builtin/pull.c

   1 /*
   2  * Builtin "git pull"
   3  *
   4  * Based on git-pull.sh by Junio C Hamano
   5  *
   6  * Fetch one or more remote refs and merge it/them into the current HEAD.
   7  */
   8 #include "cache.h"
   9 #include "config.h"
  10 #include "builtin.h"
  11 #include "parse-options.h"
  12 #include "exec-cmd.h"
  13 #include "run-command.h"
  14 #include "sha1-array.h"
  15 #include "remote.h"
  16 #include "dir.h"
  17 #include "refs.h"
  18 #include "refspec.h"
  19 #include "revision.h"
  20 #include "submodule.h"
  21 #include "submodule-config.h"
  22 #include "tempfile.h"
  23 #include "lockfile.h"
  24 #include "wt-status.h"
  25
  26 enum rebase_type {
  27         REBASE_INVALID = -1,
  28         REBASE_FALSE = 0,
  29         REBASE_TRUE,
  30         REBASE_PRESERVE,
  31         REBASE_MERGES,
  32         REBASE_INTERACTIVE
  33 };
  34
  35 /**
  36  * Parses the value of --rebase. If value is a false value, returns
  37  * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is
  38  * "merges", returns REBASE_MERGES. If value is "preserve", returns
  39  * REBASE_PRESERVE. If value is a invalid value, dies with a fatal error if
  40  * fatal is true, otherwise returns REBASE_INVALID.
  41  */
  42 static enum rebase_type parse_config_rebase(const char *key, const char *value,
  43                 int fatal)
  44 {
  45         int v = git_parse_maybe_bool(value);
  46
  47         if (!v)
  48                 return REBASE_FALSE;
  49         else if (v > 0)
  50                 return REBASE_TRUE;
  51         else if (!strcmp(value, "preserve") || !strcmp(value, "p"))
  52                 return REBASE_PRESERVE;
  53         else if (!strcmp(value, "merges") || !strcmp(value, "m"))
  54                 return REBASE_MERGES;
  55         else if (!strcmp(value, "interactive") || !strcmp(value, "i"))
  56                 return REBASE_INTERACTIVE;
  57
  58         if (fatal)
  59                 die(_("Invalid value for %s: %s"), key, value);
  60         else
  61                 error(_("Invalid value for %s: %s"), key, value);
  62
  63         return REBASE_INVALID;
  64 }
  65
  66 /**
  67  * Callback for --rebase, which parses arg with parse_config_rebase().
  68  */
  69 static int parse_opt_rebase(const struct option *opt, const char *arg, int unset)
  70 {
  71         enum rebase_type *value = opt->value;
  72
  73         if (arg)
  74                 *value = parse_config_rebase("--rebase", arg, 0);
  75         else
  76                 *value = unset ? REBASE_FALSE : REBASE_TRUE;
  77         return *value == REBASE_INVALID ? -1 : 0;
  78 }
  79
  80 static const char * const pull_usage[] = {
  81         N_("git pull [<options>] [<repository> [<refspec>...]]"),
  82         NULL
  83 };
  84
  85 /* Shared options */
  86 static int opt_verbosity;
  87 static char *opt_progress;
  88 static int recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
  89
  90 /* Options passed to git-merge or git-rebase */
  91 static enum rebase_type opt_rebase = -1;
  92 static char *opt_diffstat;
  93 static char *opt_log;
  94 static char *opt_signoff;
  95 static char *opt_squash;
  96 static char *opt_commit;
  97 static char *opt_edit;
  98 static char *opt_ff;
  99 static char *opt_verify_signatures;
 100 static int opt_autostash = -1;
 101 static int config_autostash;
 102 static struct argv_array opt_strategies = ARGV_ARRAY_INIT;
 103 static struct argv_array opt_strategy_opts = ARGV_ARRAY_INIT;
 104 static char *opt_gpg_sign;
 105 static int opt_allow_unrelated_histories;
 106
 107 /* Options passed to git-fetch */
 108 static char *opt_all;
 109 static char *opt_append;
 110 static char *opt_upload_pack;
 111 static int opt_force;
 112 static char *opt_tags;
 113 static char *opt_prune;
 114 static char *max_children;
 115 static int opt_dry_run;
 116 static char *opt_keep;
 117 static char *opt_depth;
 118 static char *opt_unshallow;
 119 static char *opt_update_shallow;
 120 static char *opt_refmap;
 121 static char *opt_ipv4;
 122 static char *opt_ipv6;
 123
 124 static struct option pull_options[] = {
 125         /* Shared options */
 126         OPT__VERBOSITY(&opt_verbosity),
 127         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 128                 N_("force progress reporting"),
 129                 PARSE_OPT_NOARG),
 130         { OPTION_CALLBACK, 0, "recurse-submodules",
 131                    &recurse_submodules, N_("on-demand"),
 132                    N_("control for recursive fetching of submodules"),
 133                    PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules },
 134
 135         /* Options passed to git-merge or git-rebase */
 136         OPT_GROUP(N_("Options related to merging")),
 137         { OPTION_CALLBACK, 'r', "rebase", &opt_rebase,
 138           "(false|true|merges|preserve|interactive)",
 139           N_("incorporate changes by rebasing rather than merging"),
 140           PARSE_OPT_OPTARG, parse_opt_rebase },
 141         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 142                 N_("do not show a diffstat at the end of the merge"),
 143                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 144         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 145                 N_("show a diffstat at the end of the merge"),
