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
 133 static struct option pull_options[] = {
 134         /* Shared options */
 135         OPT__VERBOSITY(&opt_verbosity),
 136         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 137                 N_("force progress reporting"),
 138                 PARSE_OPT_NOARG),
 139         { OPTION_CALLBACK, 0, "recurse-submodules",
 140                    &recurse_submodules, N_("on-demand"),
 141                    N_("control for recursive fetching of submodules"),
 142                    PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules },
 143
 144         /* Options passed to git-merge or git-rebase */
 145         OPT_GROUP(N_("Options related to merging")),
 146         { OPTION_CALLBACK, 'r', "rebase", &opt_rebase,
 147           "(false|true|merges|preserve|interactive)",
 148           N_("incorporate changes by rebasing rather than merging"),
 149           PARSE_OPT_OPTARG, parse_opt_rebase },
 150         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 151                 N_("do not show a diffstat at the end of the merge"),
 152                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 153         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 154                 N_("show a diffstat at the end of the merge"),
 155                 PARSE_OPT_NOARG),
 156         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 157                 N_("(synonym to --stat)"),
 158                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 159         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 160                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 161                 PARSE_OPT_OPTARG),
 162         OPT_PASSTHRU(0, "signoff", &opt_signoff, NULL,
 163                 N_("add Signed-off-by:"),
 164                 PARSE_OPT_OPTARG),
 165         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 166                 N_("create a single commit instead of doing a merge"),
 167                 PARSE_OPT_NOARG),
 168         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 169                 N_("perform a commit if the merge succeeds (default)"),
 170                 PARSE_OPT_NOARG),
 171         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 172                 N_("edit message before committing"),
 173                 PARSE_OPT_NOARG),
 174         OPT_CLEANUP(&cleanup_arg),
 175         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 176                 N_("allow fast-forward"),
 177                 PARSE_OPT_NOARG),
 178         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 179                 N_("abort if fast-forward is not possible"),
 180                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 181         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 182                 N_("verify that the named commit has a valid GPG signature"),
 183                 PARSE_OPT_NOARG),
 184         OPT_BOOL(0, "autostash", &opt_autostash,
 185                 N_("automatically stash/stash pop before and after rebase")),
 186         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 187                 N_("merge strategy to use"),
 188                 0),
 189         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 190                 N_("option=value"),
 191                 N_("option for selected merge strategy"),
 192                 0),
 193         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 194                 N_("GPG sign commit"),
 195                 PARSE_OPT_OPTARG),
 196         OPT_SET_INT(0, "allow-unrelated-histories",
 197                     &opt_allow_unrelated_histories,
 198                     N_("allow merging unrelated histories"), 1),
 199
 200         /* Options passed to git-fetch */
 201         OPT_GROUP(N_("Options related to fetching")),
 202         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 203                 N_("fetch from all remotes"),
 204                 PARSE_OPT_NOARG),
 205         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 206                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 207                 PARSE_OPT_NOARG),
 208         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 209                 N_("path to upload pack on remote end"),
 210                 0),
 211         OPT__FORCE(&opt_force, N_("force overwrite of local branch"), 0),
 212         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 213                 N_("fetch all tags and associated objects"),
 214                 PARSE_OPT_NOARG),
 215         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 216                 N_("prune remote-tracking branches no longer on remote"),
 217                 PARSE_OPT_NOARG),
 218         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 219                 N_("number of submodules pulled in parallel"),
 220                 PARSE_OPT_OPTARG),
 221         OPT_BOOL(0, "dry-run", &opt_dry_run,
 222                 N_("dry run")),
 223         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 224                 N_("keep downloaded pack"),
 225                 PARSE_OPT_NOARG),
 226         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 227                 N_("deepen history of shallow clone"),
 228                 0),
 229         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 230                 N_("convert to a complete repository"),
 231                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 232         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 233                 N_("accept refs that update .git/shallow"),
 234                 PARSE_OPT_NOARG),
 235         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 236                 N_("specify fetch refmap"),
 237                 PARSE_OPT_NONEG),
 238         OPT_PASSTHRU('4',  "ipv4", &opt_ipv4, NULL,
 239                 N_("use IPv4 addresses only"),
 240                 PARSE_OPT_NOARG),
 241         OPT_PASSTHRU('6',  "ipv6", &opt_ipv6, NULL,
 242                 N_("use IPv6 addresses only"),
 243                 PARSE_OPT_NOARG),
 244         OPT_BOOL(0, "show-forced-updates", &opt_show_forced_updates,
 245                  N_("check for forced-updates on all updated branches")),
 246
 247         OPT_END()
 248 };
 249
 250 /**
 251  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 252  */
 253 static void argv_push_verbosity(struct argv_array *arr)
 254 {
 255         int verbosity;
 256
 257         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 258                 argv_array_push(arr, "-v");
 259
 260         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 261                 argv_array_push(arr, "-q");
 262 }
 263
 264 /**
 265  * Pushes "-f" switches into arr to match the opt_force level.
