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_VARIABLE
   9 #include "builtin.h"
  10 #include "advice.h"
  11 #include "config.h"
  12 #include "gettext.h"
  13 #include "hex.h"
  14 #include "merge.h"
  15 #include "object-name.h"
  16 #include "parse-options.h"
  17 #include "exec-cmd.h"
  18 #include "run-command.h"
  19 #include "oid-array.h"
  20 #include "remote.h"
  21 #include "dir.h"
  22 #include "path.h"
  23 #include "read-cache-ll.h"
  24 #include "rebase.h"
  25 #include "refs.h"
  26 #include "refspec.h"
  27 #include "revision.h"
  28 #include "submodule.h"
  29 #include "submodule-config.h"
  30 #include "tempfile.h"
  31 #include "lockfile.h"
  32 #include "wt-status.h"
  33 #include "commit-reach.h"
  34 #include "sequencer.h"
  35 #include "packfile.h"
  36
  37 /**
  38  * Parses the value of --rebase. If value is a false value, returns
  39  * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is
  40  * "merges", returns REBASE_MERGES. If value is a invalid value, dies with
  41  * a fatal error if fatal is true, otherwise returns REBASE_INVALID.
  42  */
  43 static enum rebase_type parse_config_rebase(const char *key, const char *value,
  44                 int fatal)
  45 {
  46         enum rebase_type v = rebase_parse_value(value);
  47         if (v != REBASE_INVALID)
  48                 return v;
  49
  50         if (fatal)
  51                 die(_("invalid value for '%s': '%s'"), key, value);
  52         else
  53                 error(_("invalid value for '%s': '%s'"), key, value);
  54
  55         return REBASE_INVALID;
  56 }
  57
  58 /**
  59  * Callback for --rebase, which parses arg with parse_config_rebase().
  60  */
  61 static int parse_opt_rebase(const struct option *opt, const char *arg, int unset)
  62 {
  63         enum rebase_type *value = opt->value;
  64
  65         if (arg)
  66                 *value = parse_config_rebase("--rebase", arg, 0);
  67         else
  68                 *value = unset ? REBASE_FALSE : REBASE_TRUE;
  69         return *value == REBASE_INVALID ? -1 : 0;
  70 }
  71
  72 static const char * const pull_usage[] = {
  73         N_("git pull [<options>] [<repository> [<refspec>...]]"),
  74         NULL
  75 };
  76
  77 /* Shared options */
  78 static int opt_verbosity;
  79 static char *opt_progress;
  80 static int recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
  81 static int recurse_submodules_cli = RECURSE_SUBMODULES_DEFAULT;
  82
  83 /* Options passed to git-merge or git-rebase */
  84 static enum rebase_type opt_rebase = -1;
  85 static char *opt_diffstat;
  86 static char *opt_log;
  87 static char *opt_signoff;
  88 static char *opt_squash;
  89 static char *opt_commit;
  90 static char *opt_edit;
  91 static char *cleanup_arg;
  92 static char *opt_ff;
  93 static char *opt_verify_signatures;
  94 static char *opt_verify;
  95 static int opt_autostash = -1;
  96 static int config_autostash;
  97 static int check_trust_level = 1;
  98 static struct strvec opt_strategies = STRVEC_INIT;
  99 static struct strvec opt_strategy_opts = STRVEC_INIT;
 100 static char *opt_gpg_sign;
 101 static int opt_allow_unrelated_histories;
 102
 103 /* Options passed to git-fetch */
 104 static char *opt_all;
 105 static char *opt_append;
 106 static char *opt_upload_pack;
 107 static int opt_force;
 108 static char *opt_tags;
 109 static char *opt_prune;
 110 static char *max_children;
 111 static int opt_dry_run;
 112 static char *opt_keep;
 113 static char *opt_depth;
 114 static char *opt_unshallow;
 115 static char *opt_update_shallow;
 116 static char *opt_refmap;
 117 static char *opt_ipv4;
 118 static char *opt_ipv6;
 119 static int opt_show_forced_updates = -1;
 120 static char *set_upstream;
 121 static struct strvec opt_fetch = STRVEC_INIT;
 122
 123 static struct option pull_options[] = {
 124         /* Shared options */
 125         OPT__VERBOSITY(&opt_verbosity),
 126         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 127                 N_("force progress reporting"),
 128                 PARSE_OPT_NOARG),
 129         OPT_CALLBACK_F(0, "recurse-submodules",
 130                    &recurse_submodules_cli, N_("on-demand"),
 131                    N_("control for recursive fetching of submodules"),
 132                    PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules),
 133
 134         /* Options passed to git-merge or git-rebase */
 135         OPT_GROUP(N_("Options related to merging")),
 136         OPT_CALLBACK_F('r', "rebase", &opt_rebase,
 137                 "(false|true|merges|interactive)",
 138                 N_("incorporate changes by rebasing rather than merging"),
 139                 PARSE_OPT_OPTARG, parse_opt_rebase),
 140         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 141                 N_("do not show a diffstat at the end of the merge"),
 142                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 143         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 144                 N_("show a diffstat at the end of the merge"),
 145                 PARSE_OPT_NOARG),
 146         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 147                 N_("(synonym to --stat)"),
 148                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 149         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 150                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 151                 PARSE_OPT_OPTARG),
 152         OPT_PASSTHRU(0, "signoff", &opt_signoff, NULL,
 153                 N_("add a Signed-off-by trailer"),
 154                 PARSE_OPT_OPTARG),
 155         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 156                 N_("create a single commit instead of doing a merge"),
