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         REBASE_INTERACTIVE
  27 };
  28
  29 /**
  30  * Parses the value of --rebase. If value is a false value, returns
  31  * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is
  32  * "preserve", returns REBASE_PRESERVE. If value is a invalid value, dies with
  33  * a fatal error if fatal is true, otherwise returns REBASE_INVALID.
  34  */
  35 static enum rebase_type parse_config_rebase(const char *key, const char *value,
  36                 int fatal)
  37 {
  38         int v = git_config_maybe_bool("pull.rebase", value);
  39
  40         if (!v)
  41                 return REBASE_FALSE;
  42         else if (v > 0)
  43                 return REBASE_TRUE;
  44         else if (!strcmp(value, "preserve"))
  45                 return REBASE_PRESERVE;
  46         else if (!strcmp(value, "interactive"))
  47                 return REBASE_INTERACTIVE;
  48
  49         if (fatal)
  50                 die(_("Invalid value for %s: %s"), key, value);
  51         else
  52                 error(_("Invalid value for %s: %s"), key, value);
  53
  54         return REBASE_INVALID;
  55 }
  56
  57 /**
  58  * Callback for --rebase, which parses arg with parse_config_rebase().
  59  */
  60 static int parse_opt_rebase(const struct option *opt, const char *arg, int unset)
  61 {
  62         enum rebase_type *value = opt->value;
  63
  64         if (arg)
  65                 *value = parse_config_rebase("--rebase", arg, 0);
  66         else
  67                 *value = unset ? REBASE_FALSE : REBASE_TRUE;
  68         return *value == REBASE_INVALID ? -1 : 0;
  69 }
  70
  71 static const char * const pull_usage[] = {
  72         N_("git pull [<options>] [<repository> [<refspec>...]]"),
  73         NULL
  74 };
  75
  76 /* Shared options */
  77 static int opt_verbosity;
  78 static char *opt_progress;
  79
  80 /* Options passed to git-merge or git-rebase */
  81 static enum rebase_type opt_rebase = -1;
  82 static char *opt_diffstat;
  83 static char *opt_log;
  84 static char *opt_squash;
  85 static char *opt_commit;
  86 static char *opt_edit;
  87 static char *opt_ff;
  88 static char *opt_verify_signatures;
  89 static int opt_autostash = -1;
  90 static int config_autostash;
  91 static struct argv_array opt_strategies = ARGV_ARRAY_INIT;
  92 static struct argv_array opt_strategy_opts = ARGV_ARRAY_INIT;
  93 static char *opt_gpg_sign;
  94
  95 /* Options passed to git-fetch */
  96 static char *opt_all;
  97 static char *opt_append;
  98 static char *opt_upload_pack;
  99 static int opt_force;
 100 static char *opt_tags;
 101 static char *opt_prune;
 102 static char *opt_recurse_submodules;
 103 static char *max_children;
 104 static int opt_dry_run;
 105 static char *opt_keep;
 106 static char *opt_depth;
 107 static char *opt_unshallow;
 108 static char *opt_update_shallow;
 109 static char *opt_refmap;
 110
 111 static struct option pull_options[] = {
 112         /* Shared options */
 113         OPT__VERBOSITY(&opt_verbosity),
 114         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 115                 N_("force progress reporting"),
 116                 PARSE_OPT_NOARG),
 117
 118         /* Options passed to git-merge or git-rebase */
 119         OPT_GROUP(N_("Options related to merging")),
 120         { OPTION_CALLBACK, 'r', "rebase", &opt_rebase,
 121           "false|true|preserve|interactive",
 122           N_("incorporate changes by rebasing rather than merging"),
 123           PARSE_OPT_OPTARG, parse_opt_rebase },
 124         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 125                 N_("do not show a diffstat at the end of the merge"),
 126                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 127         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 128                 N_("show a diffstat at the end of the merge"),
 129                 PARSE_OPT_NOARG),
 130         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 131                 N_("(synonym to --stat)"),
 132                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 133         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 134                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 135                 PARSE_OPT_OPTARG),
 136         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 137                 N_("create a single commit instead of doing a merge"),
 138                 PARSE_OPT_NOARG),
 139         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 140                 N_("perform a commit if the merge succeeds (default)"),
 141                 PARSE_OPT_NOARG),
 142         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 143                 N_("edit message before committing"),
 144                 PARSE_OPT_NOARG),
 145         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 146                 N_("allow fast-forward"),
