git.oblomov.eu Git - git/blob - refs.c

   1 /*
   2  * The backend-independent part of the reference module.
   3  */
   4
   5 #include "cache.h"
   6 #include "config.h"
   7 #include "hashmap.h"
   8 #include "lockfile.h"
   9 #include "iterator.h"
  10 #include "refs.h"
  11 #include "refs/refs-internal.h"
  12 #include "object-store.h"
  13 #include "object.h"
  14 #include "tag.h"
  15 #include "submodule.h"
  16 #include "worktree.h"
  17 #include "argv-array.h"
  18 #include "repository.h"
  19
  20 /*
  21  * List of all available backends
  22  */
  23 static struct ref_storage_be *refs_backends = &refs_be_files;
  24
  25 static struct ref_storage_be *find_ref_storage_backend(const char *name)
  26 {
  27         struct ref_storage_be *be;
  28         for (be = refs_backends; be; be = be->next)
  29                 if (!strcmp(be->name, name))
  30                         return be;
  31         return NULL;
  32 }
  33
  34 int ref_storage_backend_exists(const char *name)
  35 {
  36         return find_ref_storage_backend(name) != NULL;
  37 }
  38
  39 /*
  40  * How to handle various characters in refnames:
  41  * 0: An acceptable character for refs
  42  * 1: End-of-component
  43  * 2: ., look for a preceding . to reject .. in refs
  44  * 3: {, look for a preceding @ to reject @{ in refs
  45  * 4: A bad character: ASCII control characters, and
  46  *    ":", "?", "[", "\", "^", "~", SP, or TAB
  47  * 5: *, reject unless REFNAME_REFSPEC_PATTERN is set
  48  */
  49 static unsigned char refname_disposition[256] = {
  50         1, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
  51         4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
  52         4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 2, 1,
  53         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 4,
  54         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  55         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 0, 4, 0,
  56         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  57         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 4, 4
  58 };
  59
  60 /*
  61  * Try to read one refname component from the front of refname.
  62  * Return the length of the component found, or -1 if the component is
  63  * not legal.  It is legal if it is something reasonable to have under
  64  * ".git/refs/"; We do not like it if:
  65  *
  66  * - it begins with ".", or
  67  * - it has double dots "..", or
  68  * - it has ASCII control characters, or
  69  * - it has ":", "?", "[", "\", "^", "~", SP, or TAB anywhere, or
  70  * - it has "*" anywhere unless REFNAME_REFSPEC_PATTERN is set, or
  71  * - it ends with a "/", or
  72  * - it ends with ".lock", or
  73  * - it contains a "@{" portion
  74  *
  75  * When sanitized is not NULL, instead of rejecting the input refname
  76  * as an error, try to come up with a usable replacement for the input
  77  * refname in it.
  78  */
  79 static int check_refname_component(const char *refname, int *flags,
  80                                    struct strbuf *sanitized)
  81 {
  82         const char *cp;
  83         char last = '\0';
  84         size_t component_start = 0; /* garbage - not a reasonable initial value */
  85
  86         if (sanitized)
  87                 component_start = sanitized->len;
  88
  89         for (cp = refname; ; cp++) {
  90                 int ch = *cp & 255;
  91                 unsigned char disp = refname_disposition[ch];
  92
  93                 if (sanitized && disp != 1)
  94                         strbuf_addch(sanitized, ch);
  95
  96                 switch (disp) {
  97                 case 1:
  98                         goto out;
  99                 case 2:
 100                         if (last == '.') { /* Refname contains "..". */
 101                                 if (sanitized)
 102                                         /* collapse ".." to single "." */
 103                                         strbuf_setlen(sanitized, sanitized->len - 1);
 104                                 else
 105                                         return -1;
 106                         }
 107                         break;
 108                 case 3:
 109                         if (last == '@') { /* Refname contains "@{". */
 110                                 if (sanitized)
 111                                         sanitized->buf[sanitized->len-1] = '-';
 112                                 else
 113                                         return -1;
 114                         }
 115                         break;
 116                 case 4:
 117                         /* forbidden char */
 118                         if (sanitized)
 119                                 sanitized->buf[sanitized->len-1] = '-';
 120                         else
 121                                 return -1;
 122                         break;
 123                 case 5:
 124                         if (!(*flags & REFNAME_REFSPEC_PATTERN)) {
 125                                 /* refspec can't be a pattern */
 126                                 if (sanitized)
 127                                         sanitized->buf[sanitized->len-1] = '-';
 128                                 else
 129                                         return -1;
 130                         }
 131
 132                         /*
 133                          * Unset the pattern flag so that we only accept
 134                          * a single asterisk for one side of refspec.