 157                 PARSE_OPT_NOARG),
 158         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 159                 N_("perform a commit if the merge succeeds (default)"),
 160                 PARSE_OPT_NOARG),
 161         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 162                 N_("edit message before committing"),
 163                 PARSE_OPT_NOARG),
 164         OPT_CLEANUP(&cleanup_arg),
 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", &opt_verify, NULL,
 172                 N_("control use of pre-merge-commit and commit-msg hooks"),
 173                 PARSE_OPT_NOARG),
 174         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 175                 N_("verify that the named commit has a valid GPG signature"),
 176                 PARSE_OPT_NOARG),
 177         OPT_BOOL(0, "autostash", &opt_autostash,
 178                 N_("automatically stash/stash pop before and after")),
 179         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 180                 N_("merge strategy to use"),
 181                 0),
 182         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 183                 N_("option=value"),
 184                 N_("option for selected merge strategy"),
 185                 0),
 186         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 187                 N_("GPG sign commit"),
 188                 PARSE_OPT_OPTARG),
 189         OPT_SET_INT(0, "allow-unrelated-histories",
 190                     &opt_allow_unrelated_histories,
 191                     N_("allow merging unrelated histories"), 1),
 192
 193         /* Options passed to git-fetch */
 194         OPT_GROUP(N_("Options related to fetching")),
 195         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 196                 N_("fetch from all remotes"),
 197                 PARSE_OPT_NOARG),
 198         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 199                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 200                 PARSE_OPT_NOARG),
 201         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 202                 N_("path to upload pack on remote end"),
 203                 0),
 204         OPT__FORCE(&opt_force, N_("force overwrite of local branch"), 0),
 205         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 206                 N_("fetch all tags and associated objects"),
 207                 PARSE_OPT_NOARG),
 208         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 209                 N_("prune remote-tracking branches no longer on remote"),
 210                 PARSE_OPT_NOARG),
 211         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 212                 N_("number of submodules pulled in parallel"),
 213                 PARSE_OPT_OPTARG),
 214         OPT_BOOL(0, "dry-run", &opt_dry_run,
 215                 N_("dry run")),
 216         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 217                 N_("keep downloaded pack"),
 218                 PARSE_OPT_NOARG),
 219         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 220                 N_("deepen history of shallow clone"),
 221                 0),
 222         OPT_PASSTHRU_ARGV(0, "shallow-since", &opt_fetch, N_("time"),
 223                 N_("deepen history of shallow repository based on time"),
 224                 0),
 225         OPT_PASSTHRU_ARGV(0, "shallow-exclude", &opt_fetch, N_("revision"),
 226                 N_("deepen history of shallow clone, excluding rev"),
 227                 0),
 228         OPT_PASSTHRU_ARGV(0, "deepen", &opt_fetch, N_("n"),
 229                 N_("deepen history of shallow clone"),
 230                 0),
 231         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 232                 N_("convert to a complete repository"),
 233                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 234         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 235                 N_("accept refs that update .git/shallow"),
 236                 PARSE_OPT_NOARG),
 237         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 238                 N_("specify fetch refmap"),
 239                 PARSE_OPT_NONEG),
 240         OPT_PASSTHRU_ARGV('o', "server-option", &opt_fetch,
 241                 N_("server-specific"),
 242                 N_("option to transmit"),
 243                 0),
 244         OPT_PASSTHRU('4',  "ipv4", &opt_ipv4, NULL,
 245                 N_("use IPv4 addresses only"),
 246                 PARSE_OPT_NOARG),
 247         OPT_PASSTHRU('6',  "ipv6", &opt_ipv6, NULL,
 248                 N_("use IPv6 addresses only"),
 249                 PARSE_OPT_NOARG),
 250         OPT_PASSTHRU_ARGV(0, "negotiation-tip", &opt_fetch, N_("revision"),
 251                 N_("report that we have only objects reachable from this object"),
 252                 0),
 253         OPT_BOOL(0, "show-forced-updates", &opt_show_forced_updates,
 254                  N_("check for forced-updates on all updated branches")),
 255         OPT_PASSTHRU(0, "set-upstream", &set_upstream, NULL,
 256                 N_("set upstream for git pull/fetch"),
 257                 PARSE_OPT_NOARG),
 258
 259         OPT_END()
 260 };
 261
 262 /**
 263  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 264  */
 265 static void argv_push_verbosity(struct strvec *arr)
 266 {
 267         int verbosity;
 268
 269         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 270                 strvec_push(arr, "-v");
 271
 272         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 273                 strvec_push(arr, "-q");
 274 }
 275
 276 /**
 277  * Pushes "-f" switches into arr to match the opt_force level.
