_TRUE;
  53         else if (!strcmp(value, "preserve") || !strcmp(value, "p"))
  54                 return REBASE_PRESERVE;
  55         else if (!strcmp(value, "merges") || !strcmp(value, "m"))
  56                 return REBASE_MERGES;
  57         else if (!strcmp(value, "interactive") || !strcmp(value, "i"))
  58                 return REBASE_INTERACTIVE;
  59
  60         if (fatal)
  61                 die(_("Invalid value for %s: %s"), key, value);
  62         else
  63                 error(_("Invalid value for %s: %s"), key, value);
  64
  65         return REBASE_INVALID;
  66 }
  67
  68 /**
  69  * Callback for --rebase, which parses arg with parse_config_rebase().
  70  */
  71 static int parse_opt_rebase(const struct option *opt, const char *arg, int unset)
  72 {
  73         enum rebase_type *value = opt->value;
  74
  75         if (arg)
  76                 *value = parse_config_rebase("--rebase", arg, 0);
  77         else
  78                 *value = unset ? REBASE_FALSE : REBASE_TRUE;
  79         return *value == REBASE_INVALID ? -1 : 0;
  80 }
  81
  82 static const char * const pull_usage[] = {
  83         N_("git pull [<options>] [<repository> [<refspec>...]]"),
  84         NULL
  85 };
  86
  87 /* Shared options */
  88 static int opt_verbosity;
  89 static char *opt_progress;
  90 static int recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
  91
  92 /* Options passed to git-merge or git-rebase */
  93 static enum rebase_type opt_rebase = -1;
  94 static char *opt_diffstat;
  95 static char *opt_log;
  96 static char *opt_signoff;
  97 static char *opt_squash;
  98 static char *opt_commit;
  99 static char *opt_edit;
 100 static char *opt_ff;
 101 static char *opt_verify_signatures;
 102 static int opt_autostash = -1;
 103 static int config_autostash;
 104 static struct argv_array opt_strategies = ARGV_ARRAY_INIT;
 105 static struct argv_array opt_strategy_opts = ARGV_ARRAY_INIT;
 106 static char *opt_gpg_sign;
 107 static int opt_allow_unrelated_histories;
 108
 109 /* Options passed to git-fetch */
 110 static char *opt_all;
 111 static char *opt_append;
 112 static char *opt_upload_pack;
 113 static int opt_force;
 114 static char *opt_tags;
 115 static char *opt_prune;
 116 static char *max_children;
 117 static int opt_dry_run;
 118 static char *opt_keep;
 119 static char *opt_depth;
 120 static char *opt_unshallow;
 121 static char *opt_update_shallow;
 122 static char *opt_refmap;
 123 static char *opt_ipv4;
 124 static char *opt_ipv6;
 125
 126 static struct option pull_options[] = {
 127         /* Shared options */
 128         OPT__VERBOSITY(&opt_verbosity),
 129         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 130                 N_("force progress reporting"),
 131                 PARSE_OPT_NOARG),
 132         { OPTION_CALLBACK, 0, "recurse-submodules",
 133                    &recurse_submodules, N_("on-demand"),
 134                    N_("control for recursive fetching of submodules"),
 135                    PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules },
 136
 137         /* Options passed to git-merge or git-rebase */
 138         OPT_GROUP(N_("Options related to merging")),
 139         { OPTION_CALLBACK, 'r', "rebase", &opt_rebase,
 140           "(false|true|merges|preserve|interactive)",
 141           N_("incorporate changes by rebasing rather than merging"),
 142           PARSE_OPT_OPTARG, parse_opt_rebase },
 143         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 144                 N_("do not show a diffstat at the end of the merge"),
 145                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 146         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 147                 N_("show a diffstat at the end of the merge"),
 148                 PARSE_OPT_NOARG),
 149         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 150                 N_("(synonym to --stat)"),
 151                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 152         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 153                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 154                 PARSE_OPT_OPTARG),
 155         OPT_PASSTHRU(0, "signoff", &opt_signoff, NULL,
 156                 N_("add Signed-off-by:"),
 157                 PARSE_OPT_OPTARG),
 158         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 159                 N_("create a single commit instead of doing a merge"),
 160                 PARSE_OPT_NOARG),
 161         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 162                 N_("perform a commit if the merge succeeds (default)"),
 163                 PARSE_OPT_NOARG),
 164         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 165                 N_("edit message before committing"),
 166                 PARSE_OPT_NOARG),
 167         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 168                 N_("allow fast-forward"),
 169                 PARSE_OPT_NOARG),