 146                 PARSE_OPT_NOARG),
 147         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 148                 N_("(synonym to --stat)"),
 149                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 150         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 151                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 152                 PARSE_OPT_OPTARG),
 153         OPT_PASSTHRU(0, "signoff", &opt_signoff, NULL,
 154                 N_("add Signed-off-by:"),
 155                 PARSE_OPT_OPTARG),
 156         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 157                 N_("create a single commit instead of doing a merge"),
 158                 PARSE_OPT_NOARG),
 159         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 160                 N_("perform a commit if the merge succeeds (default)"),
 161                 PARSE_OPT_NOARG),
 162         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 163                 N_("edit message before committing"),
 164                 PARSE_OPT_NOARG),
 165         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 166                 N_("allow fast-forward"),
 167                 PARSE_OPT_NOARG),
 168         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 169                 N_("abort if fast-forward is not possible"),
 170                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 171         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 172                 N_("verify that the named commit has a valid GPG signature"),
 173                 PARSE_OPT_NOARG),
 174         OPT_BOOL(0, "autostash", &opt_autostash,
 175                 N_("automatically stash/stash pop before and after rebase")),
 176         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 177                 N_("merge strategy to use"),
 178                 0),
 179         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 180                 N_("option=value"),
 181                 N_("option for selected merge strategy"),
 182                 0),
 183         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 184                 N_("GPG sign commit"),
 185                 PARSE_OPT_OPTARG),
 186         OPT_SET_INT(0, "allow-unrelated-histories",
 187                     &opt_allow_unrelated_histories,
 188                     N_("allow merging unrelated histories"), 1),
 189
 190         /* Options passed to git-fetch */
 191         OPT_GROUP(N_("Options related to fetching")),
 192         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 193                 N_("fetch from all remotes"),
 194                 PARSE_OPT_NOARG),
 195         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 196                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 197                 PARSE_OPT_NOARG),
 198         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 199                 N_("path to upload pack on remote end"),
 200                 0),
 201         OPT__FORCE(&opt_force, N_("force overwrite of local branch"), 0),
 202         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 203                 N_("fetch all tags and associated objects"),
 204                 PARSE_OPT_NOARG),
 205         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 206                 N_("prune remote-tracking branches no longer on remote"),
 207                 PARSE_OPT_NOARG),
 208         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 209                 N_("number of submodules pulled in parallel"),
 210                 PARSE_OPT_OPTARG),
 211         OPT_BOOL(0, "dry-run", &opt_dry_run,
 212                 N_("dry run")),
 213         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 214                 N_("keep downloaded pack"),
 215                 PARSE_OPT_NOARG),
 216         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 217                 N_("deepen history of shallow clone"),
 218                 0),
 219         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 220                 N_("convert to a complete repository"),
 221                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 222         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 223                 N_("accept refs that update .git/shallow"),
 224                 PARSE_OPT_NOARG),
 225         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 226                 N_("specify fetch refmap"),
 227                 PARSE_OPT_NONEG),
 228         OPT_PASSTHRU('4',  "ipv4", &opt_ipv4, NULL,
 229                 N_("use IPv4 addresses only"),
 230                 PARSE_OPT_NOARG),
 231         OPT_PASSTHRU('6',  "ipv6", &opt_ipv6, NULL,
 232                 N_("use IPv6 addresses only"),
 233                 PARSE_OPT_NOARG),
 234
 235         OPT_END()
 236 };
 237
 238 /**
 239  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 240  */
 241 static void argv_push_verbosity(struct argv_array *arr)
 242 {
 243         int verbosity;
 244
 245         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 246                 argv_array_push(arr, "-v");
 247
 248         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 249                 argv_array_push(arr, "-q");
 250 }
 251
 252 /**
 253  * Pushes "-f" switches into arr to match the opt_force level.
