worktree.c

   1 #include "git-compat-util.h"
   2 #include "abspath.h"
   3 #include "environment.h"
   4 #include "gettext.h"
   5 #include "path.h"
   6 #include "repository.h"
   7 #include "refs.h"
   8 #include "setup.h"
   9 #include "strbuf.h"
  10 #include "worktree.h"
  11 #include "dir.h"
  12 #include "wt-status.h"
  13 #include "config.h"
  14
  15 void free_worktree(struct worktree *worktree)
  16 {
  17         if (!worktree)
  18                 return;
  19         free(worktree->path);
  20         free(worktree->id);
  21         free(worktree->head_ref);
  22         free(worktree->lock_reason);
  23         free(worktree->prune_reason);
  24         free(worktree);
  25 }
  26
  27 void free_worktrees(struct worktree **worktrees)
  28 {
  29         int i = 0;
  30         for (i = 0; worktrees[i]; i++)
  31                 free_worktree(worktrees[i]);
  32         free (worktrees);
  33 }
  34
  35 /**
  36  * Update head_oid, head_ref and is_detached of the given worktree
  37  */
  38 static void add_head_info(struct worktree *wt)
  39 {
  40         int flags;
  41         const char *target;
  42
  43         target = refs_resolve_ref_unsafe(get_worktree_ref_store(wt),
  44                                          "HEAD",
  45                                          0,
  46                                          &wt->head_oid, &flags);
  47         if (!target)
  48                 return;
  49
  50         if (flags & REF_ISSYMREF)
  51                 wt->head_ref = xstrdup(target);
  52         else
  53                 wt->is_detached = 1;
  54 }
  55
  56 /**
  57  * get the main worktree
  58  */
  59 static struct worktree *get_main_worktree(int skip_reading_head)
  60 {
  61         struct worktree *worktree = NULL;
  62         struct strbuf worktree_path = STRBUF_INIT;
  63
  64         strbuf_add_real_path(&worktree_path, get_git_common_dir());
  65         strbuf_strip_suffix(&worktree_path, "/.git");
  66
  67         CALLOC_ARRAY(worktree, 1);
  68         worktree->path = strbuf_detach(&worktree_path, NULL);
  69         /*
  70          * NEEDSWORK: If this function is called from a secondary worktree and
  71          * config.worktree is present, is_bare_repository_cfg will reflect the
  72          * contents of config.worktree, not the contents of the main worktree.
  73          * This means that worktree->is_bare may be set to 0 even if the main
  74          * worktree is configured to be bare.
  75          */
  76         worktree->is_bare = (is_bare_repository_cfg == 1) ||
  77                 is_bare_repository();
  78         if (!skip_reading_head)
  79                 add_head_info(worktree);
  80         return worktree;
  81 }
  82
  83 struct worktree *get_linked_worktree(const char *id,
  84                                      int skip_reading_head)
  85 {
  86         struct worktree *worktree = NULL;
  87         struct strbuf path = STRBUF_INIT;
  88         struct strbuf worktree_path = STRBUF_INIT;
  89
  90         if (!id)
  91                 die("Missing linked worktree name");
  92
  93         strbuf_git_common_path(&path, the_repository, "worktrees/%s/gitdir", id);
  94         if (strbuf_read_file(&worktree_path, path.buf, 0) <= 0)
  95                 /* invalid gitdir file */
  96                 goto done;
  97         strbuf_rtrim(&worktree_path);
  98         strbuf_strip_suffix(&worktree_path, "/.git");
  99
 100         CALLOC_ARRAY(worktree, 1);
 101         worktree->path = strbuf_detach(&worktree_path, NULL);
 102         worktree->id = xstrdup(id);
 103         if (!skip_reading_head)
 104                 add_head_info(worktree);
 105
 106 done:
 107         strbuf_release(&path);
 108         strbuf_release(&worktree_path);
 109         return worktree;
 110 }
 111
 112 static void mark_current_worktree(struct worktree **worktrees)
 113 {
 114         char *git_dir = absolute_pathdup(get_git_dir());
 115         int i;
 116
 117         for (i = 0; worktrees[i]; i++) {
 118                 struct worktree *wt = worktrees[i];
 119                 const char *wt_git_dir = get_worktree_git_dir(wt);
 120
 121                 if (!fspathcmp(git_dir, absolute_path(wt_git_dir))) {
 122                         wt->is_current = 1;
 123                         break;
 124                 }
 125         }
 126         free(git_dir);
 127 }
 128
 129 /*
 130  * NEEDSWORK: This function exists so that we can look up metadata of a
 131  * worktree without trying to access any of its internals like the refdb. It
 132  * would be preferable to instead have a corruption-tolerant function for
 133  * retrieving worktree metadata that could be used when the worktree is known
 134  * to not be in a healthy state, e.g. when creating or repairing it.