 170         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 171                 N_("abort if fast-forward is not possible"),
 172                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 173         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 174                 N_("verify that the named commit has a valid GPG signature"),
 175                 PARSE_OPT_NOARG),
 176         OPT_BOOL(0, "autostash", &opt_autostash,
 177                 N_("automatically stash/stash pop before and after rebase")),
 178         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 179                 N_("merge strategy to use"),
 180                 0),
 181         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 182                 N_("option=value"),
 183                 N_("option for selected merge strategy"),
 184                 0),
 185         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 186                 N_("GPG sign commit"),
 187                 PARSE_OPT_OPTARG),
 188         OPT_SET_INT(0, "allow-unrelated-histories",
 189                     &opt_allow_unrelated_histories,
 190                     N_("allow merging unrelated histories"), 1),
 191
 192         /* Options passed to git-fetch */
 193         OPT_GROUP(N_("Options related to fetching")),
 194         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 195                 N_("fetch from all remotes"),
 196                 PARSE_OPT_NOARG),
 197         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 198                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 199                 PARSE_OPT_NOARG),
 200         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 201                 N_("path to upload pack on remote end"),
 202                 0),
 203         OPT__FORCE(&opt_force, N_("force overwrite of local branch"), 0),
 204         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 205                 N_("fetch all tags and associated objects"),
 206                 PARSE_OPT_NOARG),
 207         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 208                 N_("prune remote-tracking branches no longer on remote"),
 209                 PARSE_OPT_NOARG),
 210         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 211                 N_("number of submodules pulled in parallel"),
 212                 PARSE_OPT_OPTARG),
 213         OPT_BOOL(0, "dry-run", &opt_dry_run,
 214                 N_("dry run")),
 215         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 216                 N_("keep downloaded pack"),
 217                 PARSE_OPT_NOARG),
 218         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 219                 N_("deepen history of shallow clone"),
 220                 0),
 221         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 222                 N_("convert to a complete repository"),
 223                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 224         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 225                 N_("accept refs that update .git/shallow"),
 226                 PARSE_OPT_NOARG),
 227         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 228                 N_("specify fetch refmap"),
 229                 PARSE_OPT_NONEG),
 230         OPT_PASSTHRU('4',  "ipv4", &opt_ipv4, NULL,
 231                 N_("use IPv4 addresses only"),
 232                 PARSE_OPT_NOARG),
 233         OPT_PASSTHRU('6',  "ipv6", &opt_ipv6, NULL,
 234                 N_("use IPv6 addresses only"),
 235                 PARSE_OPT_NOARG),
 236
 237         OPT_END()
 238 };
 239
 240 /**
 241  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 242  */
 243 static void argv_push_verbosity(struct argv_array *arr)
 244 {
 245         int verbosity;
 246
 247         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 248                 argv_array_push(arr, "-v");
 249
 250         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 251                 argv_array_push(arr, "-q");
 252 }
 253
 254 /**
 255  * Pushes "-f" switches into arr to match the opt_force level.
 256  */
 257 static void argv_push_force(struct argv_array *arr)
 258 {
 259         int force = opt_force;
 260         while (force-- > 0)
 261                 argv_array_push(arr, "-f");
 262 }
 263
 264 /**
 265  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 266  */
 267 static void set_reflog_message(int argc, const char **argv)
 268 {
 269         int i;
 270         struct strbuf msg = STRBUF_INIT;
 271
 272         for (i = 0; i < argc; i++) {
 273                 if (i)
 274                         strbuf_addch(&msg, ' ');
 275                 strbuf_addstr(&msg, argv[i]);
 276         }
 277
 278         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 279
 280         strbuf_release(&msg);
 281 }
 282
 283 /**
 284  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 285  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 286  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 287  * error.
