builtin/pull.c

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