 135  */
 136 static struct worktree **get_worktrees_internal(int skip_reading_head)
 137 {
 138         struct worktree **list = NULL;
 139         struct strbuf path = STRBUF_INIT;
 140         DIR *dir;
 141         struct dirent *d;
 142         int counter = 0, alloc = 2;
 143
 144         ALLOC_ARRAY(list, alloc);
 145
 146         list[counter++] = get_main_worktree(skip_reading_head);
 147
 148         strbuf_addf(&path, "%s/worktrees", get_git_common_dir());
 149         dir = opendir(path.buf);
 150         strbuf_release(&path);
 151         if (dir) {
 152                 while ((d = readdir_skip_dot_and_dotdot(dir)) != NULL) {
 153                         struct worktree *linked = NULL;
 154
 155                         if ((linked = get_linked_worktree(d->d_name, skip_reading_head))) {
 156                                 ALLOC_GROW(list, counter + 1, alloc);
 157                                 list[counter++] = linked;
 158                         }
 159                 }
 160                 closedir(dir);
 161         }
 162         ALLOC_GROW(list, counter + 1, alloc);
 163         list[counter] = NULL;
 164
 165         mark_current_worktree(list);
 166         return list;
 167 }
 168
 169 struct worktree **get_worktrees(void)
 170 {
 171         return get_worktrees_internal(0);
 172 }
 173
 174 const char *get_worktree_git_dir(const struct worktree *wt)
 175 {
 176         if (!wt)
 177                 return get_git_dir();
 178         else if (!wt->id)
 179                 return get_git_common_dir();
 180         else
 181                 return git_common_path("worktrees/%s", wt->id);
 182 }
 183
 184 static struct worktree *find_worktree_by_suffix(struct worktree **list,
 185                                                 const char *suffix)
 186 {
 187         struct worktree *found = NULL;
 188         int nr_found = 0, suffixlen;
 189
 190         suffixlen = strlen(suffix);
 191         if (!suffixlen)
 192                 return NULL;
 193
 194         for (; *list && nr_found < 2; list++) {
 195                 const char      *path    = (*list)->path;
 196                 int              pathlen = strlen(path);
 197                 int              start   = pathlen - suffixlen;
 198
 199                 /* suffix must start at directory boundary */
 200                 if ((!start || (start > 0 && is_dir_sep(path[start - 1]))) &&
 201                     !fspathcmp(suffix, path + start)) {
 202                         found = *list;
 203                         nr_found++;
 204                 }
 205         }
 206         return nr_found == 1 ? found : NULL;
 207 }
 208
 209 struct worktree *find_worktree(struct worktree **list,
 210                                const char *prefix,
 211                                const char *arg)
 212 {
 213         struct worktree *wt;
 214         char *to_free = NULL;
 215
 216         if ((wt = find_worktree_by_suffix(list, arg)))
 217                 return wt;
 218
 219         if (prefix)
 220                 arg = to_free = prefix_filename(prefix, arg);
 221         wt = find_worktree_by_path(list, arg);
 222         free(to_free);
 223         return wt;
 224 }
 225
 226 struct worktree *find_worktree_by_path(struct worktree **list, const char *p)
 227 {
 228         struct strbuf wt_path = STRBUF_INIT;
 229         char *path = real_pathdup(p, 0);
 230
 231         if (!path)
 232                 return NULL;
 233         for (; *list; list++) {
 234                 if (!strbuf_realpath(&wt_path, (*list)->path, 0))
 235                         continue;
 236
