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 "builtin.h"
  10 #include "parse-options.h"
  11 #include "exec_cmd.h"
  12 #include "run-command.h"
  13 #include "sha1-array.h"
  14 #include "remote.h"
  15 #include "dir.h"
  16 #include "refs.h"
  17 #include "revision.h"
  18 #include "tempfile.h"
  19 #include "lockfile.h"
  20
  21 enum rebase_type {
  22         REBASE_INVALID = -1,
  23         REBASE_FALSE = 0,
  24         REBASE_TRUE,
  25         REBASE_PRESERVE
  26 };
  27
  28 /**
  29  * Parses the value of --rebase. If value is a false value, returns
  30  * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is
  31  * "preserve", returns REBASE_PRESERVE. If value is a invalid value, dies with
  32  * a fatal error if fatal is true, otherwise returns REBASE_INVALID.
  33  */
  34 static enum rebase_type parse_config_rebase(const char *key, const char *value,
  35                 int fatal)
  36 {
  37         int v = git_config_maybe_bool("pull.rebase", value);
  38
  39         if (!v)
  40                 return REBASE_FALSE;
  41         else if (v > 0)
  42                 return REBASE_TRUE;
  43         else if (!strcmp(value, "preserve"))
  44                 return REBASE_PRESERVE;
  45
  46         if (fatal)
  47                 die(_("Invalid value for %s: %s"), key, value);
  48         else
  49                 error(_("Invalid value for %s: %s"), key, value);
  50
  51         return REBASE_INVALID;
  52 }
  53
  54 /**
  55  * Callback for --rebase, which parses arg with parse_config_rebase().
  56  */
  57 static int parse_opt_rebase(const struct option *opt, const char *arg, int unset)
  58 {
  59         enum rebase_type *value = opt->value;
  60
  61         if (arg)
  62                 *value = parse_config_rebase("--rebase", arg, 0);
  63         else
  64                 *value = unset ? REBASE_FALSE : REBASE_TRUE;
  65         return *value == REBASE_INVALID ? -1 : 0;
  66 }
  67
  68 static const char * const pull_usage[] = {
  69         N_("git pull [options] [<repository> [<refspec>...]]"),
  70         NULL
  71 };
  72
  73 /* Shared options */
  74 static int opt_verbosity;
  75 static char *opt_progress;
  76
  77 /* Options passed to git-merge or git-rebase */
  78 static enum rebase_type opt_rebase = -1;
  79 static char *opt_diffstat;
  80 static char *opt_log;
  81 static char *opt_squash;
  82 static char *opt_commit;
  83 static char *opt_edit;
  84 static char *opt_ff;
  85 static char *opt_verify_signatures;
  86 static struct argv_array opt_strategies = ARGV_ARRAY_INIT;
  87 static struct argv_array opt_strategy_opts = ARGV_ARRAY_INIT;
  88 static char *opt_gpg_sign;
  89
  90 /* Options passed to git-fetch */
  91 static char *opt_all;
  92 static char *opt_append;
  93 static char *opt_upload_pack;
  94 static int opt_force;
  95 static char *opt_tags;
  96 static char *opt_prune;
  97 static char *opt_recurse_submodules;
  98 static int opt_dry_run;
  99 static char *opt_keep;
 100 static char *opt_depth;
 101 static char *opt_unshallow;
 102 static char *opt_update_shallow;
 103 static char *opt_refmap;
 104
 105 static struct option pull_options[] = {
 106         /* Shared options */
 107         OPT__VERBOSITY(&opt_verbosity),
 108         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 109                 N_("force progress reporting"),
 110                 PARSE_OPT_NOARG),
 111
 112         /* Options passed to git-merge or git-rebase */
 113         OPT_GROUP(N_("Options related to merging")),
 114         { OPTION_CALLBACK, 'r', "rebase", &opt_rebase,
 115           N_("false|true|preserve"),
 116           N_("incorporate changes by rebasing rather than merging"),
 117           PARSE_OPT_OPTARG, parse_opt_rebase },
 118         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 119                 N_("do not show a diffstat at the end of the merge"),
 120                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 121         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 122                 N_("show a diffstat at the end of the merge"),
 123                 PARSE_OPT_NOARG),
 124         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 125                 N_("(synonym to --stat)"),
 126                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 127         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 128                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 129                 PARSE_OPT_OPTARG),
 130         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 131                 N_("create a single commit instead of doing a merge"),
 132                 PARSE_OPT_NOARG),
 133         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 134                 N_("perform a commit if the merge succeeds (default)"),
 135                 PARSE_OPT_NOARG),
 136         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 137                 N_("edit message before committing"),
 138                 PARSE_OPT_NOARG),
 139         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 140                 N_("allow fast-forward"),
 141                 PARSE_OPT_NOARG),
 142         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 143                 N_("abort if fast-forward is not possible"),
