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