 254  */
 255 static void argv_push_force(struct argv_array *arr)
 256 {
 257         int force = opt_force;
 258         while (force-- > 0)
 259                 argv_array_push(arr, "-f");
 260 }
 261
 262 /**
 263  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 264  */
 265 static void set_reflog_message(int argc, const char **argv)
 266 {
 267         int i;
 268         struct strbuf msg = STRBUF_INIT;
 269
 270         for (i = 0; i < argc; i++) {
 271                 if (i)
 272                         strbuf_addch(&msg, ' ');
 273                 strbuf_addstr(&msg, argv[i]);
 274         }
 275
 276         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 277
 278         strbuf_release(&msg);
 279 }
 280
 281 /**
 282  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 283  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 284  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 285  * error.
 286  */
 287 static const char *config_get_ff(void)
 288 {
 289         const char *value;
 290
 291         if (git_config_get_value("pull.ff", &value))
 292                 return NULL;
 293
 294         switch (git_parse_maybe_bool(value)) {
 295         case 0:
 296                 return "--no-ff";
 297         case 1:
 298                 return "--ff";
 299         }
 300
 301         if (!strcmp(value, "only"))
 302                 return "--ff-only";
 303
 304         die(_("Invalid value for pull.ff: %s"), value);
 305 }
 306
 307 /**
 308  * Returns the default configured value for --rebase. It first looks for the
 309  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 310  * branch, and if HEAD is detached or the configuration key does not exist,
 311  * looks for the value of "pull.rebase". If both configuration keys do not
 312  * exist, returns REBASE_FALSE.
 313  */
 314 static enum rebase_type config_get_rebase(void)
 315 {
 316         struct branch *curr_branch = branch_get("HEAD");
 317         const char *value;
 318
 319         if (curr_branch) {
 320                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 321
 322                 if (!git_config_get_value(key, &value)) {
 323                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 324                         free(key);
 325                         return ret;
 326                 }
 327
 328                 free(key);
 329         }
 330
 331         if (!git_config_get_value("pull.rebase", &value))
 332                 return parse_config_rebase("pull.rebase", value, 1);
 333
 334         return REBASE_FALSE;
 335 }
 336
 337 /**
 338  * Read config variables.
 339  */
 340 static int git_pull_config(const char *var, const char *value, void *cb)
 341 {
 342         if (!strcmp(var, "rebase.autostash")) {
 343                 config_autostash = git_config_bool(var, value);
 344                 return 0;
 345         } else if (!strcmp(var, "submodule.recurse")) {
 346                 recurse_submodules = git_config_bool(var, value) ?
 347                         RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
 348                 return 0;
 349         }
 350         return git_default_config(var, value, cb);
 351 }
 352
 353 /**
 354  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 355  * into merge_heads.
 356  */
 357 static void get_merge_heads(struct oid_array *merge_heads)
 358 {
 359         const char *filename = git_path_fetch_head(the_repository);
 360         FILE *fp;
 361         struct strbuf sb = STRBUF_INIT;
 362         struct object_id oid;
 363
 364         fp = xfopen(filename, "r");
 365         while (strbuf_getline_lf(&sb, fp) != EOF) {
 366                 if (get_oid_hex(sb.buf, &oid))
 367                         continue;  /* invalid line: does not start with SHA1 */
 368                 if (starts_with(sb.buf + GIT_SHA1_HEXSZ, "\tnot-for-merge\t"))
 369                         continue;  /* ref is not-for-merge */
 370                 oid_array_append(merge_heads, &oid);
 371         }
 372         fclose(fp);
 373         strbuf_release(&sb);
 374 }
 375
 376 /**
 377  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 378  * retrieve the name of the remote if the repository only has one remote.