 144                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 145         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 146                 N_("verify that the named commit has a valid GPG signature"),
 147                 PARSE_OPT_NOARG),
 148         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 149                 N_("merge strategy to use"),
 150                 0),
 151         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 152                 N_("option=value"),
 153                 N_("option for selected merge strategy"),
 154                 0),
 155         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 156                 N_("GPG sign commit"),
 157                 PARSE_OPT_OPTARG),
 158
 159         /* Options passed to git-fetch */
 160         OPT_GROUP(N_("Options related to fetching")),
 161         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 162                 N_("fetch from all remotes"),
 163                 PARSE_OPT_NOARG),
 164         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 165                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 166                 PARSE_OPT_NOARG),
 167         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 168                 N_("path to upload pack on remote end"),
 169                 0),
 170         OPT__FORCE(&opt_force, N_("force overwrite of local branch")),
 171         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 172                 N_("fetch all tags and associated objects"),
 173                 PARSE_OPT_NOARG),
 174         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 175                 N_("prune remote-tracking branches no longer on remote"),
 176                 PARSE_OPT_NOARG),
 177         OPT_PASSTHRU(0, "recurse-submodules", &opt_recurse_submodules,
 178                 N_("on-demand"),
 179                 N_("control recursive fetching of submodules"),
 180                 PARSE_OPT_OPTARG),
 181         OPT_BOOL(0, "dry-run", &opt_dry_run,
 182                 N_("dry run")),
 183         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 184                 N_("keep downloaded pack"),
 185                 PARSE_OPT_NOARG),
 186         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 187                 N_("deepen history of shallow clone"),
 188                 0),
 189         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 190                 N_("convert to a complete repository"),
 191                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 192         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 193                 N_("accept refs that update .git/shallow"),
 194                 PARSE_OPT_NOARG),
 195         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 196                 N_("specify fetch refmap"),
 197                 PARSE_OPT_NONEG),
 198
 199         OPT_END()
 200 };
 201
 202 /**
 203  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 204  */
 205 static void argv_push_verbosity(struct argv_array *arr)
 206 {
 207         int verbosity;
 208
 209         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 210                 argv_array_push(arr, "-v");
 211
 212         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 213                 argv_array_push(arr, "-q");
 214 }
 215
 216 /**
 217  * Pushes "-f" switches into arr to match the opt_force level.
 218  */
 219 static void argv_push_force(struct argv_array *arr)
 220 {
 221         int force = opt_force;
 222         while (force-- > 0)
 223                 argv_array_push(arr, "-f");
 224 }
 225
 226 /**
 227  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 228  */
 229 static void set_reflog_message(int argc, const char **argv)
 230 {
 231         int i;
 232         struct strbuf msg = STRBUF_INIT;
 233
 234         for (i = 0; i < argc; i++) {
 235                 if (i)
 236                         strbuf_addch(&msg, ' ');
 237                 strbuf_addstr(&msg, argv[i]);
 238         }
 239
 240         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 241
 242         strbuf_release(&msg);
 243 }
 244
 245 /**
 246  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 247  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 248  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 249  * error.
 250  */
 251 static const char *config_get_ff(void)
 252 {
 253         const char *value;
 254
 255         if (git_config_get_value("pull.ff", &value))
 256                 return NULL;
 257
 258         switch (git_config_maybe_bool("pull.ff", value)) {
 259         case 0:
 260                 return "--no-ff";
 261         case 1:
 262                 return "--ff";
 263         }
 264
 265         if (!strcmp(value, "only"))
 266                 return "--ff-only";
 267
 268         die(_("Invalid value for pull.ff: %s"), value);
 269 }
 270
 271 /**
 272  * Returns the default configured value for --rebase. It first looks for the
 273  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 274  * branch, and if HEAD is detached or the configuration key does not exist,
 275  * looks for the value of "pull.rebase". If both configuration keys do not
 276  * exist, returns REBASE_FALSE.