 288  */
 289 static const char *config_get_ff(void)
 290 {
 291         const char *value;
 292
 293         if (git_config_get_value("pull.ff", &value))
 294                 return NULL;
 295
 296         switch (git_parse_maybe_bool(value)) {
 297         case 0:
 298                 return "--no-ff";
 299         case 1:
 300                 return "--ff";
 301         }
 302
 303         if (!strcmp(value, "only"))
 304                 return "--ff-only";
 305
 306         die(_("Invalid value for pull.ff: %s"), value);
 307 }
 308
 309 /**
 310  * Returns the default configured value for --rebase. It first looks for the
 311  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 312  * branch, and if HEAD is detached or the configuration key does not exist,
 313  * looks for the value of "pull.rebase". If both configuration keys do not
 314  * exist, returns REBASE_FALSE.
 315  */
 316 static enum rebase_type config_get_rebase(void)
 317 {
 318         struct branch *curr_branch = branch_get("HEAD");
 319         const char *value;
 320
 321         if (curr_branch) {
 322                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 323
 324                 if (!git_config_get_value(key, &value)) {
 325                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 326                         free(key);
 327                         return ret;
 328                 }
 329
 330                 free(key);
 331         }
 332
 333         if (!git_config_get_value("pull.rebase", &value))
 334                 return parse_config_rebase("pull.rebase", value, 1);
 335
 336         return REBASE_FALSE;
 337 }
 338
 339 /**
 340  * Read config variables.
 341  */
 342 static int git_pull_config(const char *var, const char *value, void *cb)
 343 {
 344         if (!strcmp(var, "rebase.autostash")) {
 345                 config_autostash = git_config_bool(var, value);
 346                 return 0;
 347         } else if (!strcmp(var, "submodule.recurse")) {
 348                 recurse_submodules = git_config_bool(var, value) ?
 349                         RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
 350                 return 0;
 351         }
 352         return git_default_config(var, value, cb);
 353 }
 354
 355 /**
 356  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 357  * into merge_heads.
 358  */
 359 static void get_merge_heads(struct oid_array *merge_heads)
 360 {
 361         const char *filename = git_path_fetch_head(the_repository);
 362         FILE *fp;
 363         struct strbuf sb = STRBUF_INIT;
 364         struct object_id oid;
 365
 366         fp = xfopen(filename, "r");
 367         while (strbuf_getline_lf(&sb, fp) != EOF) {
 368                 if (get_oid_hex(sb.buf, &oid))
 369                         continue;  /* invalid line: does not start with SHA1 */
 370                 if (starts_with(sb.buf + GIT_SHA1_HEXSZ, "\tnot-for-merge\t"))
 371                         continue;  /* ref is not-for-merge */
 372                 oid_array_append(merge_heads, &oid);
 373         }
 374         fclose(fp);
 375         strbuf_release(&sb);
 376 }
 377
 378 /**
 379  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 380  * retrieve the name of the remote if the repository only has one remote.
 381  */
 382 static int get_only_remote(struct remote *remote, void *cb_data)
 383 {
 384         const char **remote_name = cb_data;
 385
 386         if (*remote_name)
 387                 return -1;
 388
 389         *remote_name = remote->name;
 390         return 0;
 391 }
 392
 393 /**
 394  * Dies with the appropriate reason for why there are no merge candidates:
 395  *
 396  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 397  *    up not fetching anything. This is usually because the user provided a
 398  *    wildcard refspec which had no matches on the remote end.
 399  *
 400  * 2. We fetched from a non-default remote, but didn't specify a branch to
 401  *    merge. We can't use the configured one because it applies to the default
 402  *    remote, thus the user must specify the branches to merge.
 403  *
 404  * 3. We fetched from the branch's or repo's default remote, but:
 405  *
 406  *    a. We are not on a branch, so there will never be a configured branch to
 407  *       merge with.
 408  *
 409  *    b. We are on a branch, but there is no configured branch to merge with.