 278  */
 279 static void argv_push_force(struct strvec *arr)
 280 {
 281         int force = opt_force;
 282         while (force-- > 0)
 283                 strvec_push(arr, "-f");
 284 }
 285
 286 /**
 287  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 288  */
 289 static void set_reflog_message(int argc, const char **argv)
 290 {
 291         int i;
 292         struct strbuf msg = STRBUF_INIT;
 293
 294         for (i = 0; i < argc; i++) {
 295                 if (i)
 296                         strbuf_addch(&msg, ' ');
 297                 strbuf_addstr(&msg, argv[i]);
 298         }
 299
 300         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 301
 302         strbuf_release(&msg);
 303 }
 304
 305 /**
 306  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 307  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 308  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 309  * error.
 310  */
 311 static const char *config_get_ff(void)
 312 {
 313         const char *value;
 314
 315         if (git_config_get_value("pull.ff", &value))
 316                 return NULL;
 317
 318         switch (git_parse_maybe_bool(value)) {
 319         case 0:
 320                 return "--no-ff";
 321         case 1:
 322                 return "--ff";
 323         }
 324
 325         if (!strcmp(value, "only"))
 326                 return "--ff-only";
 327
 328         die(_("invalid value for '%s': '%s'"), "pull.ff", value);
 329 }
 330
 331 /**
 332  * Returns the default configured value for --rebase. It first looks for the
 333  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 334  * branch, and if HEAD is detached or the configuration key does not exist,
 335  * looks for the value of "pull.rebase". If both configuration keys do not
 336  * exist, returns REBASE_FALSE.
 337  */
 338 static enum rebase_type config_get_rebase(int *rebase_unspecified)
 339 {
 340         struct branch *curr_branch = branch_get("HEAD");
 341         const char *value;
 342
 343         if (curr_branch) {
 344                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 345
 346                 if (!git_config_get_value(key, &value)) {
 347                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 348                         free(key);
 349                         return ret;
 350                 }
 351
 352                 free(key);
 353         }
 354
 355         if (!git_config_get_value("pull.rebase", &value))
 356                 return parse_config_rebase("pull.rebase", value, 1);
 357
 358         *rebase_unspecified = 1;
 359
 360         return REBASE_FALSE;
 361 }
 362
 363 /**
 364  * Read config variables.
 365  */
 366 static int git_pull_config(const char *var, const char *value,
 367                            const struct config_context *ctx, void *cb)
 368 {
 369         if (!strcmp(var, "rebase.autostash")) {
 370                 config_autostash = git_config_bool(var, value);
 371                 return 0;
 372         } else if (!strcmp(var, "submodule.recurse")) {
 373                 recurse_submodules = git_config_bool(var, value) ?
 374                         RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
 375                 return 0;
 376         } else if (!strcmp(var, "gpg.mintrustlevel")) {
 377                 check_trust_level = 0;
 378         }
 379
 380         return git_default_config(var, value, ctx, cb);
 381 }
 382
 383 /**
 384  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 385  * into merge_heads.
 386  */
 387 static void get_merge_heads(struct oid_array *merge_heads)
 388 {
 389         const char *filename = git_path_fetch_head(the_repository);
 390         FILE *fp;
 391         struct strbuf sb = STRBUF_INIT;
 392         struct object_id oid;
 393
 394         fp = xfopen(filename, "r");
 395         while (strbuf_getline_lf(&sb, fp) != EOF) {
 396                 const char *p;
 397                 if (parse_oid_hex(sb.buf, &oid, &p))
 398                         continue;  /* invalid line: does not start with object ID */
 399                 if (starts_with(p, "\tnot-for-merge\t"))
 400                         continue;  /* ref is not-for-merge */
 401                 oid_array_append(merge_heads, &oid);
 402         }
 403         fclose(fp);
 404         strbuf_release(&sb);
 405 }
 406
 407 /**
 408  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 409  * retrieve the name of the remote if the repository only has one remote.
 410  */
 411 static int get_only_remote(struct remote *remote, void *cb_data)
 412 {
 413         const char **remote_name = cb_data;
 414
 415         if (*remote_name)
 416                 return -1;
 417
 418         *remote_name = remote->name;
 419         return 0;
 420 }
 421
 422 /**
 423  * Dies with the appropriate reason for why there are no merge candidates:
 424  *
 425  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 426  *    up not fetching anything. This is usually because the user provided a
 427  *    wildcard refspec which had no matches on the remote end.
 428  *
 429  * 2. We fetched from a non-default remote, but didn't specify a branch to
 430  *    merge. We can't use the configured one because it applies to the default
 431  *    remote, thus the user must specify the branches to merge.
 432  *
 433  * 3. We fetched from the branch's or repo's default remote, but:
 434  *
 435  *    a. We are not on a branch, so there will never be a configured branch to
 436  *       merge with.
 437  *
 438  *    b. We are on a branch, but there is no configured branch to merge with.
 439  *
 440  * 4. We fetched from the branch's or repo's default remote, but the configured
 441  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 442  *    part of the configured fetch refspec.)