 147                 PARSE_OPT_NOARG),
 148         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 149                 N_("abort if fast-forward is not possible"),
 150                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 151         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 152                 N_("verify that the named commit has a valid GPG signature"),
 153                 PARSE_OPT_NOARG),
 154         OPT_BOOL(0, "autostash", &opt_autostash,
 155                 N_("automatically stash/stash pop before and after rebase")),
 156         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 157                 N_("merge strategy to use"),
 158                 0),
 159         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 160                 N_("option=value"),
 161                 N_("option for selected merge strategy"),
 162                 0),
 163         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 164                 N_("GPG sign commit"),
 165                 PARSE_OPT_OPTARG),
 166
 167         /* Options passed to git-fetch */
 168         OPT_GROUP(N_("Options related to fetching")),
 169         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 170                 N_("fetch from all remotes"),
 171                 PARSE_OPT_NOARG),
 172         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 173                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 174                 PARSE_OPT_NOARG),
 175         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 176                 N_("path to upload pack on remote end"),
 177                 0),
 178         OPT__FORCE(&opt_force, N_("force overwrite of local branch")),
 179         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 180                 N_("fetch all tags and associated objects"),
 181                 PARSE_OPT_NOARG),
 182         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 183                 N_("prune remote-tracking branches no longer on remote"),
 184                 PARSE_OPT_NOARG),
 185         OPT_PASSTHRU(0, "recurse-submodules", &opt_recurse_submodules,
 186                 N_("on-demand"),
 187                 N_("control recursive fetching of submodules"),
 188                 PARSE_OPT_OPTARG),
 189         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 190                 N_("number of submodules pulled in parallel"),
 191                 PARSE_OPT_OPTARG),
 192         OPT_BOOL(0, "dry-run", &opt_dry_run,
 193                 N_("dry run")),
 194         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 195                 N_("keep downloaded pack"),
 196                 PARSE_OPT_NOARG),
 197         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 198                 N_("deepen history of shallow clone"),
 199                 0),
 200         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 201                 N_("convert to a complete repository"),
 202                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 203         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 204                 N_("accept refs that update .git/shallow"),
 205                 PARSE_OPT_NOARG),
 206         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 207                 N_("specify fetch refmap"),
 208                 PARSE_OPT_NONEG),
 209
 210         OPT_END()
 211 };
 212
 213 /**
 214  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 215  */
 216 static void argv_push_verbosity(struct argv_array *arr)
 217 {
 218         int verbosity;
 219
 220         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 221                 argv_array_push(arr, "-v");
 222
 223         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 224                 argv_array_push(arr, "-q");
 225 }
 226
 227 /**
 228  * Pushes "-f" switches into arr to match the opt_force level.
 229  */
 230 static void argv_push_force(struct argv_array *arr)
 231 {
 232         int force = opt_force;
 233         while (force-- > 0)
 234                 argv_array_push(arr, "-f");
 235 }
 236
 237 /**
 238  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 239  */
 240 static void set_reflog_message(int argc, const char **argv)
 241 {
 242         int i;
 243         struct strbuf msg = STRBUF_INIT;
 244
 245         for (i = 0; i < argc; i++) {
 246                 if (i)
 247                         strbuf_addch(&msg, ' ');
 248                 strbuf_addstr(&msg, argv[i]);
 249         }
 250
 251         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 252
 253         strbuf_release(&msg);
 254 }
 255
 256 /**
 257  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 258  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 259  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 260  * error.