 266  */
 267 static void argv_push_force(struct argv_array *arr)
 268 {
 269         int force = opt_force;
 270         while (force-- > 0)
 271                 argv_array_push(arr, "-f");
 272 }
 273
 274 /**
 275  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 276  */
 277 static void set_reflog_message(int argc, const char **argv)
 278 {
 279         int i;
 280         struct strbuf msg = STRBUF_INIT;
 281
 282         for (i = 0; i < argc; i++) {
 283                 if (i)
 284                         strbuf_addch(&msg, ' ');
 285                 strbuf_addstr(&msg, argv[i]);
 286         }
 287
 288         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 289
 290         strbuf_release(&msg);
 291 }
 292
 293 /**
 294  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 295  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 296  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 297  * error.
 298  */
 299 static const char *config_get_ff(void)
 300 {
 301         const char *value;
 302
 303         if (git_config_get_value("pull.ff", &value))
 304                 return NULL;
 305
 306         switch (git_parse_maybe_bool(value)) {
 307         case 0:
 308                 return "--no-ff";
 309         case 1:
 310                 return "--ff";
 311         }
 312
 313         if (!strcmp(value, "only"))
 314                 return "--ff-only";
 315
 316         die(_("Invalid value for pull.ff: %s"), value);
 317 }
 318
 319 /**
 320  * Returns the default configured value for --rebase. It first looks for the
 321  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 322  * branch, and if HEAD is detached or the configuration key does not exist,
 323  * looks for the value of "pull.rebase". If both configuration keys do not
 324  * exist, returns REBASE_FALSE.
 325  */
 326 static enum rebase_type config_get_rebase(void)
 327 {
 328         struct branch *curr_branch = branch_get("HEAD");
 329         const char *value;
 330
 331         if (curr_branch) {
 332                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 333
 334                 if (!git_config_get_value(key, &value)) {
 335                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 336                         free(key);
 337                         return ret;
 338                 }
 339
 340                 free(key);
 341         }
 342
 343         if (!git_config_get_value("pull.rebase", &value))
 344                 return parse_config_rebase("pull.rebase", value, 1);
 345
 346         return REBASE_FALSE;
 347 }
 348
 349 /**
 350  * Read config variables.
 351  */
 352 static int git_pull_config(const char *var, const char *value, void *cb)
 353 {
 354         if (!strcmp(var, "rebase.autostash")) {
 355                 config_autostash = git_config_bool(var, value);
 356                 return 0;
 357         } else if (!strcmp(var, "submodule.recurse")) {
 358                 recurse_submodules = git_config_bool(var, value) ?
 359                         RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
 360                 return 0;
 361         }
 362         return git_default_config(var, value, cb);
 363 }
 364
 365 /**
 366  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 367  * into merge_heads.
 368  */
 369 static void get_merge_heads(struct oid_array *merge_heads)
 370 {
 371         const char *filename = git_path_fetch_head(the_repository);
 372         FILE *fp;
 373         struct strbuf sb = STRBUF_INIT;
 374         struct object_id oid;
 375
 376         fp = xfopen(filename, "r");
 377         while (strbuf_getline_lf(&sb, fp) != EOF) {
 378                 const char *p;
 379                 if (parse_oid_hex(sb.buf, &oid, &p))
 380                         continue;  /* invalid line: does not start with object ID */
 381                 if (starts_with(p, "\tnot-for-merge\t"))
 382                         continue;  /* ref is not-for-merge */
 383                 oid_array_append(merge_heads, &oid);
 384         }
 385         fclose(fp);
 386         strbuf_release(&sb);
 387 }
 388
 389 /**
 390  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 391  * retrieve the name of the remote if the repository only has one remote.
