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 "oid-array.h"
  16 #include "remote.h"
  17 #include "dir.h"
  18 #include "rebase.h"
  19 #include "refs.h"
  20 #include "refspec.h"
  21 #include "revision.h"
  22 #include "submodule.h"
  23 #include "submodule-config.h"
  24 #include "tempfile.h"
  25 #include "lockfile.h"
  26 #include "wt-status.h"
  27 #include "commit-reach.h"
  28 #include "sequencer.h"
  29
  30 /**
  31  * Parses the value of --rebase. If value is a false value, returns
  32  * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is
  33  * "merges", returns REBASE_MERGES. If value is "preserve", returns
  34  * REBASE_PRESERVE. If value is a invalid value, dies with a fatal error if
  35  * fatal is true, otherwise returns REBASE_INVALID.
  36  */
  37 static enum rebase_type parse_config_rebase(const char *key, const char *value,
  38                 int fatal)
  39 {
  40         enum rebase_type v = rebase_parse_value(value);
  41         if (v != REBASE_INVALID)
  42                 return v;
  43
  44         if (fatal)
  45                 die(_("Invalid value for %s: %s"), key, value);
  46         else
  47                 error(_("Invalid value for %s: %s"), key, value);
  48
  49         return REBASE_INVALID;
  50 }
  51
  52 /**
  53  * Callback for --rebase, which parses arg with parse_config_rebase().
  54  */
  55 static int parse_opt_rebase(const struct option *opt, const char *arg, int unset)
  56 {
  57         enum rebase_type *value = opt->value;
  58
  59         if (arg)
  60                 *value = parse_config_rebase("--rebase", arg, 0);
  61         else
  62                 *value = unset ? REBASE_FALSE : REBASE_TRUE;
  63         return *value == REBASE_INVALID ? -1 : 0;
  64 }
  65
  66 static const char * const pull_usage[] = {
  67         N_("git pull [<options>] [<repository> [<refspec>...]]"),
  68         NULL
  69 };
  70
  71 /* Shared options */
  72 static int opt_verbosity;
  73 static char *opt_progress;
  74 static int recurse_submodules = RECURSE_SUBMODULES_DEFAULT;
  75
  76 /* Options passed to git-merge or git-rebase */
  77 static enum rebase_type opt_rebase = -1;
  78 static char *opt_diffstat;
  79 static char *opt_log;
  80 static char *opt_signoff;
  81 static char *opt_squash;
  82 static char *opt_commit;
  83 static char *opt_edit;
  84 static char *cleanup_arg;
  85 static char *opt_ff;
  86 static char *opt_verify_signatures;
  87 static int opt_autostash = -1;
  88 static int config_autostash;
  89 static int check_trust_level = 1;
  90 static struct strvec opt_strategies = STRVEC_INIT;
  91 static struct strvec opt_strategy_opts = STRVEC_INIT;
  92 static char *opt_gpg_sign;
  93 static int opt_allow_unrelated_histories;
  94
  95 /* Options passed to git-fetch */
  96 static char *opt_all;
  97 static char *opt_append;
  98 static char *opt_upload_pack;
  99 static int opt_force;
 100 static char *opt_tags;
 101 static char *opt_prune;
 102 static char *max_children;
 103 static int opt_dry_run;
 104 static char *opt_keep;
 105 static char *opt_depth;
 106 static char *opt_unshallow;
 107 static char *opt_update_shallow;
 108 static char *opt_refmap;
 109 static char *opt_ipv4;
 110 static char *opt_ipv6;
 111 static int opt_show_forced_updates = -1;
 112 static char *set_upstream;
 113 static struct strvec opt_fetch = STRVEC_INIT;
 114
 115 static struct option pull_options[] = {
 116         /* Shared options */
 117         OPT__VERBOSITY(&opt_verbosity),
 118         OPT_PASSTHRU(0, "progress", &opt_progress, NULL,
 119                 N_("force progress reporting"),
 120                 PARSE_OPT_NOARG),
 121         OPT_CALLBACK_F(0, "recurse-submodules",
 122                    &recurse_submodules, N_("on-demand"),
 123                    N_("control for recursive fetching of submodules"),
 124                    PARSE_OPT_OPTARG, option_fetch_parse_recurse_submodules),
 125
 126         /* Options passed to git-merge or git-rebase */
 127         OPT_GROUP(N_("Options related to merging")),
 128         OPT_CALLBACK_F('r', "rebase", &opt_rebase,
 129                 "(false|true|merges|preserve|interactive)",
 130                 N_("incorporate changes by rebasing rather than merging"),
 131                 PARSE_OPT_OPTARG, parse_opt_rebase),
 132         OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
 133                 N_("do not show a diffstat at the end of the merge"),
 134                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 135         OPT_PASSTHRU(0, "stat", &opt_diffstat, NULL,
 136                 N_("show a diffstat at the end of the merge"),
 137                 PARSE_OPT_NOARG),
 138         OPT_PASSTHRU(0, "summary", &opt_diffstat, NULL,
 139                 N_("(synonym to --stat)"),
 140                 PARSE_OPT_NOARG | PARSE_OPT_HIDDEN),
 141         OPT_PASSTHRU(0, "log", &opt_log, N_("n"),
 142                 N_("add (at most <n>) entries from shortlog to merge commit message"),
 143                 PARSE_OPT_OPTARG),
 144         OPT_PASSTHRU(0, "signoff", &opt_signoff, NULL,
 145                 N_("add a Signed-off-by trailer"),
 146                 PARSE_OPT_OPTARG),
 147         OPT_PASSTHRU(0, "squash", &opt_squash, NULL,
 148                 N_("create a single commit instead of doing a merge"),
 149                 PARSE_OPT_NOARG),