 379  */
 380 static int get_only_remote(struct remote *remote, void *cb_data)
 381 {
 382         const char **remote_name = cb_data;
 383
 384         if (*remote_name)
 385                 return -1;
 386
 387         *remote_name = remote->name;
 388         return 0;
 389 }
 390
 391 /**
 392  * Dies with the appropriate reason for why there are no merge candidates:
 393  *
 394  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 395  *    up not fetching anything. This is usually because the user provided a
 396  *    wildcard refspec which had no matches on the remote end.
 397  *
 398  * 2. We fetched from a non-default remote, but didn't specify a branch to
 399  *    merge. We can't use the configured one because it applies to the default
 400  *    remote, thus the user must specify the branches to merge.
 401  *
 402  * 3. We fetched from the branch's or repo's default remote, but:
 403  *
 404  *    a. We are not on a branch, so there will never be a configured branch to
 405  *       merge with.
 406  *
 407  *    b. We are on a branch, but there is no configured branch to merge with.
 408  *
 409  * 4. We fetched from the branch's or repo's default remote, but the configured
 410  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 411  *    part of the configured fetch refspec.)
 412  */
 413 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 414 {
 415         struct branch *curr_branch = branch_get("HEAD");
 416         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 417
 418         if (*refspecs) {
 419                 if (opt_rebase)
 420                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 421                 else
 422                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 423                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 424                                         "matches on the remote end."));
 425         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 426                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 427                         "a branch. Because this is not the default configured remote\n"
 428                         "for your current branch, you must specify a branch on the command line."),
 429                         repo);
 430         } else if (!curr_branch) {
 431                 fprintf_ln(stderr, _("You are not currently on a branch."));
 432                 if (opt_rebase)
 433                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 434                 else
 435                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 436                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 437                 fprintf(stderr, "\n");
 438                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 439                 fprintf(stderr, "\n");
 440         } else if (!curr_branch->merge_nr) {
 441                 const char *remote_name = NULL;
 442
 443                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 444                         remote_name = _("<remote>");
 445
 446                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 447                 if (opt_rebase)
 448                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 449                 else
 450                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 451                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 452                 fprintf(stderr, "\n");
 453                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 454                 fprintf(stderr, "\n");
 455                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));
 456                 fprintf(stderr, "\n");
 457                 fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",
 458                                 remote_name, _("<branch>"), curr_branch->name);
 459         } else
 460                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 461                         "from the remote, but no such ref was fetched."),
 462                         *curr_branch->merge_name);
 463         exit(1);
 464 }
 465
 466 /**
 467  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 468  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 469  * is not provided in argv, it is set to NULL.
 470  */
 471 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 472                 const char ***refspecs)
 473 {
 474         if (argc > 0) {
 475                 *repo = *argv++;
 476                 argc--;
 477         } else
 478                 *repo = NULL;
 479         *refspecs = argv;
 480 }
 481
 482 /**
 483  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 484  * repository and refspecs to fetch, or NULL if they are not provided.
