builtin/pull.c

   1 /*
   2  * Builtin "git pull"
   3  *
   4  * Based on git-pull.sh by Junio C Hamano
   5  *
   6  * Fetch one or more remote refs and merge it/them into the current HEAD.
   7  */
   8 #define USE_THE_INDEX_COMPATIBILITY_MACROS
   9 #include "cache.h"
  10 #include "config.h"
  11 #include "builtin.h"
  12 #include "parse-options.h"
  13 #include "exec-cmd.h"
  14 #include "run-command.h"
  15 #include "sha1-array.h"
  16 #include "remote.h"
  17 #include "dir.h"
  18 #include "refs.h"
  19 #include "refspec.h"
  20 #include "revision.h"
  21 #include "submodule.h"
  22 #include "submodule-config.h"
  23 #include "tempfile.h"
  24 #include "lockfile.h"
  25 #include "wt-status.h"
  26 #include "commit-reach.h"
  27 #include "sequencer.h"
  28
  29 enum rebase_type {
  30         REBASE_INVALID = -1,
  31         REBASE_FALSE = 0,
  32         REBASE_TRUE,
  33         REBASE_PRESERVE,
  34         REBASE_MERGES,
  35         REBASE_INTERACTIVE
  36 };
  37
  38 /**
  39  * Parses the value of --rebase. If value is a false value, returns
  40  * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is
  41  * "merges", returns REBASE_MERGES. If value is "preserve", returns
  42  * REBASE_PRESERVE. If value is a invalid value, dies with a fatal error if
  43  * fatal is true, otherwise returns REBASE_INVALID.
  44  */
  45 static enum rebase_type parse_config_rebase(const char *key, const char *value,
  46                 int fatal)
  47 {
  48         int v = git_parse_maybe_bool(value);
  49
  50         if (!v)
  51                 return REBASE_FALSE;
  52         else if (v > 0)
  53                 return REBASE_TRUE;
  54         else if (!strcmp(value, "preserve") || !strcmp(value, "p"))
  55                 return REBASE_PRESERVE;
  56         else if (!strcmp(value, "merges") || !strcmp(value, "m"))
  57                 return REBASE_MERGES;
  58         else if (!strcmp(value, "interactive") || !strcmp(value, "i"))
  59                 return REBASE_INTERACTIVE;
  60         /*
  61          * Please update _git_config() in git-completion.bash when you
  62          * add new rebase modes.
  63          */
  64
  65         if (fatal)
  66                 die(_("Invalid value for %s: %s"), key, value);
  67         else
  68                 error(_("Invalid value for %s: %s"), key, value);
  69
  70         return REBASE_INVALID;
  71 }
  72
  73 /**
  74  * Callback for --rebase, which parses arg with parse_config_rebase().
  75  */
  76 static int parse_opt_rebase(const struct option *opt, const char *arg, int unset)
  77 {
  78         enum rebase_type *value = opt->value;
  79
  80         if (arg)
  81                 *value = parse_config_rebase("--rebase", arg, 0);
  82         else
  83                 *value = unset ? REBASE_FALSE : REBASE_TRUE;
  84         return *value == REBASE_INVALID ? -1 : 0;
  85 }
  86
  87 static const char * const pull_usage[] = {
  88         N_("git pull [<options>] [<repository> [<refspec>...]]"),
  89         NULL
  90 };
  91
  92 /* Shared options */
  93 static int opt_verbosity;
  94 static char *opt_progress;
  95 static int recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
  96
  97 /* Options passed to git-merge or git-rebase */
  98 static enum rebase_type opt_rebase = -1;
  99 static char *opt_diffstat;
 100 static char *opt_log;
 101 static char *opt_signoff;
 102 static char *opt_squash;
 103 static char *opt_commit;
 104 static char *opt_edit;
 105 static char *cleanup_arg;
 106 static char *opt_ff;
 107 static char *opt_verify_signatures;
 108 static int opt_autostash = -1;
 109 static int config_autostash;
 110 static struct argv_array opt_strategies = ARGV_ARRAY_INIT;
 111 static struct argv_array opt_strategy_opts = ARGV_ARRAY_INIT;
 112 static char *opt_gpg_sign;
 113 static int opt_allow_unrelated_histories;
 114
 115 /* Options passed to git-fetch */
 116 static char *opt_all;
 117 static char *opt_append;
 118 static char *opt_upload_pack;
 119 static int opt_force;
 120 static char *opt_tags;
 121 static char *opt_prune;
 122 static char *max_children;
 123 static int opt_dry_run;
 124 static char *opt_keep;
 125 static char *opt_depth;
 126 static char *opt_unshallow;
 127 static char *opt_update_shallow;
 128 static char *opt_refmap;
 129 static char *opt_ipv4;
 130 static char *opt_ipv6;
 131 static int opt_show_forced_updates = -1;
 132 static char *set_upstream;
 133
 134 static struct option pull_options[] = {
 135         /* Shared options */
 136         OPT__VERBOSITY(&opt_verbosity),
 137         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 138                 N_("force progress reporting"),
 139                 PARSE_OPT_NOARG),
 140         { OPTION_CALLBACK, 0, "recurse-submodules",
 141                    &recurse_submodules, N_("on-demand"),
 142                    N_("control for recursive fetching of submodules"),
 143                    PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules },
 144
 145         /* Options passed to git-merge or git-rebase */
 146         OPT_GROUP(N_("Options related to merging")),
 147         { OPTION_CALLBACK, 'r', "rebase", &opt_rebase,
 148           "(false|true|merges|preserve|interactive)",
 149           N_("incorporate changes by rebasing rather than merging"),
 150           PARSE_OPT_OPTARG, parse_opt_rebase },
 151         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 152                 N_("do not show a diffstat at the end of the merge"),
 153                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 154         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 155                 N_("show a diffstat at the end of the merge"),