 277  */
 278 static enum rebase_type config_get_rebase(void)
 279 {
 280         struct branch *curr_branch = branch_get("HEAD");
 281         const char *value;
 282
 283         if (curr_branch) {
 284                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 285
 286                 if (!git_config_get_value(key, &value)) {
 287                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 288                         free(key);
 289                         return ret;
 290                 }
 291
 292                 free(key);
 293         }
 294
 295         if (!git_config_get_value("pull.rebase", &value))
 296                 return parse_config_rebase("pull.rebase", value, 1);
 297
 298         return REBASE_FALSE;
 299 }
 300
 301 /**
 302  * Returns 1 if there are unstaged changes, 0 otherwise.
 303  */
 304 static int has_unstaged_changes(const char *prefix)
 305 {
 306         struct rev_info rev_info;
 307         int result;
 308
 309         init_revisions(&rev_info, prefix);
 310         DIFF_OPT_SET(&rev_info.diffopt, IGNORE_SUBMODULES);
 311         DIFF_OPT_SET(&rev_info.diffopt, QUICK);
 312         diff_setup_done(&rev_info.diffopt);
 313         result = run_diff_files(&rev_info, 0);
 314         return diff_result_code(&rev_info.diffopt, result);
 315 }
 316
 317 /**
 318  * Returns 1 if there are uncommitted changes, 0 otherwise.
 319  */
 320 static int has_uncommitted_changes(const char *prefix)
 321 {
 322         struct rev_info rev_info;
 323         int result;
 324
 325         if (is_cache_unborn())
 326                 return 0;
 327
 328         init_revisions(&rev_info, prefix);
 329         DIFF_OPT_SET(&rev_info.diffopt, IGNORE_SUBMODULES);
 330         DIFF_OPT_SET(&rev_info.diffopt, QUICK);
 331         add_head_to_pending(&rev_info);
 332         diff_setup_done(&rev_info.diffopt);
 333         result = run_diff_index(&rev_info, 1);
 334         return diff_result_code(&rev_info.diffopt, result);
 335 }
 336
 337 /**
 338  * If the work tree has unstaged or uncommitted changes, dies with the
 339  * appropriate message.
 340  */
 341 static void die_on_unclean_work_tree(const char *prefix)
 342 {
 343         struct lock_file *lock_file = xcalloc(1, sizeof(*lock_file));
 344         int do_die = 0;
 345
 346         hold_locked_index(lock_file, 0);
 347         refresh_cache(REFRESH_QUIET);
 348         update_index_if_able(&the_index, lock_file);
 349         rollback_lock_file(lock_file);
 350
 351         if (has_unstaged_changes(prefix)) {
 352                 error(_("Cannot pull with rebase: You have unstaged changes."));
 353                 do_die = 1;
 354         }
 355
 356         if (has_uncommitted_changes(prefix)) {
 357                 if (do_die)
 358                         error(_("Additionally, your index contains uncommitted changes."));
 359                 else
 360                         error(_("Cannot pull with rebase: Your index contains uncommitted changes."));
 361                 do_die = 1;
 362         }
 363
 364         if (do_die)
 365                 exit(1);
 366 }
 367
 368 /**
 369  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 370  * into merge_heads.
 371  */
 372 static void get_merge_heads(struct sha1_array *merge_heads)
 373 {
 374         const char *filename = git_path("FETCH_HEAD");
 375         FILE *fp;
 376         struct strbuf sb = STRBUF_INIT;
 377         unsigned char sha1[GIT_SHA1_RAWSZ];
 378
 379         if (!(fp = fopen(filename, "r")))
 380                 die_errno(_("could not open '%s' for reading"), filename);
 381         while (strbuf_getline(&sb, fp, '\n') != EOF) {
 382                 if (get_sha1_hex(sb.buf, sha1))
 383                         continue;  /* invalid line: does not start with SHA1 */
 384                 if (starts_with(sb.buf + GIT_SHA1_HEXSZ, "\tnot-for-merge\t"))
 385                         continue;  /* ref is not-for-merge */
 386                 sha1_array_append(merge_heads, sha1);
 387         }
 388         fclose(fp);
 389         strbuf_release(&sb);
 390 }
 391
 392 /**
 393  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 394  * retrieve the name of the remote if the repository only has one remote.