 261  */
 262 static const char *config_get_ff(void)
 263 {
 264         const char *value;
 265
 266         if (git_config_get_value("pull.ff", &value))
 267                 return NULL;
 268
 269         switch (git_config_maybe_bool("pull.ff", value)) {
 270         case 0:
 271                 return "--no-ff";
 272         case 1:
 273                 return "--ff";
 274         }
 275
 276         if (!strcmp(value, "only"))
 277                 return "--ff-only";
 278
 279         die(_("Invalid value for pull.ff: %s"), value);
 280 }
 281
 282 /**
 283  * Returns the default configured value for --rebase. It first looks for the
 284  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 285  * branch, and if HEAD is detached or the configuration key does not exist,
 286  * looks for the value of "pull.rebase". If both configuration keys do not
 287  * exist, returns REBASE_FALSE.
 288  */
 289 static enum rebase_type config_get_rebase(void)
 290 {
 291         struct branch *curr_branch = branch_get("HEAD");
 292         const char *value;
 293
 294         if (curr_branch) {
 295                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 296
 297                 if (!git_config_get_value(key, &value)) {
 298                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 299                         free(key);
 300                         return ret;
 301                 }
 302
 303                 free(key);
 304         }
 305
 306         if (!git_config_get_value("pull.rebase", &value))
 307                 return parse_config_rebase("pull.rebase", value, 1);
 308
 309         return REBASE_FALSE;
 310 }
 311
 312 /**
 313  * Read config variables.
 314  */
 315 static int git_pull_config(const char *var, const char *value, void *cb)
 316 {
 317         if (!strcmp(var, "rebase.autostash")) {
 318                 config_autostash = git_config_bool(var, value);
 319                 return 0;
 320         }
 321         return git_default_config(var, value, cb);
 322 }
 323
 324 /**
 325  * Returns 1 if there are unstaged changes, 0 otherwise.
 326  */
 327 static int has_unstaged_changes(const char *prefix)
 328 {
 329         struct rev_info rev_info;
 330         int result;
 331
 332         init_revisions(&rev_info, prefix);
 333         DIFF_OPT_SET(&rev_info.diffopt, IGNORE_SUBMODULES);
 334         DIFF_OPT_SET(&rev_info.diffopt, QUICK);
 335         diff_setup_done(&rev_info.diffopt);
 336         result = run_diff_files(&rev_info, 0);
 337         return diff_result_code(&rev_info.diffopt, result);
 338 }
 339
 340 /**
 341  * Returns 1 if there are uncommitted changes, 0 otherwise.
 342  */
 343 static int has_uncommitted_changes(const char *prefix)
 344 {
 345         struct rev_info rev_info;
 346         int result;
 347
 348         if (is_cache_unborn())
 349                 return 0;
 350
 351         init_revisions(&rev_info, prefix);
 352         DIFF_OPT_SET(&rev_info.diffopt, IGNORE_SUBMODULES);
 353         DIFF_OPT_SET(&rev_info.diffopt, QUICK);
 354         add_head_to_pending(&rev_info);
 355         diff_setup_done(&rev_info.diffopt);
 356         result = run_diff_index(&rev_info, 1);
 357         return diff_result_code(&rev_info.diffopt, result);
 358 }
 359
 360 /**
 361  * If the work tree has unstaged or uncommitted changes, dies with the
 362  * appropriate message.