 156                 PARSE_OPT_NOARG),
 157         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 158                 N_("(synonym to --stat)"),
 159                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 160         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 161                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 162                 PARSE_OPT_OPTARG),
 163         OPT_PASSTHRU(0, "signoff", &opt_signoff, NULL,
 164                 N_("add Signed-off-by:"),
 165                 PARSE_OPT_OPTARG),
 166         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 167                 N_("create a single commit instead of doing a merge"),
 168                 PARSE_OPT_NOARG),
 169         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 170                 N_("perform a commit if the merge succeeds (default)"),
 171                 PARSE_OPT_NOARG),
 172         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 173                 N_("edit message before committing"),
 174                 PARSE_OPT_NOARG),
 175         OPT_CLEANUP(&cleanup_arg),
 176         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 177                 N_("allow fast-forward"),
 178                 PARSE_OPT_NOARG),
 179         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 180                 N_("abort if fast-forward is not possible"),
 181                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 182         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 183                 N_("verify that the named commit has a valid GPG signature"),
 184                 PARSE_OPT_NOARG),
 185         OPT_BOOL(0, "autostash", &opt_autostash,
 186                 N_("automatically stash/stash pop before and after rebase")),
 187         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 188                 N_("merge strategy to use"),
 189                 0),
 190         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 191                 N_("option=value"),
 192                 N_("option for selected merge strategy"),
 193                 0),
 194         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 195                 N_("GPG sign commit"),
 196                 PARSE_OPT_OPTARG),
 197         OPT_SET_INT(0, "allow-unrelated-histories",
 198                     &opt_allow_unrelated_histories,
 199                     N_("allow merging unrelated histories"), 1),
 200
 201         /* Options passed to git-fetch */
 202         OPT_GROUP(N_("Options related to fetching")),
 203         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 204                 N_("fetch from all remotes"),
 205                 PARSE_OPT_NOARG),
 206         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 207                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 208                 PARSE_OPT_NOARG),
 209         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 210                 N_("path to upload pack on remote end"),
 211                 0),
 212         OPT__FORCE(&opt_force, N_("force overwrite of local branch"), 0),
 213         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 214                 N_("fetch all tags and associated objects"),
 215                 PARSE_OPT_NOARG),
 216         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 217                 N_("prune remote-tracking branches no longer on remote"),
 218                 PARSE_OPT_NOARG),
 219         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 220                 N_("number of submodules pulled in parallel"),
 221                 PARSE_OPT_OPTARG),
 222         OPT_BOOL(0, "dry-run", &opt_dry_run,
 223                 N_("dry run")),
 224         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 225                 N_("keep downloaded pack"),
 226                 PARSE_OPT_NOARG),
 227         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 228                 N_("deepen history of shallow clone"),
 229                 0),
 230         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 231                 N_("convert to a complete repository"),
 232                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 233         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 234                 N_("accept refs that update .git/shallow"),
 235                 PARSE_OPT_NOARG),
 236         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 237                 N_("specify fetch refmap"),
 238                 PARSE_OPT_NONEG),
 239         OPT_PASSTHRU('4',  "ipv4", &opt_ipv4, NULL,
 240                 N_("use IPv4 addresses only"),
 241                 PARSE_OPT_NOARG),
 242         OPT_PASSTHRU('6',  "ipv6", &opt_ipv6, NULL,
 243                 N_("use IPv6 addresses only"),
 244                 PARSE_OPT_NOARG),
 245         OPT_BOOL(0, "show-forced-updates", &opt_show_forced_updates,
 246                  N_("check for forced-updates on all updated branches")),
 247         OPT_PASSTHRU(0, "set-upstream", &set_upstream, NULL,
 248                 N_("set upstream for git pull/fetch"),
 249                 PARSE_OPT_NOARG),
 250
 251         OPT_END()
 252 };
 253
 254 /**
 255  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 256  */
 257 static void argv_push_verbosity(struct argv_array *arr)
 258 {
 259         int verbosity;
 260
 261         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 262                 argv_array_push(arr, "-v");
 263
 264         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 265                 argv_array_push(arr, "-q");
 266 }
 267
 268 /**
 269  * Pushes "-f" switches into arr to match the opt_force level.