 392  */
 393 static int get_only_remote(struct remote *remote, void *cb_data)
 394 {
 395         const char **remote_name = cb_data;
 396
 397         if (*remote_name)
 398                 return -1;
 399
 400         *remote_name = remote->name;
 401         return 0;
 402 }
 403
 404 /**
 405  * Dies with the appropriate reason for why there are no merge candidates:
 406  *
 407  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 408  *    up not fetching anything. This is usually because the user provided a
 409  *    wildcard refspec which had no matches on the remote end.
 410  *
 411  * 2. We fetched from a non-default remote, but didn't specify a branch to
 412  *    merge. We can't use the configured one because it applies to the default
 413  *    remote, thus the user must specify the branches to merge.
 414  *
 415  * 3. We fetched from the branch's or repo's default remote, but:
 416  *
 417  *    a. We are not on a branch, so there will never be a configured branch to
 418  *       merge with.
 419  *
 420  *    b. We are on a branch, but there is no configured branch to merge with.
 421  *
 422  * 4. We fetched from the branch's or repo's default remote, but the configured
 423  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 424  *    part of the configured fetch refspec.)
 425  */
 426 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 427 {
 428         struct branch *curr_branch = branch_get("HEAD");
 429         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 430
 431         if (*refspecs) {
 432                 if (opt_rebase)
 433                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 434                 else
 435                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 436                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 437                                         "matches on the remote end."));
 438         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 439                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 440                         "a branch. Because this is not the default configured remote\n"
 441                         "for your current branch, you must specify a branch on the command line."),
 442                         repo);
 443         } else if (!curr_branch) {
 444                 fprintf_ln(stderr, _("You are not currently on a branch."));
 445                 if (opt_rebase)
 446                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 447                 else
 448                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 449                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 450                 fprintf(stderr, "\n");
 451                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 452                 fprintf(stderr, "\n");
 453         } else if (!curr_branch->merge_nr) {
 454                 const char *remote_name = NULL;
 455
 456                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 457                         remote_name = _("<remote>");
 458
 459                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 460                 if (opt_rebase)
 461                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 462                 else
 463                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 464                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 465                 fprintf(stderr, "\n");
 466                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 467                 fprintf(stderr, "\n");
 468                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));
 469                 fprintf(stderr, "\n");
 470                 fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",
 471                                 remote_name, _("<branch>"), curr_branch->name);
 472         } else
 473                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 474                         "from the remote, but no such ref was fetched."),
 475                         *curr_branch->merge_name);
 476         exit(1);
 477 }
 478
 479 /**
 480  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 481  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 482  * is not provided in argv, it is set to NULL.
 483  */
 484 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 485                 const char ***refspecs)
 486 {
 487         if (argc > 0) {
 488                 *repo = *argv++;
 489                 argc--;
 490         } else
 491                 *repo = NULL;
 492         *refspecs = argv;
 493 }
 494
 495 /**
 496  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 497  * repository and refspecs to fetch, or NULL if they are not provided.
 498  */
 499 static int run_fetch(const char *repo, const char **refspecs)
 500 {
 501         struct argv_array args = ARGV_ARRAY_INIT;
 502         int ret;
 503
 504         argv_array_pushl(&args, "fetch", "--update-head-ok", NULL);