 485  */
 486 static int run_fetch(const char *repo, const char **refspecs)
 487 {
 488         struct argv_array args = ARGV_ARRAY_INIT;
 489         int ret;
 490
 491         argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
 492
 493         /* Shared options */
 494         argv_push_verbosity(&args);
 495         if (opt_progress)
 496                 argv_array_push(&args, opt_progress);
 497
 498         /* Options passed to git-fetch */
 499         if (opt_all)
 500                 argv_array_push(&args, opt_all);
 501         if (opt_append)
 502                 argv_array_push(&args, opt_append);
 503         if (opt_upload_pack)
 504                 argv_array_push(&args, opt_upload_pack);
 505         argv_push_force(&args);
 506         if (opt_tags)
 507                 argv_array_push(&args, opt_tags);
 508         if (opt_prune)
 509                 argv_array_push(&args, opt_prune);
 510         if (recurse_submodules != RECURSE_SUBMODULES_DEFAULT)
 511                 switch (recurse_submodules) {
 512                 case RECURSE_SUBMODULES_ON:
 513                         argv_array_push(&args, "--recurse-submodules=on");
 514                         break;
 515                 case RECURSE_SUBMODULES_OFF:
 516                         argv_array_push(&args, "--recurse-submodules=no");
 517                         break;
 518                 case RECURSE_SUBMODULES_ON_DEMAND:
 519                         argv_array_push(&args, "--recurse-submodules=on-demand");
 520                         break;
 521                 default:
 522                         BUG("submodule recursion option not understood");
 523                 }
 524         if (max_children)
 525                 argv_array_push(&args, max_children);
 526         if (opt_dry_run)
 527                 argv_array_push(&args, "--dry-run");
 528         if (opt_keep)
 529                 argv_array_push(&args, opt_keep);
 530         if (opt_depth)
 531                 argv_array_push(&args, opt_depth);
 532         if (opt_unshallow)
 533                 argv_array_push(&args, opt_unshallow);
 534         if (opt_update_shallow)
 535                 argv_array_push(&args, opt_update_shallow);
 536         if (opt_refmap)
 537                 argv_array_push(&args, opt_refmap);
 538         if (opt_ipv4)
 539                 argv_array_push(&args, opt_ipv4);
 540         if (opt_ipv6)
 541                 argv_array_push(&args, opt_ipv6);
 542
 543         if (repo) {
 544                 argv_array_push(&args, repo);
 545                 argv_array_pushv(&args, refspecs);
 546         } else if (*refspecs)
 547                 BUG("refspecs without repo?");
 548         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 549         argv_array_clear(&args);
 550         return ret;
 551 }
 552
 553 /**
 554  * "Pulls into void" by branching off merge_head.
 555  */
 556 static int pull_into_void(const struct object_id *merge_head,
 557                 const struct object_id *curr_head)
 558 {
 559         /*
 560          * Two-way merge: we treat the index as based on an empty tree,
 561          * and try to fast-forward to HEAD. This ensures we will not lose
 562          * index/worktree changes that the user already made on the unborn
 563          * branch.
 564          */
 565         if (checkout_fast_forward(the_hash_algo->empty_tree, merge_head, 0))
 566                 return 1;
 567
 568         if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 569                 return 1;
 570
 571         return 0;
 572 }
 573
 574 static int rebase_submodules(void)
 575 {
 576         struct child_process cp = CHILD_PROCESS_INIT;
 577
 578         cp.git_cmd = 1;
 579         cp.no_stdin = 1;
 580         argv_array_pushl(&cp.args, "submodule", "update",
 581                                    "--recursive", "--rebase", NULL);
 582         argv_push_verbosity(&cp.args);
 583
 584         return run_command(&cp);
 585 }
 586
 587 static int update_submodules(void)
 588 {
 589         struct child_process cp = CHILD_PROCESS_INIT;
 590
 591         cp.git_cmd = 1;
 592         cp.no_stdin = 1;
 593         argv_array_pushl(&cp.args, "submodule", "update",
 594                                    "--recursive", "--checkout", NULL);
 595         argv_push_verbosity(&cp.args);
 596
 597         return run_command(&cp);
 598 }
 599
 600 /**
 601  * Runs git-merge, returning its exit status.