 410  *
 411  * 4. We fetched from the branch's or repo's default remote, but the configured
 412  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 413  *    part of the configured fetch refspec.)
 414  */
 415 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 416 {
 417         struct branch *curr_branch = branch_get("HEAD");
 418         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 419
 420         if (*refspecs) {
 421                 if (opt_rebase)
 422                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 423                 else
 424                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 425                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 426                                         "matches on the remote end."));
 427         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 428                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 429                         "a branch. Because this is not the default configured remote\n"
 430                         "for your current branch, you must specify a branch on the command line."),
 431                         repo);
 432         } else if (!curr_branch) {
 433                 fprintf_ln(stderr, _("You are not currently on a branch."));
 434                 if (opt_rebase)
 435                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 436                 else
 437                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 438                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 439                 fprintf(stderr, "\n");
 440                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 441                 fprintf(stderr, "\n");
 442         } else if (!curr_branch->merge_nr) {
 443                 const char *remote_name = NULL;
 444
 445                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 446                         remote_name = _("<remote>");
 447
 448                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 449                 if (opt_rebase)
 450                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 451                 else
 452                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 453                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 454                 fprintf(stderr, "\n");
 455                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 456                 fprintf(stderr, "\n");
 457                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));
 458                 fprintf(stderr, "\n");
 459                 fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",
 460                                 remote_name, _("<branch>"), curr_branch->name);
 461         } else
 462                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 463                         "from the remote, but no such ref was fetched."),
 464                         *curr_branch->merge_name);
 465         exit(1);
 466 }
 467
 468 /**
 469  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 470  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 471  * is not provided in argv, it is set to NULL.
 472  */
 473 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 474                 const char ***refspecs)
 475 {
 476         if (argc > 0) {
 477                 *repo = *argv++;
 478                 argc--;
 479         } else
 480                 *repo = NULL;
 481         *refspecs = argv;
 482 }
 483
 484 /**
 485  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 486  * repository and refspecs to fetch, or NULL if they are not provided.
 487  */
 488 static int run_fetch(const char *repo, const char **refspecs)
 489 {
 490         struct argv_array args = ARGV_ARRAY_INIT;
 491         int ret;
 492
 493         argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
 494
 495         /* Shared options */
 496         argv_push_verbosity(&args);
 497         if (opt_progress)
 498                 argv_array_push(&args, opt_progress);
 499
 500         /* Options passed to git-fetch */
 501         if (opt_all)
 502                 argv_array_push(&args, opt_all);
 503         if (opt_append)
 504                 argv_array_push(&args, opt_append);
 505         if (opt_upload_pack)
 506                 argv_array_push(&args, opt_upload_pack);
 507         argv_push_force(&args);
 508         if (opt_tags)
 509                 argv_array_push(&args, opt_tags);
 510         if (opt_prune)
 511                 argv_array_push(&args, opt_prune);
 512         if (recurse_submodules != RECURSE_SUBMODULES_DEFAULT)
 513                 switch (recurse_submodules) {
 514                 case RECURSE_SUBMODULES_ON:
 515                         argv_array_push(&args, "--recurse-submodules=on");
 516                         break;
 517                 case RECURSE_SUBMODULES_OFF:
 518                         argv_array_push(&args, "--recurse-submodules=no");
 519                         break;
 520                 case RECURSE_SUBMODULES_ON_DEMAND:
 521                         argv_array_push(&args, "--recurse-submodules=on-demand");
 522                         break;
 523                 default:
 524                         BUG("submodule recursion option not understood");
 525                 }
 526         if (max_children)
 527                 argv_array_push(&args, max_children);
 528         if (opt_dry_run)
 529                 argv_array_push(&args, "--dry-run");
 530         if (opt_keep)
 531                 argv_array_push(&args, opt_keep);
 532         if (opt_depth)
 533                 argv_array_push(&args, opt_depth);
 534         if (opt_unshallow)
 535                 argv_array_push(&args, opt_unshallow);
 536         if (opt_update_shallow)
 537                 argv_array_push(&args, opt_update_shallow);
 538         if (opt_refmap)
 539                 argv_array_push(&args, opt_refmap);
 540         if (opt_ipv4)
 541                 argv_array_push(&args, opt_ipv4);
 542         if (opt_ipv6)
 543                 argv_array_push(&args, opt_ipv6);
 544
 545         if (repo) {
 546                 argv_array_push(&args, repo);
 547                 argv_array_pushv(&args, refspecs);
 548         } else if (*refspecs)
 549                 BUG("refspecs without repo?");
 550         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 551         argv_array_clear(&args);
 552         return ret;
 553 }
 554
 555 /**
 556  * "Pulls into void" by branching off merge_head.