 150         OPT_PASSTHRU(0, "commit", &opt_commit, NULL,
 151                 N_("perform a commit if the merge succeeds (default)"),
 152                 PARSE_OPT_NOARG),
 153         OPT_PASSTHRU(0, "edit", &opt_edit, NULL,
 154                 N_("edit message before committing"),
 155                 PARSE_OPT_NOARG),
 156         OPT_CLEANUP(&cleanup_arg),
 157         OPT_PASSTHRU(0, "ff", &opt_ff, NULL,
 158                 N_("allow fast-forward"),
 159                 PARSE_OPT_NOARG),
 160         OPT_PASSTHRU(0, "ff-only", &opt_ff, NULL,
 161                 N_("abort if fast-forward is not possible"),
 162                 PARSE_OPT_NOARG | PARSE_OPT_NONEG),
 163         OPT_PASSTHRU(0, "verify-signatures", &opt_verify_signatures, NULL,
 164                 N_("verify that the named commit has a valid GPG signature"),
 165                 PARSE_OPT_NOARG),
 166         OPT_BOOL(0, "autostash", &opt_autostash,
 167                 N_("automatically stash/stash pop before and after")),
 168         OPT_PASSTHRU_ARGV('s', "strategy", &opt_strategies, N_("strategy"),
 169                 N_("merge strategy to use"),
 170                 0),
 171         OPT_PASSTHRU_ARGV('X', "strategy-option", &opt_strategy_opts,
 172                 N_("option=value"),
 173                 N_("option for selected merge strategy"),
 174                 0),
 175         OPT_PASSTHRU('S', "gpg-sign", &opt_gpg_sign, N_("key-id"),
 176                 N_("GPG sign commit"),
 177                 PARSE_OPT_OPTARG),
 178         OPT_SET_INT(0, "allow-unrelated-histories",
 179                     &opt_allow_unrelated_histories,
 180                     N_("allow merging unrelated histories"), 1),
 181
 182         /* Options passed to git-fetch */
 183         OPT_GROUP(N_("Options related to fetching")),
 184         OPT_PASSTHRU(0, "all", &opt_all, NULL,
 185                 N_("fetch from all remotes"),
 186                 PARSE_OPT_NOARG),
 187         OPT_PASSTHRU('a', "append", &opt_append, NULL,
 188                 N_("append to .git/FETCH_HEAD instead of overwriting"),
 189                 PARSE_OPT_NOARG),
 190         OPT_PASSTHRU(0, "upload-pack", &opt_upload_pack, N_("path"),
 191                 N_("path to upload pack on remote end"),
 192                 0),
 193         OPT__FORCE(&opt_force, N_("force overwrite of local branch"), 0),
 194         OPT_PASSTHRU('t', "tags", &opt_tags, NULL,
 195                 N_("fetch all tags and associated objects"),
 196                 PARSE_OPT_NOARG),
 197         OPT_PASSTHRU('p', "prune", &opt_prune, NULL,
 198                 N_("prune remote-tracking branches no longer on remote"),
 199                 PARSE_OPT_NOARG),
 200         OPT_PASSTHRU('j', "jobs", &max_children, N_("n"),
 201                 N_("number of submodules pulled in parallel"),
 202                 PARSE_OPT_OPTARG),
 203         OPT_BOOL(0, "dry-run", &opt_dry_run,
 204                 N_("dry run")),
 205         OPT_PASSTHRU('k', "keep", &opt_keep, NULL,
 206                 N_("keep downloaded pack"),
 207                 PARSE_OPT_NOARG),
 208         OPT_PASSTHRU(0, "depth", &opt_depth, N_("depth"),
 209                 N_("deepen history of shallow clone"),
 210                 0),
 211         OPT_PASSTHRU_ARGV(0, "shallow-since", &opt_fetch, N_("time"),
 212                 N_("deepen history of shallow repository based on time"),
 213                 0),
 214         OPT_PASSTHRU_ARGV(0, "shallow-exclude", &opt_fetch, N_("revision"),
 215                 N_("deepen history of shallow clone, excluding rev"),
 216                 0),
 217         OPT_PASSTHRU_ARGV(0, "deepen", &opt_fetch, N_("n"),
 218                 N_("deepen history of shallow clone"),
 219                 0),
 220         OPT_PASSTHRU(0, "unshallow", &opt_unshallow, NULL,
 221                 N_("convert to a complete repository"),
 222                 PARSE_OPT_NONEG | PARSE_OPT_NOARG),
 223         OPT_PASSTHRU(0, "update-shallow", &opt_update_shallow, NULL,
 224                 N_("accept refs that update .git/shallow"),
 225                 PARSE_OPT_NOARG),
 226         OPT_PASSTHRU(0, "refmap", &opt_refmap, N_("refmap"),
 227                 N_("specify fetch refmap"),
 228                 PARSE_OPT_NONEG),
 229         OPT_PASSTHRU_ARGV('o', "server-option", &opt_fetch,
 230                 N_("server-specific"),
 231                 N_("option to transmit"),
 232                 0),
 233         OPT_PASSTHRU('4',  "ipv4", &opt_ipv4, NULL,
 234                 N_("use IPv4 addresses only"),
 235                 PARSE_OPT_NOARG),
 236         OPT_PASSTHRU('6',  "ipv6", &opt_ipv6, NULL,
 237                 N_("use IPv6 addresses only"),
 238                 PARSE_OPT_NOARG),
 239         OPT_PASSTHRU_ARGV(0, "negotiation-tip", &opt_fetch, N_("revision"),
 240                 N_("report that we have only objects reachable from this object"),
 241                 0),
 242         OPT_BOOL(0, "show-forced-updates", &opt_show_forced_updates,
 243                  N_("check for forced-updates on all updated branches")),
 244         OPT_PASSTHRU(0, "set-upstream", &set_upstream, NULL,
 245                 N_("set upstream for git pull/fetch"),
 246                 PARSE_OPT_NOARG),
 247
 248         OPT_END()
 249 };
 250
 251 /**
 252  * Pushes "-q" or "-v" switches into arr to match the opt_verbosity level.