 602  */
 603 static int run_merge(void)
 604 {
 605         int ret;
 606         struct argv_array args = ARGV_ARRAY_INIT;
 607
 608         argv_array_pushl(&args, "merge", NULL);
 609
 610         /* Shared options */
 611         argv_push_verbosity(&args);
 612         if (opt_progress)
 613                 argv_array_push(&args, opt_progress);
 614
 615         /* Options passed to git-merge */
 616         if (opt_diffstat)
 617                 argv_array_push(&args, opt_diffstat);
 618         if (opt_log)
 619                 argv_array_push(&args, opt_log);
 620         if (opt_signoff)
 621                 argv_array_push(&args, opt_signoff);
 622         if (opt_squash)
 623                 argv_array_push(&args, opt_squash);
 624         if (opt_commit)
 625                 argv_array_push(&args, opt_commit);
 626         if (opt_edit)
 627                 argv_array_push(&args, opt_edit);
 628         if (opt_ff)
 629                 argv_array_push(&args, opt_ff);
 630         if (opt_verify_signatures)
 631                 argv_array_push(&args, opt_verify_signatures);
 632         argv_array_pushv(&args, opt_strategies.argv);
 633         argv_array_pushv(&args, opt_strategy_opts.argv);
 634         if (opt_gpg_sign)
 635                 argv_array_push(&args, opt_gpg_sign);
 636         if (opt_allow_unrelated_histories > 0)
 637                 argv_array_push(&args, "--allow-unrelated-histories");
 638
 639         argv_array_push(&args, "FETCH_HEAD");
 640         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 641         argv_array_clear(&args);
 642         return ret;
 643 }
 644
 645 /**
 646  * Returns remote's upstream branch for the current branch. If remote is NULL,
 647  * the current branch's configured default remote is used. Returns NULL if
 648  * `remote` does not name a valid remote, HEAD does not point to a branch,
 649  * remote is not the branch's configured remote or the branch does not have any
 650  * configured upstream branch.
 651  */
 652 static const char *get_upstream_branch(const char *remote)
 653 {
 654         struct remote *rm;
 655         struct branch *curr_branch;
 656         const char *curr_branch_remote;
 657
 658         rm = remote_get(remote);
 659         if (!rm)
 660                 return NULL;
 661
 662         curr_branch = branch_get("HEAD");
 663         if (!curr_branch)
 664                 return NULL;
 665
 666         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 667         assert(curr_branch_remote);
 668
 669         if (strcmp(curr_branch_remote, rm->name))
 670                 return NULL;
 671
 672         return branch_get_upstream(curr_branch, NULL);
 673 }
 674
 675 /**
 676  * Derives the remote-tracking branch from the remote and refspec.
 677  *
 678  * FIXME: The current implementation assumes the default mapping of
 679  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 680  */
 681 static const char *get_tracking_branch(const char *remote, const char *refspec)
 682 {
 683         struct refspec_item spec;
 684         const char *spec_src;
 685         const char *merge_branch;
 686
 687         refspec_item_init_or_die(&spec, refspec, REFSPEC_FETCH);
 688         spec_src = spec.src;
 689         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 690                 spec_src = "HEAD";
 691         else if (skip_prefix(spec_src, "heads/", &spec_src))
 692                 ;
 693         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 694                 ;
 695         else if (starts_with(spec_src, "refs/") ||
 696                 starts_with(spec_src, "tags/") ||
 697                 starts_with(spec_src, "remotes/"))
 698                 spec_src = "";
 699
 700         if (*spec_src) {
 701                 if (!strcmp(remote, "."))
 702                         merge_branch = mkpath("refs/heads/%s", spec_src);
 703                 else
 704                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 705         } else
 706                 merge_branch = NULL;
 707
 708         refspec_item_clear(&spec);
 709         return merge_branch;
 710 }
 711
 712 /**
 713  * Given the repo and refspecs, sets fork_point to the point at which the
 714  * current branch forked from its remote-tracking branch. Returns 0 on success,
 715  * -1 on failure.