 505
 506         /* Shared options */
 507         argv_push_verbosity(&args);
 508         if (opt_progress)
 509                 argv_array_push(&args, opt_progress);
 510
 511         /* Options passed to git-fetch */
 512         if (opt_all)
 513                 argv_array_push(&args, opt_all);
 514         if (opt_append)
 515                 argv_array_push(&args, opt_append);
 516         if (opt_upload_pack)
 517                 argv_array_push(&args, opt_upload_pack);
 518         argv_push_force(&args);
 519         if (opt_tags)
 520                 argv_array_push(&args, opt_tags);
 521         if (opt_prune)
 522                 argv_array_push(&args, opt_prune);
 523         if (recurse_submodules != RECURSE_SUBMODULES_DEFAULT)
 524                 switch (recurse_submodules) {
 525                 case RECURSE_SUBMODULES_ON:
 526                         argv_array_push(&args, "--recurse-submodules=on");
 527                         break;
 528                 case RECURSE_SUBMODULES_OFF:
 529                         argv_array_push(&args, "--recurse-submodules=no");
 530                         break;
 531                 case RECURSE_SUBMODULES_ON_DEMAND:
 532                         argv_array_push(&args, "--recurse-submodules=on-demand");
 533                         break;
 534                 default:
 535                         BUG("submodule recursion option not understood");
 536                 }
 537         if (max_children)
 538                 argv_array_push(&args, max_children);
 539         if (opt_dry_run)
 540                 argv_array_push(&args, "--dry-run");
 541         if (opt_keep)
 542                 argv_array_push(&args, opt_keep);
 543         if (opt_depth)
 544                 argv_array_push(&args, opt_depth);
 545         if (opt_unshallow)
 546                 argv_array_push(&args, opt_unshallow);
 547         if (opt_update_shallow)
 548                 argv_array_push(&args, opt_update_shallow);
 549         if (opt_refmap)
 550                 argv_array_push(&args, opt_refmap);
 551         if (opt_ipv4)
 552                 argv_array_push(&args, opt_ipv4);
 553         if (opt_ipv6)
 554                 argv_array_push(&args, opt_ipv6);
 555         if (opt_show_forced_updates > 0)
 556                 argv_array_push(&args, "--show-forced-updates");
 557         else if (opt_show_forced_updates == 0)
 558                 argv_array_push(&args, "--no-show-forced-updates");
 559
 560         if (repo) {
 561                 argv_array_push(&args, repo);
 562                 argv_array_pushv(&args, refspecs);
 563         } else if (*refspecs)
 564                 BUG("refspecs without repo?");
 565         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 566         argv_array_clear(&args);
 567         return ret;
 568 }
 569
 570 /**
 571  * "Pulls into void" by branching off merge_head.
 572  */
 573 static int pull_into_void(const struct object_id *merge_head,
 574                 const struct object_id *curr_head)
 575 {
 576         if (opt_verify_signatures) {
 577                 struct commit *commit;
 578
 579                 commit = lookup_commit(the_repository, merge_head);
 580                 if (!commit)
 581                         die(_("unable to access commit %s"),
 582                             oid_to_hex(merge_head));
 583
 584                 verify_merge_signature(commit, opt_verbosity);
 585         }
 586
 587         /*
 588          * Two-way merge: we treat the index as based on an empty tree,
 589          * and try to fast-forward to HEAD. This ensures we will not lose
 590          * index/worktree changes that the user already made on the unborn
 591          * branch.
 592          */
 593         if (checkout_fast_forward(the_repository,
 594                                   the_hash_algo->empty_tree,
 595                                   merge_head, 0))
 596                 return 1;
 597
 598         if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 599                 return 1;
 600
 601         return 0;
 602 }
 603
 604 static int rebase_submodules(void)
 605 {
 606         struct child_process cp = CHILD_PROCESS_INIT;
 607
 608         cp.git_cmd = 1;
 609         cp.no_stdin = 1;
 610         argv_array_pushl(&cp.args, "submodule", "update",
 611                                    "--recursive", "--rebase", NULL);
 612         argv_push_verbosity(&cp.args);
 613
 614         return run_command(&cp);
 615 }
 616
 617 static int update_submodules(void)
 618 {
 619         struct child_process cp = CHILD_PROCESS_INIT;
 620
 621         cp.git_cmd = 1;
 622         cp.no_stdin = 1;
 623         argv_array_pushl(&cp.args, "submodule", "update",
 624                                    "--recursive", "--checkout", NULL);
 625         argv_push_verbosity(&cp.args);
 626
 627         return run_command(&cp);
 628 }
 629
 630 /**
 631  * Runs git-merge, returning its exit status.