 237                 if (!fspathcmp(path, wt_path.buf))
 238                         break;
 239         }
 240         free(path);
 241         strbuf_release(&wt_path);
 242         return *list;
 243 }
 244
 245 int is_main_worktree(const struct worktree *wt)
 246 {
 247         return !wt->id;
 248 }
 249
 250 const char *worktree_lock_reason(struct worktree *wt)
 251 {
 252         if (is_main_worktree(wt))
 253                 return NULL;
 254
 255         if (!wt->lock_reason_valid) {
 256                 struct strbuf path = STRBUF_INIT;
 257
 258                 strbuf_addstr(&path, worktree_git_path(wt, "locked"));
 259                 if (file_exists(path.buf)) {
 260                         struct strbuf lock_reason = STRBUF_INIT;
 261                         if (strbuf_read_file(&lock_reason, path.buf, 0) < 0)
 262                                 die_errno(_("failed to read '%s'"), path.buf);
 263                         strbuf_trim(&lock_reason);
 264                         wt->lock_reason = strbuf_detach(&lock_reason, NULL);
 265                 } else
 266                         wt->lock_reason = NULL;
 267                 wt->lock_reason_valid = 1;
 268                 strbuf_release(&path);
 269         }
 270
 271         return wt->lock_reason;
 272 }
 273
 274 const char *worktree_prune_reason(struct worktree *wt, timestamp_t expire)
 275 {
 276         struct strbuf reason = STRBUF_INIT;
 277         char *path = NULL;
 278
 279         if (is_main_worktree(wt))
 280                 return NULL;
 281         if (wt->prune_reason_valid)
 282                 return wt->prune_reason;
 283
 284         if (should_prune_worktree(wt->id, &reason, &path, expire))
 285                 wt->prune_reason = strbuf_detach(&reason, NULL);
 286         wt->prune_reason_valid = 1;
 287
 288         strbuf_release(&reason);
 289         free(path);
 290         return wt->prune_reason;
 291 }
 292
 293 /* convenient wrapper to deal with NULL strbuf */
 294 __attribute__((format (printf, 2, 3)))
 295 static void strbuf_addf_gently(struct strbuf *buf, const char *fmt, ...)
 296 {
 297         va_list params;
 298
 299         if (!buf)
 300                 return;
 301
 302         va_start(params, fmt);
 303         strbuf_vaddf(buf, fmt, params);
 304         va_end(params);
 305 }
 306
 307 int validate_worktree(const struct worktree *wt, struct strbuf *errmsg,
 308                       unsigned flags)
 309 {
 310         struct strbuf wt_path = STRBUF_INIT;
 311         struct strbuf realpath = STRBUF_INIT;
 312         char *path = NULL;
 313         int err, ret = -1;
 314
 315         strbuf_addf(&wt_path, "%s/.git", wt->path);
 316
 317         if (is_main_worktree(wt)) {
 318                 if (is_directory(wt_path.buf)) {
 319                         ret = 0;
 320                         goto done;
 321                 }
 322                 /*
 323                  * Main worktree using .git file to point to the
 324                  * repository would make it impossible to know where
 325                  * the actual worktree is if this function is executed
 326                  * from another worktree. No .git file support for now.
 327                  */
 328                 strbuf_addf_gently(errmsg,
 329                                    _("'%s' at main working tree is not the repository directory"),
 330                                    wt_path.buf);
 331                 goto done;
 332         }
 333
 334         /*
 335          * Make sure "gitdir" file points to a real .git file and that
 336          * file points back here.