 135                          */
 136                         *flags &= ~ REFNAME_REFSPEC_PATTERN;
 137                         break;
 138                 }
 139                 last = ch;
 140         }
 141 out:
 142         if (cp == refname)
 143                 return 0; /* Component has zero length. */
 144
 145         if (refname[0] == '.') { /* Component starts with '.'. */
 146                 if (sanitized)
 147                         sanitized->buf[component_start] = '-';
 148                 else
 149                         return -1;
 150         }
 151         if (cp - refname >= LOCK_SUFFIX_LEN &&
 152             !memcmp(cp - LOCK_SUFFIX_LEN, LOCK_SUFFIX, LOCK_SUFFIX_LEN)) {
 153                 if (!sanitized)
 154                         return -1;
 155                 /* Refname ends with ".lock". */
 156                 while (strbuf_strip_suffix(sanitized, LOCK_SUFFIX)) {
 157                         /* try again in case we have .lock.lock */
 158                 }
 159         }
 160         return cp - refname;
 161 }
 162
 163 static int check_or_sanitize_refname(const char *refname, int flags,
 164                                      struct strbuf *sanitized)
 165 {
 166         int component_len, component_count = 0;
 167
 168         if (!strcmp(refname, "@")) {
 169                 /* Refname is a single character '@'. */
 170                 if (sanitized)
 171                         strbuf_addch(sanitized, '-');
 172                 else
 173                         return -1;
 174         }
 175
 176         while (1) {
 177                 if (sanitized && sanitized->len)
 178                         strbuf_complete(sanitized, '/');
 179
 180                 /* We are at the start of a path component. */
 181                 component_len = check_refname_component(refname, &flags,
 182                                                         sanitized);
 183                 if (sanitized && component_len == 0)
 184                         ; /* OK, omit empty component */
 185                 else if (component_len <= 0)
 186                         return -1;
 187
 188                 component_count++;
 189                 if (refname[component_len] == '\0')
 190                         break;
 191                 /* Skip to next component. */
 192                 refname += component_len + 1;
 193         }
 194
 195         if (refname[component_len - 1] == '.') {
 196                 /* Refname ends with '.'. */
 197                 if (sanitized)
 198                         ; /* omit ending dot */
 199                 else
 200                         return -1;
 201         }
 202         if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
 203                 return -1; /* Refname has only one component. */
 204         return 0;
 205 }
 206
 207 int check_refname_format(const char *refname, int flags)
 208 {
 209         return check_or_sanitize_refname(refname, flags, NULL);
 210 }
 211
 212 void sanitize_refname_component(const char *refname, struct strbuf *out)
 213 {
 214         if (check_or_sanitize_refname(refname, REFNAME_ALLOW_ONELEVEL, out))
 215                 BUG("sanitizing refname '%s' check returned error", refname);
 216 }
 217
 218 int refname_is_safe(const char *refname)
 219 {
 220         const char *rest;
 221
 222         if (skip_prefix(refname, "refs/", &rest)) {
 223                 char *buf;
 224                 int result;
 225                 size_t restlen = strlen(rest);
 226
 227                 /* rest must not be empty, or start or end with "/" */
 228                 if (!restlen || *rest == '/' || rest[restlen - 1] == '/')
 229                         return 0;
 230
 231                 /*
 232                  * Does the refname try to escape refs/?