 253  */
 254 static void argv_push_verbosity(struct strvec *arr)
 255 {
 256         int verbosity;
 257
 258         for (verbosity = opt_verbosity; verbosity > 0; verbosity--)
 259                 strvec_push(arr, "-v");
 260
 261         for (verbosity = opt_verbosity; verbosity < 0; verbosity++)
 262                 strvec_push(arr, "-q");
 263 }
 264
 265 /**
 266  * Pushes "-f" switches into arr to match the opt_force level.
 267  */
 268 static void argv_push_force(struct strvec *arr)
 269 {
 270         int force = opt_force;
 271         while (force-- > 0)
 272                 strvec_push(arr, "-f");
 273 }
 274
 275 /**
 276  * Sets the GIT_REFLOG_ACTION environment variable to the concatenation of argv
 277  */
 278 static void set_reflog_message(int argc, const char **argv)
 279 {
 280         int i;
 281         struct strbuf msg = STRBUF_INIT;
 282
 283         for (i = 0; i < argc; i++) {
 284                 if (i)
 285                         strbuf_addch(&msg, ' ');
 286                 strbuf_addstr(&msg, argv[i]);
 287         }
 288
 289         setenv("GIT_REFLOG_ACTION", msg.buf, 0);
 290
 291         strbuf_release(&msg);
 292 }
 293
 294 /**
 295  * If pull.ff is unset, returns NULL. If pull.ff is "true", returns "--ff". If
 296  * pull.ff is "false", returns "--no-ff". If pull.ff is "only", returns
 297  * "--ff-only". Otherwise, if pull.ff is set to an invalid value, die with an
 298  * error.
 299  */
 300 static const char *config_get_ff(void)
 301 {
 302         const char *value;
 303
 304         if (git_config_get_value("pull.ff", &value))
 305                 return NULL;
 306
 307         switch (git_parse_maybe_bool(value)) {
 308         case 0:
 309                 return "--no-ff";
 310         case 1:
 311                 return "--ff";
 312         }
 313
 314         if (!strcmp(value, "only"))
 315                 return "--ff-only";
 316
 317         die(_("Invalid value for pull.ff: %s"), value);
 318 }
 319
 320 /**
 321  * Returns the default configured value for --rebase. It first looks for the
 322  * value of "branch.$curr_branch.rebase", where $curr_branch is the current
 323  * branch, and if HEAD is detached or the configuration key does not exist,
 324  * looks for the value of "pull.rebase". If both configuration keys do not
 325  * exist, returns REBASE_FALSE.
 326  */
 327 static enum rebase_type config_get_rebase(int *rebase_unspecified)
 328 {
 329         struct branch *curr_branch = branch_get("HEAD");
 330         const char *value;
 331
 332         if (curr_branch) {
 333                 char *key = xstrfmt("branch.%s.rebase", curr_branch->name);
 334
 335                 if (!git_config_get_value(key, &value)) {
 336                         enum rebase_type ret = parse_config_rebase(key, value, 1);
 337                         free(key);
 338                         return ret;
 339                 }
 340
 341                 free(key);
 342         }
 343
 344         if (!git_config_get_value("pull.rebase", &value))
 345                 return parse_config_rebase("pull.rebase", value, 1);
 346
 347         *rebase_unspecified = 1;
 348
 349         return REBASE_FALSE;
 350 }
 351
 352 /**
 353  * Read config variables.
 354  */
 355 static int git_pull_config(const char *var, const char *value, void *cb)
 356 {
 357         int status;
 358
 359         if (!strcmp(var, "rebase.autostash")) {
 360                 config_autostash = git_config_bool(var, value);
 361                 return 0;
 362         } else if (!strcmp(var, "submodule.recurse")) {
 363                 recurse_submodules = git_config_bool(var, value) ?
 364                         RECURSE_SUBMODULES_ON : RECURSE_SUBMODULES_OFF;
 365                 return 0;
 366         } else if (!strcmp(var, "gpg.mintrustlevel")) {
 367                 check_trust_level = 0;
 368         }
 369
 370         status = git_gpg_config(var, value, cb);
 371         if (status)
 372                 return status;
 373
 374         return git_default_config(var, value, cb);
 375 }
 376
 377 /**
 378  * Appends merge candidates from FETCH_HEAD that are not marked not-for-merge
 379  * into merge_heads.
 380  */
 381 static void get_merge_heads(struct oid_array *merge_heads)
 382 {
 383         const char *filename = git_path_fetch_head(the_repository);
 384         FILE *fp;
 385         struct strbuf sb = STRBUF_INIT;
 386         struct object_id oid;
 387
 388         fp = xfopen(filename, "r");
 389         while (strbuf_getline_lf(&sb, fp) != EOF) {
 390                 const char *p;
 391                 if (parse_oid_hex(sb.buf, &oid, &p))
 392                         continue;  /* invalid line: does not start with object ID */
 393                 if (starts_with(p, "\tnot-for-merge\t"))
 394                         continue;  /* ref is not-for-merge */
 395                 oid_array_append(merge_heads, &oid);
 396         }
 397         fclose(fp);
 398         strbuf_release(&sb);
 399 }
 400
 401 /**
 402  * Used by die_no_merge_candidates() as a for_each_remote() callback to
 403  * retrieve the name of the remote if the repository only has one remote.