 363  */
 364 static void die_on_unclean_work_tree(const char *prefix)
 365 {
 366         struct lock_file *lock_file = xcalloc(1, sizeof(*lock_file));
 367         int do_die = 0;
 368
 369         hold_locked_index(lock_file, 0);
 370         refresh_cache(REFRESH_QUIET);
 371         update_index_if_able(&the_index, lock_file);
 372         rollback_lock_file(lock_file);
 373
 374         if (has_unstaged_changes(prefix)) {
 375                 error(_("Cannot pull with rebase: You have unstaged changes."));
 376                 do_die = 1;
 377         }
 378
 379         if (has_uncommitted_changes(prefix)) {
 380                 if (do_die)
 381                         error(_("Additionally, your index contains uncommitted changes."));
 382                 else
 383                         error(_("Cannot pull with rebase: Your index contains uncommitted changes."));
 384                 do_die = 1;
 385         }
 386
 387         if (do_die)
 388                 exit(1);
 389 }
 390
 391 /**
 392  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 393  * into merge_heads.
 394  */
 395 static void get_merge_heads(struct sha1_array *merge_heads)
 396 {
 397         const char *filename = git_path("FETCH_HEAD");
 398         FILE *fp;
 399         struct strbuf sb = STRBUF_INIT;
 400         unsigned char sha1[GIT_SHA1_RAWSZ];
 401
 402         if (!(fp = fopen(filename, "r")))
 403                 die_errno(_("could not open '%s' for reading"), filename);
 404         while (strbuf_getline_lf(&sb, fp) != EOF) {
 405                 if (get_sha1_hex(sb.buf, sha1))
 406                         continue;  /* invalid line: does not start with SHA1 */
 407                 if (starts_with(sb.buf + GIT_SHA1_HEXSZ, "\tnot-for-merge\t"))
 408                         continue;  /* ref is not-for-merge */
 409                 sha1_array_append(merge_heads, sha1);
 410         }
 411         fclose(fp);
 412         strbuf_release(&sb);
 413 }
 414
 415 /**
 416  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 417  * retrieve the name of the remote if the repository only has one remote.
 418  */
 419 static int get_only_remote(struct remote *remote, void *cb_data)
 420 {
 421         const char **remote_name = cb_data;
 422
 423         if (*remote_name)
 424                 return -1;
 425
 426         *remote_name = remote->name;
 427         return 0;
 428 }
 429
 430 /**
 431  * Dies with the appropriate reason for why there are no merge candidates:
 432  *
 433  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 434  *    up not fetching anything. This is usually because the user provided a
 435  *    wildcard refspec which had no matches on the remote end.
 436  *
 437  * 2. We fetched from a non-default remote, but didn't specify a branch to
 438  *    merge. We can't use the configured one because it applies to the default
 439  *    remote, thus the user must specify the branches to merge.
 440  *
 441  * 3. We fetched from the branch's or repo's default remote, but:
 442  *
 443  *    a. We are not on a branch, so there will never be a configured branch to
 444  *       merge with.
 445  *
 446  *    b. We are on a branch, but there is no configured branch to merge with.
 447  *
 448  * 4. We fetched from the branch's or repo's default remote, but the configured
 449  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 450  *    part of the configured fetch refspec.)
 451  */
 452 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 453 {
 454         struct branch *curr_branch = branch_get("HEAD");
 455         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 456
 457         if (*refspecs) {
 458                 if (opt_rebase)
 459                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 460                 else
 461                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 462                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 463                                         "matches on the remote end."));
 464         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 465                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 466                         "a branch. Because this is not the default configured remote\n"
 467                         "for your current branch, you must specify a branch on the command line."),
 468                         repo);
 469         } else if (!curr_branch) {
 470                 fprintf_ln(stderr, _("You are not currently on a branch."));
 471                 if (opt_rebase)
 472                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 473                 else
 474                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 475                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 476                 fprintf(stderr, "\n");
 477                 fprintf_ln(stderr, "    git pull <remote> <branch>");
 478                 fprintf(stderr, "\n");
 479         } else if (!curr_branch->merge_nr) {
 480                 const char *remote_name = NULL;
 481
 482                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 483                         remote_name = "<remote>";
 484
 485                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 486                 if (opt_rebase)
 487                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 488                 else
 489                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 490                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 491                 fprintf(stderr, "\n");
 492                 fprintf_ln(stderr, "    git pull <remote> <branch>");
 493                 fprintf(stderr, "\n");
 494                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:\n"
 495                                 "\n"
 496                                 "    git branch --set-upstream-to=%s/<branch> %s\n"),
 497                                 remote_name, curr_branch->name);
 498         } else
 499                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 500                         "from the remote, but no such ref was fetched."),
 501                         *curr_branch->merge_name);
 502         exit(1);
 503 }
 504
 505 /**
 506  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 507  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 508  * is not provided in argv, it is set to NULL.