 443  */
 444 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 445 {
 446         struct branch *curr_branch = branch_get("HEAD");
 447         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 448
 449         if (*refspecs) {
 450                 if (opt_rebase)
 451                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 452                 else
 453                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 454                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 455                                         "matches on the remote end."));
 456         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 457                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 458                         "a branch. Because this is not the default configured remote\n"
 459                         "for your current branch, you must specify a branch on the command line."),
 460                         repo);
 461         } else if (!curr_branch) {
 462                 fprintf_ln(stderr, _("You are not currently on a branch."));
 463                 if (opt_rebase)
 464                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 465                 else
 466                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 467                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 468                 fprintf(stderr, "\n");
 469                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 470                 fprintf(stderr, "\n");
 471         } else if (!curr_branch->merge_nr) {
 472                 const char *remote_name = NULL;
 473
 474                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 475                         remote_name = _("<remote>");
 476
 477                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 478                 if (opt_rebase)
 479                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 480                 else
 481                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 482                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 483                 fprintf(stderr, "\n");
 484                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 485                 fprintf(stderr, "\n");
 486                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));
 487                 fprintf(stderr, "\n");
 488                 fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",
 489                                 remote_name, _("<branch>"), curr_branch->name);
 490         } else
 491                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 492                         "from the remote, but no such ref was fetched."),
 493                         *curr_branch->merge_name);
 494         exit(1);
 495 }
 496
 497 /**
 498  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 499  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 500  * is not provided in argv, it is set to NULL.
 501  */
 502 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 503                 const char ***refspecs)
 504 {
 505         if (argc > 0) {
 506                 *repo = *argv++;
 507                 argc--;
 508         } else
 509                 *repo = NULL;
 510         *refspecs = argv;
 511 }
 512
 513 /**
 514  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 515  * repository and refspecs to fetch, or NULL if they are not provided.
 516  */
 517 static int run_fetch(const char *repo, const char **refspecs)
 518 {
 519         struct child_process cmd = CHILD_PROCESS_INIT;
 520
 521         strvec_pushl(&cmd.args, "fetch", "--update-head-ok", NULL);
 522
 523         /* Shared options */
 524         argv_push_verbosity(&cmd.args);
 525         if (opt_progress)
 526                 strvec_push(&cmd.args, opt_progress);
 527
 528         /* Options passed to git-fetch */
 529         if (opt_all)
 530                 strvec_push(&cmd.args, opt_all);
 531         if (opt_append)
 532                 strvec_push(&cmd.args, opt_append);
 533         if (opt_upload_pack)
 534                 strvec_push(&cmd.args, opt_upload_pack);
 535         argv_push_force(&cmd.args);
 536         if (opt_tags)
 537                 strvec_push(&cmd.args, opt_tags);
 538         if (opt_prune)
 539                 strvec_push(&cmd.args, opt_prune);
 540         if (recurse_submodules_cli != RECURSE_SUBMODULES_DEFAULT)
 541                 switch (recurse_submodules_cli) {
 542                 case RECURSE_SUBMODULES_ON:
 543                         strvec_push(&cmd.args, "--recurse-submodules=on");
 544                         break;
 545                 case RECURSE_SUBMODULES_OFF:
 546                         strvec_push(&cmd.args, "--recurse-submodules=no");
 547                         break;
 548                 case RECURSE_SUBMODULES_ON_DEMAND:
 549                         strvec_push(&cmd.args, "--recurse-submodules=on-demand");
 550                         break;
 551                 default:
 552                         BUG("submodule recursion option not understood");
 553                 }
 554         if (max_children)
 555                 strvec_push(&cmd.args, max_children);
 556         if (opt_dry_run)
 557                 strvec_push(&cmd.args, "--dry-run");
 558         if (opt_keep)
 559                 strvec_push(&cmd.args, opt_keep);
 560         if (opt_depth)
 561                 strvec_push(&cmd.args, opt_depth);
 562         if (opt_unshallow)
 563                 strvec_push(&cmd.args, opt_unshallow);
 564         if (opt_update_shallow)
 565                 strvec_push(&cmd.args, opt_update_shallow);
 566         if (opt_refmap)
 567                 strvec_push(&cmd.args, opt_refmap);
 568         if (opt_ipv4)
 569                 strvec_push(&cmd.args, opt_ipv4);
 570         if (opt_ipv6)
 571                 strvec_push(&cmd.args, opt_ipv6);
 572         if (opt_show_forced_updates > 0)
 573                 strvec_push(&cmd.args, "--show-forced-updates");
 574         else if (opt_show_forced_updates == 0)
 575                 strvec_push(&cmd.args, "--no-show-forced-updates");
 576         if (set_upstream)
 577                 strvec_push(&cmd.args, set_upstream);
 578         strvec_pushv(&cmd.args, opt_fetch.v);
 579
 580         if (repo) {
 581                 strvec_push(&cmd.args, repo);
 582                 strvec_pushv(&cmd.args, refspecs);
 583         } else if (*refspecs)
 584                 BUG("refspecs without repo?");
 585         cmd.git_cmd = 1;
 586         cmd.close_object_store = 1;
 587         return run_command(&cmd);
 588 }
 589
 590 /**
 591  * "Pulls into void" by branching off merge_head.
 592  */
 593 static int pull_into_void(const struct object_id *merge_head,
 594                 const struct object_id *curr_head)
 595 {
 596         if (opt_verify_signatures) {
 597                 struct commit *commit;
 598
 599                 commit = lookup_commit(the_repository, merge_head);
 600                 if (!commit)
 601                         die(_("unable to access commit %s"),
 602                             oid_to_hex(merge_head));
 603
 604                 verify_merge_signature(commit, opt_verbosity,
 605                                        check_trust_level);
 606         }
 607
 608         /*
 609          * Two-way merge: we treat the index as based on an empty tree,
 610          * and try to fast-forward to HEAD. This ensures we will not lose
 611          * index/worktree changes that the user already made on the unborn
 612          * branch.