 395  */
 396 static int get_only_remote(struct remote *remote, void *cb_data)
 397 {
 398         const char **remote_name = cb_data;
 399
 400         if (*remote_name)
 401                 return -1;
 402
 403         *remote_name = remote->name;
 404         return 0;
 405 }
 406
 407 /**
 408  * Dies with the appropriate reason for why there are no merge candidates:
 409  *
 410  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 411  *    up not fetching anything. This is usually because the user provided a
 412  *    wildcard refspec which had no matches on the remote end.
 413  *
 414  * 2. We fetched from a non-default remote, but didn't specify a branch to
 415  *    merge. We can't use the configured one because it applies to the default
 416  *    remote, thus the user must specify the branches to merge.
 417  *
 418  * 3. We fetched from the branch's or repo's default remote, but:
 419  *
 420  *    a. We are not on a branch, so there will never be a configured branch to
 421  *       merge with.
 422  *
 423  *    b. We are on a branch, but there is no configured branch to merge with.
 424  *
 425  * 4. We fetched from the branch's or repo's default remote, but the configured
 426  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 427  *    part of the configured fetch refspec.)
 428  */
 429 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 430 {
 431         struct branch *curr_branch = branch_get("HEAD");
 432         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 433
 434         if (*refspecs) {
 435                 if (opt_rebase)
 436                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 437                 else
 438                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 439                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 440                                         "matches on the remote end."));
 441         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 442                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 443                         "a branch. Because this is not the default configured remote\n"
 444                         "for your current branch, you must specify a branch on the command line."),
 445                         repo);
 446         } else if (!curr_branch) {
 447                 fprintf_ln(stderr, _("You are not currently on a branch."));
 448                 if (opt_rebase)
 449                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 450                 else
 451                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 452                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 453                 fprintf(stderr, "\n");
 454                 fprintf_ln(stderr, "    git pull <remote> <branch>");
 455                 fprintf(stderr, "\n");
 456         } else if (!curr_branch->merge_nr) {
 457                 const char *remote_name = NULL;
 458
 459                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 460                         remote_name = "<remote>";
 461
 462                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 463                 if (opt_rebase)
 464                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 465                 else
 466                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 467                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 468                 fprintf(stderr, "\n");
 469                 fprintf_ln(stderr, "    git pull <remote> <branch>");
 470                 fprintf(stderr, "\n");
 471                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:\n"
 472                                 "\n"
 473                                 "    git branch --set-upstream-to=%s/<branch> %s\n"),
 474                                 remote_name, curr_branch->name);
 475         } else
 476                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 477                         "from the remote, but no such ref was fetched."),
 478                         *curr_branch->merge_name);
 479         exit(1);
 480 }
 481
 482 /**
 483  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 484  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 485  * is not provided in argv, it is set to NULL.
 486  */
 487 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 488                 const char ***refspecs)
 489 {
 490         if (argc > 0) {
 491                 *repo = *argv++;
 492                 argc--;
 493         } else
 494                 *repo = NULL;
 495         *refspecs = argv;
 496 }
 497
 498 /**
 499  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 500  * repository and refspecs to fetch, or NULL if they are not provided.
 501  */
 502 static int run_fetch(const char *repo, const char **refspecs)
 503 {
 504         struct argv_array args = ARGV_ARRAY_INIT;
 505         int ret;
 506
 507         argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
 508
 509         /* Shared options */
 510         argv_push_verbosity(&args);
 511         if (opt_progress)
 512                 argv_array_push(&args, opt_progress);
 513
 514         /* Options passed to git-fetch */
 515         if (opt_all)
 516                 argv_array_push(&args, opt_all);
 517         if (opt_append)
 518                 argv_array_push(&args, opt_append);
 519         if (opt_upload_pack)
 520                 argv_array_push(&args, opt_upload_pack);
 521         argv_push_force(&args);
 522         if (opt_tags)
 523                 argv_array_push(&args, opt_tags);
 524         if (opt_prune)
 525                 argv_array_push(&args, opt_prune);
 526         if (opt_recurse_submodules)
 527                 argv_array_push(&args, opt_recurse_submodules);
 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
 541         if (repo) {
 542                 argv_array_push(&args, repo);
 543                 argv_array_pushv(&args, refspecs);
 544         } else if (*refspecs)
 545                 die("BUG: refspecs without repo?");
 546         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 547         argv_array_clear(&args);
 548         return ret;
 549 }
 550
 551 /**
 552  * "Pulls into void" by branching off merge_head.