 509  */
 510 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 511                 const char ***refspecs)
 512 {
 513         if (argc > 0) {
 514                 *repo = *argv++;
 515                 argc--;
 516         } else
 517                 *repo = NULL;
 518         *refspecs = argv;
 519 }
 520
 521 /**
 522  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 523  * repository and refspecs to fetch, or NULL if they are not provided.
 524  */
 525 static int run_fetch(const char *repo, const char **refspecs)
 526 {
 527         struct argv_array args = ARGV_ARRAY_INIT;
 528         int ret;
 529
 530         argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
 531
 532         /* Shared options */
 533         argv_push_verbosity(&args);
 534         if (opt_progress)
 535                 argv_array_push(&args, opt_progress);
 536
 537         /* Options passed to git-fetch */
 538         if (opt_all)
 539                 argv_array_push(&args, opt_all);
 540         if (opt_append)
 541                 argv_array_push(&args, opt_append);
 542         if (opt_upload_pack)
 543                 argv_array_push(&args, opt_upload_pack);
 544         argv_push_force(&args);
 545         if (opt_tags)
 546                 argv_array_push(&args, opt_tags);
 547         if (opt_prune)
 548                 argv_array_push(&args, opt_prune);
 549         if (opt_recurse_submodules)
 550                 argv_array_push(&args, opt_recurse_submodules);
 551         if (max_children)
 552                 argv_array_push(&args, max_children);
 553         if (opt_dry_run)
 554                 argv_array_push(&args, "--dry-run");
 555         if (opt_keep)
 556                 argv_array_push(&args, opt_keep);
 557         if (opt_depth)
 558                 argv_array_push(&args, opt_depth);
 559         if (opt_unshallow)
 560                 argv_array_push(&args, opt_unshallow);
 561         if (opt_update_shallow)
 562                 argv_array_push(&args, opt_update_shallow);
 563         if (opt_refmap)
 564                 argv_array_push(&args, opt_refmap);
 565
 566         if (repo) {
 567                 argv_array_push(&args, repo);
 568                 argv_array_pushv(&args, refspecs);
 569         } else if (*refspecs)
 570                 die("BUG: refspecs without repo?");
 571         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 572         argv_array_clear(&args);
 573         return ret;
 574 }
 575
 576 /**
 577  * "Pulls into void" by branching off merge_head.
 578  */
 579 static int pull_into_void(const unsigned char *merge_head,
 580                 const unsigned char *curr_head)
 581 {
 582         /*
 583          * Two-way merge: we treat the index as based on an empty tree,
 584          * and try to fast-forward to HEAD. This ensures we will not lose
 585          * index/worktree changes that the user already made on the unborn
 586          * branch.
 587          */
 588         if (checkout_fast_forward(EMPTY_TREE_SHA1_BIN, merge_head, 0))
 589                 return 1;
 590
 591         if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 592                 return 1;
 593
 594         return 0;
 595 }
 596
 597 /**
 598  * Runs git-merge, returning its exit status.