 404  */
 405 static int get_only_remote(struct remote *remote, void *cb_data)
 406 {
 407         const char **remote_name = cb_data;
 408
 409         if (*remote_name)
 410                 return -1;
 411
 412         *remote_name = remote->name;
 413         return 0;
 414 }
 415
 416 /**
 417  * Dies with the appropriate reason for why there are no merge candidates:
 418  *
 419  * 1. We fetched from a specific remote, and a refspec was given, but it ended
 420  *    up not fetching anything. This is usually because the user provided a
 421  *    wildcard refspec which had no matches on the remote end.
 422  *
 423  * 2. We fetched from a non-default remote, but didn't specify a branch to
 424  *    merge. We can't use the configured one because it applies to the default
 425  *    remote, thus the user must specify the branches to merge.
 426  *
 427  * 3. We fetched from the branch's or repo's default remote, but:
 428  *
 429  *    a. We are not on a branch, so there will never be a configured branch to
 430  *       merge with.
 431  *
 432  *    b. We are on a branch, but there is no configured branch to merge with.
 433  *
 434  * 4. We fetched from the branch's or repo's default remote, but the configured
 435  *    branch to merge didn't get fetched. (Either it doesn't exist, or wasn't
 436  *    part of the configured fetch refspec.)
 437  */
 438 static void NORETURN die_no_merge_candidates(const char *repo, const char **refspecs)
 439 {
 440         struct branch *curr_branch = branch_get("HEAD");
 441         const char *remote = curr_branch ? curr_branch->remote_name : NULL;
 442
 443         if (*refspecs) {
 444                 if (opt_rebase)
 445                         fprintf_ln(stderr, _("There is no candidate for rebasing against among the refs that you just fetched."));
 446                 else
 447                         fprintf_ln(stderr, _("There are no candidates for merging among the refs that you just fetched."));
 448                 fprintf_ln(stderr, _("Generally this means that you provided a wildcard refspec which had no\n"
 449                                         "matches on the remote end."));
 450         } else if (repo && curr_branch && (!remote || strcmp(repo, remote))) {
 451                 fprintf_ln(stderr, _("You asked to pull from the remote '%s', but did not specify\n"
 452                         "a branch. Because this is not the default configured remote\n"
 453                         "for your current branch, you must specify a branch on the command line."),
 454                         repo);
 455         } else if (!curr_branch) {
 456                 fprintf_ln(stderr, _("You are not currently on a branch."));
 457                 if (opt_rebase)
 458                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 459                 else
 460                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 461                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 462                 fprintf(stderr, "\n");
 463                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 464                 fprintf(stderr, "\n");
 465         } else if (!curr_branch->merge_nr) {
 466                 const char *remote_name = NULL;
 467
 468                 if (for_each_remote(get_only_remote, &remote_name) || !remote_name)
 469                         remote_name = _("<remote>");
 470
 471                 fprintf_ln(stderr, _("There is no tracking information for the current branch."));
 472                 if (opt_rebase)
 473                         fprintf_ln(stderr, _("Please specify which branch you want to rebase against."));
 474                 else
 475                         fprintf_ln(stderr, _("Please specify which branch you want to merge with."));
 476                 fprintf_ln(stderr, _("See git-pull(1) for details."));
 477                 fprintf(stderr, "\n");
 478                 fprintf_ln(stderr, "    git pull %s %s", _("<remote>"), _("<branch>"));
 479                 fprintf(stderr, "\n");
 480                 fprintf_ln(stderr, _("If you wish to set tracking information for this branch you can do so with:"));
 481                 fprintf(stderr, "\n");
 482                 fprintf_ln(stderr, "    git branch --set-upstream-to=%s/%s %s\n",
 483                                 remote_name, _("<branch>"), curr_branch->name);
 484         } else
 485                 fprintf_ln(stderr, _("Your configuration specifies to merge with the ref '%s'\n"
 486                         "from the remote, but no such ref was fetched."),
 487                         *curr_branch->merge_name);
 488         exit(1);
 489 }
 490
 491 /**
 492  * Parses argv into [<repo> [<refspecs>...]], returning their values in `repo`
 493  * as a string and `refspecs` as a null-terminated array of strings. If `repo`
 494  * is not provided in argv, it is set to NULL.
 495  */
 496 static void parse_repo_refspecs(int argc, const char **argv, const char **repo,
 497                 const char ***refspecs)
 498 {
 499         if (argc > 0) {
 500                 *repo = *argv++;
 501                 argc--;
 502         } else
 503                 *repo = NULL;
 504         *refspecs = argv;
 505 }
 506
 507 /**
 508  * Runs git-fetch, returning its exit status. `repo` and `refspecs` are the
 509  * repository and refspecs to fetch, or NULL if they are not provided.