 233                  * For example: refs/foo/../bar is safe but refs/foo/../../bar
 234                  * is not.
 235                  */
 236                 buf = xmallocz(restlen);
 237                 result = !normalize_path_copy(buf, rest) && !strcmp(buf, rest);
 238                 free(buf);
 239                 return result;
 240         }
 241
 242         do {
 243                 if (!isupper(*refname) && *refname != '_')
 244                         return 0;
 245                 refname++;
 246         } while (*refname);
 247         return 1;
 248 }
 249
 250 /*
 251  * Return true if refname, which has the specified oid and flags, can
 252  * be resolved to an object in the database. If the referred-to object
 253  * does not exist, emit a warning and return false.
 254  */
 255 int ref_resolves_to_object(const char *refname,
 256                            const struct object_id *oid,
 257                            unsigned int flags)
 258 {
 259         if (flags & REF_ISBROKEN)
 260                 return 0;
 261         if (!has_object_file(oid)) {
 262                 error(_("%s does not point to a valid object!"), refname);
 263                 return 0;
 264         }
 265         return 1;
 266 }
 267
 268 char *refs_resolve_refdup(struct ref_store *refs,
 269                           const char *refname, int resolve_flags,
 270                           struct object_id *oid, int *flags)
 271 {
 272         const char *result;
 273
 274         result = refs_resolve_ref_unsafe(refs, refname, resolve_flags,
 275                                          oid, flags);
 276         return xstrdup_or_null(result);
 277 }
 278
 279 char *resolve_refdup(const char *refname, int resolve_flags,
 280                      struct object_id *oid, int *flags)
 281 {
 282         return refs_resolve_refdup(get_main_ref_store(the_repository),
 283                                    refname, resolve_flags,
 284                                    oid, flags);
 285 }
 286
 287 /* The argument to filter_refs */
 288 struct ref_filter {
 289         const char *pattern;
 290         const char *prefix;
 291         each_ref_fn *fn;
 292         void *cb_data;
 293 };
 294
 295 int refs_read_ref_full(struct ref_store *refs, const char *refname,
 296                        int resolve_flags, struct object_id *oid, int *flags)
 297 {
 298         if (refs_resolve_ref_unsafe(refs, refname, resolve_flags, oid, flags))
 299                 return 0;
 300         return -1;
 301 }
 302
 303 int read_ref_full(const char *refname, int resolve_flags, struct object_id *oid, int *flags)
 304 {
 305         return refs_read_ref_full(get_main_ref_store(the_repository), refname,
 306                                   resolve_flags, oid, flags);
 307 }
 308
 309 int read_ref(const char *refname, struct object_id *oid)
 310 {
 311         return read_ref_full(refname, RESOLVE_REF_READING, oid, NULL);
 312 }
 313
 314 static int refs_ref_exists(struct ref_store *refs, const char *refname)
 315 {
 316         return !!refs_resolve_ref_unsafe(refs, refname, RESOLVE_REF_READING, NULL, NULL);
 317 }
 318
 319 int ref_exists(const char *refname)
 320 {
 321         return refs_ref_exists(get_main_ref_store(the_repository), refname);
 322 }
 323
 324 static int filter_refs(const char *refname, const struct object_id *oid,
 325                            int flags, void *data)
 326 {
 327         struct ref_filter *filter = (struct ref_filter *)data;
 328
 329         if (wildmatch(filter->pattern, refname, 0))
 330                 return 0;
 331         if (filter->prefix)
 332                 skip_prefix(refname, filter->prefix, &refname);
 333         return filter->fn(refname, oid, flags, filter->cb_data);
 334 }
 335
 336 enum peel_status peel_object(const struct object_id *name, struct object_id *oid)
 337 {
 338         struct object *o = lookup_unknown_object(name);
