10eff03967e0b9cb473d262b443949c55681fd1b
   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
  21enum 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 */
  35static 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 */
  60static 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
  71static const char * const pull_usage[] = {
  72        N_("git pull [<options>] [<repository> [<refspec>...]]"),
  73        NULL
  74};
  75
  76/* Shared options */
  77static int opt_verbosity;
  78static char *opt_progress;
  79
  80/* Options passed to git-merge or git-rebase */
  81static enum rebase_type opt_rebase = -1;
  82static char *opt_diffstat;
  83static char *opt_log;
  84static char *opt_squash;
  85static char *opt_commit;
  86static char *opt_edit;
  87static char *opt_ff;
  88static char *opt_verify_signatures;
  89static struct argv_array opt_strategies = ARGV_ARRAY_INIT;
  90static struct argv_array opt_strategy_opts = ARGV_ARRAY_INIT;
  91static char *opt_gpg_sign;
  92
  93/* Options passed to git-fetch */
  94static char *opt_all;
  95static char *opt_append;
  96static char *opt_upload_pack;
  97static int opt_force;
  98static char *opt_tags;
  99static char *opt_prune;
 100static char *opt_recurse_submodules;
 101static char *max_children;
 102static int opt_dry_run;
 103static char *opt_keep;
 104static char *opt_depth;
 105static char *opt_unshallow;
 106static char *opt_update_shallow;
 107static char *opt_refmap;
 108
 109static struct option pull_options[] = {
 110        /* Shared options */
 111        OPT__VERBOSITY(&opt_verbosity),
 112        OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 113                N_("force progress reporting"),
 114                PARSE_OPT_NOARG),
 115
 116        /* Options passed to git-merge or git-rebase */
 117        OPT_GROUP(N_("Options related to merging")),
 118        { OPTION_CALLBACK, 'r', "rebase", &opt_rebase,
 119          "false|true|preserve|interactive",
 120          N_("incorporate changes by rebasing rather than merging"),
 121          PARSE_OPT_OPTARG, parse_opt_rebase },
 122        OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 123                N_("do not show a diffstat at the end of the merge"),
 124                PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 125        OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 126                N_("show a diffstat at the end of the merge"),
 127                PARSE_OPT_NOARG),
 128        OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 129                N_("(synonym to --stat)"),
 130                PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 131        OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 132                N_("add (at most <n>) entries from shortlog to merge commit message"),
 133                PARSE_OPT_OPTARG),
 134        OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 135                N_("create a single commit instead of doing a merge"),
 136                PARSE_OPT_NOARG),
 137        OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 138                N_("perform a commit if the merge succeeds (default)"),
 139                PARSE_OPT_NOARG),
 140        OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 141                N_("edit message before committing"),
 142                PARSE_OPT_NOARG),
 143        OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 144                N_("allow fast-forward"),
 145                PARSE_OPT_NOARG),
 146        OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 147                N_("abort if fast-forward is not possible"),
 148                PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 149        OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 150                N_("verify that the named commit has a valid GPG signature"),
 151                PARSE_OPT_NOARG),
 152        OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 153                N_("merge strategy to use"),
 154                0),
 155        OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 156                N_("option=value"),
 157                N_("option for selected merge strategy"),
 158                0),
 159        OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 160                N_("GPG sign commit"),
 161                PARSE_OPT_OPTARG),
 162
 163        /* Options passed to git-fetch */
 164        OPT_GROUP(N_("Options related to fetching")),
 165        OPT_PASSTHRU(0, "all", &opt_all, NULL,
 166                N_("fetch from all remotes"),
 167                PARSE_OPT_NOARG),
 168        OPT_PASSTHRU('a', "append", &opt_append, NULL,
 169                N_("append to .git/FETCH_HEAD instead of overwriting"),
 170                PARSE_OPT_NOARG),
 171        OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 172                N_("path to upload pack on remote end"),
 173                0),
 174        OPT__FORCE(&opt_force, N_("force overwrite of local branch")),
 175        OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 176                N_("fetch all tags and associated objects"),
 177                PARSE_OPT_NOARG),