 510  */
 511 static int run_fetch(const char *repo, const char **refspecs)
 512 {
 513         struct strvec args = STRVEC_INIT;
 514         int ret;
 515
 516         strvec_pushl(&args, "fetch", "--update-head-ok", NULL);
 517
 518         /* Shared options */
 519         argv_push_verbosity(&args);
 520         if (opt_progress)
 521                 strvec_push(&args, opt_progress);
 522
 523         /* Options passed to git-fetch */
 524         if (opt_all)
 525                 strvec_push(&args, opt_all);
 526         if (opt_append)
 527                 strvec_push(&args, opt_append);
 528         if (opt_upload_pack)
 529                 strvec_push(&args, opt_upload_pack);
 530         argv_push_force(&args);
 531         if (opt_tags)
 532                 strvec_push(&args, opt_tags);
 533         if (opt_prune)
 534                 strvec_push(&args, opt_prune);
 535         if (recurse_submodules != RECURSE_SUBMODULES_DEFAULT)
 536                 switch (recurse_submodules) {
 537                 case RECURSE_SUBMODULES_ON:
 538                         strvec_push(&args, "--recurse-submodules=on");
 539                         break;
 540                 case RECURSE_SUBMODULES_OFF:
 541                         strvec_push(&args, "--recurse-submodules=no");
 542                         break;
 543                 case RECURSE_SUBMODULES_ON_DEMAND:
 544                         strvec_push(&args, "--recurse-submodules=on-demand");
 545                         break;
 546                 default:
 547                         BUG("submodule recursion option not understood");
 548                 }
 549         if (max_children)
 550                 strvec_push(&args, max_children);
 551         if (opt_dry_run)
 552                 strvec_push(&args, "--dry-run");
 553         if (opt_keep)
 554                 strvec_push(&args, opt_keep);
 555         if (opt_depth)
 556                 strvec_push(&args, opt_depth);
 557         if (opt_unshallow)
 558                 strvec_push(&args, opt_unshallow);
 559         if (opt_update_shallow)
 560                 strvec_push(&args, opt_update_shallow);
 561         if (opt_refmap)
 562                 strvec_push(&args, opt_refmap);
 563         if (opt_ipv4)
 564                 strvec_push(&args, opt_ipv4);
 565         if (opt_ipv6)
 566                 strvec_push(&args, opt_ipv6);
 567         if (opt_show_forced_updates > 0)
 568                 strvec_push(&args, "--show-forced-updates");
 569         else if (opt_show_forced_updates == 0)
 570                 strvec_push(&args, "--no-show-forced-updates");
 571         if (set_upstream)
 572                 strvec_push(&args, set_upstream);
 573         strvec_pushv(&args, opt_fetch.v);
 574
 575         if (repo) {
 576                 strvec_push(&args, repo);
 577                 strvec_pushv(&args, refspecs);
 578         } else if (*refspecs)
 579                 BUG("refspecs without repo?");
 580         ret = run_command_v_opt(args.v, RUN_GIT_CMD);
 581         strvec_clear(&args);
 582         return ret;
 583 }
 584
 585 /**
 586  * "Pulls into void" by branching off merge_head.
 587  */
 588 static int pull_into_void(const struct object_id *merge_head,
 589                 const struct object_id *curr_head)
 590 {
 591         if (opt_verify_signatures) {
 592                 struct commit *commit;
 593
 594                 commit = lookup_commit(the_repository, merge_head);
 595                 if (!commit)
 596                         die(_("unable to access commit %s"),
 597                             oid_to_hex(merge_head));
 598
 599                 verify_merge_signature(commit, opt_verbosity,
 600                                        check_trust_level);
 601         }
 602
 603         /*
 604          * Two-way merge: we treat the index as based on an empty tree,
 605          * and try to fast-forward to HEAD. This ensures we will not lose
 606          * index/worktree changes that the user already made on the unborn
 607          * branch.
 608          */
 609         if (checkout_fast_forward(the_repository,
 610                                   the_hash_algo->empty_tree,
 611                                   merge_head, 0))
 612                 return 1;
 613
 614         if (update_ref("initial pull", "HEAD", merge_head, curr_head, 0, UPDATE_REFS_DIE_ON_ERR))
 615                 return 1;
 616
 617         return 0;
 618 }
 619
 620 static int rebase_submodules(void)
 621 {
 622         struct child_process cp = CHILD_PROCESS_INIT;
 623
 624         cp.git_cmd = 1;
 625         cp.no_stdin = 1;
 626         strvec_pushl(&cp.args, "submodule", "update",
 627                      "--recursive", "--rebase", NULL);
 628         argv_push_verbosity(&cp.args);
 629
 630         return run_command(&cp);
 631 }
 632
 633 static int update_submodules(void)
 634 {
 635         struct child_process cp = CHILD_PROCESS_INIT;
 636
 637         cp.git_cmd = 1;
 638         cp.no_stdin = 1;
 639         strvec_pushl(&cp.args, "submodule", "update",
 640                      "--recursive", "--checkout", NULL);
 641         argv_push_verbosity(&cp.args);
 642
 643         return run_command(&cp);
 644 }
 645
 646 /**
 647  * Runs git-merge, returning its exit status.
 648  */
 649 static int run_merge(void)
 650 {
 651         int ret;
 652         struct strvec args = STRVEC_INIT;
 653
 654         strvec_pushl(&args, "merge", NULL);
 655
 656         /* Shared options */
 657         argv_push_verbosity(&args);
 658         if (opt_progress)
 659                 strvec_push(&args, opt_progress);
 660
 661         /* Options passed to git-merge */
 662         if (opt_diffstat)
 663                 strvec_push(&args, opt_diffstat);
 664         if (opt_log)
 665                 strvec_push(&args, opt_log);
 666         if (opt_signoff)
 667                 strvec_push(&args, opt_signoff);
 668         if (opt_squash)
 669                 strvec_push(&args, opt_squash);
 670         if (opt_commit)
 671                 strvec_push(&args, opt_commit);
 672         if (opt_edit)
 673                 strvec_push(&args, opt_edit);
 674         if (cleanup_arg)
 675                 strvec_pushf(&args, "--cleanup=%s", cleanup_arg);
 676         if (opt_ff)
 677                 strvec_push(&args, opt_ff);
 678         if (opt_verify_signatures)
 679                 strvec_push(&args, opt_verify_signatures);
 680         strvec_pushv(&args, opt_strategies.v);
 681         strvec_pushv(&args, opt_strategy_opts.v);
 682         if (opt_gpg_sign)
 683                 strvec_push(&args, opt_gpg_sign);
 684         if (opt_autostash == 0)
 685                 strvec_push(&args, "--no-autostash");
 686         else if (opt_autostash == 1)
 687                 strvec_push(&args, "--autostash");
 688         if (opt_allow_unrelated_histories > 0)
 689                 strvec_push(&args, "--allow-unrelated-histories");
 690
 691         strvec_push(&args, "FETCH_HEAD");
 692         ret = run_command_v_opt(args.v, RUN_GIT_CMD);
 693         strvec_clear(&args);
 694         return ret;
 695 }
 696
 697 /**
 698  * Returns remote's upstream branch for the current branch. If remote is NULL,
 699  * the current branch's configured default remote is used. Returns NULL if
 700  * `remote` does not name a valid remote, HEAD does not point to a branch,
 701  * remote is not the branch's configured remote or the branch does not have any
 702  * configured upstream branch.