 337          */
 338         if (!is_absolute_path(wt->path)) {
 339                 strbuf_addf_gently(errmsg,
 340                                    _("'%s' file does not contain absolute path to the working tree location"),
 341                                    git_common_path("worktrees/%s/gitdir", wt->id));
 342                 goto done;
 343         }
 344
 345         if (flags & WT_VALIDATE_WORKTREE_MISSING_OK &&
 346             !file_exists(wt->path)) {
 347                 ret = 0;
 348                 goto done;
 349         }
 350
 351         if (!file_exists(wt_path.buf)) {
 352                 strbuf_addf_gently(errmsg, _("'%s' does not exist"), wt_path.buf);
 353                 goto done;
 354         }
 355
 356         path = xstrdup_or_null(read_gitfile_gently(wt_path.buf, &err));
 357         if (!path) {
 358                 strbuf_addf_gently(errmsg, _("'%s' is not a .git file, error code %d"),
 359                                    wt_path.buf, err);
 360                 goto done;
 361         }
 362
 363         strbuf_realpath(&realpath, git_common_path("worktrees/%s", wt->id), 1);
 364         ret = fspathcmp(path, realpath.buf);
 365
 366         if (ret)
 367                 strbuf_addf_gently(errmsg, _("'%s' does not point back to '%s'"),
 368                                    wt->path, git_common_path("worktrees/%s", wt->id));
 369 done:
 370         free(path);
 371         strbuf_release(&wt_path);
 372         strbuf_release(&realpath);
 373         return ret;
 374 }
 375
 376 void update_worktree_location(struct worktree *wt, const char *path_)
 377 {
 378         struct strbuf path = STRBUF_INIT;
 379
 380         if (is_main_worktree(wt))
 381                 BUG("can't relocate main worktree");
 382
 383         strbuf_realpath(&path, path_, 1);
 384         if (fspathcmp(wt->path, path.buf)) {
 385                 write_file(git_common_path("worktrees/%s/gitdir", wt->id),
 386                            "%s/.git", path.buf);
 387                 free(wt->path);
 388                 wt->path = strbuf_detach(&path, NULL);
 389         }
 390         strbuf_release(&path);
 391 }
 392
 393 int is_worktree_being_rebased(const struct worktree *wt,
 394                               const char *target)
 395 {
 396         struct wt_status_state state;
 397         int found_rebase;
 398
 399         memset(&state, 0, sizeof(state));
 400         found_rebase = wt_status_check_rebase(wt, &state) &&
 401                        (state.rebase_in_progress ||
 402                         state.rebase_interactive_in_progress) &&
 403                        state.branch &&
 404                        skip_prefix(target, "refs/heads/", &target) &&
 405                        !strcmp(state.branch, target);
 406         wt_status_state_free_buffers(&state);
 407         return found_rebase;
 408 }
 409
 410 int is_worktree_being_bisected(const struct worktree *wt,
 411                                const char *target)
 412 {
 413         struct wt_status_state state;
 414         int found_bisect;
 415
 416         memset(&state, 0, sizeof(state));
 417         found_bisect = wt_status_check_bisect(wt, &state) &&
 418                        state.bisecting_from &&
 419                        skip_prefix(target, "refs/heads/", &target) &&
 420                        !strcmp(state.bisecting_from, target);
 421         wt_status_state_free_buffers(&state);
 422         return found_bisect;
 423 }
 424
 425 /*
 426  * note: this function should be able to detect shared symref even if
 427  * HEAD is temporarily detached (e.g. in the middle of rebase or
 428  * bisect). New commands that do similar things should update this
 429  * function as well.