 613          */
 614         if (checkout_fast_forward(the_repository,
 615                                   the_hash_algo->empty_tree,
 616                                   merge_head, 0))
 617                 return 1;
 618
 619         if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 620                 return 1;
 621
 622         return 0;
 623 }
 624
 625 static int rebase_submodules(void)
 626 {
 627         struct child_process cp = CHILD_PROCESS_INIT;
 628
 629         cp.git_cmd = 1;
 630         cp.no_stdin = 1;
 631         strvec_pushl(&cp.args, "submodule", "update",
 632                      "--recursive", "--rebase", NULL);
 633         argv_push_verbosity(&cp.args);
 634
 635         return run_command(&cp);
 636 }
 637
 638 static int update_submodules(void)
 639 {
 640         struct child_process cp = CHILD_PROCESS_INIT;
 641
 642         cp.git_cmd = 1;
 643         cp.no_stdin = 1;
 644         strvec_pushl(&cp.args, "submodule", "update",
 645                      "--recursive", "--checkout", NULL);
 646         argv_push_verbosity(&cp.args);
 647
 648         return run_command(&cp);
 649 }
 650
 651 /**
 652  * Runs git-merge, returning its exit status.
 653  */
 654 static int run_merge(void)
 655 {
 656         struct child_process cmd = CHILD_PROCESS_INIT;
 657
 658         strvec_pushl(&cmd.args, "merge", NULL);
 659
 660         /* Shared options */
 661         argv_push_verbosity(&cmd.args);
 662         if (opt_progress)
 663                 strvec_push(&cmd.args, opt_progress);
 664
 665         /* Options passed to git-merge */
 666         if (opt_diffstat)
 667                 strvec_push(&cmd.args, opt_diffstat);
 668         if (opt_log)
 669                 strvec_push(&cmd.args, opt_log);
 670         if (opt_signoff)
 671                 strvec_push(&cmd.args, opt_signoff);
 672         if (opt_squash)
 673                 strvec_push(&cmd.args, opt_squash);
 674         if (opt_commit)
 675                 strvec_push(&cmd.args, opt_commit);
 676         if (opt_edit)
 677                 strvec_push(&cmd.args, opt_edit);
 678         if (cleanup_arg)
 679                 strvec_pushf(&cmd.args, "--cleanup=%s", cleanup_arg);
 680         if (opt_ff)
 681                 strvec_push(&cmd.args, opt_ff);
 682         if (opt_verify)
 683                 strvec_push(&cmd.args, opt_verify);
 684         if (opt_verify_signatures)
 685                 strvec_push(&cmd.args, opt_verify_signatures);
 686         strvec_pushv(&cmd.args, opt_strategies.v);
 687         strvec_pushv(&cmd.args, opt_strategy_opts.v);
 688         if (opt_gpg_sign)
 689                 strvec_push(&cmd.args, opt_gpg_sign);
 690         if (opt_autostash == 0)
 691                 strvec_push(&cmd.args, "--no-autostash");
 692         else if (opt_autostash == 1)
 693                 strvec_push(&cmd.args, "--autostash");
 694         if (opt_allow_unrelated_histories > 0)
 695                 strvec_push(&cmd.args, "--allow-unrelated-histories");
 696
 697         strvec_push(&cmd.args, "FETCH_HEAD");
 698         cmd.git_cmd = 1;
 699         return run_command(&cmd);
 700 }
 701
 702 /**
 703  * Returns remote's upstream branch for the current branch. If remote is NULL,
 704  * the current branch's configured default remote is used. Returns NULL if
 705  * `remote` does not name a valid remote, HEAD does not point to a branch,
 706  * remote is not the branch's configured remote or the branch does not have any
 707  * configured upstream branch.
 708  */
 709 static const char *get_upstream_branch(const char *remote)
 710 {
 711         struct remote *rm;
 712         struct branch *curr_branch;
 713         const char *curr_branch_remote;
 714
 715         rm = remote_get(remote);
 716         if (!rm)
 717                 return NULL;
 718
 719         curr_branch = branch_get("HEAD");
 720         if (!curr_branch)
 721                 return NULL;
 722
 723         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 724         assert(curr_branch_remote);
 725
 726         if (strcmp(curr_branch_remote, rm->name))
 727                 return NULL;
 728
 729         return branch_get_upstream(curr_branch, NULL);
 730 }
 731
 732 /**
 733  * Derives the remote-tracking branch from the remote and refspec.
 734  *
 735  * FIXME: The current implementation assumes the default mapping of
 736  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 737  */
 738 static const char *get_tracking_branch(const char *remote, const char *refspec)
 739 {
 740         struct refspec_item spec;
 741         const char *spec_src;
 742         const char *merge_branch;
 743
 744         refspec_item_init_or_die(&spec, refspec, REFSPEC_FETCH);
 745         spec_src = spec.src;
 746         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 747                 spec_src = "HEAD";
 748         else if (skip_prefix(spec_src, "heads/", &spec_src))
 749                 ;
 750         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 751                 ;
 752         else if (starts_with(spec_src, "refs/") ||
 753                 starts_with(spec_src, "tags/") ||
 754                 starts_with(spec_src, "remotes/"))
 755                 spec_src = "";
 756
 757         if (*spec_src) {
 758                 if (!strcmp(remote, "."))