 339
 340         if (o->type == OBJ_NONE) {
 341                 int type = oid_object_info(the_repository, name, NULL);
 342                 if (type < 0 || !object_as_type(the_repository, o, type, 0))
 343                         return PEEL_INVALID;
 344         }
 345
 346         if (o->type != OBJ_TAG)
 347                 return PEEL_NON_TAG;
 348
 349         o = deref_tag_noverify(o);
 350         if (!o)
 351                 return PEEL_INVALID;
 352
 353         oidcpy(oid, &o->oid);
 354         return PEEL_PEELED;
 355 }
 356
 357 struct warn_if_dangling_data {
 358         FILE *fp;
 359         const char *refname;
 360         const struct string_list *refnames;
 361         const char *msg_fmt;
 362 };
 363
 364 static int warn_if_dangling_symref(const char *refname, const struct object_id *oid,
 365                                    int flags, void *cb_data)
 366 {
 367         struct warn_if_dangling_data *d = cb_data;
 368         const char *resolves_to;
 369
 370         if (!(flags & REF_ISSYMREF))
 371                 return 0;
 372
 373         resolves_to = resolve_ref_unsafe(refname, 0, NULL, NULL);
 374         if (!resolves_to
 375             || (d->refname
 376                 ? strcmp(resolves_to, d->refname)
 377                 : !string_list_has_string(d->refnames, resolves_to))) {
 378                 return 0;
 379         }
 380
 381         fprintf(d->fp, d->msg_fmt, refname);
 382         fputc('\n', d->fp);
 383         return 0;
 384 }
 385
 386 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 387 {
 388         struct warn_if_dangling_data data;
 389
 390         data.fp = fp;
 391         data.refname = refname;
 392         data.refnames = NULL;
 393         data.msg_fmt = msg_fmt;
 394         for_each_rawref(warn_if_dangling_symref, &data);
 395 }
 396
 397 void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames)
 398 {
 399         struct warn_if_dangling_data data;
 400
 401         data.fp = fp;
 402         data.refname = NULL;
 403         data.refnames = refnames;
 404         data.msg_fmt = msg_fmt;
 405         for_each_rawref(warn_if_dangling_symref, &data);
 406 }
 407
 408 int refs_for_each_tag_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 409 {
 410         return refs_for_each_ref_in(refs, "refs/tags/", fn, cb_data);
 411 }
 412
 413 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 414 {
 415         return refs_for_each_tag_ref(get_main_ref_store(the_repository), fn, cb_data);
 416 }
 417
 418 int refs_for_each_branch_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 419 {
 420         return refs_for_each_ref_in(refs, "refs/heads/", fn, cb_data);
 421 }
 422
 423 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 424 {
 425         return refs_for_each_branch_ref(get_main_ref_store(the_repository), fn, cb_data);
 426 }
 427
 428 int refs_for_each_remote_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 429 {
 430         return refs_for_each_ref_in(refs, "refs/remotes/", fn, cb_data);
 431 }
 432
 433 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 434 {
 435         return refs_for_each_remote_ref(get_main_ref_store(the_repository), fn, cb_data);
 436 }
 437
 438 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
 439 {
 440         struct strbuf buf = STRBUF_INIT;
 441         int ret = 0;
 442         struct object_id oid;
 443         int flag;
 444
 445         strbuf_addf(&buf, "%sHEAD", get_git_namespace());
 446         if (!read_ref_full(buf.buf, RESOLVE_REF_READING, &oid, &flag))
 447                 ret = fn(buf.buf, &oid, flag, cb_data);
 448         strbuf_release(&buf);
 449
 450         return ret;
 451 }
 452
 453 void normalize_glob_ref(struct string_list_item *item, const char *prefix,
 454                         const char *pattern)
 455 {
 456         struct strbuf normalized_pattern = STRBUF_INIT;
 457
 458         if (*pattern == '/')