 599  */
 600 static int run_merge(void)
 601 {
 602         int ret;
 603         struct argv_array args = ARGV_ARRAY_INIT;
 604
 605         argv_array_pushl(&args, "merge", NULL);
 606
 607         /* Shared options */
 608         argv_push_verbosity(&args);
 609         if (opt_progress)
 610                 argv_array_push(&args, opt_progress);
 611
 612         /* Options passed to git-merge */
 613         if (opt_diffstat)
 614                 argv_array_push(&args, opt_diffstat);
 615         if (opt_log)
 616                 argv_array_push(&args, opt_log);
 617         if (opt_squash)
 618                 argv_array_push(&args, opt_squash);
 619         if (opt_commit)
 620                 argv_array_push(&args, opt_commit);
 621         if (opt_edit)
 622                 argv_array_push(&args, opt_edit);
 623         if (opt_ff)
 624                 argv_array_push(&args, opt_ff);
 625         if (opt_verify_signatures)
 626                 argv_array_push(&args, opt_verify_signatures);
 627         argv_array_pushv(&args, opt_strategies.argv);
 628         argv_array_pushv(&args, opt_strategy_opts.argv);
 629         if (opt_gpg_sign)
 630                 argv_array_push(&args, opt_gpg_sign);
 631
 632         argv_array_push(&args, "FETCH_HEAD");
 633         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 634         argv_array_clear(&args);
 635         return ret;
 636 }
 637
 638 /**
 639  * Returns remote's upstream branch for the current branch. If remote is NULL,
 640  * the current branch's configured default remote is used. Returns NULL if
 641  * `remote` does not name a valid remote, HEAD does not point to a branch,
 642  * remote is not the branch's configured remote or the branch does not have any
 643  * configured upstream branch.
 644  */
 645 static const char *get_upstream_branch(const char *remote)
 646 {
 647         struct remote *rm;
 648         struct branch *curr_branch;
 649         const char *curr_branch_remote;
 650
 651         rm = remote_get(remote);
 652         if (!rm)
 653                 return NULL;
 654
 655         curr_branch = branch_get("HEAD");
 656         if (!curr_branch)
 657                 return NULL;
 658
 659         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 660         assert(curr_branch_remote);
 661
 662         if (strcmp(curr_branch_remote, rm->name))
 663                 return NULL;
 664
 665         return branch_get_upstream(curr_branch, NULL);
 666 }
 667
 668 /**
 669  * Derives the remote tracking branch from the remote and refspec.
 670  *
 671  * FIXME: The current implementation assumes the default mapping of
 672  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 673  */
 674 static const char *get_tracking_branch(const char *remote, const char *refspec)
 675 {
 676         struct refspec *spec;
 677         const char *spec_src;
 678         const char *merge_branch;
 679
 680         spec = parse_fetch_refspec(1, &refspec);
 681         spec_src = spec->src;
 682         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 683                 spec_src = "HEAD";
 684         else if (skip_prefix(spec_src, "heads/", &spec_src))
 685                 ;
 686         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 687                 ;
 688         else if (starts_with(spec_src, "refs/") ||
 689                 starts_with(spec_src, "tags/") ||
 690                 starts_with(spec_src, "remotes/"))
 691                 spec_src = "";
 692
 693         if (*spec_src) {
 694                 if (!strcmp(remote, "."))
 695                         merge_branch = mkpath("refs/heads/%s", spec_src);
 696                 else
 697                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 698         } else
 699                 merge_branch = NULL;
 700
 701         free_refspec(1, spec);
 702         return merge_branch;
 703 }
 704
 705 /**
 706  * Given the repo and refspecs, sets fork_point to the point at which the
 707  * current branch forked from its remote tracking branch. Returns 0 on success,
 708  * -1 on failure.
