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 "tempfile.h"
  20 #include "lockfile.h"
  21 #include "wt-status.h"
  22
  23 enum rebase_type {
  24         REBASE_INVALID = -1,
  25         REBASE_FALSE = 0,
  26         REBASE_TRUE,
  27         REBASE_PRESERVE,
  28         REBASE_INTERACTIVE
  29 };
  30
  31 /**
  32  * Parses the value of --rebase. If value is a false value, returns
  33  * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is
  34  * "preserve", returns REBASE_PRESERVE. If value is a invalid value, dies with
  35  * a fatal error if fatal is true, otherwise returns REBASE_INVALID.
  36  */
  37 static enum rebase_type parse_config_rebase(const char *key, const char *value,
  38                 int fatal)
  39 {
  40         int v = git_config_maybe_bool("pull.rebase", value);
  41
  42         if (!v)
  43                 return REBASE_FALSE;
  44         else if (v > 0)
  45                 return REBASE_TRUE;
  46         else if (!strcmp(value, "preserve"))
  47                 return REBASE_PRESERVE;
  48         else if (!strcmp(value, "interactive"))
  49                 return REBASE_INTERACTIVE;
  50
  51         if (fatal)
  52                 die(_("Invalid value for %s: %s"), key, value);
  53         else
  54                 error(_("Invalid value for %s: %s"), key, value);
  55
  56         return REBASE_INVALID;
  57 }
  58
  59 /**
  60  * Callback for --rebase, which parses arg with parse_config_rebase().
  61  */
  62 static int parse_opt_rebase(const struct option *opt, const char *arg, int unset)
  63 {
  64         enum rebase_type *value = opt->value;
  65
  66         if (arg)
  67                 *value = parse_config_rebase("--rebase", arg, 0);
  68         else
  69                 *value = unset ? REBASE_FALSE : REBASE_TRUE;
  70         return *value == REBASE_INVALID ? -1 : 0;
  71 }
  72
  73 static const char * const pull_usage[] = {
  74         N_("git pull [<options>] [<repository> [<refspec>...]]"),
  75         NULL
  76 };
  77
  78 /* Shared options */
  79 static int opt_verbosity;
  80 static char *opt_progress;
  81
  82 /* Options passed to git-merge or git-rebase */
  83 static enum rebase_type opt_rebase = -1;
  84 static char *opt_diffstat;
  85 static char *opt_log;
  86 static char *opt_squash;
  87 static char *opt_commit;
  88 static char *opt_edit;
  89 static char *opt_ff;
  90 static char *opt_verify_signatures;
  91 static int opt_autostash = -1;
  92 static int config_autostash;
  93 static struct argv_array opt_strategies = ARGV_ARRAY_INIT;
  94 static struct argv_array opt_strategy_opts = ARGV_ARRAY_INIT;
  95 static char *opt_gpg_sign;
  96 static int opt_allow_unrelated_histories;
  97
  98 /* Options passed to git-fetch */
  99 static char *opt_all;
 100 static char *opt_append;
 101 static char *opt_upload_pack;
 102 static int opt_force;
 103 static char *opt_tags;
 104 static char *opt_prune;
 105 static char *opt_recurse_submodules;
 106 static char *max_children;
 107 static int opt_dry_run;
 108 static char *opt_keep;
 109 static char *opt_depth;
 110 static char *opt_unshallow;
 111 static char *opt_update_shallow;
 112 static char *opt_refmap;
 113
 114 static struct option pull_options[] = {
 115         /* Shared options */
 116         OPT__VERBOSITY(&opt_verbosity),
 117         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 118                 N_("force progress reporting"),
 119                 PARSE_OPT_NOARG),
 120
 121         /* Options passed to git-merge or git-rebase */
 122         OPT_GROUP(N_("Options related to merging")),
 123         { OPTION_CALLBACK, 'r', "rebase", &opt_rebase,
 124           "false|true|preserve|interactive",
 125           N_("incorporate changes by rebasing rather than merging"),
 126           PARSE_OPT_OPTARG, parse_opt_rebase },
 127         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 128                 N_("do not show a diffstat at the end of the merge"),
 129                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 130         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 131                 N_("show a diffstat at the end of the merge"),
 132                 PARSE_OPT_NOARG),
 133         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 134                 N_("(synonym to --stat)"),
 135                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 136         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 137                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 138                 PARSE_OPT_OPTARG),
 139         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 140                 N_("create a single commit instead of doing a merge"),
 141                 PARSE_OPT_NOARG),
 142         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 143                 N_("perform a commit if the merge succeeds (default)"),
 144                 PARSE_OPT_NOARG),
 145         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 146                 N_("edit message before committing"),
 147                 PARSE_OPT_NOARG),