 459                 BUG("pattern must not start with '/'");
 460
 461         if (prefix) {
 462                 strbuf_addstr(&normalized_pattern, prefix);
 463         }
 464         else if (!starts_with(pattern, "refs/"))
 465                 strbuf_addstr(&normalized_pattern, "refs/");
 466         strbuf_addstr(&normalized_pattern, pattern);
 467         strbuf_strip_suffix(&normalized_pattern, "/");
 468
 469         item->string = strbuf_detach(&normalized_pattern, NULL);
 470         item->util = has_glob_specials(pattern) ? NULL : item->string;
 471         strbuf_release(&normalized_pattern);
 472 }
 473
 474 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 475         const char *prefix, void *cb_data)
 476 {
 477         struct strbuf real_pattern = STRBUF_INIT;
 478         struct ref_filter filter;
 479         int ret;
 480
 481         if (!prefix && !starts_with(pattern, "refs/"))
 482                 strbuf_addstr(&real_pattern, "refs/");
 483         else if (prefix)
 484                 strbuf_addstr(&real_pattern, prefix);
 485         strbuf_addstr(&real_pattern, pattern);
 486
 487         if (!has_glob_specials(pattern)) {
 488                 /* Append implied '/' '*' if not present. */
 489                 strbuf_complete(&real_pattern, '/');
 490                 /* No need to check for '*', there is none. */
 491                 strbuf_addch(&real_pattern, '*');
 492         }
 493
 494         filter.pattern = real_pattern.buf;
 495         filter.prefix = prefix;
 496         filter.fn = fn;
 497         filter.cb_data = cb_data;
 498         ret = for_each_ref(filter_refs, &filter);
 499
 500         strbuf_release(&real_pattern);
 501         return ret;
 502 }
 503
 504 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 505 {
 506         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
 507 }
 508
 509 const char *prettify_refname(const char *name)
 510 {
 511         if (skip_prefix(name, "refs/heads/", &name) ||
 512             skip_prefix(name, "refs/tags/", &name) ||
 513             skip_prefix(name, "refs/remotes/", &name))
 514                 ; /* nothing */
 515         return name;
 516 }
 517
 518 static const char *ref_rev_parse_rules[] = {
 519         "%.*s",
 520         "refs/%.*s",
 521         "refs/tags/%.*s",
 522         "refs/heads/%.*s",
 523         "refs/remotes/%.*s",
 524         "refs/remotes/%.*s/HEAD",
 525         NULL
 526 };
 527
 528 #define NUM_REV_PARSE_RULES (ARRAY_SIZE(ref_rev_parse_rules) - 1)
 529
 530 /*
 531  * Is it possible that the caller meant full_name with abbrev_name?
 532  * If so return a non-zero value to signal "yes"; the magnitude of
 533  * the returned value gives the precedence used for disambiguation.
 534  *
 535  * If abbrev_name cannot mean full_name, return 0.
 536  */
 537 int refname_match(const char *abbrev_name, const char *full_name)
 538 {
 539         const char **p;
 540         const int abbrev_name_len = strlen(abbrev_name);
 541         const int num_rules = NUM_REV_PARSE_RULES;
 542
 543         for (p = ref_rev_parse_rules; *p; p++)
 544                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name)))
 545                         return &ref_rev_parse_rules[num_rules] - p;
 546
 547         return 0;
 548 }
 549
 550 /*
 551  * Given a 'prefix' expand it by the rules in 'ref_rev_parse_rules' and add
 552  * the results to 'prefixes'
 553  */
 554 void expand_ref_prefix(struct argv_array *prefixes, const char *prefix)
 555 {
 556         const char **p;
 557         int len = strlen(prefix);
 558
 559         for (p = ref_rev_parse_rules; *p; p++)
 560                 argv_array_pushf(prefixes, *p, len, prefix);
 561 }
 562
 563 /*
 564  * *string and *len will only be substituted, and *string returned (for
 565  * later free()ing) if the string passed in is a magic short-hand form
 566  * to name a branch.