 270  */
 271 static void argv_push_force(struct argv_array *arr)
 272 {
 273         int force = opt_force;
 274         while (force-- > 0)
 275                 argv_array_push(arr, "-f");
 276 }
 277
 278 /**
 279  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 280  */
 281 static void set_reflog_message(int argc, const char **argv)
 282 {
 283         int i;
 284         struct strbuf msg = STRBUF_INIT;
 285
 286         for (i = 0; i < argc; i++) {
 287                 if (i)
 288                         strbuf_addch(&msg, ' ');
 289                 strbuf_addstr(&msg, argv[i]);
 290         }
 291
 292         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 293
 294         strbuf_release(&msg);
 295 }
 296
 297 /**
 298  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 299  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 300  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 301  * error.
 302  */
 303 static const char *config_get_ff(void)
 304 {
 305         const char *value;
 306
 307         if (git_config_get_value("pull.ff", &value))
 308                 return NULL;
 309
 310         switch (git_parse_maybe_bool(value)) {
 311         case 0:
 312                 return "--no-ff";
 313         case 1:
 314                 return "--ff";
 315         }
 316
 317         if (!strcmp(value, "only"))
 318                 return "--ff-only";
 319
 320         die(_("Invalid value for pull.ff: %s"), value);
 321 }
 322
 323 /**
 324  * Returns the default configured value for --rebase. It first looks for the
 325  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 326  * branch, and if HEAD is detached or the configuration key does not exist,
 327  * looks for the value of "pull.rebase". If both configuration keys do not
 328  * exist, returns REBASE_FALSE.
 329  */
 330 static enum rebase_type config_get_rebase(void)
 331 {
 332         struct branch *curr_branch = branch_get("HEAD");
 333         const char *value;
 334
 335         if (curr_branch) {
 336                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 337
 338                 if (!git_config_get_value(key, &value)) {
 339                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 340                         free(key);
 341                         return ret;
 342                 }
 343
 344                 free(key);
 345         }
 346
 347         if (!git_config_get_value("pull.rebase", &value))
 348                 return parse_config_rebase("pull.rebase", value, 1);
 349
 350         return REBASE_FALSE;
 351 }
 352
 353 /**
 354  * Read config variables.
 355  */
 356 static int git_pull_config(const char *var, const char *value, void *cb)
 357 {
 358         if (!strcmp(var, "rebase.autostash")) {
 359                 config_autostash = git_config_bool(var, value);
 360                 return 0;
 361         } else if (!strcmp(var, "submodule.recurse")) {
 362                 recurse_submodules = git_config_bool(var, value) ?
 363                         RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
 364                 return 0;
 365         }
 366         return git_default_config(var, value, cb);
 367 }
 368
 369 /**
 370  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 371  * into merge_heads.
 372  */
 373 static void get_merge_heads(struct oid_array *merge_heads)
 374 {
 375         const char *filename = git_path_fetch_head(the_repository);
 376         FILE *fp;
 377         struct strbuf sb = STRBUF_INIT;
 378         struct object_id oid;
 379
 380         fp = xfopen(filename, "r");
 381         while (strbuf_getline_lf(&sb, fp) != EOF) {
 382                 const char *p;
 383                 if (parse_oid_hex(sb.buf, &oid, &p))
 384                         continue;  /* invalid line: does not start with object ID */
 385                 if (starts_with(p, "\tnot-for-merge\t"))
 386                         continue;  /* ref is not-for-merge */
 387                 oid_array_append(merge_heads, &oid);
 388         }
 389         fclose(fp);
 390         strbuf_release(&sb);
 391 }
 392
 393 /**
 394  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 395  * retrieve the name of the remote if the repository only has one remote.