 148         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 149                 N_("allow fast-forward"),
 150                 PARSE_OPT_NOARG),
 151         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 152                 N_("abort if fast-forward is not possible"),
 153                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 154         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 155                 N_("verify that the named commit has a valid GPG signature"),
 156                 PARSE_OPT_NOARG),
 157         OPT_BOOL(0, "autostash", &opt_autostash,
 158                 N_("automatically stash/stash pop before and after rebase")),
 159         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 160                 N_("merge strategy to use"),
 161                 0),
 162         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 163                 N_("option=value"),
 164                 N_("option for selected merge strategy"),
 165                 0),
 166         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 167                 N_("GPG sign commit"),
 168                 PARSE_OPT_OPTARG),
 169         OPT_SET_INT(0, "allow-unrelated-histories",
 170                     &opt_allow_unrelated_histories,
 171                     N_("allow merging unrelated histories"), 1),
 172
 173         /* Options passed to git-fetch */
 174         OPT_GROUP(N_("Options related to fetching")),
 175         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 176                 N_("fetch from all remotes"),
 177                 PARSE_OPT_NOARG),
 178         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 179                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 180                 PARSE_OPT_NOARG),
 181         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 182                 N_("path to upload pack on remote end"),
 183                 0),
 184         OPT__FORCE(&opt_force, N_("force overwrite of local branch")),
 185         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 186                 N_("fetch all tags and associated objects"),
 187                 PARSE_OPT_NOARG),
 188         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 189                 N_("prune remote-tracking branches no longer on remote"),
 190                 PARSE_OPT_NOARG),
 191         OPT_PASSTHRU(0, "recurse-submodules", &opt_recurse_submodules,
 192                 N_("on-demand"),
 193                 N_("control recursive fetching of submodules"),
 194                 PARSE_OPT_OPTARG),
 195         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 196                 N_("number of submodules pulled in parallel"),
 197                 PARSE_OPT_OPTARG),
 198         OPT_BOOL(0, "dry-run", &opt_dry_run,
 199                 N_("dry run")),
 200         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 201                 N_("keep downloaded pack"),
 202                 PARSE_OPT_NOARG),
 203         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 204                 N_("deepen history of shallow clone"),
 205                 0),
 206         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 207                 N_("convert to a complete repository"),
 208                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 209         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 210                 N_("accept refs that update .git/shallow"),
 211                 PARSE_OPT_NOARG),
 212         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 213                 N_("specify fetch refmap"),
 214                 PARSE_OPT_NONEG),
 215
 216         OPT_END()
 217 };
 218
 219 /**
 220  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 221  */
 222 static void argv_push_verbosity(struct argv_array *arr)
 223 {
 224         int verbosity;
 225
 226         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 227                 argv_array_push(arr, "-v");
 228
 229         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 230                 argv_array_push(arr, "-q");
 231 }
 232
 233 /**
 234  * Pushes "-f" switches into arr to match the opt_force level.
 235  */
 236 static void argv_push_force(struct argv_array *arr)
 237 {
 238         int force = opt_force;
 239         while (force-- > 0)
 240                 argv_array_push(arr, "-f");
 241 }
 242
 243 /**
 244  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 245  */
 246 static void set_reflog_message(int argc, const char **argv)
 247 {
 248         int i;
 249         struct strbuf msg = STRBUF_INIT;
 250
 251         for (i = 0; i < argc; i++) {
 252                 if (i)
 253                         strbuf_addch(&msg, ' ');
 254                 strbuf_addstr(&msg, argv[i]);
 255         }
 256
 257         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 258
 259         strbuf_release(&msg);
 260 }
 261
 262 /**
 263  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 264  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 265  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 266  * error.