 759                         merge_branch = mkpath("refs/heads/%s", spec_src);
 760                 else
 761                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 762         } else
 763                 merge_branch = NULL;
 764
 765         refspec_item_clear(&spec);
 766         return merge_branch;
 767 }
 768
 769 /**
 770  * Given the repo and refspecs, sets fork_point to the point at which the
 771  * current branch forked from its remote-tracking branch. Returns 0 on success,
 772  * -1 on failure.
 773  */
 774 static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,
 775                 const char *refspec)
 776 {
 777         int ret;
 778         struct branch *curr_branch;
 779         const char *remote_branch;
 780         struct child_process cp = CHILD_PROCESS_INIT;
 781         struct strbuf sb = STRBUF_INIT;
 782
 783         curr_branch = branch_get("HEAD");
 784         if (!curr_branch)
 785                 return -1;
 786
 787         if (refspec)
 788                 remote_branch = get_tracking_branch(repo, refspec);
 789         else
 790                 remote_branch = get_upstream_branch(repo);
 791
 792         if (!remote_branch)
 793                 return -1;
 794
 795         strvec_pushl(&cp.args, "merge-base", "--fork-point",
 796                      remote_branch, curr_branch->name, NULL);
 797         cp.no_stdin = 1;
 798         cp.no_stderr = 1;
 799         cp.git_cmd = 1;
 800
 801         ret = capture_command(&cp, &sb, GIT_MAX_HEXSZ);
 802         if (ret)
 803                 goto cleanup;
 804
 805         ret = get_oid_hex(sb.buf, fork_point);
 806         if (ret)
 807                 goto cleanup;
 808
 809 cleanup:
 810         strbuf_release(&sb);
 811         return ret ? -1 : 0;
 812 }
 813
 814 /**
 815  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 816  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 817  */
 818 static int get_octopus_merge_base(struct object_id *merge_base,
 819                 const struct object_id *curr_head,
 820                 const struct object_id *merge_head,
 821                 const struct object_id *fork_point)
 822 {
 823         struct commit_list *revs = NULL, *result;
 824
 825         commit_list_insert(lookup_commit_reference(the_repository, curr_head),
 826                            &revs);
 827         commit_list_insert(lookup_commit_reference(the_repository, merge_head),
 828                            &revs);
 829         if (!is_null_oid(fork_point))
 830                 commit_list_insert(lookup_commit_reference(the_repository, fork_point),
 831                                    &revs);
 832
 833         result = get_octopus_merge_bases(revs);
 834         free_commit_list(revs);
 835         reduce_heads_replace(&result);
 836
 837         if (!result)
 838                 return 1;
 839
 840         oidcpy(merge_base, &result->item->object.oid);
 841         free_commit_list(result);
 842         return 0;
 843 }
 844
 845 /**
 846  * Given the current HEAD oid, the merge head returned from git-fetch and the
 847  * fork point calculated by get_rebase_fork_point(), compute the <newbase> and
 848  * <upstream> arguments to use for the upcoming git-rebase invocation.
 849  */
 850 static int get_rebase_newbase_and_upstream(struct object_id *newbase,
 851                 struct object_id *upstream,
 852                 const struct object_id *curr_head,
 853                 const struct object_id *merge_head,
 854                 const struct object_id *fork_point)
 855 {
 856         struct object_id oct_merge_base;
 857
 858         if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))
 859                 if (!is_null_oid(fork_point) && oideq(&oct_merge_base, fork_point))
 860                         fork_point = NULL;
 861
 862         if (fork_point && !is_null_oid(fork_point))
 863                 oidcpy(upstream, fork_point);
 864         else
 865                 oidcpy(upstream, merge_head);
 866
 867         oidcpy(newbase, merge_head);
 868
 869         return 0;
 870 }
 871
 872 /**
 873  * Given the <newbase> and <upstream> calculated by
 874  * get_rebase_newbase_and_upstream(), runs git-rebase with the
 875  * appropriate arguments and returns its exit status.