 557  */
 558 static int pull_into_void(const struct object_id *merge_head,
 559                 const struct object_id *curr_head)
 560 {
 561         if (opt_verify_signatures) {
 562                 struct commit *commit;
 563
 564                 commit = lookup_commit(the_repository, merge_head);
 565                 if (!commit)
 566                         die(_("unable to access commit %s"),
 567                             oid_to_hex(merge_head));
 568
 569                 verify_merge_signature(commit, opt_verbosity);
 570         }
 571
 572         /*
 573          * Two-way merge: we treat the index as based on an empty tree,
 574          * and try to fast-forward to HEAD. This ensures we will not lose
 575          * index/worktree changes that the user already made on the unborn
 576          * branch.
 577          */
 578         if (checkout_fast_forward(the_repository,
 579                                   the_hash_algo->empty_tree,
 580                                   merge_head, 0))
 581                 return 1;
 582
 583         if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 584                 return 1;
 585
 586         return 0;
 587 }
 588
 589 static int rebase_submodules(void)
 590 {
 591         struct child_process cp = CHILD_PROCESS_INIT;
 592
 593         cp.git_cmd = 1;
 594         cp.no_stdin = 1;
 595         argv_array_pushl(&cp.args, "submodule", "update",
 596                                    "--recursive", "--rebase", NULL);
 597         argv_push_verbosity(&cp.args);
 598
 599         return run_command(&cp);
 600 }
 601
 602 static int update_submodules(void)
 603 {
 604         struct child_process cp = CHILD_PROCESS_INIT;
 605
 606         cp.git_cmd = 1;
 607         cp.no_stdin = 1;
 608         argv_array_pushl(&cp.args, "submodule", "update",
 609                                    "--recursive", "--checkout", NULL);
 610         argv_push_verbosity(&cp.args);
 611
 612         return run_command(&cp);
 613 }
 614
 615 /**
 616  * Runs git-merge, returning its exit status.
 617  */
 618 static int run_merge(void)
 619 {
 620         int ret;
 621         struct argv_array args = ARGV_ARRAY_INIT;
 622
 623         argv_array_pushl(&args, "merge", NULL);
 624
 625         /* Shared options */
 626         argv_push_verbosity(&args);
 627         if (opt_progress)
 628                 argv_array_push(&args, opt_progress);
 629
 630         /* Options passed to git-merge */
 631         if (opt_diffstat)
 632                 argv_array_push(&args, opt_diffstat);
 633         if (opt_log)
 634                 argv_array_push(&args, opt_log);
 635         if (opt_signoff)
 636                 argv_array_push(&args, opt_signoff);
 637         if (opt_squash)
 638                 argv_array_push(&args, opt_squash);
 639         if (opt_commit)
 640                 argv_array_push(&args, opt_commit);
 641         if (opt_edit)
 642                 argv_array_push(&args, opt_edit);
 643         if (opt_ff)
 644                 argv_array_push(&args, opt_ff);
 645         if (opt_verify_signatures)
 646                 argv_array_push(&args, opt_verify_signatures);
 647         argv_array_pushv(&args, opt_strategies.argv);
 648         argv_array_pushv(&args, opt_strategy_opts.argv);
 649         if (opt_gpg_sign)
 650                 argv_array_push(&args, opt_gpg_sign);
 651         if (opt_allow_unrelated_histories > 0)
 652                 argv_array_push(&args, "--allow-unrelated-histories");
 653
 654         argv_array_push(&args, "FETCH_HEAD");
 655         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 656         argv_array_clear(&args);
 657         return ret;
 658 }
 659
 660 /**
 661  * Returns remote's upstream branch for the current branch. If remote is NULL,
 662  * the current branch's configured default remote is used. Returns NULL if
 663  * `remote` does not name a valid remote, HEAD does not point to a branch,
 664  * remote is not the branch's configured remote or the branch does not have any
 665  * configured upstream branch.