 396  */
 397 static int get_only_remote(struct remote *remote, void *cb_data)
 398 {
 399         const char **remote_name = cb_data;
 400
 401         if (*remote_name)
 402                 return -1;
 403
 404         *remote_name = remote->name;
 405         return 0;
 406 }
 407
 408 /**
 409  * Dies with the appropriate reason for why there are no merge candidates:
 410  *
 411  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 412  *    up not fetching anything. This is usually because the user provided a
 413  *    wildcard refspec which had no matches on the remote end.
 414  *
 415  * 2. We fetched from a non-default remote, but didn't specify a branch to
 416  *    merge. We can't use the configured one because it applies to the default
 417  *    remote, thus the user must specify the branches to merge.
 418  *
 419  * 3. We fetched from the branch's or repo's default remote, but:
 420  *
 421  *    a. We are not on a branch, so there will never be a configured branch to
 422  *       merge with.
 423  *
 424  *    b. We are on a branch, but there is no configured branch to merge with.
 425  *
 426  * 4. We fetched from the branch's or repo's default remote, but the configured
 427  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 428  *    part of the configured fetch refspec.)
 429  */
 430 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 431 {
 432         struct branch *curr_branch = branch_get("HEAD");
 433         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 434
 435         if (*refspecs) {
 436                 if (opt_rebase)
 437                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 438                 else
 439                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 440                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 441                                         "matches on the remote end."));
 442         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 443                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 444                         "a branch. Because this is not the default configured remote\n"
 445                         "for your current branch, you must specify a branch on the command line."),
 446                         repo);
 447         } else if (!curr_branch) {
 448                 fprintf_ln(stderr, _("You are not currently on a branch."));
 449                 if (opt_rebase)
 450                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 451                 else
 452                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 453                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 454                 fprintf(stderr, "\n");
 455                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 456                 fprintf(stderr, "\n");
 457         } else if (!curr_branch->merge_nr) {
 458                 const char *remote_name = NULL;
 459
 460                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 461                         remote_name = _("<remote>");
 462
 463                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 464                 if (opt_rebase)
 465                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 466                 else
 467                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 468                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 469                 fprintf(stderr, "\n");
 470                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 471                 fprintf(stderr, "\n");
 472                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));
 473                 fprintf(stderr, "\n");
 474                 fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",
 475                                 remote_name, _("<branch>"), curr_branch->name);
 476         } else
 477                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 478                         "from the remote, but no such ref was fetched."),
 479                         *curr_branch->merge_name);
 480         exit(1);
 481 }
 482
 483 /**
 484  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 485  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 486  * is not provided in argv, it is set to NULL.
 487  */
 488 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 489                 const char ***refspecs)
 490 {
 491         if (argc > 0) {
 492                 *repo = *argv++;
 493                 argc--;
 494         } else
 495                 *repo = NULL;
 496         *refspecs = argv;
 497 }
 498
 499 /**
 500  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 501  * repository and refspecs to fetch, or NULL if they are not provided.