 178        OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 179                N_("prune remote-tracking branches no longer on remote"),
 180                PARSE_OPT_NOARG),
 181        OPT_PASSTHRU(0, "recurse-submodules", &opt_recurse_submodules,
 182                N_("on-demand"),
 183                N_("control recursive fetching of submodules"),
 184                PARSE_OPT_OPTARG),
 185        OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 186                N_("number of submodules pulled in parallel"),
 187                PARSE_OPT_OPTARG),
 188        OPT_BOOL(0, "dry-run", &opt_dry_run,
 189                N_("dry run")),
 190        OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 191                N_("keep downloaded pack"),
 192                PARSE_OPT_NOARG),
 193        OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 194                N_("deepen history of shallow clone"),
 195                0),
 196        OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 197                N_("convert to a complete repository"),
 198                PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 199        OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 200                N_("accept refs that update .git/shallow"),
 201                PARSE_OPT_NOARG),
 202        OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 203                N_("specify fetch refmap"),
 204                PARSE_OPT_NONEG),
 205
 206        OPT_END()
 207};
 208
 209/**
 210 * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 211 */
 212static void argv_push_verbosity(struct argv_array *arr)
 213{
 214        int verbosity;
 215
 216        for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 217                argv_array_push(arr, "-v");
 218
 219        for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 220                argv_array_push(arr, "-q");
 221}
 222
 223/**
 224 * Pushes "-f" switches into arr to match the opt_force level.
 225 */
 226static void argv_push_force(struct argv_array *arr)
 227{
 228        int force = opt_force;
 229        while (force-- > 0)
 230                argv_array_push(arr, "-f");
 231}
 232
 233/**
 234 * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 235 */
 236static void set_reflog_message(int argc, const char **argv)
 237{
 238        int i;
 239        struct strbuf msg = STRBUF_INIT;
 240
 241        for (i = 0; i < argc; i++) {
 242                if (i)
 243                        strbuf_addch(&msg, ' ');
 244                strbuf_addstr(&msg, argv[i]);
 245        }
 246
 247        setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 248
 249        strbuf_release(&msg);
 250}
 251
 252/**
 253 * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 254 * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 255 * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 256 * error.
 257 */
 258static const char *config_get_ff(void)
 259{
 260        const char *value;
 261
 262        if (git_config_get_value("pull.ff", &value))
 263                return NULL;
 264
 265        switch (git_config_maybe_bool("pull.ff", value)) {
 266        case 0:
 267                return "--no-ff";
 268        case 1:
 269                return "--ff";
 270        }
 271
 272        if (!strcmp(value, "only"))
 273                return "--ff-only";
 274
 275        die(_("Invalid value for pull.ff: %s"), value);
 276}
 277
 278/**
 279 * Returns the default configured value for --rebase. It first looks for the
 280 * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 281 * branch, and if HEAD is detached or the configuration key does not exist,
 282 * looks for the value of "pull.rebase". If both configuration keys do not
 283 * exist, returns REBASE_FALSE.
 284 */
 285static enum rebase_type config_get_rebase(void)
 286{
 287        struct branch *curr_branch = branch_get("HEAD");
 288        const char *value;
 289
 290        if (curr_branch) {
 291                char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 292
 293                if (!git_config_get_value(key, &value)) {
 294                        enum rebase_type ret = parse_config_rebase(key, value, 1);
 295                        free(key);
 296                        return ret;
 297                }
 298
 299                free(key);
 300        }
 301
 302        if (!git_config_get_value("pull.rebase", &value))
 303                return parse_config_rebase("pull.rebase", value, 1);
 304
 305        return REBASE_FALSE;
 306}
 307
 308/**
 309 * Returns 1 if there are unstaged changes, 0 otherwise.
 310 */
 311static int has_unstaged_changes(const char *prefix)
 312{
 313        struct rev_info rev_info;
 314        int result;
 315
 316        init_revisions(&rev_info, prefix);
 317        DIFF_OPT_SET(&rev_info.diffopt, IGNORE_SUBMODULES);
 318        DIFF_OPT_SET(&rev_info.diffopt, QUICK);
 319        diff_setup_done(&rev_info.diffopt);
 320        result = run_diff_files(&rev_info, 0);
 321        return diff_result_code(&rev_info.diffopt, result);
 322}
 323
 324/**
 325 * Returns 1 if there are uncommitted changes, 0 otherwise.