 567  */
 568 static char *substitute_branch_name(struct repository *r,
 569                                     const char **string, int *len)
 570 {
 571         struct strbuf buf = STRBUF_INIT;
 572         int ret = repo_interpret_branch_name(r, *string, *len, &buf, 0);
 573
 574         if (ret == *len) {
 575                 size_t size;
 576                 *string = strbuf_detach(&buf, &size);
 577                 *len = size;
 578                 return (char *)*string;
 579         }
 580
 581         return NULL;
 582 }
 583
 584 int repo_dwim_ref(struct repository *r, const char *str, int len,
 585                   struct object_id *oid, char **ref)
 586 {
 587         char *last_branch = substitute_branch_name(r, &str, &len);
 588         int   refs_found  = expand_ref(r, str, len, oid, ref);
 589         free(last_branch);
 590         return refs_found;
 591 }
 592
 593 int dwim_ref(const char *str, int len, struct object_id *oid, char **ref)
 594 {
 595         return repo_dwim_ref(the_repository, str, len, oid, ref);
 596 }
 597
 598 int expand_ref(struct repository *repo, const char *str, int len,
 599                struct object_id *oid, char **ref)
 600 {
 601         const char **p, *r;
 602         int refs_found = 0;
 603         struct strbuf fullref = STRBUF_INIT;
 604
 605         *ref = NULL;
 606         for (p = ref_rev_parse_rules; *p; p++) {
 607                 struct object_id oid_from_ref;
 608                 struct object_id *this_result;
 609                 int flag;
 610
 611                 this_result = refs_found ? &oid_from_ref : oid;
 612                 strbuf_reset(&fullref);
 613                 strbuf_addf(&fullref, *p, len, str);
 614                 r = refs_resolve_ref_unsafe(get_main_ref_store(repo),
 615                                             fullref.buf, RESOLVE_REF_READING,
 616                                             this_result, &flag);
 617                 if (r) {
 618                         if (!refs_found++)
 619                                 *ref = xstrdup(r);
 620                         if (!warn_ambiguous_refs)
 621                                 break;
 622                 } else if ((flag & REF_ISSYMREF) && strcmp(fullref.buf, "HEAD")) {
 623                         warning(_("ignoring dangling symref %s"), fullref.buf);
 624                 } else if ((flag & REF_ISBROKEN) && strchr(fullref.buf, '/')) {
 625                         warning(_("ignoring broken ref %s"), fullref.buf);
 626                 }
 627         }
 628         strbuf_release(&fullref);
 629         return refs_found;
 630 }
 631
 632 int repo_dwim_log(struct repository *r, const char *str, int len,
 633                   struct object_id *oid, char **log)
 634 {
 635         struct ref_store *refs = get_main_ref_store(r);
 636         char *last_branch = substitute_branch_name(r, &str, &len);
 637         const char **p;
 638         int logs_found = 0;
 639         struct strbuf path = STRBUF_INIT;
 640
 641         *log = NULL;
 642         for (p = ref_rev_parse_rules; *p; p++) {
 643                 struct object_id hash;
 644                 const char *ref, *it;
 645
 646                 strbuf_reset(&path);
 647                 strbuf_addf(&path, *p, len, str);
 648                 ref = refs_resolve_ref_unsafe(refs, path.buf,
 649                                               RESOLVE_REF_READING,
 650                                               &hash, NULL);
 651                 if (!ref)
 652                         continue;
 653                 if (refs_reflog_exists(refs, path.buf))
 654                         it = path.buf;
 655                 else if (strcmp(ref, path.buf) &&
 656                          refs_reflog_exists(refs, ref))
 657                         it = ref;
 658                 else
 659                         continue;
 660                 if (!logs_found++) {
 661                         *log = xstrdup(it);
 662                         oidcpy(oid, &hash);
 663                 }
 664                 if (!warn_ambiguous_refs)
 665                         break;
 666         }
 667         strbuf_release(&path);
 668         free(last_branch);
 669         return logs_found;
 670 }
 671
 672 int dwim_log(const char *str, int len, struct object_id *oid, char **log)
 673 {
 674         return repo_dwim_log(the_repository, str, len, oid, log);
 675 }