 666  */
 667 static const char *get_upstream_branch(const char *remote)
 668 {
 669         struct remote *rm;
 670         struct branch *curr_branch;
 671         const char *curr_branch_remote;
 672
 673         rm = remote_get(remote);
 674         if (!rm)
 675                 return NULL;
 676
 677         curr_branch = branch_get("HEAD");
 678         if (!curr_branch)
 679                 return NULL;
 680
 681         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 682         assert(curr_branch_remote);
 683
 684         if (strcmp(curr_branch_remote, rm->name))
 685                 return NULL;
 686
 687         return branch_get_upstream(curr_branch, NULL);
 688 }
 689
 690 /**
 691  * Derives the remote-tracking branch from the remote and refspec.
 692  *
 693  * FIXME: The current implementation assumes the default mapping of
 694  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 695  */
 696 static const char *get_tracking_branch(const char *remote, const char *refspec)
 697 {
 698         struct refspec_item spec;
 699         const char *spec_src;
 700         const char *merge_branch;
 701
 702         refspec_item_init_or_die(&spec, refspec, REFSPEC_FETCH);
 703         spec_src = spec.src;
 704         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 705                 spec_src = "HEAD";
 706         else if (skip_prefix(spec_src, "heads/", &spec_src))
 707                 ;
 708         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 709                 ;
 710         else if (starts_with(spec_src, "refs/") ||
 711                 starts_with(spec_src, "tags/") ||
 712                 starts_with(spec_src, "remotes/"))
 713                 spec_src = "";
 714
 715         if (*spec_src) {
 716                 if (!strcmp(remote, "."))
 717                         merge_branch = mkpath("refs/heads/%s", spec_src);
 718                 else
 719                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 720         } else
 721                 merge_branch = NULL;
 722
 723         refspec_item_clear(&spec);
 724         return merge_branch;
 725 }
 726
 727 /**
 728  * Given the repo and refspecs, sets fork_point to the point at which the
 729  * current branch forked from its remote-tracking branch. Returns 0 on success,
 730  * -1 on failure.
 731  */
 732 static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,
 733                 const char *refspec)
 734 {
 735         int ret;
 736         struct branch *curr_branch;
 737         const char *remote_branch;
 738         struct child_process cp = CHILD_PROCESS_INIT;
 739         struct strbuf sb = STRBUF_INIT;
 740
 741         curr_branch = branch_get("HEAD");
 742         if (!curr_branch)
 743                 return -1;
 744
 745         if (refspec)
 746                 remote_branch = get_tracking_branch(repo, refspec);
 747         else
 748                 remote_branch = get_upstream_branch(repo);
 749
 750         if (!remote_branch)
 751                 return -1;
 752
 753         argv_array_pushl(&cp.args, "merge-base", "--fork-point",
 754                         remote_branch, curr_branch->name, NULL);
 755         cp.no_stdin = 1;
 756         cp.no_stderr = 1;
 757         cp.git_cmd = 1;
 758
 759         ret = capture_command(&cp, &sb, GIT_SHA1_HEXSZ);
 760         if (ret)
 761                 goto cleanup;
 762
 763         ret = get_oid_hex(sb.buf, fork_point);
 764         if (ret)
 765                 goto cleanup;
 766
 767 cleanup:
 768         strbuf_release(&sb);
 769         return ret ? -1 : 0;
 770 }
 771
 772 /**
 773  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 774  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 775  */
 776 static int get_octopus_merge_base(struct object_id *merge_base,
 777                 const struct object_id *curr_head,
 778                 const struct object_id *merge_head,
 779                 const struct object_id *fork_point)
 780 {
 781         struct commit_list *revs = NULL, *result;
 782
 783         commit_list_insert(lookup_commit_reference(the_repository, curr_head),
 784                            &revs);
 785         commit_list_insert(lookup_commit_reference(the_repository, merge_head),
 786                            &revs);
 787         if (!is_null_oid(fork_point))
 788                 commit_list_insert(lookup_commit_reference(the_repository, fork_point),
 789                                    &revs);
 790
 791         result = get_octopus_merge_bases(revs);
 792         free_commit_list(revs);
 793         reduce_heads_replace(&result);
 794
 795         if (!result)
 796                 return 1;
 797
 798         oidcpy(merge_base, &result->item->object.oid);
 799         free_commit_list(result);
 800         return 0;
 801 }
 802
 803 /**
 804  * Given the current HEAD SHA1, the merge head returned from git-fetch and the
 805  * fork point calculated by get_rebase_fork_point(), runs git-rebase with the
 806  * appropriate arguments and returns its exit status.