 876  */
 877 static int run_rebase(const struct object_id *newbase,
 878                 const struct object_id *upstream)
 879 {
 880         struct child_process cmd = CHILD_PROCESS_INIT;
 881
 882         strvec_push(&cmd.args, "rebase");
 883
 884         /* Shared options */
 885         argv_push_verbosity(&cmd.args);
 886
 887         /* Options passed to git-rebase */
 888         if (opt_rebase == REBASE_MERGES)
 889                 strvec_push(&cmd.args, "--rebase-merges");
 890         else if (opt_rebase == REBASE_INTERACTIVE)
 891                 strvec_push(&cmd.args, "--interactive");
 892         if (opt_diffstat)
 893                 strvec_push(&cmd.args, opt_diffstat);
 894         strvec_pushv(&cmd.args, opt_strategies.v);
 895         strvec_pushv(&cmd.args, opt_strategy_opts.v);
 896         if (opt_gpg_sign)
 897                 strvec_push(&cmd.args, opt_gpg_sign);
 898         if (opt_signoff)
 899                 strvec_push(&cmd.args, opt_signoff);
 900         if (opt_autostash == 0)
 901                 strvec_push(&cmd.args, "--no-autostash");
 902         else if (opt_autostash == 1)
 903                 strvec_push(&cmd.args, "--autostash");
 904         if (opt_verify_signatures &&
 905             !strcmp(opt_verify_signatures, "--verify-signatures"))
 906                 warning(_("ignoring --verify-signatures for rebase"));
 907
 908         strvec_push(&cmd.args, "--onto");
 909         strvec_push(&cmd.args, oid_to_hex(newbase));
 910
 911         strvec_push(&cmd.args, oid_to_hex(upstream));
 912
 913         cmd.git_cmd = 1;
 914         return run_command(&cmd);
 915 }
 916
 917 static int get_can_ff(struct object_id *orig_head,
 918                       struct oid_array *merge_heads)
 919 {
 920         int ret;
 921         struct commit_list *list = NULL;
 922         struct commit *merge_head, *head;
 923         struct object_id *orig_merge_head;
 924
 925         if (merge_heads->nr > 1)
 926                 return 0;
 927
 928         orig_merge_head = &merge_heads->oid[0];
 929         head = lookup_commit_reference(the_repository, orig_head);
 930         commit_list_insert(head, &list);
 931         merge_head = lookup_commit_reference(the_repository, orig_merge_head);
 932         ret = repo_is_descendant_of(the_repository, merge_head, list);
 933         free_commit_list(list);
 934         return ret;
 935 }
 936
 937 /*
 938  * Is orig_head a descendant of _all_ merge_heads?
 939  * Unfortunately is_descendant_of() cannot be used as it asks
 940  * if orig_head is a descendant of at least one of them.
 941  */
 942 static int already_up_to_date(struct object_id *orig_head,
 943                               struct oid_array *merge_heads)
 944 {
 945         int i;
 946         struct commit *ours;
 947
 948         ours = lookup_commit_reference(the_repository, orig_head);
 949         for (i = 0; i < merge_heads->nr; i++) {
 950                 struct commit_list *list = NULL;
 951                 struct commit *theirs;
 952                 int ok;
 953
 954                 theirs = lookup_commit_reference(the_repository, &merge_heads->oid[i]);
 955                 commit_list_insert(theirs, &list);
 956                 ok = repo_is_descendant_of(the_repository, ours, list);
 957                 free_commit_list(list);
 958                 if (!ok)
 959                         return 0;
 960         }
 961         return 1;
 962 }
 963
 964 static void show_advice_pull_non_ff(void)
 965 {
 966         advise(_("You have divergent branches and need to specify how to reconcile them.\n"
 967                  "You can do so by running one of the following commands sometime before\n"
 968                  "your next pull:\n"
 969                  "\n"
 970                  "  git config pull.rebase false  # merge\n"
 971                  "  git config pull.rebase true   # rebase\n"
 972                  "  git config pull.ff only       # fast-forward only\n"
 973                  "\n"
 974                  "You can replace \"git config\" with \"git config --global\" to set a default\n"
 975                  "preference for all repositories. You can also pass --rebase, --no-rebase,\n"
 976                  "or --ff-only on the command line to override the configured default per\n"
 977                  "invocation.\n"));
 978 }
 979
 980 int cmd_pull(int argc, const char **argv, const char *prefix)
 981 {
 982         const char *repo, **refspecs;
 983         struct oid_array merge_heads = OID_ARRAY_INIT;
 984         struct object_id orig_head, curr_head;
 985         struct object_id rebase_fork_point;
 986         int rebase_unspecified = 0;
 987         int can_ff;
 988         int divergent;
 989         int ret;
 990
 991         if (!getenv("GIT_REFLOG_ACTION"))
 992                 set_reflog_message(argc, argv);
 993
 994         git_config(git_pull_config, NULL);
 995         if (the_repository->gitdir) {
 996                 prepare_repo_settings(the_repository);
 997                 the_repository->settings.command_requires_full_index = 0;
 998         }
 999
1000         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
1001
1002         if (recurse_submodules_cli != RECURSE_SUBMODULES_DEFAULT)
1003                 recurse_submodules = recurse_submodules_cli;
1004
1005         if (cleanup_arg)
1006                 /*
1007                  * this only checks the validity of cleanup_arg; we don't need
1008                  * a valid value for use_editor
1009                  */
1010                 get_cleanup_mode(cleanup_arg, 0);
1011
1012         parse_repo_refspecs(argc, argv, &repo, &refspecs);
1013
1014         if (!opt_ff) {
1015                 opt_ff = xstrdup_or_null(config_get_ff());
1016                 /*
1017                  * A subtle point: opt_ff was set on the line above via
1018                  * reading from config.  opt_rebase, in contrast, is set
1019                  * before this point via command line options.  The setting
1020                  * of opt_rebase via reading from config (using
1021                  * config_get_rebase()) does not happen until later.  We
1022                  * are relying on the next if-condition happening before
1023                  * the config_get_rebase() call so that an explicit
1024                  * "--rebase" can override a config setting of
1025                  * pull.ff=only.
