worktree.c

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