 716  */
 717 static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,
 718                 const char *refspec)
 719 {
 720         int ret;
 721         struct branch *curr_branch;
 722         const char *remote_branch;
 723         struct child_process cp = CHILD_PROCESS_INIT;
 724         struct strbuf sb = STRBUF_INIT;
 725
 726         curr_branch = branch_get("HEAD");
 727         if (!curr_branch)
 728                 return -1;
 729
 730         if (refspec)
 731                 remote_branch = get_tracking_branch(repo, refspec);
 732         else
 733                 remote_branch = get_upstream_branch(repo);
 734
 735         if (!remote_branch)
 736                 return -1;
 737
 738         argv_array_pushl(&cp.args, "merge-base", "--fork-point",
 739                         remote_branch, curr_branch->name, NULL);
 740         cp.no_stdin = 1;
 741         cp.no_stderr = 1;
 742         cp.git_cmd = 1;
 743
 744         ret = capture_command(&cp, &sb, GIT_SHA1_HEXSZ);
 745         if (ret)
 746                 goto cleanup;
 747
 748         ret = get_oid_hex(sb.buf, fork_point);
 749         if (ret)
 750                 goto cleanup;
 751
 752 cleanup:
 753         strbuf_release(&sb);
 754         return ret ? -1 : 0;
 755 }
 756
 757 /**
 758  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 759  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 760  */
 761 static int get_octopus_merge_base(struct object_id *merge_base,
 762                 const struct object_id *curr_head,
 763                 const struct object_id *merge_head,
 764                 const struct object_id *fork_point)
 765 {
 766         struct commit_list *revs = NULL, *result;
 767
 768         commit_list_insert(lookup_commit_reference(the_repository, curr_head),
 769                            &revs);
 770         commit_list_insert(lookup_commit_reference(the_repository, merge_head),
 771                            &revs);
 772         if (!is_null_oid(fork_point))
 773                 commit_list_insert(lookup_commit_reference(the_repository, fork_point),
 774                                    &revs);
 775
 776         result = get_octopus_merge_bases(revs);
 777         free_commit_list(revs);
 778         reduce_heads_replace(&result);
 779
 780         if (!result)
 781                 return 1;
 782
 783         oidcpy(merge_base, &result->item->object.oid);
 784         free_commit_list(result);
 785         return 0;
 786 }
 787
 788 /**
 789  * Given the current HEAD SHA1, the merge head returned from git-fetch and the
 790  * fork point calculated by get_rebase_fork_point(), runs git-rebase with the
 791  * appropriate arguments and returns its exit status.
 792  */
 793 static int run_rebase(const struct object_id *curr_head,
 794                 const struct object_id *merge_head,
 795                 const struct object_id *fork_point)
 796 {
 797         int ret;
 798         struct object_id oct_merge_base;
 799         struct argv_array args = ARGV_ARRAY_INIT;
 800
 801         if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))
 802                 if (!is_null_oid(fork_point) && !oidcmp(&oct_merge_base, fork_point))
 803                         fork_point = NULL;
 804
 805         argv_array_push(&args, "rebase");
 806
 807         /* Shared options */
 808         argv_push_verbosity(&args);
 809
 810         /* Options passed to git-rebase */
 811         if (opt_rebase == REBASE_MERGES)
 812                 argv_array_push(&args, "--rebase-merges");
 813         else if (opt_rebase == REBASE_PRESERVE)
 814                 argv_array_push(&args, "--preserve-merges");
 815         else if (opt_rebase == REBASE_INTERACTIVE)
 816                 argv_array_push(&args, "--interactive");
 817         if (opt_diffstat)
 818                 argv_array_push(&args, opt_diffstat);
 819         argv_array_pushv(&args, opt_strategies.argv);
 820         argv_array_pushv(&args, opt_strategy_opts.argv);
 821         if (opt_gpg_sign)
 822                 argv_array_push(&args, opt_gpg_sign);
 823         if (opt_autostash == 0)
 824                 argv_array_push(&args, "--no-autostash");
 825         else if (opt_autostash == 1)
 826                 argv_array_push(&args, "--autostash");
 827         if (opt_verify_signatures &&
 828             !strcmp(opt_verify_signatures, "--verify-signatures"))
 829                 warning(_("ignoring --verify-signatures for rebase"));
 830
 831         argv_array_push(&args, "--onto");
 832         argv_array_push(&args, oid_to_hex(merge_head));
 833
 834         if (fork_point && !is_null_oid(fork_point))
 835                 argv_array_push(&args, oid_to_hex(fork_point));
 836         else
 837                 argv_array_push(&args, oid_to_hex(merge_head));
 838
 839         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 840         argv_array_clear(&args);
 841         return ret;
 842 }
 843
 844 int cmd_pull(int argc, const char **argv, const char *prefix)
 845 {
 846         const char *repo, **refspecs;
 847         struct oid_array merge_heads = OID_ARRAY_INIT;
 848         struct object_id orig_head, curr_head;
 849         struct object_id rebase_fork_point;
 850         int autostash;
 851
 852         if (!getenv("GIT_REFLOG_ACTION"))
 853                 set_reflog_message(argc, argv);
 854
 855         git_config(git_pull_config, NULL);
 856