 553  */
 554 static int pull_into_void(const unsigned char *merge_head,
 555                 const unsigned char *curr_head)
 556 {
 557         /*
 558          * Two-way merge: we treat the index as based on an empty tree,
 559          * and try to fast-forward to HEAD. This ensures we will not lose
 560          * index/worktree changes that the user already made on the unborn
 561          * branch.
 562          */
 563         if (checkout_fast_forward(EMPTY_TREE_SHA1_BIN, merge_head, 0))
 564                 return 1;
 565
 566         if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 567                 return 1;
 568
 569         return 0;
 570 }
 571
 572 /**
 573  * Runs git-merge, returning its exit status.
 574  */
 575 static int run_merge(void)
 576 {
 577         int ret;
 578         struct argv_array args = ARGV_ARRAY_INIT;
 579
 580         argv_array_pushl(&args, "merge", NULL);
 581
 582         /* Shared options */
 583         argv_push_verbosity(&args);
 584         if (opt_progress)
 585                 argv_array_push(&args, opt_progress);
 586
 587         /* Options passed to git-merge */
 588         if (opt_diffstat)
 589                 argv_array_push(&args, opt_diffstat);
 590         if (opt_log)
 591                 argv_array_push(&args, opt_log);
 592         if (opt_squash)
 593                 argv_array_push(&args, opt_squash);
 594         if (opt_commit)
 595                 argv_array_push(&args, opt_commit);
 596         if (opt_edit)
 597                 argv_array_push(&args, opt_edit);
 598         if (opt_ff)
 599                 argv_array_push(&args, opt_ff);
 600         if (opt_verify_signatures)
 601                 argv_array_push(&args, opt_verify_signatures);
 602         argv_array_pushv(&args, opt_strategies.argv);
 603         argv_array_pushv(&args, opt_strategy_opts.argv);
 604         if (opt_gpg_sign)
 605                 argv_array_push(&args, opt_gpg_sign);
 606
 607         argv_array_push(&args, "FETCH_HEAD");
 608         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 609         argv_array_clear(&args);
 610         return ret;
 611 }
 612
 613 /**
 614  * Returns remote's upstream branch for the current branch. If remote is NULL,
 615  * the current branch's configured default remote is used. Returns NULL if
 616  * `remote` does not name a valid remote, HEAD does not point to a branch,
 617  * remote is not the branch's configured remote or the branch does not have any
 618  * configured upstream branch.
 619  */
 620 static const char *get_upstream_branch(const char *remote)
 621 {
 622         struct remote *rm;
 623         struct branch *curr_branch;
 624         const char *curr_branch_remote;
 625
 626         rm = remote_get(remote);
 627         if (!rm)
 628                 return NULL;
 629
 630         curr_branch = branch_get("HEAD");
 631         if (!curr_branch)
 632                 return NULL;
 633
 634         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 635         assert(curr_branch_remote);
 636
 637         if (strcmp(curr_branch_remote, rm->name))
 638                 return NULL;
 639
 640         return branch_get_upstream(curr_branch, NULL);
 641 }
 642
 643 /**
 644  * Derives the remote tracking branch from the remote and refspec.
 645  *
 646  * FIXME: The current implementation assumes the default mapping of
 647  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 648  */
 649 static const char *get_tracking_branch(const char *remote, const char *refspec)
 650 {
 651         struct refspec *spec;
 652         const char *spec_src;
 653         const char *merge_branch;
 654
 655         spec = parse_fetch_refspec(1, &refspec);
 656         spec_src = spec->src;
 657         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 658                 spec_src = "HEAD";
 659         else if (skip_prefix(spec_src, "heads/", &spec_src))
 660                 ;
 661         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 662                 ;
 663         else if (starts_with(spec_src, "refs/") ||
 664                 starts_with(spec_src, "tags/") ||
 665                 starts_with(spec_src, "remotes/"))
 666                 spec_src = "";
 667
 668         if (*spec_src) {
 669                 if (!strcmp(remote, "."))