 502  */
 503 static int run_fetch(const char *repo, const char **refspecs)
 504 {
 505         struct argv_array args = ARGV_ARRAY_INIT;
 506         int ret;
 507
 508         argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
 509
 510         /* Shared options */
 511         argv_push_verbosity(&args);
 512         if (opt_progress)
 513                 argv_array_push(&args, opt_progress);
 514
 515         /* Options passed to git-fetch */
 516         if (opt_all)
 517                 argv_array_push(&args, opt_all);
 518         if (opt_append)
 519                 argv_array_push(&args, opt_append);
 520         if (opt_upload_pack)
 521                 argv_array_push(&args, opt_upload_pack);
 522         argv_push_force(&args);
 523         if (opt_tags)
 524                 argv_array_push(&args, opt_tags);
 525         if (opt_prune)
 526                 argv_array_push(&args, opt_prune);
 527         if (recurse_submodules != RECURSE_SUBMODULES_DEFAULT)
 528                 switch (recurse_submodules) {
 529                 case RECURSE_SUBMODULES_ON:
 530                         argv_array_push(&args, "--recurse-submodules=on");
 531                         break;
 532                 case RECURSE_SUBMODULES_OFF:
 533                         argv_array_push(&args, "--recurse-submodules=no");
 534                         break;
 535                 case RECURSE_SUBMODULES_ON_DEMAND:
 536                         argv_array_push(&args, "--recurse-submodules=on-demand");
 537                         break;
 538                 default:
 539                         BUG("submodule recursion option not understood");
 540                 }
 541         if (max_children)
 542                 argv_array_push(&args, max_children);
 543         if (opt_dry_run)
 544                 argv_array_push(&args, "--dry-run");
 545         if (opt_keep)
 546                 argv_array_push(&args, opt_keep);
 547         if (opt_depth)
 548                 argv_array_push(&args, opt_depth);
 549         if (opt_unshallow)
 550                 argv_array_push(&args, opt_unshallow);
 551         if (opt_update_shallow)
 552                 argv_array_push(&args, opt_update_shallow);
 553         if (opt_refmap)
 554                 argv_array_push(&args, opt_refmap);
 555         if (opt_ipv4)
 556                 argv_array_push(&args, opt_ipv4);
 557         if (opt_ipv6)
 558                 argv_array_push(&args, opt_ipv6);
 559         if (opt_show_forced_updates > 0)
 560                 argv_array_push(&args, "--show-forced-updates");
 561         else if (opt_show_forced_updates == 0)
 562                 argv_array_push(&args, "--no-show-forced-updates");
 563         if (set_upstream)
 564                 argv_array_push(&args, set_upstream);
 565
 566         if (repo) {
 567                 argv_array_push(&args, repo);
 568                 argv_array_pushv(&args, refspecs);
 569         } else if (*refspecs)
 570                 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 struct object_id *merge_head,
 580                 const struct object_id *curr_head)
 581 {
 582         if (opt_verify_signatures) {
 583                 struct commit *commit;
 584
 585                 commit = lookup_commit(the_repository, merge_head);
 586                 if (!commit)
 587                         die(_("unable to access commit %s"),
 588                             oid_to_hex(merge_head));
 589
 590                 verify_merge_signature(commit, opt_verbosity);
 591         }
 592
 593         /*
 594          * Two-way merge: we treat the index as based on an empty tree,
 595          * and try to fast-forward to HEAD. This ensures we will not lose
 596          * index/worktree changes that the user already made on the unborn
 597          * branch.
 598          */
 599         if (checkout_fast_forward(the_repository,
 600                                   the_hash_algo->empty_tree,
 601                                   merge_head, 0))
 602                 return 1;
 603
 604         if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 605                 return 1;
 606
 607         return 0;
 608 }
 609
 610 static int rebase_submodules(void)
 611 {
 612         struct child_process cp = CHILD_PROCESS_INIT;
 613
 614         cp.git_cmd = 1;
 615         cp.no_stdin = 1;
 616         argv_array_pushl(&cp.args, "submodule", "update",
 617                                    "--recursive", "--rebase", NULL);
 618         argv_push_verbosity(&cp.args);
 619
 620         return run_command(&cp);
 621 }
 622
 623 static int update_submodules(void)
 624 {
 625         struct child_process cp = CHILD_PROCESS_INIT;
 626
 627         cp.git_cmd = 1;
 628         cp.no_stdin = 1;
 629         argv_array_pushl(&cp.args, "submodule", "update",
 630                                    "--recursive", "--checkout", NULL);
 631         argv_push_verbosity(&cp.args);
 632
 633         return run_command(&cp);
 634 }
 635
 636 /**
 637  * Runs git-merge, returning its exit status.