 632  */
 633 static int run_merge(void)
 634 {
 635         int ret;
 636         struct argv_array args = ARGV_ARRAY_INIT;
 637
 638         argv_array_pushl(&args, "merge", NULL);
 639
 640         /* Shared options */
 641         argv_push_verbosity(&args);
 642         if (opt_progress)
 643                 argv_array_push(&args, opt_progress);
 644
 645         /* Options passed to git-merge */
 646         if (opt_diffstat)
 647                 argv_array_push(&args, opt_diffstat);
 648         if (opt_log)
 649                 argv_array_push(&args, opt_log);
 650         if (opt_signoff)
 651                 argv_array_push(&args, opt_signoff);
 652         if (opt_squash)
 653                 argv_array_push(&args, opt_squash);
 654         if (opt_commit)
 655                 argv_array_push(&args, opt_commit);
 656         if (opt_edit)
 657                 argv_array_push(&args, opt_edit);
 658         if (cleanup_arg)
 659                 argv_array_pushf(&args, "--cleanup=%s", cleanup_arg);
 660         if (opt_ff)
 661                 argv_array_push(&args, opt_ff);
 662         if (opt_verify_signatures)
 663                 argv_array_push(&args, opt_verify_signatures);
 664         argv_array_pushv(&args, opt_strategies.argv);
 665         argv_array_pushv(&args, opt_strategy_opts.argv);
 666         if (opt_gpg_sign)
 667                 argv_array_push(&args, opt_gpg_sign);
 668         if (opt_allow_unrelated_histories > 0)
 669                 argv_array_push(&args, "--allow-unrelated-histories");
 670
 671         argv_array_push(&args, "FETCH_HEAD");
 672         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 673         argv_array_clear(&args);
 674         return ret;
 675 }
 676
 677 /**
 678  * Returns remote's upstream branch for the current branch. If remote is NULL,
 679  * the current branch's configured default remote is used. Returns NULL if
 680  * `remote` does not name a valid remote, HEAD does not point to a branch,
 681  * remote is not the branch's configured remote or the branch does not have any
 682  * configured upstream branch.
 683  */
 684 static const char *get_upstream_branch(const char *remote)
 685 {
 686         struct remote *rm;
 687         struct branch *curr_branch;
 688         const char *curr_branch_remote;
 689
 690         rm = remote_get(remote);
 691         if (!rm)
 692                 return NULL;
 693
 694         curr_branch = branch_get("HEAD");
 695         if (!curr_branch)
 696                 return NULL;
 697
 698         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 699         assert(curr_branch_remote);
 700
 701         if (strcmp(curr_branch_remote, rm->name))
 702                 return NULL;
 703
 704         return branch_get_upstream(curr_branch, NULL);
 705 }
 706
 707 /**
 708  * Derives the remote-tracking branch from the remote and refspec.
 709  *
 710  * FIXME: The current implementation assumes the default mapping of
 711  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 712  */
 713 static const char *get_tracking_branch(const char *remote, const char *refspec)
 714 {
 715         struct refspec_item spec;
 716         const char *spec_src;
 717         const char *merge_branch;
 718
 719         refspec_item_init_or_die(&spec, refspec, REFSPEC_FETCH);
 720         spec_src = spec.src;
 721         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 722                 spec_src = "HEAD";
 723         else if (skip_prefix(spec_src, "heads/", &spec_src))
 724                 ;
 725         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 726                 ;
 727         else if (starts_with(spec_src, "refs/") ||
 728                 starts_with(spec_src, "tags/") ||
 729                 starts_with(spec_src, "remotes/"))
 730                 spec_src = "";
 731
 732         if (*spec_src) {
 733                 if (!strcmp(remote, "."))
 734                         merge_branch = mkpath("refs/heads/%s", spec_src);
 735                 else
 736                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 737         } else
 738                 merge_branch = NULL;
 739
 740         refspec_item_clear(&spec);
 741         return merge_branch;
 742 }
 743
 744 /**
 745  * Given the repo and refspecs, sets fork_point to the point at which the
 746  * current branch forked from its remote-tracking branch. Returns 0 on success,
 747  * -1 on failure.