 267  */
 268 static const char *config_get_ff(void)
 269 {
 270         const char *value;
 271
 272         if (git_config_get_value("pull.ff", &value))
 273                 return NULL;
 274
 275         switch (git_config_maybe_bool("pull.ff", value)) {
 276         case 0:
 277                 return "--no-ff";
 278         case 1:
 279                 return "--ff";
 280         }
 281
 282         if (!strcmp(value, "only"))
 283                 return "--ff-only";
 284
 285         die(_("Invalid value for pull.ff: %s"), value);
 286 }
 287
 288 /**
 289  * Returns the default configured value for --rebase. It first looks for the
 290  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 291  * branch, and if HEAD is detached or the configuration key does not exist,
 292  * looks for the value of "pull.rebase". If both configuration keys do not
 293  * exist, returns REBASE_FALSE.
 294  */
 295 static enum rebase_type config_get_rebase(void)
 296 {
 297         struct branch *curr_branch = branch_get("HEAD");
 298         const char *value;
 299
 300         if (curr_branch) {
 301                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 302
 303                 if (!git_config_get_value(key, &value)) {
 304                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 305                         free(key);
 306                         return ret;
 307                 }
 308
 309                 free(key);
 310         }
 311
 312         if (!git_config_get_value("pull.rebase", &value))
 313                 return parse_config_rebase("pull.rebase", value, 1);
 314
 315         return REBASE_FALSE;
 316 }
 317
 318 /**
 319  * Read config variables.
 320  */
 321 static int git_pull_config(const char *var, const char *value, void *cb)
 322 {
 323         if (!strcmp(var, "rebase.autostash")) {
 324                 config_autostash = git_config_bool(var, value);
 325                 return 0;
 326         }
 327         return git_default_config(var, value, cb);
 328 }
 329
 330 /**
 331  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 332  * into merge_heads.
 333  */
 334 static void get_merge_heads(struct oid_array *merge_heads)
 335 {
 336         const char *filename = git_path_fetch_head();
 337         FILE *fp;
 338         struct strbuf sb = STRBUF_INIT;
 339         struct object_id oid;
 340
 341         if (!(fp = fopen(filename, "r")))
 342                 die_errno(_("could not open '%s' for reading"), filename);
 343         while (strbuf_getline_lf(&sb, fp) != EOF) {
 344                 if (get_oid_hex(sb.buf, &oid))
 345                         continue;  /* invalid line: does not start with SHA1 */
 346                 if (starts_with(sb.buf + GIT_SHA1_HEXSZ, "\tnot-for-merge\t"))
 347                         continue;  /* ref is not-for-merge */
 348                 oid_array_append(merge_heads, &oid);
 349         }
 350         fclose(fp);
 351         strbuf_release(&sb);
 352 }
 353
 354 /**
 355  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 356  * retrieve the name of the remote if the repository only has one remote.
 357  */
 358 static int get_only_remote(struct remote *remote, void *cb_data)
 359 {
 360         const char **remote_name = cb_data;
 361
 362         if (*remote_name)
 363                 return -1;
 364
 365         *remote_name = remote->name;
 366         return 0;
 367 }
 368
 369 /**
 370  * Dies with the appropriate reason for why there are no merge candidates:
 371  *
 372  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 373  *    up not fetching anything. This is usually because the user provided a
 374  *    wildcard refspec which had no matches on the remote end.
 375  *
 376  * 2. We fetched from a non-default remote, but didn't specify a branch to
 377  *    merge. We can't use the configured one because it applies to the default
 378  *    remote, thus the user must specify the branches to merge.
 379  *
 380  * 3. We fetched from the branch's or repo's default remote, but:
 381  *
 382  *    a. We are not on a branch, so there will never be a configured branch to
 383  *       merge with.
 384  *
 385  *    b. We are on a branch, but there is no configured branch to merge with.
 386  *
 387  * 4. We fetched from the branch's or repo's default remote, but the configured
 388  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 389  *    part of the configured fetch refspec.)