 703  */
 704 static const char *get_upstream_branch(const char *remote)
 705 {
 706         struct remote *rm;
 707         struct branch *curr_branch;
 708         const char *curr_branch_remote;
 709
 710         rm = remote_get(remote);
 711         if (!rm)
 712                 return NULL;
 713
 714         curr_branch = branch_get("HEAD");
 715         if (!curr_branch)
 716                 return NULL;
 717
 718         curr_branch_remote = remote_for_branch(curr_branch, NULL);
 719         assert(curr_branch_remote);
 720
 721         if (strcmp(curr_branch_remote, rm->name))
 722                 return NULL;
 723
 724         return branch_get_upstream(curr_branch, NULL);
 725 }
 726
 727 /**
 728  * Derives the remote-tracking branch from the remote and refspec.
 729  *
 730  * FIXME: The current implementation assumes the default mapping of
 731  * refs/heads/<branch_name> to refs/remotes/<remote_name>/<branch_name>.
 732  */
 733 static const char *get_tracking_branch(const char *remote, const char *refspec)
 734 {
 735         struct refspec_item spec;
 736         const char *spec_src;
 737         const char *merge_branch;
 738
 739         refspec_item_init_or_die(&spec, refspec, REFSPEC_FETCH);
 740         spec_src = spec.src;
 741         if (!*spec_src || !strcmp(spec_src, "HEAD"))
 742                 spec_src = "HEAD";
 743         else if (skip_prefix(spec_src, "heads/", &spec_src))
 744                 ;
 745         else if (skip_prefix(spec_src, "refs/heads/", &spec_src))
 746                 ;
 747         else if (starts_with(spec_src, "refs/") ||
 748                 starts_with(spec_src, "tags/") ||
 749                 starts_with(spec_src, "remotes/"))
 750                 spec_src = "";
 751
 752         if (*spec_src) {
 753                 if (!strcmp(remote, "."))
 754                         merge_branch = mkpath("refs/heads/%s", spec_src);
 755                 else
 756                         merge_branch = mkpath("refs/remotes/%s/%s", remote, spec_src);
 757         } else
 758                 merge_branch = NULL;
 759
 760         refspec_item_clear(&spec);
 761         return merge_branch;
 762 }
 763
 764 /**
 765  * Given the repo and refspecs, sets fork_point to the point at which the
 766  * current branch forked from its remote-tracking branch. Returns 0 on success,
 767  * -1 on failure.
 768  */
 769 static int get_rebase_fork_point(struct object_id *fork_point, const char *repo,
 770                 const char *refspec)
 771 {
 772         int ret;
 773         struct branch *curr_branch;
 774         const char *remote_branch;
 775         struct child_process cp = CHILD_PROCESS_INIT;
 776         struct strbuf sb = STRBUF_INIT;
 777
 778         curr_branch = branch_get("HEAD");
 779         if (!curr_branch)
 780                 return -1;
 781
 782         if (refspec)
 783                 remote_branch = get_tracking_branch(repo, refspec);
 784         else
 785                 remote_branch = get_upstream_branch(repo);
 786
 787         if (!remote_branch)
 788                 return -1;
 789
 790         strvec_pushl(&cp.args, "merge-base", "--fork-point",
 791                      remote_branch, curr_branch->name, NULL);
 792         cp.no_stdin = 1;
 793         cp.no_stderr = 1;
 794         cp.git_cmd = 1;
 795
 796         ret = capture_command(&cp, &sb, GIT_MAX_HEXSZ);
 797         if (ret)
 798                 goto cleanup;
 799
 800         ret = get_oid_hex(sb.buf, fork_point);
 801         if (ret)
 802                 goto cleanup;
 803
 804 cleanup:
 805         strbuf_release(&sb);
 806         return ret ? -1 : 0;
 807 }
 808
 809 /**
 810  * Sets merge_base to the octopus merge base of curr_head, merge_head and
 811  * fork_point. Returns 0 if a merge base is found, 1 otherwise.
 812  */
 813 static int get_octopus_merge_base(struct object_id *merge_base,
 814                 const struct object_id *curr_head,
 815                 const struct object_id *merge_head,
 816                 const struct object_id *fork_point)
 817 {
 818         struct commit_list *revs = NULL, *result;
 819
 820         commit_list_insert(lookup_commit_reference(the_repository, curr_head),
 821                            &revs);
 822         commit_list_insert(lookup_commit_reference(the_repository, merge_head),
 823                            &revs);
 824         if (!is_null_oid(fork_point))
 825                 commit_list_insert(lookup_commit_reference(the_repository, fork_point),
 826                                    &revs);
 827
 828         result = get_octopus_merge_bases(revs);
 829         free_commit_list(revs);
 830         reduce_heads_replace(&result);
 831
 832         if (!result)
 833                 return 1;
 834
 835         oidcpy(merge_base, &result->item->object.oid);
 836         free_commit_list(result);
 837         return 0;
 838 }
 839
 840 /**
 841  * Given the current HEAD oid, the merge head returned from git-fetch and the
 842  * fork point calculated by get_rebase_fork_point(), compute the <newbase> and
 843  * <upstream> arguments to use for the upcoming git-rebase invocation.