 638  */
 639 static int run_merge(void)
 640 {
 641         int ret;
 642         struct argv_array args = ARGV_ARRAY_INIT;
 643
 644         argv_array_pushl(&args, "merge", NULL);
 645
 646         /* Shared options */
 647         argv_push_verbosity(&args);
 648         if (opt_progress)
 649                 argv_array_push(&args, opt_progress);
 650
 651         /* Options passed to git-merge */
 652         if (opt_diffstat)
 653                 argv_array_push(&args, opt_diffstat);
 654         if (opt_log)
 655                 argv_array_push(&args, opt_log);
 656         if (opt_signoff)
 657                 argv_array_push(&args, opt_signoff);
 658         if (opt_squash)
 659                 argv_array_push(&args, opt_squash);
 660         if (opt_commit)
 661                 argv_array_push(&args, opt_commit);
 662         if (opt_edit)
 663                 argv_array_push(&args, opt_edit);
 664         if (cleanup_arg)
 665                 argv_array_pushf(&args, "--cleanup=%s", cleanup_arg);
 666         if (opt_ff)
 667                 argv_array_push(&args, opt_ff);
 668         if (opt_verify_signatures)
 669                 argv_array_push(&args, opt_verify_signatures);
 670         argv_array_pushv(&args, opt_strategies.argv);
 671         argv_array_pushv(&args, opt_strategy_opts.argv);
 672         if (opt_gpg_sign)
 673                 argv_array_push(&args, opt_gpg_sign);
 674         if (opt_allow_unrelated_histories > 0)
 675                 argv_array_push(&args, "--allow-unrelated-histories");
 676
 677         argv_array_push(&args, "FETCH_HEAD");
 678         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 679         argv_array_clear(&args);
 680         return ret;
 681 }
 682
 683 /**
 684  * Returns remote's upstream branch for the current branch. If remote is NULL,
 685  * the current branch's configured default remote is used. Returns NULL if
 686  * `remote` does not name a valid remote, HEAD does not point to a branch,
 687  * remote is not the branch's configured remote or the branch does not have any
 688  * configured upstream branch.
 689  */
 690 static const char *get_upstream_branch(const char *remote)
 691 {
 692         struct remote *rm;
 693         struct branch *curr_branch;
 694         const char *curr_branch_remote;
 695
 696         rm = remote_get(remote);
 697         if (!rm)
 698                 return NULL;
 699
 700         curr_branch = branch_get("HEAD");
 701         if (!curr_branch)
 702                 return NULL;
 703
 704         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 705         assert(curr_branch_remote);
 706
 707         if (strcmp(curr_branch_remote, rm->name))
 708                 return NULL;
 709
 710         return branch_get_upstream(curr_branch, NULL);
 711 }
 712
 713 /**
 714  * Derives the remote-tracking branch from the remote and refspec.
 715  *
 716  * FIXME: The current implementation assumes the default mapping of
 717  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 718  */
 719 static const char *get_tracking_branch(const char *remote, const char *refspec)
 720 {
 721         struct refspec_item spec;
 722         const char *spec_src;
 723         const char *merge_branch;
 724
 725         refspec_item_init_or_die(&spec, refspec, REFSPEC_FETCH);
 726         spec_src = spec.src;
 727         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 728                 spec_src = "HEAD";
 729         else if (skip_prefix(spec_src, "heads/", &spec_src))
 730                 ;
 731         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 732                 ;
 733         else if (starts_with(spec_src, "refs/") ||
 734                 starts_with(spec_src, "tags/") ||
 735                 starts_with(spec_src, "remotes/"))
 736                 spec_src = "";
 737
 738         if (*spec_src) {
 739                 if (!strcmp(remote, "."))
 740                         merge_branch = mkpath("refs/heads/%s", spec_src);
 741                 else
 742                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 743         } else
 744                 merge_branch = NULL;
 745
 746         refspec_item_clear(&spec);
 747         return merge_branch;
 748 }
 749
 750 /**
 751  * Given the repo and refspecs, sets fork_point to the point at which the
 752  * current branch forked from its remote-tracking branch. Returns 0 on success,
 753  * -1 on failure.