 390  */
 391 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 392 {
 393         struct branch *curr_branch = branch_get("HEAD");
 394         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 395
 396         if (*refspecs) {
 397                 if (opt_rebase)
 398                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 399                 else
 400                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 401                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 402                                         "matches on the remote end."));
 403         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 404                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 405                         "a branch. Because this is not the default configured remote\n"
 406                         "for your current branch, you must specify a branch on the command line."),
 407                         repo);
 408         } else if (!curr_branch) {
 409                 fprintf_ln(stderr, _("You are not currently on a branch."));
 410                 if (opt_rebase)
 411                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 412                 else
 413                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 414                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 415                 fprintf(stderr, "\n");
 416                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 417                 fprintf(stderr, "\n");
 418         } else if (!curr_branch->merge_nr) {
 419                 const char *remote_name = NULL;
 420
 421                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 422                         remote_name = _("<remote>");
 423
 424                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 425                 if (opt_rebase)
 426                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 427                 else
 428                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 429                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 430                 fprintf(stderr, "\n");
 431                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 432                 fprintf(stderr, "\n");
 433                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));
 434                 fprintf(stderr, "\n");
 435                 fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",
 436                                 remote_name, _("<branch>"), curr_branch->name);
 437         } else
 438                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 439                         "from the remote, but no such ref was fetched."),
 440                         *curr_branch->merge_name);
 441         exit(1);
 442 }
 443
 444 /**
 445  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 446  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 447  * is not provided in argv, it is set to NULL.
 448  */
 449 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 450                 const char ***refspecs)
 451 {
 452         if (argc > 0) {
 453                 *repo = *argv++;
 454                 argc--;
 455         } else
 456                 *repo = NULL;
 457         *refspecs = argv;
 458 }
 459
 460 /**
 461  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 462  * repository and refspecs to fetch, or NULL if they are not provided.
 463  */
 464 static int run_fetch(const char *repo, const char **refspecs)
 465 {
 466         struct argv_array args = ARGV_ARRAY_INIT;
 467         int ret;
 468
 469         argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
 470
 471         /* Shared options */
 472         argv_push_verbosity(&args);
 473         if (opt_progress)
 474                 argv_array_push(&args, opt_progress);
 475
 476         /* Options passed to git-fetch */
 477         if (opt_all)
 478                 argv_array_push(&args, opt_all);
 479         if (opt_append)
 480                 argv_array_push(&args, opt_append);
 481         if (opt_upload_pack)
 482                 argv_array_push(&args, opt_upload_pack);
 483         argv_push_force(&args);
 484         if (opt_tags)
 485                 argv_array_push(&args, opt_tags);
 486         if (opt_prune)
 487                 argv_array_push(&args, opt_prune);
 488         if (opt_recurse_submodules)
 489                 argv_array_push(&args, opt_recurse_submodules);
 490         if (max_children)
 491                 argv_array_push(&args, max_children);
 492         if (opt_dry_run)
 493                 argv_array_push(&args, "--dry-run");
 494         if (opt_keep)
 495                 argv_array_push(&args, opt_keep);
 496         if (opt_depth)
 497                 argv_array_push(&args, opt_depth);
 498         if (opt_unshallow)
 499                 argv_array_push(&args, opt_unshallow);
 500         if (opt_update_shallow)
 501                 argv_array_push(&args, opt_update_shallow);
 502         if (opt_refmap)
 503                 argv_array_push(&args, opt_refmap);
 504
 505         if (repo) {
 506                 argv_array_push(&args, repo);
 507                 argv_array_pushv(&args, refspecs);
 508         } else if (*refspecs)
 509                 die("BUG: refspecs without repo?");
 510         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 511         argv_array_clear(&args);
 512         return ret;
 513 }
 514
 515 /**
 516  * "Pulls into void" by branching off merge_head.
 517  */
 518 static int pull_into_void(const struct object_id *merge_head,
 519                 const struct object_id *curr_head)
 520 {
 521         /*
 522          * Two-way merge: we treat the index as based on an empty tree,
 523          * and try to fast-forward to HEAD. This ensures we will not lose
 524          * index/worktree changes that the user already made on the unborn
 525          * branch.
 526          */
 527         if (checkout_fast_forward(EMPTY_TREE_SHA1_BIN, merge_head->hash, 0))
 528                 return 1;
 529
 530         if (update_ref("initial pull", "HEAD", merge_head->hash, curr_head->hash, 0, UPDATE_REFS_DIE_ON_ERR))
 531                 return 1;
 532
 533         return 0;
 534 }
 535
 536 /**
 537  * Runs git-merge, returning its exit status.
