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