 326 */
 327static int has_uncommitted_changes(const char *prefix)
 328{
 329        struct rev_info rev_info;
 330        int result;
 331
 332        if (is_cache_unborn())
 333                return 0;
 334
 335        init_revisions(&rev_info, prefix);
 336        DIFF_OPT_SET(&rev_info.diffopt, IGNORE_SUBMODULES);
 337        DIFF_OPT_SET(&rev_info.diffopt, QUICK);
 338        add_head_to_pending(&rev_info);
 339        diff_setup_done(&rev_info.diffopt);
 340        result = run_diff_index(&rev_info, 1);
 341        return diff_result_code(&rev_info.diffopt, result);
 342}
 343
 344/**
 345 * If the work tree has unstaged or uncommitted changes, dies with the
 346 * appropriate message.
 347 */
 348static void die_on_unclean_work_tree(const char *prefix)
 349{
 350        struct lock_file *lock_file = xcalloc(1, sizeof(*lock_file));
 351        int do_die = 0;
 352
 353        hold_locked_index(lock_file, 0);
 354        refresh_cache(REFRESH_QUIET);
 355        update_index_if_able(&the_index, lock_file);
 356        rollback_lock_file(lock_file);
 357
 358        if (has_unstaged_changes(prefix)) {
 359                error(_("Cannot pull with rebase: You have unstaged changes."));
 360                do_die = 1;
 361        }
 362
 363        if (has_uncommitted_changes(prefix)) {
 364                if (do_die)
 365                        error(_("Additionally, your index contains uncommitted changes."));
 366                else
 367                        error(_("Cannot pull with rebase: Your index contains uncommitted changes."));
 368                do_die = 1;
 369        }
 370
 371        if (do_die)
 372                exit(1);
 373}
 374
 375/**
 376 * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 377 * into merge_heads.
 378 */
 379static void get_merge_heads(struct sha1_array *merge_heads)
 380{
 381        const char *filename = git_path("FETCH_HEAD");
 382        FILE *fp;
 383        struct strbuf sb = STRBUF_INIT;
 384        unsigned char sha1[GIT_SHA1_RAWSZ];
 385
 386        if (!(fp = fopen(filename, "r")))
 387                die_errno(_("could not open '%s' for reading"), filename);
 388        while (strbuf_getline_lf(&sb, fp) != EOF) {
 389                if (get_sha1_hex(sb.buf, sha1))
 390                        continue;  /* invalid line: does not start with SHA1 */
 391                if (starts_with(sb.buf + GIT_SHA1_HEXSZ, "\tnot-for-merge\t"))
 392                        continue;  /* ref is not-for-merge */
 393                sha1_array_append(merge_heads, sha1);
 394        }
 395        fclose(fp);
 396        strbuf_release(&sb);
 397}
 398
 399/**
 400 * Used by die_no_merge_candidates() as a for_each_remote() callback to
 401 * retrieve the name of the remote if the repository only has one remote.
 402 */
 403static int get_only_remote(struct remote *remote, void *cb_data)
 404{
 405        const char **remote_name = cb_data;
 406
 407        if (*remote_name)
 408                return -1;
 409
 410        *remote_name = remote->name;
 411        return 0;
 412}
 413
 414/**
 415 * Dies with the appropriate reason for why there are no merge candidates:
 416 *
 417 * 1. We fetched from a specific remote, and a refspec was given, but it ended
 418 *    up not fetching anything. This is usually because the user provided a
 419 *    wildcard refspec which had no matches on the remote end.
 420 *
 421 * 2. We fetched from a non-default remote, but didn't specify a branch to
 422 *    merge. We can't use the configured one because it applies to the default
 423 *    remote, thus the user must specify the branches to merge.
 424 *
 425 * 3. We fetched from the branch's or repo's default remote, but:
 426 *
 427 *    a. We are not on a branch, so there will never be a configured branch to
 428 *       merge with.
 429 *
 430 *    b. We are on a branch, but there is no configured branch to merge with.