 538  */
 539 static int run_merge(void)
 540 {
 541         int ret;
 542         struct argv_array args = ARGV_ARRAY_INIT;
 543
 544         argv_array_pushl(&args, "merge", NULL);
 545
 546         /* Shared options */
 547         argv_push_verbosity(&args);
 548         if (opt_progress)
 549                 argv_array_push(&args, opt_progress);
 550
 551         /* Options passed to git-merge */
 552         if (opt_diffstat)
 553                 argv_array_push(&args, opt_diffstat);
 554         if (opt_log)
 555                 argv_array_push(&args, opt_log);
 556         if (opt_squash)
 557                 argv_array_push(&args, opt_squash);
 558         if (opt_commit)
 559                 argv_array_push(&args, opt_commit);
 560         if (opt_edit)
 561                 argv_array_push(&args, opt_edit);
 562         if (opt_ff)
 563                 argv_array_push(&args, opt_ff);
 564         if (opt_verify_signatures)
 565                 argv_array_push(&args, opt_verify_signatures);
 566         argv_array_pushv(&args, opt_strategies.argv);
 567         argv_array_pushv(&args, opt_strategy_opts.argv);
 568         if (opt_gpg_sign)
 569                 argv_array_push(&args, opt_gpg_sign);
 570         if (opt_allow_unrelated_histories > 0)
 571                 argv_array_push(&args, "--allow-unrelated-histories");
 572
 573         argv_array_push(&args, "FETCH_HEAD");
 574         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 575         argv_array_clear(&args);
 576         return ret;
 577 }
 578
 579 /**
 580  * Returns remote's upstream branch for the current branch. If remote is NULL,
 581  * the current branch's configured default remote is used. Returns NULL if
 582  * `remote` does not name a valid remote, HEAD does not point to a branch,
 583  * remote is not the branch's configured remote or the branch does not have any
 584  * configured upstream branch.
 585  */
 586 static const char *get_upstream_branch(const char *remote)
 587 {
 588         struct remote *rm;
 589         struct branch *curr_branch;
 590         const char *curr_branch_remote;
 591
 592         rm = remote_get(remote);
 593         if (!rm)
 594                 return NULL;
 595
 596         curr_branch = branch_get("HEAD");
 597         if (!curr_branch)
 598                 return NULL;
 599
 600         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 601         assert(curr_branch_remote);
 602
 603         if (strcmp(curr_branch_remote, rm->name))
 604                 return NULL;
 605
 606         return branch_get_upstream(curr_branch, NULL);
 607 }
 608
 609 /**
 610  * Derives the remote tracking branch from the remote and refspec.
 611  *
 612  * FIXME: The current implementation assumes the default mapping of
 613  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 614  */
 615 static const char *get_tracking_branch(const char *remote, const char *refspec)
 616 {
 617         struct refspec *spec;
 618         const char *spec_src;
 619         const char *merge_branch;
 620
 621         spec = parse_fetch_refspec(1, &refspec);
 622         spec_src = spec->src;
 623         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 624                 spec_src = "HEAD";
 625         else if (skip_prefix(spec_src, "heads/", &spec_src))
 626                 ;
 627         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 628                 ;
 629         else if (starts_with(spec_src, "refs/") ||
 630                 starts_with(spec_src, "tags/") ||
 631                 starts_with(spec_src, "remotes/"))
 632                 spec_src = "";
 633
 634         if (*spec_src) {
 635                 if (!strcmp(remote, "."))
 636                         merge_branch = mkpath("refs/heads/%s", spec_src);
 637                 else
 638                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 639         } else
 640                 merge_branch = NULL;
 641
 642         free_refspec(1, spec);
 643         return merge_branch;
 644 }
 645
 646 /**
 647  * Given the repo and refspecs, sets fork_point to the point at which the
 648  * current branch forked from its remote tracking branch. Returns 0 on success,
 649  * -1 on failure.