 709  */
 710 static int get_rebase_fork_point(unsigned char *fork_point, const char *repo,
 711                 const char *refspec)
 712 {
 713         int ret;
 714         struct branch *curr_branch;
 715         const char *remote_branch;
 716         struct child_process cp = CHILD_PROCESS_INIT;
 717         struct strbuf sb = STRBUF_INIT;
 718
 719         curr_branch = branch_get("HEAD");
 720         if (!curr_branch)
 721                 return -1;
 722
 723         if (refspec)
 724                 remote_branch = get_tracking_branch(repo, refspec);
 725         else
 726                 remote_branch = get_upstream_branch(repo);
 727
 728         if (!remote_branch)
 729                 return -1;
 730
 731         argv_array_pushl(&cp.args, "merge-base", "--fork-point",
 732                         remote_branch, curr_branch->name, NULL);
 733         cp.no_stdin = 1;
 734         cp.no_stderr = 1;
 735         cp.git_cmd = 1;
 736
 737         ret = capture_command(&cp, &sb, GIT_SHA1_HEXSZ);
 738         if (ret)
 739                 goto cleanup;
 740
 741         ret = get_sha1_hex(sb.buf, fork_point);
 742         if (ret)
 743                 goto cleanup;
 744
 745 cleanup:
 746         strbuf_release(&sb);
 747         return ret ? -1 : 0;
 748 }
 749
 750 /**
 751  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 752  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 753  */
 754 static int get_octopus_merge_base(unsigned char *merge_base,
 755                 const unsigned char *curr_head,
 756                 const unsigned char *merge_head,
 757                 const unsigned char *fork_point)
 758 {
 759         struct commit_list *revs = NULL, *result;
 760
 761         commit_list_insert(lookup_commit_reference(curr_head), &revs);
 762         commit_list_insert(lookup_commit_reference(merge_head), &revs);
 763         if (!is_null_sha1(fork_point))
 764                 commit_list_insert(lookup_commit_reference(fork_point), &revs);
 765
 766         result = reduce_heads(get_octopus_merge_bases(revs));
 767         free_commit_list(revs);
 768         if (!result)
 769                 return 1;
 770
 771         hashcpy(merge_base, result->item->object.oid.hash);
 772         return 0;
 773 }
 774
 775 /**
 776  * Given the current HEAD SHA1, the merge head returned from git-fetch and the
 777  * fork point calculated by get_rebase_fork_point(), runs git-rebase with the
 778  * appropriate arguments and returns its exit status.
 779  */
 780 static int run_rebase(const unsigned char *curr_head,
 781                 const unsigned char *merge_head,
 782                 const unsigned char *fork_point)
 783 {
 784         int ret;
 785         unsigned char oct_merge_base[GIT_SHA1_RAWSZ];
 786         struct argv_array args = ARGV_ARRAY_INIT;
 787
 788         if (!get_octopus_merge_base(oct_merge_base, curr_head, merge_head, fork_point))
 789                 if (!is_null_sha1(fork_point) && !hashcmp(oct_merge_base, fork_point))
 790                         fork_point = NULL;
 791
 792         argv_array_push(&args, "rebase");
 793
 794         /* Shared options */
 795         argv_push_verbosity(&args);
 796
 797         /* Options passed to git-rebase */
 798         if (opt_rebase == REBASE_PRESERVE)
 799                 argv_array_push(&args, "--preserve-merges");
 800         else if (opt_rebase == REBASE_INTERACTIVE)
 801                 argv_array_push(&args, "--interactive");
 802         if (opt_diffstat)
 803                 argv_array_push(&args, opt_diffstat);
 804         argv_array_pushv(&args, opt_strategies.argv);
 805         argv_array_pushv(&args, opt_strategy_opts.argv);
 806         if (opt_gpg_sign)
 807                 argv_array_push(&args, opt_gpg_sign);
 808         if (opt_autostash == 0)
 809                 argv_array_push(&args, "--no-autostash");
 810         else if (opt_autostash == 1)
 811                 argv_array_push(&args, "--autostash");
 812
 813         argv_array_push(&args, "--onto");
 814         argv_array_push(&args, sha1_to_hex(merge_head));
 815
 816         if (fork_point && !is_null_sha1(fork_point))
 817                 argv_array_push(&args, sha1_to_hex(fork_point));
 818         else