 430  */
 431 int is_shared_symref(const struct worktree *wt, const char *symref,
 432                      const char *target)
 433 {
 434         const char *symref_target;
 435         struct ref_store *refs;
 436         int flags;
 437
 438         if (wt->is_bare)
 439                 return 0;
 440
 441         if (wt->is_detached && !strcmp(symref, "HEAD")) {
 442                 if (is_worktree_being_rebased(wt, target))
 443                         return 1;
 444                 if (is_worktree_being_bisected(wt, target))
 445                         return 1;
 446         }
 447
 448         refs = get_worktree_ref_store(wt);
 449         symref_target = refs_resolve_ref_unsafe(refs, symref, 0,
 450                                                 NULL, &flags);
 451         if ((flags & REF_ISSYMREF) &&
 452             symref_target && !strcmp(symref_target, target))
 453                 return 1;
 454
 455         return 0;
 456 }
 457
 458 const struct worktree *find_shared_symref(struct worktree **worktrees,
 459                                           const char *symref,
 460                                           const char *target)
 461 {
 462
 463         for (int i = 0; worktrees[i]; i++)
 464                 if (is_shared_symref(worktrees[i], symref, target))
 465                         return worktrees[i];
 466
 467         return NULL;
 468 }
 469
 470 int submodule_uses_worktrees(const char *path)
 471 {
 472         char *submodule_gitdir;
 473         struct strbuf sb = STRBUF_INIT, err = STRBUF_INIT;
 474         DIR *dir;
 475         struct dirent *d;
 476         int ret = 0;
 477         struct repository_format format = REPOSITORY_FORMAT_INIT;
 478
 479         submodule_gitdir = git_pathdup_submodule(path, "%s", "");
 480         if (!submodule_gitdir)
 481                 return 0;
 482
 483         /* The env would be set for the superproject. */
 484         get_common_dir_noenv(&sb, submodule_gitdir);
 485         free(submodule_gitdir);
 486
 487         strbuf_addstr(&sb, "/config");
 488         read_repository_format(&format, sb.buf);
 489         if (verify_repository_format(&format, &err)) {
 490                 strbuf_release(&err);
 491                 strbuf_release(&sb);
 492                 clear_repository_format(&format);
 493                 return 1;
 494         }
 495         clear_repository_format(&format);
 496         strbuf_release(&err);
 497
 498         /* Replace config by worktrees. */
 499         strbuf_setlen(&sb, sb.len - strlen("config"));
 500         strbuf_addstr(&sb, "worktrees");
 501
 502         /* See if there is any file inside the worktrees directory. */
 503         dir = opendir(sb.buf);
 504         strbuf_release(&sb);
 505
 506         if (!dir)
 507                 return 0;
 508
 509         d = readdir_skip_dot_and_dotdot(dir);
 510         if (d)
 511                 ret = 1;
 512         closedir(dir);
 513         return ret;
 514 }
 515
 516 void strbuf_worktree_ref(const struct worktree *wt,
 517                          struct strbuf *sb,
 518                          const char *refname)
 519 {
 520         if (parse_worktree_ref(refname, NULL, NULL, NULL) ==
 521                     REF_WORKTREE_CURRENT &&
 522             wt && !wt->is_current) {
 523                 if (is_main_worktree(wt))
 524                         strbuf_addstr(sb, "main-worktree/");
 525                 else
 526                         strbuf_addf(sb, "worktrees/%s/", wt->id);
 527         }
 528         strbuf_addstr(sb, refname);
 529 }
 530
 531 int other_head_refs(each_ref_fn fn, void *cb_data)
 532 {
 533         struct worktree **worktrees, **p;
 534         struct strbuf refname = STRBUF_INIT;
 535         int ret = 0;
 536
 537         worktrees = get_worktrees();
 538         for (p = worktrees; *p; p++) {
 539                 struct worktree *wt = *p;
 540                 struct object_id oid;
 541                 int flag;
 542
 543                 if (wt->is_current)
 544                         continue;
 545
 546                 strbuf_reset(&refname);
 547                 strbuf_worktree_ref(wt, &refname, "HEAD");
 548                 if (refs_resolve_ref_unsafe(get_main_ref_store(the_repository),
 549                                             refname.buf,
 550                                             RESOLVE_REF_READING,
 551                                             &oid, &flag))
 552                         ret = fn(refname.buf, &oid, flag, cb_data);
 553                 if (ret)
 554                         break;
 555         }
 556         free_worktrees(worktrees);
 557         strbuf_release(&refname);
 558         return ret;
 559 }
 560
 561 /*
 562  * Repair worktree's /path/to/worktree/.git file if missing, corrupt, or not
 563  * pointing at <repo>/worktrees/<id>.