 431 *
 432 * 4. We fetched from the branch's or repo's default remote, but the configured
 433 *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 434 *    part of the configured fetch refspec.)
 435 */
 436static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 437{
 438        struct branch *curr_branch = branch_get("HEAD");
 439        const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 440
 441        if (*refspecs) {
 442                if (opt_rebase)
 443                        fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 444                else
 445                        fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 446                fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 447                                        "matches on the remote end."));
 448        } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 449                fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 450                        "a branch. Because this is not the default configured remote\n"
 451                        "for your current branch, you must specify a branch on the command line."),
 452                        repo);
 453        } else if (!curr_branch) {
 454                fprintf_ln(stderr, _("You are not currently on a branch."));
 455                if (opt_rebase)
 456                        fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 457                else
 458                        fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 459                fprintf_ln(stderr, _("See git-pull(1) for details."));
 460                fprintf(stderr, "\n");
 461                fprintf_ln(stderr, "    git pull <remote> <branch>");
 462                fprintf(stderr, "\n");
 463        } else if (!curr_branch->merge_nr) {
 464                const char *remote_name = NULL;
 465
 466                if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 467                        remote_name = "<remote>";
 468
 469                fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 470                if (opt_rebase)
 471                        fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 472                else
 473                        fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 474                fprintf_ln(stderr, _("See git-pull(1) for details."));
 475                fprintf(stderr, "\n");
 476                fprintf_ln(stderr, "    git pull <remote> <branch>");
 477                fprintf(stderr, "\n");
 478                fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:\n"
 479                                "\n"
 480                                "    git branch --set-upstream-to=%s/<branch> %s\n"),
 481                                remote_name, curr_branch->name);
 482        } else
 483                fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 484                        "from the remote, but no such ref was fetched."),
 485                        *curr_branch->merge_name);
 486        exit(1);
 487}
 488
 489/**
 490 * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 491 * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 492 * is not provided in argv, it is set to NULL.
 493 */
 494static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 495                const char ***refspecs)
 496{
 497        if (argc > 0) {
 498                *repo = *argv++;
 499                argc--;
 500        } else
 501                *repo = NULL;
 502        *refspecs = argv;
 503}
 504
 505/**
 506 * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 507 * repository and refspecs to fetch, or NULL if they are not provided.
 508 */
 509static int run_fetch(const char *repo, const char **refspecs)
 510{
 511        struct argv_array args = ARGV_ARRAY_INIT;
 512        int ret;
 513
 514        argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
 515
 516        /* Shared options */
 517        argv_push_verbosity(&args);
 518        if (opt_progress)
 519                argv_array_push(&args, opt_progress);
 520
 521        /* Options passed to git-fetch */
 522        if (opt_all)
 523                argv_array_push(&args, opt_all);
 524        if (opt_append)
 525                argv_array_push(&args, opt_append);
 526        if (opt_upload_pack)
 527                argv_array_push(&args, opt_upload_pack);
 528        argv_push_force(&args);
 529        if (opt_tags)
 530                argv_array_push(&args, opt_tags);
 531        if (opt_prune)
 532                argv_array_push(&args, opt_prune);
 533        if (opt_recurse_submodules)
 534                argv_array_push(&args, opt_recurse_submodules);
 535        if (max_children)
 536                argv_array_push(&args, max_children);
 537        if (opt_dry_run)
 538                argv_array_push(&args, "--dry-run");
 539        if (opt_keep)
 540                argv_array_push(&args, opt_keep);
 541        if (opt_depth)
 542                argv_array_push(&args, opt_depth);
 543        if (opt_unshallow)
 544                argv_array_push(&args, opt_unshallow);
 545        if (opt_update_shallow)
 546                argv_array_push(&args, opt_update_shallow);
 547        if (opt_refmap)
 548                argv_array_push(&args, opt_refmap);
 549
 550        if (repo) {
 551                argv_array_push(&args, repo);
 552                argv_array_pushv(&args, refspecs);
 553        } else if (*refspecs)
 554                die("BUG: refspecs without repo?");
 555        ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 556        argv_array_clear(&args);
 557        return ret;
 558}
 559
 560/**
 561 * "Pulls into void" by branching off merge_head.