 748  */
 749 static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,
 750                 const char *refspec)
 751 {
 752         int ret;
 753         struct branch *curr_branch;
 754         const char *remote_branch;
 755         struct child_process cp = CHILD_PROCESS_INIT;
 756         struct strbuf sb = STRBUF_INIT;
 757
 758         curr_branch = branch_get("HEAD");
 759         if (!curr_branch)
 760                 return -1;
 761
 762         if (refspec)
 763                 remote_branch = get_tracking_branch(repo, refspec);
 764         else
 765                 remote_branch = get_upstream_branch(repo);
 766
 767         if (!remote_branch)
 768                 return -1;
 769
 770         argv_array_pushl(&cp.args, "merge-base", "--fork-point",
 771                         remote_branch, curr_branch->name, NULL);
 772         cp.no_stdin = 1;
 773         cp.no_stderr = 1;
 774         cp.git_cmd = 1;
 775
 776         ret = capture_command(&cp, &sb, GIT_MAX_HEXSZ);
 777         if (ret)
 778                 goto cleanup;
 779
 780         ret = get_oid_hex(sb.buf, fork_point);
 781         if (ret)
 782                 goto cleanup;
 783
 784 cleanup:
 785         strbuf_release(&sb);
 786         return ret ? -1 : 0;
 787 }
 788
 789 /**
 790  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 791  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 792  */
 793 static int get_octopus_merge_base(struct object_id *merge_base,
 794                 const struct object_id *curr_head,
 795                 const struct object_id *merge_head,
 796                 const struct object_id *fork_point)
 797 {
 798         struct commit_list *revs = NULL, *result;
 799
 800         commit_list_insert(lookup_commit_reference(the_repository, curr_head),
 801                            &revs);
 802         commit_list_insert(lookup_commit_reference(the_repository, merge_head),
 803                            &revs);
 804         if (!is_null_oid(fork_point))
 805                 commit_list_insert(lookup_commit_reference(the_repository, fork_point),
 806                                    &revs);
 807
 808         result = get_octopus_merge_bases(revs);
 809         free_commit_list(revs);
 810         reduce_heads_replace(&result);
 811
 812         if (!result)
 813                 return 1;
 814
 815         oidcpy(merge_base, &result->item->object.oid);
 816         free_commit_list(result);
 817         return 0;
 818 }
 819
 820 /**
 821  * Given the current HEAD oid, the merge head returned from git-fetch and the
 822  * fork point calculated by get_rebase_fork_point(), runs git-rebase with the
 823  * appropriate arguments and returns its exit status.
 824  */
 825 static int run_rebase(const struct object_id *curr_head,
 826                 const struct object_id *merge_head,
 827                 const struct object_id *fork_point)
 828 {
 829         int ret;
 830         struct object_id oct_merge_base;
 831         struct argv_array args = ARGV_ARRAY_INIT;
 832
 833         if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))
 834                 if (!is_null_oid(fork_point) && oideq(&oct_merge_base, fork_point))
 835                         fork_point = NULL;
 836
 837         argv_array_push(&args, "rebase");
 838
 839         /* Shared options */
 840         argv_push_verbosity(&args);
 841
 842         /* Options passed to git-rebase */
 843         if (opt_rebase == REBASE_MERGES)
 844                 argv_array_push(&args, "--rebase-merges");
 845         else if (opt_rebase == REBASE_PRESERVE)
 846                 argv_array_push(&args, "--preserve-merges");
 847         else if (opt_rebase == REBASE_INTERACTIVE)
 848                 argv_array_push(&args, "--interactive");
 849         if (opt_diffstat)
 850                 argv_array_push(&args, opt_diffstat);
 851         argv_array_pushv(&args, opt_strategies.argv);
 852         argv_array_pushv(&args, opt_strategy_opts.argv);
 853         if (opt_gpg_sign)
 854                 argv_array_push(&args, opt_gpg_sign);
 855         if (opt_autostash == 0)
 856                 argv_array_push(&args, "--no-autostash");
 857         else if (opt_autostash == 1)
 858                 argv_array_push(&args, "--autostash");
 859         if (opt_verify_signatures &&
 860             !strcmp(opt_verify_signatures, "--verify-signatures"))
 861                 warning(_("ignoring --verify-signatures for rebase"));
 862
 863         argv_array_push(&args, "--onto");
 864         argv_array_push(&args, oid_to_hex(merge_head));
 865
 866         if (fork_point && !is_null_oid(fork_point))
 867                 argv_array_push(&args, oid_to_hex(fork_point));
 868         else
 869                 argv_array_push(&args, oid_to_hex(merge_head));
 870
 871         ret = run_command_v_opt(args.argv, RUN_GIT_CMD);
 872         argv_array_clear(&args);
 873         return ret;
 874 }
 875
 876 int cmd_pull(int argc, const char **argv, const char *prefix)
 877 {
 878         const char *repo, **refspecs;
 879         struct oid_array merge_heads = OID_ARRAY_INIT;
 880         struct object_id orig_head, curr_head;
 881         struct object_id rebase_fork_point;
 882         int autostash;
 883
 884         if (!getenv("GIT_REFLOG_ACTION"))
 885                 set_reflog_message(argc, argv);
 886
 887         git_config(git_pull_config, NULL);
 888
 889         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 890
 891         if (cleanup_arg)
 892                 /*
 893                  * this only checks the validity of cleanup_arg; we don't need