 564  */
 565 static void repair_gitfile(struct worktree *wt,
 566                            worktree_repair_fn fn, void *cb_data)
 567 {
 568         struct strbuf dotgit = STRBUF_INIT;
 569         struct strbuf repo = STRBUF_INIT;
 570         char *backlink;
 571         const char *repair = NULL;
 572         int err;
 573
 574         /* missing worktree can't be repaired */
 575         if (!file_exists(wt->path))
 576                 return;
 577
 578         if (!is_directory(wt->path)) {
 579                 fn(1, wt->path, _("not a directory"), cb_data);
 580                 return;
 581         }
 582
 583         strbuf_realpath(&repo, git_common_path("worktrees/%s", wt->id), 1);
 584         strbuf_addf(&dotgit, "%s/.git", wt->path);
 585         backlink = xstrdup_or_null(read_gitfile_gently(dotgit.buf, &err));
 586
 587         if (err == READ_GITFILE_ERR_NOT_A_FILE)
 588                 fn(1, wt->path, _(".git is not a file"), cb_data);
 589         else if (err)
 590                 repair = _(".git file broken");
 591         else if (fspathcmp(backlink, repo.buf))
 592                 repair = _(".git file incorrect");
 593
 594         if (repair) {
 595                 fn(0, wt->path, repair, cb_data);
 596                 write_file(dotgit.buf, "gitdir: %s", repo.buf);
 597         }
 598
 599         free(backlink);
 600         strbuf_release(&repo);
 601         strbuf_release(&dotgit);
 602 }
 603
 604 static void repair_noop(int iserr UNUSED,
 605                         const char *path UNUSED,
 606                         const char *msg UNUSED,
 607                         void *cb_data UNUSED)
 608 {
 609         /* nothing */
 610 }
 611
 612 void repair_worktrees(worktree_repair_fn fn, void *cb_data)
 613 {
 614         struct worktree **worktrees = get_worktrees_internal(1);
 615         struct worktree **wt = worktrees + 1; /* +1 skips main worktree */
 616
 617         if (!fn)
 618                 fn = repair_noop;
 619         for (; *wt; wt++)
 620                 repair_gitfile(*wt, fn, cb_data);
 621         free_worktrees(worktrees);
 622 }
 623
 624 static int is_main_worktree_path(const char *path)
 625 {
 626         struct strbuf target = STRBUF_INIT;
 627         struct strbuf maindir = STRBUF_INIT;
 628         int cmp;
 629
 630         strbuf_add_real_path(&target, path);
 631         strbuf_strip_suffix(&target, "/.git");
 632         strbuf_add_real_path(&maindir, get_git_common_dir());
 633         strbuf_strip_suffix(&maindir, "/.git");
 634         cmp = fspathcmp(maindir.buf, target.buf);
 635
 636         strbuf_release(&maindir);
 637         strbuf_release(&target);
 638         return !cmp;
 639 }
 640
 641 /*
 642  * If both the main worktree and linked worktree have been moved, then the
 643  * gitfile /path/to/worktree/.git won't point into the repository, thus we
 644  * won't know which <repo>/worktrees/<id>/gitdir to repair. However, we may
 645  * be able to infer the gitdir by manually reading /path/to/worktree/.git,
 646  * extracting the <id>, and checking if <repo>/worktrees/<id> exists.
 647  */
 648 static char *infer_backlink(const char *gitfile)
 649 {
 650         struct strbuf actual = STRBUF_INIT;
 651         struct strbuf inferred = STRBUF_INIT;
 652         const char *id;
 653
 654         if (strbuf_read_file(&actual, gitfile, 0) < 0)
 655                 goto error;
 656         if (!starts_with(actual.buf, "gitdir:"))
 657                 goto error;
 658         if (!(id = find_last_dir_sep(actual.buf)))
 659                 goto error;
 660         strbuf_trim(&actual);
 661         id++; /* advance past '/' to point at <id> */
 662         if (!*id)
 663                 goto error;
 664         strbuf_git_common_path(&inferred, the_repository, "worktrees/%s", id);
 665         if (!is_directory(inferred.buf))
 666                 goto error;
 667
 668         strbuf_release(&actual);
 669         return strbuf_detach(&inferred, NULL);
 670
 671 error:
 672         strbuf_release(&actual);
 673         strbuf_release(&inferred);
 674         return NULL;
 675 }
 676
 677 /*
 678  * Repair <repo>/worktrees/<id>/gitdir if missing, corrupt, or not pointing at
 679  * the worktree's path.