 754  */
 755 static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,
 756                 const char *refspec)
 757 {
 758         int ret;
 759         struct branch *curr_branch;
 760         const char *remote_branch;
 761         struct child_process cp = CHILD_PROCESS_INIT;
 762         struct strbuf sb = STRBUF_INIT;
 763
 764         curr_branch = branch_get("HEAD");
 765         if (!curr_branch)
 766                 return -1;
 767
 768         if (refspec)
 769                 remote_branch = get_tracking_branch(repo, refspec);
 770         else
 771                 remote_branch = get_upstream_branch(repo);
 772
 773         if (!remote_branch)
 774                 return -1;
 775
 776         argv_array_pushl(&cp.args, "merge-base", "--fork-point",
 777                         remote_branch, curr_branch->name, NULL);
 778         cp.no_stdin = 1;
 779         cp.no_stderr = 1;
 780         cp.git_cmd = 1;
 781
 782         ret = capture_command(&cp, &sb, GIT_MAX_HEXSZ);
 783         if (ret)
 784                 goto cleanup;
 785
 786         ret = get_oid_hex(sb.buf, fork_point);
 787         if (ret)
 788                 goto cleanup;
 789
 790 cleanup:
 791         strbuf_release(&sb);
 792         return ret ? -1 : 0;
 793 }
 794
 795 /**
 796  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 797  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 798  */
 799 static int get_octopus_merge_base(struct object_id *merge_base,
 800                 const struct object_id *curr_head,
 801                 const struct object_id *merge_head,
 802                 const struct object_id *fork_point)
 803 {
 804         struct commit_list *revs = NULL, *result;
 805
 806         commit_list_insert(lookup_commit_reference(the_repository, curr_head),
 807                            &revs);
 808         commit_list_insert(lookup_commit_reference(the_repository, merge_head),
 809                            &revs);
 810         if (!is_null_oid(fork_point))
 811                 commit_list_insert(lookup_commit_reference(the_repository, fork_point),
 812                                    &revs);
 813
 814         result = get_octopus_merge_bases(revs);
 815         free_commit_list(revs);
 816         reduce_heads_replace(&result);
 817
 818         if (!result)
 819                 return 1;
 820
 821         oidcpy(merge_base, &result->item->object.oid);
 822         free_commit_list(result);
 823         return 0;
 824 }
 825
 826 /**
 827  * Given the current HEAD oid, the merge head returned from git-fetch and the
 828  * fork point calculated by get_rebase_fork_point(), runs git-rebase with the
 829  * appropriate arguments and returns its exit status.
 830  */
 831 static int run_rebase(const struct object_id *curr_head,
 832                 const struct object_id *merge_head,
 833                 const struct object_id *fork_point)
 834 {
 835         int ret;
 836         struct object_id oct_merge_base;
 837         struct argv_array args = ARGV_ARRAY_INIT;
 838
 839         if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))
 840                 if (!is_null_oid(fork_point) && oideq(&oct_merge_base, fork_point))
 841                         fork_point = NULL;
 842
 843         argv_array_push(&args, "rebase");
 844
 845         /* Shared options */
 846         argv_push_verbosity(&args);
 847
 848         /* Options passed to git-rebase */
 849         if (opt_rebase == REBASE_MERGES)
 850                 argv_array_push(&args, "--rebase-merges");
 851         else if (opt_rebase == REBASE_PRESERVE)
 852                 argv_array_push(&args, "--preserve-merges");
 853         else if (opt_rebase == REBASE_INTERACTIVE)
 854                 argv_array_push(&args, "--interactive");
 855         if (opt_diffstat)
 856                 argv_array_push(&args, opt_diffstat);
 857         argv_array_pushv(&args, opt_strategies.argv);
 858         argv_array_pushv(&args, opt_strategy_opts.argv);
 859         if (opt_gpg_sign)
 860                 argv_array_push(&args, opt_gpg_sign);
 861         if (opt_autostash == 0)
 862                 argv_array_push(&args, "--no-autostash");
 863         else if (opt_autostash == 1)
 864                 argv_array_push(&args, "--autostash");
 865         if (opt_verify_signatures &&
 866             !strcmp(opt_verify_signatures, "--verify-signatures"))
 867                 warning(_("ignoring --verify-signatures for rebase"));
 868
 869         argv_array_push(&args, "--onto");
 870         argv_array_push(&args, oid_to_hex(merge_head));
 871
 872         if (fork_point && !is_null_oid(fork_point))
 873                 argv_array_push(&args, oid_to_hex(fork_point));
 874         else
 875                 argv_array_push(&args, oid_to_hex(merge_head));
 876
 877         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 878         argv_array_clear(&args);
 879         return ret;
 880 }
 881
 882 int cmd_pull(int argc, const char **argv, const char *prefix)
 883 {
 884         const char *repo, **refspecs;
 885         struct oid_array merge_heads = OID_ARRAY_INIT;
 886         struct object_id orig_head, curr_head;
 887         struct object_id rebase_fork_point;
 888         int autostash;
 889
 890         if (!getenv("GIT_REFLOG_ACTION"))
 891                 set_reflog_message(argc, argv);
 892
 893         git_config(git_pull_config, NULL);
 894
 895         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 896
 897         if (cleanup_arg)
 898                 /*
 899                  * this only checks the validity of cleanup_arg; we don't need