 670                         merge_branch = mkpath("refs/heads/%s", spec_src);
 671                 else
 672                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 673         } else
 674                 merge_branch = NULL;
 675
 676         free_refspec(1, spec);
 677         return merge_branch;
 678 }
 679
 680 /**
 681  * Given the repo and refspecs, sets fork_point to the point at which the
 682  * current branch forked from its remote tracking branch. Returns 0 on success,
 683  * -1 on failure.
 684  */
 685 static int get_rebase_fork_point(unsigned char *fork_point, const char *repo,
 686                 const char *refspec)
 687 {
 688         int ret;
 689         struct branch *curr_branch;
 690         const char *remote_branch;
 691         struct child_process cp = CHILD_PROCESS_INIT;
 692         struct strbuf sb = STRBUF_INIT;
 693
 694         curr_branch = branch_get("HEAD");
 695         if (!curr_branch)
 696                 return -1;
 697
 698         if (refspec)
 699                 remote_branch = get_tracking_branch(repo, refspec);
 700         else
 701                 remote_branch = get_upstream_branch(repo);
 702
 703         if (!remote_branch)
 704                 return -1;
 705
 706         argv_array_pushl(&cp.args, "merge-base", "--fork-point",
 707                         remote_branch, curr_branch->name, NULL);
 708         cp.no_stdin = 1;
 709         cp.no_stderr = 1;
 710         cp.git_cmd = 1;
 711
 712         ret = capture_command(&cp, &sb, GIT_SHA1_HEXSZ);
 713         if (ret)
 714                 goto cleanup;
 715
 716         ret = get_sha1_hex(sb.buf, fork_point);
 717         if (ret)
 718                 goto cleanup;
 719
 720 cleanup:
 721         strbuf_release(&sb);
 722         return ret ? -1 : 0;
 723 }
 724
 725 /**
 726  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 727  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 728  */
 729 static int get_octopus_merge_base(unsigned char *merge_base,
 730                 const unsigned char *curr_head,
 731                 const unsigned char *merge_head,
 732                 const unsigned char *fork_point)
 733 {
 734         struct commit_list *revs = NULL, *result;
 735
 736         commit_list_insert(lookup_commit_reference(curr_head), &revs);
 737         commit_list_insert(lookup_commit_reference(merge_head), &revs);
 738         if (!is_null_sha1(fork_point))
 739                 commit_list_insert(lookup_commit_reference(fork_point), &revs);
 740
 741         result = reduce_heads(get_octopus_merge_bases(revs));
 742         free_commit_list(revs);
 743         if (!result)
 744                 return 1;
 745
 746         hashcpy(merge_base, result->item->object.sha1);
 747         return 0;
 748 }
 749
 750 /**
 751  * Given the current HEAD SHA1, the merge head returned from git-fetch and the
 752  * fork point calculated by get_rebase_fork_point(), runs git-rebase with the
 753  * appropriate arguments and returns its exit status.