 650  */
 651 static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,
 652                 const char *refspec)
 653 {
 654         int ret;
 655         struct branch *curr_branch;
 656         const char *remote_branch;
 657         struct child_process cp = CHILD_PROCESS_INIT;
 658         struct strbuf sb = STRBUF_INIT;
 659
 660         curr_branch = branch_get("HEAD");
 661         if (!curr_branch)
 662                 return -1;
 663
 664         if (refspec)
 665                 remote_branch = get_tracking_branch(repo, refspec);
 666         else
 667                 remote_branch = get_upstream_branch(repo);
 668
 669         if (!remote_branch)
 670                 return -1;
 671
 672         argv_array_pushl(&cp.args, "merge-base", "--fork-point",
 673                         remote_branch, curr_branch->name, NULL);
 674         cp.no_stdin = 1;
 675         cp.no_stderr = 1;
 676         cp.git_cmd = 1;
 677
 678         ret = capture_command(&cp, &sb, GIT_SHA1_HEXSZ);
 679         if (ret)
 680                 goto cleanup;
 681
 682         ret = get_oid_hex(sb.buf, fork_point);
 683         if (ret)
 684                 goto cleanup;
 685
 686 cleanup:
 687         strbuf_release(&sb);
 688         return ret ? -1 : 0;
 689 }
 690
 691 /**
 692  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 693  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 694  */
 695 static int get_octopus_merge_base(struct object_id *merge_base,
 696                 const struct object_id *curr_head,
 697                 const struct object_id *merge_head,
 698                 const struct object_id *fork_point)
 699 {
 700         struct commit_list *revs = NULL, *result;
 701
 702         commit_list_insert(lookup_commit_reference(curr_head->hash), &revs);
 703         commit_list_insert(lookup_commit_reference(merge_head->hash), &revs);
 704         if (!is_null_oid(fork_point))
 705                 commit_list_insert(lookup_commit_reference(fork_point->hash), &revs);
 706
 707         result = reduce_heads(get_octopus_merge_bases(revs));
 708         free_commit_list(revs);
 709         if (!result)
 710                 return 1;
 711
 712         oidcpy(merge_base, &result->item->object.oid);
 713         return 0;
 714 }
 715
 716 /**
 717  * Given the current HEAD SHA1, the merge head returned from git-fetch and the
 718  * fork point calculated by get_rebase_fork_point(), runs git-rebase with the
 719  * appropriate arguments and returns its exit status.
 720  */
 721 static int run_rebase(const struct object_id *curr_head,
 722                 const struct object_id *merge_head,
 723                 const struct object_id *fork_point)
 724 {
 725         int ret;
 726         struct object_id oct_merge_base;
 727         struct argv_array args = ARGV_ARRAY_INIT;
 728
 729         if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))
 730                 if (!is_null_oid(fork_point) && !oidcmp(&oct_merge_base, fork_point))
 731                         fork_point = NULL;
 732
 733         argv_array_push(&args, "rebase");
 734
 735         /* Shared options */
 736         argv_push_verbosity(&args);
 737
 738         /* Options passed to git-rebase */
 739         if (opt_rebase == REBASE_PRESERVE)
 740                 argv_array_push(&args, "--preserve-merges");
 741         else if (opt_rebase == REBASE_INTERACTIVE)
 742                 argv_array_push(&args, "--interactive");
 743         if (opt_diffstat)
 744                 argv_array_push(&args, opt_diffstat);
 745         argv_array_pushv(&args, opt_strategies.argv);
 746         argv_array_pushv(&args, opt_strategy_opts.argv);
 747         if (opt_gpg_sign)
 748                 argv_array_push(&args, opt_gpg_sign);
 749         if (opt_autostash == 0)
 750                 argv_array_push(&args, "--no-autostash");
 751         else if (opt_autostash == 1)
 752                 argv_array_push(&args, "--autostash");
 753         if (opt_verify_signatures &&
 754             !strcmp(opt_verify_signatures, "--verify-signatures"))
 755                 warning(_("ignoring --verify-signatures for rebase"));
 756
 757         argv_array_push(&args, "--onto");
 758         argv_array_push(&args, oid_to_hex(merge_head));
 759
 760         if (fork_point && !is_null_oid(fork_point))
 761                 argv_array_push(&args, oid_to_hex(fork_point));
 762         else
 763                 argv_array_push(&args, oid_to_hex(merge_head));
 764
 765         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 766         argv_array_clear(&args);
 767         return ret;
 768 }
 769
 770 int cmd_pull(int argc, const char **argv, const char *prefix)