 900                  * a valid value for use_editor
 901                  */
 902                 get_cleanup_mode(cleanup_arg, 0);
 903
 904         parse_repo_refspecs(argc, argv, &repo, &refspecs);
 905
 906         if (!opt_ff)
 907                 opt_ff = xstrdup_or_null(config_get_ff());
 908
 909         if (opt_rebase < 0)
 910                 opt_rebase = config_get_rebase();
 911
 912         if (read_cache_unmerged())
 913                 die_resolve_conflict("pull");
 914
 915         if (file_exists(git_path_merge_head(the_repository)))
 916                 die_conclude_merge();
 917
 918         if (get_oid("HEAD", &orig_head))
 919                 oidclr(&orig_head);
 920
 921         if (!opt_rebase && opt_autostash != -1)
 922                 die(_("--[no-]autostash option is only valid with --rebase."));
 923
 924         autostash = config_autostash;
 925         if (opt_rebase) {
 926                 if (opt_autostash != -1)
 927                         autostash = opt_autostash;
 928
 929                 if (is_null_oid(&orig_head) && !is_cache_unborn())
 930                         die(_("Updating an unborn branch with changes added to the index."));
 931
 932                 if (!autostash)
 933                         require_clean_work_tree(the_repository,
 934                                 N_("pull with rebase"),
 935                                 _("please commit or stash them."), 1, 0);
 936
 937                 if (get_rebase_fork_point(&rebase_fork_point, repo, *refspecs))
 938                         oidclr(&rebase_fork_point);
 939         }
 940
 941         if (run_fetch(repo, refspecs))
 942                 return 1;
 943
 944         if (opt_dry_run)
 945                 return 0;
 946
 947         if (get_oid("HEAD", &curr_head))
 948                 oidclr(&curr_head);
 949
 950         if (!is_null_oid(&orig_head) && !is_null_oid(&curr_head) &&
 951                         !oideq(&orig_head, &curr_head)) {
 952                 /*
 953                  * The fetch involved updating the current branch.
 954                  *
 955                  * The working tree and the index file are still based on
 956                  * orig_head commit, but we are merging into curr_head.
 957                  * Update the working tree to match curr_head.
 958                  */
 959
 960                 warning(_("fetch updated the current branch head.\n"
 961                         "fast-forwarding your working tree from\n"
 962                         "commit %s."), oid_to_hex(&orig_head));
 963
 964                 if (checkout_fast_forward(the_repository, &orig_head,
 965                                           &curr_head, 0))
 966                         die(_("Cannot fast-forward your working tree.\n"
 967                                 "After making sure that you saved anything precious from\n"
 968                                 "$ git diff %s\n"
 969                                 "output, run\n"
 970                                 "$ git reset --hard\n"
 971                                 "to recover."), oid_to_hex(&orig_head));
 972         }
 973
 974         get_merge_heads(&merge_heads);
 975
 976         if (!merge_heads.nr)
 977                 die_no_merge_candidates(repo, refspecs);
 978
 979         if (is_null_oid(&orig_head)) {
 980                 if (merge_heads.nr > 1)
 981                         die(_("Cannot merge multiple branches into empty head."));
 982                 return pull_into_void(merge_heads.oid, &curr_head);
 983         }
 984         if (opt_rebase && merge_heads.nr > 1)
 985                 die(_("Cannot rebase onto multiple branches."));
 986
 987         if (opt_rebase) {
 988                 int ret = 0;
 989                 if ((recurse_submodules == RECURSE_SUBMODULES_ON ||
 990                      recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) &&
 991                     submodule_touches_in_range(the_repository, &rebase_fork_point, &curr_head))
 992                         die(_("cannot rebase with locally recorded submodule modifications"));
 993                 if (!autostash) {
 994                         struct commit_list *list = NULL;
 995                         struct commit *merge_head, *head;
 996
 997                         head = lookup_commit_reference(the_repository,
 998                                                        &orig_head);
 999                         commit_list_insert(head, &list);
1000                         merge_head = lookup_commit_reference(the_repository,
1001                                                              &merge_heads.oid[0]);
1002                         if (is_descendant_of(merge_head, list)) {
1003                                 /* we can fast-forward this without invoking rebase */
1004                                 opt_ff = "--ff-only";
1005                                 ret = run_merge();
1006                         }
1007                 }
1008                 ret = run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
1009
1010                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
1011                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
1012                         ret = rebase_submodules();
1013
1014                 return ret;
1015         } else {
1016                 int ret = run_merge();
1017                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
1018                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
1019                         ret = update_submodules();
1020                 return ret;
1021         }
1022 }