 754  */
 755 static int run_rebase(const unsigned char *curr_head,
 756                 const unsigned char *merge_head,
 757                 const unsigned char *fork_point)
 758 {
 759         int ret;
 760         unsigned char oct_merge_base[GIT_SHA1_RAWSZ];
 761         struct argv_array args = ARGV_ARRAY_INIT;
 762
 763         if (!get_octopus_merge_base(oct_merge_base, curr_head, merge_head, fork_point))
 764                 if (!is_null_sha1(fork_point) && !hashcmp(oct_merge_base, fork_point))
 765                         fork_point = NULL;
 766
 767         argv_array_push(&args, "rebase");
 768
 769         /* Shared options */
 770         argv_push_verbosity(&args);
 771
 772         /* Options passed to git-rebase */
 773         if (opt_rebase == REBASE_PRESERVE)
 774                 argv_array_push(&args, "--preserve-merges");
 775         if (opt_diffstat)
 776                 argv_array_push(&args, opt_diffstat);
 777         argv_array_pushv(&args, opt_strategies.argv);
 778         argv_array_pushv(&args, opt_strategy_opts.argv);
 779         if (opt_gpg_sign)
 780                 argv_array_push(&args, opt_gpg_sign);
 781
 782         argv_array_push(&args, "--onto");
 783         argv_array_push(&args, sha1_to_hex(merge_head));
 784
 785         if (fork_point && !is_null_sha1(fork_point))
 786                 argv_array_push(&args, sha1_to_hex(fork_point));
 787         else
 788                 argv_array_push(&args, sha1_to_hex(merge_head));
 789
 790         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 791         argv_array_clear(&args);
 792         return ret;
 793 }
 794
 795 int cmd_pull(int argc, const char **argv, const char *prefix)
 796 {
 797         const char *repo, **refspecs;
 798         struct sha1_array merge_heads = SHA1_ARRAY_INIT;
 799         unsigned char orig_head[GIT_SHA1_RAWSZ], curr_head[GIT_SHA1_RAWSZ];
 800         unsigned char rebase_fork_point[GIT_SHA1_RAWSZ];
 801
 802         if (!getenv("GIT_REFLOG_ACTION"))
 803                 set_reflog_message(argc, argv);
 804
 805         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 806
 807         parse_repo_refspecs(argc, argv, &repo, &refspecs);
 808
 809         if (!opt_ff)
 810                 opt_ff = xstrdup_or_null(config_get_ff());
 811
 812         if (opt_rebase < 0)
 813                 opt_rebase = config_get_rebase();
 814
 815         git_config(git_default_config, NULL);
 816
 817         if (read_cache_unmerged())
 818                 die_resolve_conflict("Pull");
 819
 820         if (file_exists(git_path("MERGE_HEAD")))
 821                 die_conclude_merge();
 822
 823         if (get_sha1("HEAD", orig_head))
 824                 hashclr(orig_head);
 825
 826         if (opt_rebase) {
 827                 int autostash = 0;
 828
 829                 if (is_null_sha1(orig_head) && !is_cache_unborn())
 830                         die(_("Updating an unborn branch with changes added to the index."));
 831
 832                 git_config_get_bool("rebase.autostash", &autostash);
 833                 if (!autostash)
 834                         die_on_unclean_work_tree(prefix);
 835
 836                 if (get_rebase_fork_point(rebase_fork_point, repo, *refspecs))
 837                         hashclr(rebase_fork_point);
 838         }
 839
 840         if (run_fetch(repo, refspecs))
 841                 return 1;
 842
 843         if (opt_dry_run)
 844                 return 0;
 845
 846         if (get_sha1("HEAD", curr_head))
 847                 hashclr(curr_head);
 848
 849         if (!is_null_sha1(orig_head) && !is_null_sha1(curr_head) &&
 850                         hashcmp(orig_head, curr_head)) {
 851                 /*
 852                  * The fetch involved updating the current branch.
 853                  *
 854                  * The working tree and the index file are still based on
 855                  * orig_head commit, but we are merging into curr_head.
 856                  * Update the working tree to match curr_head.
 857                  */
 858
 859                 warning(_("fetch updated the current branch head.\n"
 860                         "fast-forwarding your working tree from\n"
 861                         "commit %s."), sha1_to_hex(orig_head));
 862
 863                 if (checkout_fast_forward(orig_head, curr_head, 0))
 864                         die(_("Cannot fast-forward your working tree.\n"
 865                                 "After making sure that you saved anything precious from\n"
 866                                 "$ git diff %s\n"
 867                                 "output, run\n"
 868                                 "$ git reset --hard\n"
 869                                 "to recover."), sha1_to_hex(orig_head));
 870         }
 871
 872         get_merge_heads(&merge_heads);
 873
 874         if (!merge_heads.nr)
 875                 die_no_merge_candidates(repo, refspecs);
 876
 877         if (is_null_sha1(orig_head)) {
 878                 if (merge_heads.nr > 1)
 879                         die(_("Cannot merge multiple branches into empty head."));
 880                 return pull_into_void(*merge_heads.sha1, curr_head);
 881         } else if (opt_rebase) {
 882                 if (merge_heads.nr > 1)
 883                         die(_("Cannot rebase onto multiple branches."));
 884                 return run_rebase(curr_head, *merge_heads.sha1, rebase_fork_point);
 885         } else
 886                 return run_merge();
 887 }