 894                  * a valid value for use_editor
 895                  */
 896                 get_cleanup_mode(cleanup_arg, 0);
 897
 898         parse_repo_refspecs(argc, argv, &repo, &refspecs);
 899
 900         if (!opt_ff)
 901                 opt_ff = xstrdup_or_null(config_get_ff());
 902
 903         if (opt_rebase < 0)
 904                 opt_rebase = config_get_rebase();
 905
 906         if (read_cache_unmerged())
 907                 die_resolve_conflict("pull");
 908
 909         if (file_exists(git_path_merge_head(the_repository)))
 910                 die_conclude_merge();
 911
 912         if (get_oid("HEAD", &orig_head))
 913                 oidclr(&orig_head);
 914
 915         if (!opt_rebase && opt_autostash != -1)
 916                 die(_("--[no-]autostash option is only valid with --rebase."));
 917
 918         autostash = config_autostash;
 919         if (opt_rebase) {
 920                 if (opt_autostash != -1)
 921                         autostash = opt_autostash;
 922
 923                 if (is_null_oid(&orig_head) && !is_cache_unborn())
 924                         die(_("Updating an unborn branch with changes added to the index."));
 925
 926                 if (!autostash)
 927                         require_clean_work_tree(the_repository,
 928                                 N_("pull with rebase"),
 929                                 _("please commit or stash them."), 1, 0);
 930
 931                 if (get_rebase_fork_point(&rebase_fork_point, repo, *refspecs))
 932                         oidclr(&rebase_fork_point);
 933         }
 934
 935         if (run_fetch(repo, refspecs))
 936                 return 1;
 937
 938         if (opt_dry_run)
 939                 return 0;
 940
 941         if (get_oid("HEAD", &curr_head))
 942                 oidclr(&curr_head);
 943
 944         if (!is_null_oid(&orig_head) && !is_null_oid(&curr_head) &&
 945                         !oideq(&orig_head, &curr_head)) {
 946                 /*
 947                  * The fetch involved updating the current branch.
 948                  *
 949                  * The working tree and the index file are still based on
 950                  * orig_head commit, but we are merging into curr_head.
 951                  * Update the working tree to match curr_head.
 952                  */
 953
 954                 warning(_("fetch updated the current branch head.\n"
 955                         "fast-forwarding your working tree from\n"
 956                         "commit %s."), oid_to_hex(&orig_head));
 957
 958                 if (checkout_fast_forward(the_repository, &orig_head,
 959                                           &curr_head, 0))
 960                         die(_("Cannot fast-forward your working tree.\n"
 961                                 "After making sure that you saved anything precious from\n"
 962                                 "$ git diff %s\n"
 963                                 "output, run\n"
 964                                 "$ git reset --hard\n"
 965                                 "to recover."), oid_to_hex(&orig_head));
 966         }
 967
 968         get_merge_heads(&merge_heads);
 969
 970         if (!merge_heads.nr)
 971                 die_no_merge_candidates(repo, refspecs);
 972
 973         if (is_null_oid(&orig_head)) {
 974                 if (merge_heads.nr > 1)
 975                         die(_("Cannot merge multiple branches into empty head."));
 976                 return pull_into_void(merge_heads.oid, &curr_head);
 977         }
 978         if (opt_rebase && merge_heads.nr > 1)
 979                 die(_("Cannot rebase onto multiple branches."));
 980
 981         if (opt_rebase) {
 982                 int ret = 0;
 983                 if ((recurse_submodules == RECURSE_SUBMODULES_ON ||
 984                      recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) &&
 985                     submodule_touches_in_range(the_repository, &rebase_fork_point, &curr_head))
 986                         die(_("cannot rebase with locally recorded submodule modifications"));
 987                 if (!autostash) {
 988                         struct commit_list *list = NULL;
 989                         struct commit *merge_head, *head;
 990
 991                         head = lookup_commit_reference(the_repository,
 992                                                        &orig_head);
 993                         commit_list_insert(head, &list);
 994                         merge_head = lookup_commit_reference(the_repository,
 995                                                              &merge_heads.oid[0]);
 996                         if (is_descendant_of(merge_head, list)) {
 997                                 /* we can fast-forward this without invoking rebase */
 998                                 opt_ff = "--ff-only";
 999                                 ret = run_merge();
1000                         }
1001                 }
1002                 ret = run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
1003
1004                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
1005                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
1006                         ret = rebase_submodules();
1007
1008                 return ret;
1009         } else {
1010                 int ret = run_merge();
1011                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
1012                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
1013                         ret = update_submodules();
1014                 return ret;
1015         }
1016 }