 680  */
 681 void repair_worktree_at_path(const char *path,
 682                              worktree_repair_fn fn, void *cb_data)
 683 {
 684         struct strbuf dotgit = STRBUF_INIT;
 685         struct strbuf realdotgit = STRBUF_INIT;
 686         struct strbuf gitdir = STRBUF_INIT;
 687         struct strbuf olddotgit = STRBUF_INIT;
 688         char *backlink = NULL;
 689         const char *repair = NULL;
 690         int err;
 691
 692         if (!fn)
 693                 fn = repair_noop;
 694
 695         if (is_main_worktree_path(path))
 696                 goto done;
 697
 698         strbuf_addf(&dotgit, "%s/.git", path);
 699         if (!strbuf_realpath(&realdotgit, dotgit.buf, 0)) {
 700                 fn(1, path, _("not a valid path"), cb_data);
 701                 goto done;
 702         }
 703
 704         backlink = xstrdup_or_null(read_gitfile_gently(realdotgit.buf, &err));
 705         if (err == READ_GITFILE_ERR_NOT_A_FILE) {
 706                 fn(1, realdotgit.buf, _("unable to locate repository; .git is not a file"), cb_data);
 707                 goto done;
 708         } else if (err == READ_GITFILE_ERR_NOT_A_REPO) {
 709                 if (!(backlink = infer_backlink(realdotgit.buf))) {
 710                         fn(1, realdotgit.buf, _("unable to locate repository; .git file does not reference a repository"), cb_data);
 711                         goto done;
 712                 }
 713         } else if (err) {
 714                 fn(1, realdotgit.buf, _("unable to locate repository; .git file broken"), cb_data);
 715                 goto done;
 716         }
 717
 718         strbuf_addf(&gitdir, "%s/gitdir", backlink);
 719         if (strbuf_read_file(&olddotgit, gitdir.buf, 0) < 0)
 720                 repair = _("gitdir unreadable");
 721         else {
 722                 strbuf_rtrim(&olddotgit);
 723                 if (fspathcmp(olddotgit.buf, realdotgit.buf))
 724                         repair = _("gitdir incorrect");
 725         }
 726
 727         if (repair) {
 728                 fn(0, gitdir.buf, repair, cb_data);
 729                 write_file(gitdir.buf, "%s", realdotgit.buf);
 730         }
 731 done:
 732         free(backlink);
 733         strbuf_release(&olddotgit);
 734         strbuf_release(&gitdir);
 735         strbuf_release(&realdotgit);
 736         strbuf_release(&dotgit);
 737 }
 738
 739 int should_prune_worktree(const char *id, struct strbuf *reason, char **wtpath, timestamp_t expire)
 740 {
 741         struct stat st;
 742         char *path;
 743         int fd;
 744         size_t len;
 745         ssize_t read_result;
 746
 747         *wtpath = NULL;
 748         if (!is_directory(git_path("worktrees/%s", id))) {
 749                 strbuf_addstr(reason, _("not a valid directory"));
 750                 return 1;
 751         }
 752         if (file_exists(git_path("worktrees/%s/locked", id)))
 753                 return 0;
 754         if (stat(git_path("worktrees/%s/gitdir", id), &st)) {
 755                 strbuf_addstr(reason, _("gitdir file does not exist"));
 756                 return 1;
 757         }
 758         fd = open(git_path("worktrees/%s/gitdir", id), O_RDONLY);
 759         if (fd < 0) {
 760                 strbuf_addf(reason, _("unable to read gitdir file (%s)"),
 761                             strerror(errno));
 762                 return 1;
 763         }
 764         len = xsize_t(st.st_size);
 765         path = xmallocz(len);
 766
 767         read_result = read_in_full(fd, path, len);
 768         if (read_result < 0) {
 769                 strbuf_addf(reason, _("unable to read gitdir file (%s)"),
 770                             strerror(errno));
 771                 close(fd);
 772                 free(path);
 773                 return 1;
 774         }
 775         close(fd);
 776
 777         if (read_result != len) {
 778                 strbuf_addf(reason,
 779                             _("short read (expected %"PRIuMAX" bytes, read %"PRIuMAX")"),
 780                             (uintmax_t)len, (uintmax_t)read_result);