 562 */
 563static int pull_into_void(const unsigned char *merge_head,
 564                const unsigned char *curr_head)
 565{
 566        /*
 567         * Two-way merge: we treat the index as based on an empty tree,
 568         * and try to fast-forward to HEAD. This ensures we will not lose
 569         * index/worktree changes that the user already made on the unborn
 570         * branch.
 571         */
 572        if (checkout_fast_forward(EMPTY_TREE_SHA1_BIN, merge_head, 0))
 573                return 1;
 574
 575        if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 576                return 1;
 577
 578        return 0;
 579}
 580
 581/**
 582 * Runs git-merge, returning its exit status.
 583 */
 584static int run_merge(void)
 585{
 586        int ret;
 587        struct argv_array args = ARGV_ARRAY_INIT;
 588
 589        argv_array_pushl(&args, "merge", NULL);
 590
 591        /* Shared options */
 592        argv_push_verbosity(&args);
 593        if (opt_progress)
 594                argv_array_push(&args, opt_progress);
 595
 596        /* Options passed to git-merge */
 597        if (opt_diffstat)
 598                argv_array_push(&args, opt_diffstat);
 599        if (opt_log)
 600                argv_array_push(&args, opt_log);
 601        if (opt_squash)
 602                argv_array_push(&args, opt_squash);
 603        if (opt_commit)
 604                argv_array_push(&args, opt_commit);
 605        if (opt_edit)
 606                argv_array_push(&args, opt_edit);
 607        if (opt_ff)
 608                argv_array_push(&args, opt_ff);
 609        if (opt_verify_signatures)
 610                argv_array_push(&args, opt_verify_signatures);
 611        argv_array_pushv(&args, opt_strategies.argv);
 612        argv_array_pushv(&args, opt_strategy_opts.argv);
 613        if (opt_gpg_sign)
 614                argv_array_push(&args, opt_gpg_sign);
 615
 616        argv_array_push(&args, "FETCH_HEAD");
 617        ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 618        argv_array_clear(&args);
 619        return ret;
 620}
 621
 622/**
 623 * Returns remote's upstream branch for the current branch. If remote is NULL,
 624 * the current branch's configured default remote is used. Returns NULL if
 625 * `remote` does not name a valid remote, HEAD does not point to a branch,
 626 * remote is not the branch's configured remote or the branch does not have any
 627 * configured upstream branch.
 628 */
 629static const char *get_upstream_branch(const char *remote)
 630{
 631        struct remote *rm;
 632        struct branch *curr_branch;
 633        const char *curr_branch_remote;
 634
 635        rm = remote_get(remote);
 636        if (!rm)
 637                return NULL;
 638
 639        curr_branch = branch_get("HEAD");
 640        if (!curr_branch)
 641                return NULL;
 642
 643        curr_branch_remote = remote_for_branch(curr_branch, NULL);
 644        assert(curr_branch_remote);
 645
 646        if (strcmp(curr_branch_remote, rm->name))
 647                return NULL;
 648
 649        return branch_get_upstream(curr_branch, NULL);
 650}
 651
 652/**
 653 * Derives the remote tracking branch from the remote and refspec.
 654 *
 655 * FIXME: The current implementation assumes the default mapping of
 656 * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 657 */
 658static const char *get_tracking_branch(const char *remote, const char *refspec)
 659{
 660        struct refspec *spec;
 661        const char *spec_src;
 662        const char *merge_branch;
 663
 664        spec = parse_fetch_refspec(1, &refspec);
 665        spec_src = spec->src;
 666        if (!*spec_src || !strcmp(spec_src, "HEAD"))
 667                spec_src = "HEAD";
 668        else if (skip_prefix(spec_src, "heads/", &spec_src))
 669                ;
 670        else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 671                ;
 672        else if (starts_with(spec_src, "refs/") ||
 673                starts_with(spec_src, "tags/") ||
 674                starts_with(spec_src, "remotes/"))
 675                spec_src = "";
 676
 677        if (*spec_src) {
 678                if (!strcmp(remote, "."))