 807  */
 808 static int run_rebase(const struct object_id *curr_head,
 809                 const struct object_id *merge_head,
 810                 const struct object_id *fork_point)
 811 {
 812         int ret;
 813         struct object_id oct_merge_base;
 814         struct argv_array args = ARGV_ARRAY_INIT;
 815
 816         if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))
 817                 if (!is_null_oid(fork_point) && oideq(&oct_merge_base, fork_point))
 818                         fork_point = NULL;
 819
 820         argv_array_push(&args, "rebase");
 821
 822         /* Shared options */
 823         argv_push_verbosity(&args);
 824
 825         /* Options passed to git-rebase */
 826         if (opt_rebase == REBASE_MERGES)
 827                 argv_array_push(&args, "--rebase-merges");
 828         else if (opt_rebase == REBASE_PRESERVE)
 829                 argv_array_push(&args, "--preserve-merges");
 830         else if (opt_rebase == REBASE_INTERACTIVE)
 831                 argv_array_push(&args, "--interactive");
 832         if (opt_diffstat)
 833                 argv_array_push(&args, opt_diffstat);
 834         argv_array_pushv(&args, opt_strategies.argv);
 835         argv_array_pushv(&args, opt_strategy_opts.argv);
 836         if (opt_gpg_sign)
 837                 argv_array_push(&args, opt_gpg_sign);
 838         if (opt_autostash == 0)
 839                 argv_array_push(&args, "--no-autostash");
 840         else if (opt_autostash == 1)
 841                 argv_array_push(&args, "--autostash");
 842         if (opt_verify_signatures &&
 843             !strcmp(opt_verify_signatures, "--verify-signatures"))
 844                 warning(_("ignoring --verify-signatures for rebase"));
 845
 846         argv_array_push(&args, "--onto");
 847         argv_array_push(&args, oid_to_hex(merge_head));
 848
 849         if (fork_point && !is_null_oid(fork_point))
 850                 argv_array_push(&args, oid_to_hex(fork_point));
 851         else
 852                 argv_array_push(&args, oid_to_hex(merge_head));
 853
 854         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 855         argv_array_clear(&args);
 856         return ret;
 857 }
 858
 859 int cmd_pull(int argc, const char **argv, const char *prefix)
 860 {
 861         const char *repo, **refspecs;
 862         struct oid_array merge_heads = OID_ARRAY_INIT;
 863         struct object_id orig_head, curr_head;
 864         struct object_id rebase_fork_point;
 865         int autostash;
 866
 867         if (!getenv("GIT_REFLOG_ACTION"))
 868                 set_reflog_message(argc, argv);
 869
 870         git_config(git_pull_config, NULL);
 871
 872         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 873
 874         parse_repo_refspecs(argc, argv, &repo, &refspecs);
 875
 876         if (!opt_ff)
 877                 opt_ff = xstrdup_or_null(config_get_ff());
 878
 879         if (opt_rebase < 0)
 880                 opt_rebase = config_get_rebase();
 881
 882         if (read_cache_unmerged())
 883                 die_resolve_conflict("pull");
 884
 885         if (file_exists(git_path_merge_head(the_repository)))
 886                 die_conclude_merge();
 887
 888         if (get_oid("HEAD", &orig_head))
 889                 oidclr(&orig_head);
 890
 891         if (!opt_rebase && opt_autostash != -1)
 892                 die(_("--[no-]autostash option is only valid with --rebase."));
 893
 894         autostash = config_autostash;
 895         if (opt_rebase) {
 896                 if (opt_autostash != -1)
 897                         autostash = opt_autostash;
 898
 899                 if (is_null_oid(&orig_head) && !is_cache_unborn())
 900                         die(_("Updating an unborn branch with changes added to the index."));
 901
 902                 if (!autostash)
 903                         require_clean_work_tree(the_repository,
 904                                 N_("pull with rebase"),
 905                                 _("please commit or stash them."), 1, 0);
 906
 907                 if (get_rebase_fork_point(&rebase_fork_point, repo, *refspecs))