 781                 free(path);
 782                 return 1;
 783         }
 784         while (len && (path[len - 1] == '\n' || path[len - 1] == '\r'))
 785                 len--;
 786         if (!len) {
 787                 strbuf_addstr(reason, _("invalid gitdir file"));
 788                 free(path);
 789                 return 1;
 790         }
 791         path[len] = '\0';
 792         if (!file_exists(path)) {
 793                 if (stat(git_path("worktrees/%s/index", id), &st) ||
 794                     st.st_mtime <= expire) {
 795                         strbuf_addstr(reason, _("gitdir file points to non-existent location"));
 796                         free(path);
 797                         return 1;
 798                 } else {
 799                         *wtpath = path;
 800                         return 0;
 801                 }
 802         }
 803         *wtpath = path;
 804         return 0;
 805 }
 806
 807 static int move_config_setting(const char *key, const char *value,
 808                                const char *from_file, const char *to_file)
 809 {
 810         if (git_config_set_in_file_gently(to_file, key, NULL, value))
 811                 return error(_("unable to set %s in '%s'"), key, to_file);
 812         if (git_config_set_in_file_gently(from_file, key, NULL, NULL))
 813                 return error(_("unable to unset %s in '%s'"), key, from_file);
 814         return 0;
 815 }
 816
 817 int init_worktree_config(struct repository *r)
 818 {
 819         int res = 0;
 820         int bare = 0;
 821         struct config_set cs = { { 0 } };
 822         const char *core_worktree;
 823         char *common_config_file;
 824         char *main_worktree_file;
 825
 826         /*
 827          * If the extension is already enabled, then we can skip the
 828          * upgrade process.
 829          */
 830         if (r->repository_format_worktree_config)
 831                 return 0;
 832         if ((res = git_config_set_gently("extensions.worktreeConfig", "true")))
 833                 return error(_("failed to set extensions.worktreeConfig setting"));
 834
 835         common_config_file = xstrfmt("%s/config", r->commondir);
 836         main_worktree_file = xstrfmt("%s/config.worktree", r->commondir);
 837
 838         git_configset_init(&cs);
 839         git_configset_add_file(&cs, common_config_file);
 840
 841         /*
 842          * If core.bare is true in the common config file, then we need to
 843          * move it to the main worktree's config file or it will break all
 844          * worktrees. If it is false, then leave it in place because it
 845          * _could_ be negating a global core.bare=true.
 846          */
 847         if (!git_configset_get_bool(&cs, "core.bare", &bare) && bare) {
 848                 if ((res = move_config_setting("core.bare", "true",
 849                                                common_config_file,
 850                                                main_worktree_file)))
 851                         goto cleanup;
 852         }
 853         /*
 854          * If core.worktree is set, then the main worktree is located
 855          * somewhere different than the parent of the common Git dir.
 856          * Relocate that value to avoid breaking all worktrees with this
 857          * upgrade to worktree config.
 858          */
 859         if (!git_configset_get_value(&cs, "core.worktree", &core_worktree, NULL)) {
 860                 if ((res = move_config_setting("core.worktree", core_worktree,
 861                                                common_config_file,
 862                                                main_worktree_file)))
 863                         goto cleanup;
 864         }
 865
 866         /*
 867          * Ensure that we use worktree config for the remaining lifetime
 868          * of the current process.
 869          */
 870         r->repository_format_worktree_config = 1;
 871
 872 cleanup:
 873         git_configset_clear(&cs);
 874         free(common_config_file);
 875         free(main_worktree_file);
 876         return res;
 877 }