 679                        merge_branch = mkpath("refs/heads/%s", spec_src);
 680                else
 681                        merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 682        } else
 683                merge_branch = NULL;
 684
 685        free_refspec(1, spec);
 686        return merge_branch;
 687}
 688
 689/**
 690 * Given the repo and refspecs, sets fork_point to the point at which the
 691 * current branch forked from its remote tracking branch. Returns 0 on success,
 692 * -1 on failure.
 693 */
 694static int get_rebase_fork_point(unsigned char *fork_point, const char *repo,
 695                const char *refspec)
 696{
 697        int ret;
 698        struct branch *curr_branch;
 699        const char *remote_branch;
 700        struct child_process cp = CHILD_PROCESS_INIT;
 701        struct strbuf sb = STRBUF_INIT;
 702
 703        curr_branch = branch_get("HEAD");
 704        if (!curr_branch)
 705                return -1;
 706
 707        if (refspec)
 708                remote_branch = get_tracking_branch(repo, refspec);
 709        else
 710                remote_branch = get_upstream_branch(repo);
 711
 712        if (!remote_branch)
 713                return -1;
 714
 715        argv_array_pushl(&cp.args, "merge-base", "--fork-point",
 716                        remote_branch, curr_branch->name, NULL);
 717        cp.no_stdin = 1;
 718        cp.no_stderr = 1;
 719        cp.git_cmd = 1;
 720
 721        ret = capture_command(&cp, &sb, GIT_SHA1_HEXSZ);
 722        if (ret)
 723                goto cleanup;
 724
 725        ret = get_sha1_hex(sb.buf, fork_point);
 726        if (ret)
 727                goto cleanup;
 728
 729cleanup:
 730        strbuf_release(&sb);
 731        return ret ? -1 : 0;
 732}
 733
 734/**
 735 * Sets merge_base to the octopus merge base of curr_head, merge_head and
 736 * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 737 */
 738static int get_octopus_merge_base(unsigned char *merge_base,
 739                const unsigned char *curr_head,
 740                const unsigned char *merge_head,
 741                const unsigned char *fork_point)
 742{
 743        struct commit_list *revs = NULL, *result;
 744
 745        commit_list_insert(lookup_commit_reference(curr_head), &revs);
 746        commit_list_insert(lookup_commit_reference(merge_head), &revs);
 747        if (!is_null_sha1(fork_point))
 748                commit_list_insert(lookup_commit_reference(fork_point), &revs);
 749
 750        result = reduce_heads(get_octopus_merge_bases(revs));
 751        free_commit_list(revs);
 752        if (!result)
 753                return 1;
 754
 755        hashcpy(merge_base, result->item->object.oid.hash);
 756        return 0;
 757}
 758
 759/**
 760 * Given the current HEAD SHA1, the merge head returned from git-fetch and the
 761 * fork point calculated by get_rebase_fork_point(), runs git-rebase with the
 762 * appropriate arguments and returns its exit status.
 763 */
 764static int run_rebase(const unsigned char *curr_head,
 765                const unsigned char *merge_head,
 766                const unsigned char *fork_point)
 767{
 768        int ret;
 769        unsigned char oct_merge_base[GIT_SHA1_RAWSZ];
 770        struct argv_array args = ARGV_ARRAY_INIT;
 771
 772        if (!get_octopus_merge_base(oct_merge_base, curr_head, merge_head, fork_point))
 773                if (!is_null_sha1(fork_point) && !hashcmp(oct_merge_base, fork_point))
 774                        fork_point = NULL;
 775
 776        argv_array_push(&args, "rebase");
 777
 778        /* Shared options */
 779        argv_push_verbosity(&args);
 780
 781        /* Options passed to git-rebase */
 782        if (opt_rebase == REBASE_PRESERVE)
 783                argv_array_push(&args, "--preserve-merges");
 784        else if (opt_rebase == REBASE_INTERACTIVE)
 785                argv_array_push(&args, "--interactive");
 786        if (opt_diffstat)
 787                argv_array_push(&args, opt_diffstat);
 788        argv_array_pushv(&args, opt_strategies.argv);
 789        argv_array_pushv(&args, opt_strategy_opts.argv);
 790        if (opt_gpg_sign)
 791                argv_array_push(&args, opt_gpg_sign);
 792