 908                         oidclr(&rebase_fork_point);
 909         }
 910
 911         if (run_fetch(repo, refspecs))
 912                 return 1;
 913
 914         if (opt_dry_run)
 915                 return 0;
 916
 917         if (get_oid("HEAD", &curr_head))
 918                 oidclr(&curr_head);
 919
 920         if (!is_null_oid(&orig_head) && !is_null_oid(&curr_head) &&
 921                         !oideq(&orig_head, &curr_head)) {
 922                 /*
 923                  * The fetch involved updating the current branch.
 924                  *
 925                  * The working tree and the index file are still based on
 926                  * orig_head commit, but we are merging into curr_head.
 927                  * Update the working tree to match curr_head.
 928                  */
 929
 930                 warning(_("fetch updated the current branch head.\n"
 931                         "fast-forwarding your working tree from\n"
 932                         "commit %s."), oid_to_hex(&orig_head));
 933
 934                 if (checkout_fast_forward(the_repository, &orig_head,
 935                                           &curr_head, 0))
 936                         die(_("Cannot fast-forward your working tree.\n"
 937                                 "After making sure that you saved anything precious from\n"
 938                                 "$ git diff %s\n"
 939                                 "output, run\n"
 940                                 "$ git reset --hard\n"
 941                                 "to recover."), oid_to_hex(&orig_head));
 942         }
 943
 944         get_merge_heads(&merge_heads);
 945
 946         if (!merge_heads.nr)
 947                 die_no_merge_candidates(repo, refspecs);
 948
 949         if (is_null_oid(&orig_head)) {
 950                 if (merge_heads.nr > 1)
 951                         die(_("Cannot merge multiple branches into empty head."));
 952                 return pull_into_void(merge_heads.oid, &curr_head);
 953         }
 954         if (opt_rebase && merge_heads.nr > 1)
 955                 die(_("Cannot rebase onto multiple branches."));
 956
 957         if (opt_rebase) {
 958                 int ret = 0;
 959                 if ((recurse_submodules == RECURSE_SUBMODULES_ON ||
 960                      recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) &&
 961                     submodule_touches_in_range(the_repository, &rebase_fork_point, &curr_head))
 962                         die(_("cannot rebase with locally recorded submodule modifications"));
 963                 if (!autostash) {
 964                         struct commit_list *list = NULL;
 965                         struct commit *merge_head, *head;
 966
 967                         head = lookup_commit_reference(the_repository,
 968                                                        &orig_head);
 969                         commit_list_insert(head, &list);
 970                         merge_head = lookup_commit_reference(the_repository,
 971                                                              &merge_heads.oid[0]);
 972                         if (is_descendant_of(merge_head, list)) {
 973                                 /* we can fast-forward this without invoking rebase */
 974                                 opt_ff = "--ff-only";
 975                                 ret = run_merge();
 976                         }
 977                 }
 978                 ret = run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
 979
 980                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
 981                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
 982                         ret = rebase_submodules();
 983
 984                 return ret;
 985         } else {
 986                 int ret = run_merge();
 987                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
 988                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
 989                         ret = update_submodules();
 990                 return ret;
 991         }
 992 }