 819                 argv_array_push(&args, sha1_to_hex(merge_head));
 820
 821         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 822         argv_array_clear(&args);
 823         return ret;
 824 }
 825
 826 int cmd_pull(int argc, const char **argv, const char *prefix)
 827 {
 828         const char *repo, **refspecs;
 829         struct sha1_array merge_heads = SHA1_ARRAY_INIT;
 830         unsigned char orig_head[GIT_SHA1_RAWSZ], curr_head[GIT_SHA1_RAWSZ];
 831         unsigned char rebase_fork_point[GIT_SHA1_RAWSZ];
 832
 833         if (!getenv("GIT_REFLOG_ACTION"))
 834                 set_reflog_message(argc, argv);
 835
 836         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 837
 838         parse_repo_refspecs(argc, argv, &repo, &refspecs);
 839
 840         if (!opt_ff)
 841                 opt_ff = xstrdup_or_null(config_get_ff());
 842
 843         if (opt_rebase < 0)
 844                 opt_rebase = config_get_rebase();
 845
 846         git_config(git_pull_config, NULL);
 847
 848         if (read_cache_unmerged())
 849                 die_resolve_conflict("Pull");
 850
 851         if (file_exists(git_path("MERGE_HEAD")))
 852                 die_conclude_merge();
 853
 854         if (get_sha1("HEAD", orig_head))
 855                 hashclr(orig_head);
 856
 857         if (!opt_rebase && opt_autostash != -1)
 858                 die(_("--[no-]autostash option is only valid with --rebase."));
 859
 860         if (opt_rebase) {
 861                 int autostash = config_autostash;
 862                 if (opt_autostash != -1)
 863                         autostash = opt_autostash;
 864
 865                 if (is_null_sha1(orig_head) && !is_cache_unborn())
 866                         die(_("Updating an unborn branch with changes added to the index."));
 867
 868                 if (!autostash)
 869                         die_on_unclean_work_tree(prefix);
 870
 871                 if (get_rebase_fork_point(rebase_fork_point, repo, *refspecs))
 872                         hashclr(rebase_fork_point);
 873         }
 874
 875         if (run_fetch(repo, refspecs))
 876                 return 1;
 877
 878         if (opt_dry_run)
 879                 return 0;
 880
 881         if (get_sha1("HEAD", curr_head))
 882                 hashclr(curr_head);
 883
 884         if (!is_null_sha1(orig_head) && !is_null_sha1(curr_head) &&
 885                         hashcmp(orig_head, curr_head)) {
 886                 /*
 887                  * The fetch involved updating the current branch.
 888                  *
 889                  * The working tree and the index file are still based on
 890                  * orig_head commit, but we are merging into curr_head.
 891                  * Update the working tree to match curr_head.
 892                  */
 893
 894                 warning(_("fetch updated the current branch head.\n"
 895                         "fast-forwarding your working tree from\n"
 896                         "commit %s."), sha1_to_hex(orig_head));
 897
 898                 if (checkout_fast_forward(orig_head, curr_head, 0))
 899                         die(_("Cannot fast-forward your working tree.\n"
 900                                 "After making sure that you saved anything precious from\n"
 901                                 "$ git diff %s\n"
 902                                 "output, run\n"
 903                                 "$ git reset --hard\n"
 904                                 "to recover."), sha1_to_hex(orig_head));
 905         }
 906
 907         get_merge_heads(&merge_heads);
 908
 909         if (!merge_heads.nr)
 910                 die_no_merge_candidates(repo, refspecs);
 911
 912         if (is_null_sha1(orig_head)) {
 913                 if (merge_heads.nr > 1)
 914                         die(_("Cannot merge multiple branches into empty head."));
 915                 return pull_into_void(*merge_heads.sha1, curr_head);
 916         } else if (opt_rebase) {
 917                 if (merge_heads.nr > 1)
 918                         die(_("Cannot rebase onto multiple branches."));
 919                 return run_rebase(curr_head, *merge_heads.sha1, rebase_fork_point);
 920         } else
 921                 return run_merge();
 922 }