 793        argv_array_push(&args, "--onto");
 794        argv_array_push(&args, sha1_to_hex(merge_head));
 795
 796        if (fork_point && !is_null_sha1(fork_point))
 797                argv_array_push(&args, sha1_to_hex(fork_point));
 798        else
 799                argv_array_push(&args, sha1_to_hex(merge_head));
 800
 801        ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 802        argv_array_clear(&args);
 803        return ret;
 804}
 805
 806int cmd_pull(int argc, const char **argv, const char *prefix)
 807{
 808        const char *repo, **refspecs;
 809        struct sha1_array merge_heads = SHA1_ARRAY_INIT;
 810        unsigned char orig_head[GIT_SHA1_RAWSZ], curr_head[GIT_SHA1_RAWSZ];
 811        unsigned char rebase_fork_point[GIT_SHA1_RAWSZ];
 812
 813        if (!getenv("GIT_REFLOG_ACTION"))
 814                set_reflog_message(argc, argv);
 815
 816        argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 817
 818        parse_repo_refspecs(argc, argv, &repo, &refspecs);
 819
 820        if (!opt_ff)
 821                opt_ff = xstrdup_or_null(config_get_ff());
 822
 823        if (opt_rebase < 0)
 824                opt_rebase = config_get_rebase();
 825
 826        git_config(git_default_config, NULL);
 827
 828        if (read_cache_unmerged())
 829                die_resolve_conflict("Pull");
 830
 831        if (file_exists(git_path("MERGE_HEAD")))
 832                die_conclude_merge();
 833
 834        if (get_sha1("HEAD", orig_head))
 835                hashclr(orig_head);
 836
 837        if (opt_rebase) {
 838                int autostash = 0;
 839
 840                if (is_null_sha1(orig_head) && !is_cache_unborn())
 841                        die(_("Updating an unborn branch with changes added to the index."));
 842
 843                git_config_get_bool("rebase.autostash", &autostash);
 844                if (!autostash)
 845                        die_on_unclean_work_tree(prefix);
 846
 847                if (get_rebase_fork_point(rebase_fork_point, repo, *refspecs))
 848                        hashclr(rebase_fork_point);
 849        }
 850
 851        if (run_fetch(repo, refspecs))
 852                return 1;
 853
 854        if (opt_dry_run)
 855                return 0;
 856
 857        if (get_sha1("HEAD", curr_head))
 858                hashclr(curr_head);
 859
 860        if (!is_null_sha1(orig_head) && !is_null_sha1(curr_head) &&
 861                        hashcmp(orig_head, curr_head)) {
 862                /*
 863                 * The fetch involved updating the current branch.
 864                 *
 865                 * The working tree and the index file are still based on
 866                 * orig_head commit, but we are merging into curr_head.
 867                 * Update the working tree to match curr_head.
 868                 */
 869
 870                warning(_("fetch updated the current branch head.\n"
 871                        "fast-forwarding your working tree from\n"
 872                        "commit %s."), sha1_to_hex(orig_head));
 873
 874                if (checkout_fast_forward(orig_head, curr_head, 0))
 875                        die(_("Cannot fast-forward your working tree.\n"
 876                                "After making sure that you saved anything precious from\n"
 877                                "$ git diff %s\n"
 878                                "output, run\n"
 879                                "$ git reset --hard\n"
 880                                "to recover."), sha1_to_hex(orig_head));
 881        }
 882
 883        get_merge_heads(&merge_heads);
 884
 885        if (!merge_heads.nr)
 886                die_no_merge_candidates(repo, refspecs);
 887
 888        if (is_null_sha1(orig_head)) {
 889                if (merge_heads.nr > 1)
 890                        die(_("Cannot merge multiple branches into empty head."));
 891                return pull_into_void(*merge_heads.sha1, curr_head);
 892        } else if (opt_rebase) {
 893                if (merge_heads.nr > 1)
 894                        die(_("Cannot rebase onto multiple branches."));
 895                return run_rebase(curr_head, *merge_heads.sha1, rebase_fork_point);
 896        } else
 897                return run_merge();
 898}