 844  */
 845 static int get_rebase_newbase_and_upstream(struct object_id *newbase,
 846                 struct object_id *upstream,
 847                 const struct object_id *curr_head,
 848                 const struct object_id *merge_head,
 849                 const struct object_id *fork_point)
 850 {
 851         struct object_id oct_merge_base;
 852
 853         if (!get_octopus_merge_base(&oct_merge_base, curr_head, merge_head, fork_point))
 854                 if (!is_null_oid(fork_point) && oideq(&oct_merge_base, fork_point))
 855                         fork_point = NULL;
 856
 857         if (fork_point && !is_null_oid(fork_point))
 858                 oidcpy(upstream, fork_point);
 859         else
 860                 oidcpy(upstream, merge_head);
 861
 862         oidcpy(newbase, merge_head);
 863
 864         return 0;
 865 }
 866
 867 /**
 868  * Given the <newbase> and <upstream> calculated by
 869  * get_rebase_newbase_and_upstream(), runs git-rebase with the
 870  * appropriate arguments and returns its exit status.
 871  */
 872 static int run_rebase(const struct object_id *newbase,
 873                 const struct object_id *upstream)
 874 {
 875         int ret;
 876         struct strvec args = STRVEC_INIT;
 877
 878         strvec_push(&args, "rebase");
 879
 880         /* Shared options */
 881         argv_push_verbosity(&args);
 882
 883         /* Options passed to git-rebase */
 884         if (opt_rebase == REBASE_MERGES)
 885                 strvec_push(&args, "--rebase-merges");
 886         else if (opt_rebase == REBASE_PRESERVE)
 887                 strvec_push(&args, "--preserve-merges");
 888         else if (opt_rebase == REBASE_INTERACTIVE)
 889                 strvec_push(&args, "--interactive");
 890         if (opt_diffstat)
 891                 strvec_push(&args, opt_diffstat);
 892         strvec_pushv(&args, opt_strategies.v);
 893         strvec_pushv(&args, opt_strategy_opts.v);
 894         if (opt_gpg_sign)
 895                 strvec_push(&args, opt_gpg_sign);
 896         if (opt_signoff)
 897                 strvec_push(&args, opt_signoff);
 898         if (opt_autostash == 0)
 899                 strvec_push(&args, "--no-autostash");
 900         else if (opt_autostash == 1)
 901                 strvec_push(&args, "--autostash");
 902         if (opt_verify_signatures &&
 903             !strcmp(opt_verify_signatures, "--verify-signatures"))
 904                 warning(_("ignoring --verify-signatures for rebase"));
 905
 906         strvec_push(&args, "--onto");
 907         strvec_push(&args, oid_to_hex(newbase));
 908
 909         strvec_push(&args, oid_to_hex(upstream));
 910
 911         ret = run_command_v_opt(args.v, RUN_GIT_CMD);
 912         strvec_clear(&args);
 913         return ret;
 914 }
 915
 916 static int get_can_ff(struct object_id *orig_head,
 917                       struct oid_array *merge_heads)
 918 {
 919         int ret;
 920         struct commit_list *list = NULL;
 921         struct commit *merge_head, *head;
 922         struct object_id *orig_merge_head;
 923
 924         if (merge_heads->nr > 1)
 925                 return 0;
 926
 927         orig_merge_head = &merge_heads->oid[0];
 928         head = lookup_commit_reference(the_repository, orig_head);
 929         commit_list_insert(head, &list);
 930         merge_head = lookup_commit_reference(the_repository, orig_merge_head);
 931         ret = repo_is_descendant_of(the_repository, merge_head, list);
 932         free_commit_list(list);
 933         return ret;
 934 }
 935
 936 static void show_advice_pull_non_ff(void)
 937 {
 938         advise(_("You have divergent branches and need to specify how to reconcile them.\n"
 939                  "You can do so by running one of the following commands sometime before\n"
 940                  "your next pull:\n"
 941                  "\n"
 942                  "  git config pull.rebase false  # merge (the default strategy)\n"
 943                  "  git config pull.rebase true   # rebase\n"
 944                  "  git config pull.ff only       # fast-forward only\n"
 945                  "\n"
 946                  "You can replace \"git config\" with \"git config --global\" to set a default\n"
 947                  "preference for all repositories. You can also pass --rebase, --no-rebase,\n"
 948                  "or --ff-only on the command line to override the configured default per\n"
 949                  "invocation.\n"));
 950 }
 951
 952 int cmd_pull(int argc, const char **argv, const char *prefix)
 953 {
 954         const char *repo, **refspecs;
 955         struct oid_array merge_heads = OID_ARRAY_INIT;
 956         struct object_id orig_head, curr_head;
 957         struct object_id rebase_fork_point;
 958         int rebase_unspecified = 0;
 959         int can_ff;
 960
 961         if (!getenv("GIT_REFLOG_ACTION"))
 962                 set_reflog_message(argc, argv);
 963
 964         git_config(git_pull_config, NULL);
 965
 966         argc = parse_options(argc, argv, prefix, pull_options, pull_usage, 0);
 967
 968         if (cleanup_arg)
 969                 /*
 970                  * this only checks the validity of cleanup_arg; we don't need
 971                  * a valid value for use_editor
 972                  */
 973                 get_cleanup_mode(cleanup_arg, 0);
 974
 975         parse_repo_refspecs(argc, argv, &repo, &refspecs);
 976
 977         if (!opt_ff) {
 978                 opt_ff = xstrdup_or_null(config_get_ff());
 979                 /*
 980                  * A subtle point: opt_ff was set on the line above via
 981                  * reading from config.  opt_rebase, in contrast, is set
 982                  * before this point via command line options.  The setting
 983                  * of opt_rebase via reading from config (using
 984                  * config_get_rebase()) does not happen until later.  We
 985                  * are relying on the next if-condition happening before
 986                  * the config_get_rebase() call so that an explicit
 987                  * "--rebase" can override a config setting of
 988                  * pull.ff=only.