 771 {
 772         const char *repo, **refspecs;
 773         struct oid_array merge_heads = OID_ARRAY_INIT;
 774         struct object_id orig_head, curr_head;
 775         struct object_id rebase_fork_point;
 776
 777         if (!getenv("GIT_REFLOG_ACTION"))
 778                 set_reflog_message(argc, argv);
 779
 780         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 781
 782         parse_repo_refspecs(argc, argv, &repo, &refspecs);
 783
 784         if (!opt_ff)
 785                 opt_ff = xstrdup_or_null(config_get_ff());
 786
 787         if (opt_rebase < 0)
 788                 opt_rebase = config_get_rebase();
 789
 790         git_config(git_pull_config, NULL);
 791
 792         if (read_cache_unmerged())
 793                 die_resolve_conflict("pull");
 794
 795         if (file_exists(git_path_merge_head()))
 796                 die_conclude_merge();
 797
 798         if (get_oid("HEAD", &orig_head))
 799                 oidclr(&orig_head);
 800
 801         if (!opt_rebase && opt_autostash != -1)
 802                 die(_("--[no-]autostash option is only valid with --rebase."));
 803
 804         if (opt_rebase) {
 805                 int autostash = config_autostash;
 806                 if (opt_autostash != -1)
 807                         autostash = opt_autostash;
 808
 809                 if (is_null_oid(&orig_head) && !is_cache_unborn())
 810                         die(_("Updating an unborn branch with changes added to the index."));
 811
 812                 if (!autostash)
 813                         require_clean_work_tree(N_("pull with rebase"),
 814                                 _("please commit or stash them."), 1, 0);
 815
 816                 if (get_rebase_fork_point(&rebase_fork_point, repo, *refspecs))
 817                         oidclr(&rebase_fork_point);
 818         }
 819
 820         if (run_fetch(repo, refspecs))
 821                 return 1;
 822
 823         if (opt_dry_run)
 824                 return 0;
 825
 826         if (get_oid("HEAD", &curr_head))
 827                 oidclr(&curr_head);
 828
 829         if (!is_null_oid(&orig_head) && !is_null_oid(&curr_head) &&
 830                         oidcmp(&orig_head, &curr_head)) {
 831                 /*
 832                  * The fetch involved updating the current branch.
 833                  *
 834                  * The working tree and the index file are still based on
 835                  * orig_head commit, but we are merging into curr_head.
 836                  * Update the working tree to match curr_head.
 837                  */
 838
 839                 warning(_("fetch updated the current branch head.\n"
 840                         "fast-forwarding your working tree from\n"
 841                         "commit %s."), oid_to_hex(&orig_head));
 842
 843                 if (checkout_fast_forward(orig_head.hash, curr_head.hash, 0))
 844                         die(_("Cannot fast-forward your working tree.\n"
 845                                 "After making sure that you saved anything precious from\n"
 846                                 "$ git diff %s\n"
 847                                 "output, run\n"
 848                                 "$ git reset --hard\n"
 849                                 "to recover."), oid_to_hex(&orig_head));
 850         }
 851
 852         get_merge_heads(&merge_heads);
 853
 854         if (!merge_heads.nr)
 855                 die_no_merge_candidates(repo, refspecs);
 856
 857         if (is_null_oid(&orig_head)) {
 858                 if (merge_heads.nr > 1)
 859                         die(_("Cannot merge multiple branches into empty head."));
 860                 return pull_into_void(merge_heads.oid, &curr_head);
 861         }
 862         if (opt_rebase && merge_heads.nr > 1)
 863                 die(_("Cannot rebase onto multiple branches."));
 864
 865         if (opt_rebase) {
 866                 struct commit_list *list = NULL;
 867                 struct commit *merge_head, *head;
 868
 869                 head = lookup_commit_reference(orig_head.hash);
 870                 commit_list_insert(head, &list);
 871                 merge_head = lookup_commit_reference(merge_heads.oid[0].hash);
 872                 if (is_descendant_of(merge_head, list)) {
 873                         /* we can fast-forward this without invoking rebase */
 874                         opt_ff = "--ff-only";
 875                         return run_merge();
 876                 }
 877                 return run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
 878         } else {
 879                 return run_merge();
 880         }
 881 }