 857         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 858
 859         parse_repo_refspecs(argc, argv, &repo, &refspecs);
 860
 861         if (!opt_ff)
 862                 opt_ff = xstrdup_or_null(config_get_ff());
 863
 864         if (opt_rebase < 0)
 865                 opt_rebase = config_get_rebase();
 866
 867         if (read_cache_unmerged())
 868                 die_resolve_conflict("pull");
 869
 870         if (file_exists(git_path_merge_head(the_repository)))
 871                 die_conclude_merge();
 872
 873         if (get_oid("HEAD", &orig_head))
 874                 oidclr(&orig_head);
 875
 876         if (!opt_rebase && opt_autostash != -1)
 877                 die(_("--[no-]autostash option is only valid with --rebase."));
 878
 879         autostash = config_autostash;
 880         if (opt_rebase) {
 881                 if (opt_autostash != -1)
 882                         autostash = opt_autostash;
 883
 884                 if (is_null_oid(&orig_head) && !is_cache_unborn())
 885                         die(_("Updating an unborn branch with changes added to the index."));
 886
 887                 if (!autostash)
 888                         require_clean_work_tree(N_("pull with rebase"),
 889                                 _("please commit or stash them."), 1, 0);
 890
 891                 if (get_rebase_fork_point(&rebase_fork_point, repo, *refspecs))
 892                         oidclr(&rebase_fork_point);
 893         }
 894
 895         if (run_fetch(repo, refspecs))
 896                 return 1;
 897
 898         if (opt_dry_run)
 899                 return 0;
 900
 901         if (get_oid("HEAD", &curr_head))
 902                 oidclr(&curr_head);
 903
 904         if (!is_null_oid(&orig_head) && !is_null_oid(&curr_head) &&
 905                         oidcmp(&orig_head, &curr_head)) {
 906                 /*
 907                  * The fetch involved updating the current branch.
 908                  *
 909                  * The working tree and the index file are still based on
 910                  * orig_head commit, but we are merging into curr_head.
 911                  * Update the working tree to match curr_head.
 912                  */
 913
 914                 warning(_("fetch updated the current branch head.\n"
 915                         "fast-forwarding your working tree from\n"
 916                         "commit %s."), oid_to_hex(&orig_head));
 917
 918                 if (checkout_fast_forward(&orig_head, &curr_head, 0))
 919                         die(_("Cannot fast-forward your working tree.\n"
 920                                 "After making sure that you saved anything precious from\n"
 921                                 "$ git diff %s\n"
 922                                 "output, run\n"
 923                                 "$ git reset --hard\n"
 924                                 "to recover."), oid_to_hex(&orig_head));
 925         }
 926
 927         get_merge_heads(&merge_heads);
 928
 929         if (!merge_heads.nr)
 930                 die_no_merge_candidates(repo, refspecs);
 931
 932         if (is_null_oid(&orig_head)) {
 933                 if (merge_heads.nr > 1)
 934                         die(_("Cannot merge multiple branches into empty head."));
 935                 return pull_into_void(merge_heads.oid, &curr_head);
 936         }
 937         if (opt_rebase && merge_heads.nr > 1)
 938                 die(_("Cannot rebase onto multiple branches."));
 939
 940         if (opt_rebase) {
 941                 int ret = 0;
 942                 if ((recurse_submodules == RECURSE_SUBMODULES_ON ||
 943                      recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) &&
 944                     submodule_touches_in_range(&rebase_fork_point, &curr_head))
 945                         die(_("cannot rebase with locally recorded submodule modifications"));
 946                 if (!autostash) {
 947                         struct commit_list *list = NULL;
 948                         struct commit *merge_head, *head;
 949
 950                         head = lookup_commit_reference(the_repository,
 951                                                        &orig_head);
 952                         commit_list_insert(head, &list);
 953                         merge_head = lookup_commit_reference(the_repository,
 954                                                              &merge_heads.oid[0]);
 955                         if (is_descendant_of(merge_head, list)) {
 956                                 /* we can fast-forward this without invoking rebase */
 957                                 opt_ff = "--ff-only";
 958                                 ret = run_merge();
 959                         }
 960                 }
 961                 ret = run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
 962
 963                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
 964                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
 965                         ret = rebase_submodules();
 966
 967                 return ret;
 968         } else {
 969                 int ret = run_merge();
 970                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
 971                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
 972                         ret = update_submodules();
 973                 return ret;
 974         }
 975 }