 989                  */
 990                 if (opt_rebase >= 0 && opt_ff && !strcmp(opt_ff, "--ff-only"))
 991                         opt_ff = "--ff";
 992         }
 993
 994         if (opt_rebase < 0)
 995                 opt_rebase = config_get_rebase(&rebase_unspecified);
 996
 997         if (read_cache_unmerged())
 998                 die_resolve_conflict("pull");
 999
1000         if (file_exists(git_path_merge_head(the_repository)))
1001                 die_conclude_merge();
1002
1003         if (get_oid("HEAD", &orig_head))
1004                 oidclr(&orig_head);
1005
1006         if (opt_rebase) {
1007                 int autostash = config_autostash;
1008                 if (opt_autostash != -1)
1009                         autostash = opt_autostash;
1010
1011                 if (is_null_oid(&orig_head) && !is_cache_unborn())
1012                         die(_("Updating an unborn branch with changes added to the index."));
1013
1014                 if (!autostash)
1015                         require_clean_work_tree(the_repository,
1016                                 N_("pull with rebase"),
1017                                 _("please commit or stash them."), 1, 0);
1018
1019                 if (get_rebase_fork_point(&rebase_fork_point, repo, *refspecs))
1020                         oidclr(&rebase_fork_point);
1021         }
1022
1023         if (run_fetch(repo, refspecs))
1024                 return 1;
1025
1026         if (opt_dry_run)
1027                 return 0;
1028
1029         if (get_oid("HEAD", &curr_head))
1030                 oidclr(&curr_head);
1031
1032         if (!is_null_oid(&orig_head) && !is_null_oid(&curr_head) &&
1033                         !oideq(&orig_head, &curr_head)) {
1034                 /*
1035                  * The fetch involved updating the current branch.
1036                  *
1037                  * The working tree and the index file are still based on
1038                  * orig_head commit, but we are merging into curr_head.
1039                  * Update the working tree to match curr_head.
1040                  */
1041
1042                 warning(_("fetch updated the current branch head.\n"
1043                         "fast-forwarding your working tree from\n"
1044                         "commit %s."), oid_to_hex(&orig_head));
1045
1046                 if (checkout_fast_forward(the_repository, &orig_head,
1047                                           &curr_head, 0))
1048                         die(_("Cannot fast-forward your working tree.\n"
1049                                 "After making sure that you saved anything precious from\n"
1050                                 "$ git diff %s\n"
1051                                 "output, run\n"
1052                                 "$ git reset --hard\n"
1053                                 "to recover."), oid_to_hex(&orig_head));
1054         }
1055
1056         get_merge_heads(&merge_heads);
1057
1058         if (!merge_heads.nr)
1059                 die_no_merge_candidates(repo, refspecs);
1060
1061         if (is_null_oid(&orig_head)) {
1062                 if (merge_heads.nr > 1)
1063                         die(_("Cannot merge multiple branches into empty head."));
1064                 return pull_into_void(merge_heads.oid, &curr_head);
1065         }
1066         if (merge_heads.nr > 1) {
1067                 if (opt_rebase)
1068                         die(_("Cannot rebase onto multiple branches."));
1069                 if (opt_ff && !strcmp(opt_ff, "--ff-only"))
1070                         die(_("Cannot fast-forward to multiple branches."));
1071         }
1072
1073         can_ff = get_can_ff(&orig_head, &merge_heads);
1074
1075         /* ff-only takes precedence over rebase */
1076         if (opt_ff && !strcmp(opt_ff, "--ff-only")) {
1077                 if (!can_ff)
1078                         die_ff_impossible();
1079                 opt_rebase = REBASE_FALSE;
1080         }
1081         /* If no action specified and we can't fast forward, then warn. */
1082         if (!opt_ff && rebase_unspecified && !can_ff) {
1083                 show_advice_pull_non_ff();
1084                 die(_("Need to specify how to reconcile divergent branches."));
1085         }
1086
1087         if (opt_rebase) {
1088                 int ret = 0;
1089
1090                 struct object_id newbase;
1091                 struct object_id upstream;
1092                 get_rebase_newbase_and_upstream(&newbase, &upstream, &curr_head,
1093                                                 merge_heads.oid, &rebase_fork_point);
1094
1095                 if ((recurse_submodules == RECURSE_SUBMODULES_ON ||
1096                      recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND) &&
1097                     submodule_touches_in_range(the_repository, &upstream, &curr_head))
1098                         die(_("cannot rebase with locally recorded submodule modifications"));
1099
1100                 if (can_ff) {
1101                         /* we can fast-forward this without invoking rebase */
1102                         opt_ff = "--ff-only";
1103                         ret = run_merge();
1104                 } else {
1105                         ret = run_rebase(&newbase, &upstream);
1106                 }
1107
1108                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
1109                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
1110                         ret = rebase_submodules();
1111
1112                 return ret;
1113         } else {
1114                 int ret = run_merge();
1115                 if (!ret && (recurse_submodules == RECURSE_SUBMODULES_ON ||
1116                              recurse_submodules == RECURSE_SUBMODULES_ON_DEMAND))
1117                         ret = update_submodules();
1118                 return ret;
1119         }
1120 }