1026                  */
1027                 if (opt_rebase >= 0 && opt_ff && !strcmp(opt_ff, "--ff-only"))
1028                         opt_ff = "--ff";
1029         }
1030
1031         if (opt_rebase < 0)
1032                 opt_rebase = config_get_rebase(&rebase_unspecified);
1033
1034         if (repo_read_index_unmerged(the_repository))
1035                 die_resolve_conflict("pull");
1036
1037         if (file_exists(git_path_merge_head(the_repository)))
1038                 die_conclude_merge();
1039
1040         if (repo_get_oid(the_repository, "HEAD", &orig_head))
1041                 oidclr(&orig_head);
1042
1043         if (opt_rebase) {
1044                 if (opt_autostash == -1)
1045                         opt_autostash = config_autostash;
1046
1047                 if (is_null_oid(&orig_head) && !is_index_unborn(&the_index))
1048                         die(_("Updating an unborn branch with changes added to the index."));
1049
1050                 if (!opt_autostash)
1051                         require_clean_work_tree(the_repository,
1052                                 N_("pull with rebase"),
1053                                 _("Please commit or stash them."), 1, 0);
1054
1055                 if (get_rebase_fork_point(&rebase_fork_point, repo, *refspecs))
1056                         oidclr(&rebase_fork_point);
1057         }
1058
1059         if (run_fetch(repo, refspecs))
1060                 return 1;
1061
1062         if (opt_dry_run)
1063                 return 0;
1064
1065         if (repo_get_oid(the_repository, "HEAD", &curr_head))
1066                 oidclr(&curr_head);
1067
1068         if (!is_null_oid(&orig_head) && !is_null_oid(&curr_head) &&
1069                         !oideq(&orig_head, &curr_head)) {
1070                 /*
1071                  * The fetch involved updating the current branch.
1072                  *
1073                  * The working tree and the index file are still based on
1074                  * orig_head commit, but we are merging into curr_head.
1075                  * Update the working tree to match curr_head.
1076                  */
1077
1078                 warning(_("fetch updated the current branch head.\n"
1079                         "fast-forwarding your working tree from\n"
1080                         "commit %s."), oid_to_hex(&orig_head));
1081
1082                 if (checkout_fast_forward(the_repository, &orig_head,
1083                                           &curr_head, 0))
1084                         die(_("Cannot fast-forward your working tree.\n"
1085                                 "After making sure that you saved anything precious from\n"
1086                                 "$ git diff %s\n"
1087                                 "output, run\n"
1088                                 "$ git reset --hard\n"
1089                                 "to recover."), oid_to_hex(&orig_head));
1090         }
1091
1092         get_merge_heads(&merge_heads);
1093
1094         if (!merge_heads.nr)
1095                 die_no_merge_candidates(repo, refspecs);
1096
1097         if (is_null_oid(&orig_head)) {
1098                 if (merge_heads.nr > 1)
1099                         die(_("Cannot merge multiple branches into empty head."));
1100                 ret = pull_into_void(merge_heads.oid, &curr_head);
1101                 goto cleanup;
1102         }
1103         if (merge_heads.nr > 1) {
1104                 if (opt_rebase)
1105                         die(_("Cannot rebase onto multiple branches."));
1106                 if (opt_ff && !strcmp(opt_ff, "--ff-only"))
1107                         die(_("Cannot fast-forward to multiple branches."));
1108         }
1109
1110         can_ff = get_can_ff(&orig_head, &merge_heads);
1111         divergent = !can_ff && !already_up_to_date(&orig_head, &merge_heads);
1112
1113         /* ff-only takes precedence over rebase */
1114         if (opt_ff && !strcmp(opt_ff, "--ff-only")) {
1115                 if (divergent)
1116                         die_ff_impossible();
1117                 opt_rebase = REBASE_FALSE;
1118         }
1119         /* If no action specified and we can't fast forward, then warn. */
1120         if (!opt_ff && rebase_unspecified && divergent) {
1121                 show_advice_pull_non_ff();
1122                 die(_("Need to specify how to reconcile divergent branches."));
1123         }
1124
1125         if (opt_rebase) {
1126                 struct object_id newbase;
1127                 struct object_id upstream;
1128                 get_rebase_newbase_and_upstream(&newbase, &upstream, &curr_head,
1129                                                 merge_heads.oid, &rebase_fork_point);
1130
1131                 if ((recurse_submodules == RECURSE_SUBMODULES_ON ||
1132                      recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) &&
1133                     submodule_touches_in_range(the_repository, &upstream, &curr_head))
1134                         die(_("cannot rebase with locally recorded submodule modifications"));
1135
1136                 if (can_ff) {
1137                         /* we can fast-forward this without invoking rebase */
1138                         opt_ff = "--ff-only";
1139                         ret = run_merge();
1140                 } else {
1141                         ret = run_rebase(&newbase, &upstream);
1142                 }
1143
1144                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
1145                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
1146                         ret = rebase_submodules();
1147
1148                 goto cleanup;
1149         } else {
1150                 ret = run_merge();
1151                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
1152                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
1153                         ret = update_submodules();
1154                 goto cleanup;
1155         }
1156
1157 cleanup:
1158         oid_array_clear(&merge_heads);
1159         return ret;
1160 }