 676
 677 static int is_per_worktree_ref(const char *refname)
 678 {
 679         return !strcmp(refname, "HEAD") ||
 680                 starts_with(refname, "refs/worktree/") ||
 681                 starts_with(refname, "refs/bisect/") ||
 682                 starts_with(refname, "refs/rewritten/");
 683 }
 684
 685 static int is_pseudoref_syntax(const char *refname)
 686 {
 687         const char *c;
 688
 689         for (c = refname; *c; c++) {
 690                 if (!isupper(*c) && *c != '-' && *c != '_')
 691                         return 0;
 692         }
 693
 694         return 1;
 695 }
 696
 697 static int is_main_pseudoref_syntax(const char *refname)
 698 {
 699         return skip_prefix(refname, "main-worktree/", &refname) &&
 700                 *refname &&
 701                 is_pseudoref_syntax(refname);
 702 }
 703
 704 static int is_other_pseudoref_syntax(const char *refname)
 705 {
 706         if (!skip_prefix(refname, "worktrees/", &refname))
 707                 return 0;
 708         refname = strchr(refname, '/');
 709         if (!refname || !refname[1])
 710                 return 0;
 711         return is_pseudoref_syntax(refname + 1);
 712 }
 713
 714 enum ref_type ref_type(const char *refname)
 715 {
 716         if (is_per_worktree_ref(refname))
 717                 return REF_TYPE_PER_WORKTREE;
 718         if (is_pseudoref_syntax(refname))
 719                 return REF_TYPE_PSEUDOREF;
 720         if (is_main_pseudoref_syntax(refname))
 721                 return REF_TYPE_MAIN_PSEUDOREF;
 722         if (is_other_pseudoref_syntax(refname))
 723                 return REF_TYPE_OTHER_PSEUDOREF;
 724         return REF_TYPE_NORMAL;
 725 }
 726
 727 long get_files_ref_lock_timeout_ms(void)
 728 {
 729         static int configured = 0;
 730
 731         /* The default timeout is 100 ms: */
 732         static int timeout_ms = 100;
 733
 734         if (!configured) {
 735                 git_config_get_int("core.filesreflocktimeout", &timeout_ms);
 736                 configured = 1;
 737         }
 738
 739         return timeout_ms;
 740 }
 741
 742 static int write_pseudoref(const char *pseudoref, const struct object_id *oid,
 743                            const struct object_id *old_oid, struct strbuf *err)
 744 {
 745         const char *filename;
 746         int fd;
 747         struct lock_file lock = LOCK_INIT;
 748         struct strbuf buf = STRBUF_INIT;
 749         int ret = -1;
 750
 751         if (!oid)
 752                 return 0;
 753
 754         strbuf_addf(&buf, "%s\n", oid_to_hex(oid));
 755
 756         filename = git_path("%s", pseudoref);
 757         fd = hold_lock_file_for_update_timeout(&lock, filename, 0,
 758                                                get_files_ref_lock_timeout_ms());
 759         if (fd < 0) {
 760                 strbuf_addf(err, _("could not open '%s' for writing: %s"),
 761                             filename, strerror(errno));
 762                 goto done;
 763         }
 764
 765         if (old_oid) {
 766                 struct object_id actual_old_oid;
 767
 768                 if (read_ref(pseudoref, &actual_old_oid)) {
 769                         if (!is_null_oid(old_oid)) {
 770                                 strbuf_addf(err, _("could not read ref '%s'"),
 771                                             pseudoref);
 772                                 rollback_lock_file(&lock);
 773                                 goto done;
 774                         }
 775                 } else if (is_null_oid(old_oid)) {
 776                         strbuf_addf(err, _("ref '%s' already exists"),
 777                                     pseudoref);
 778                         rollback_lock_file(&lock);
 779                         goto done;
 780                 } else if (!oideq(&actual_old_oid, old_oid)) {
 781                         strbuf_addf(err, _("unexpected object ID when writing '%s'"),
 782                                     pseudoref);
 783                         rollback_lock_file(&lock);
 784                         goto done;
 785                 }
 786         }
 787
 788         if (write_in_full(fd, buf.buf, buf.len) < 0) {
 789                 strbuf_addf(err, _("could not write to '%s'"), filename);
 790                 rollback_lock_file(&lock);
 791                 goto done;
 792         }
 793
 794         commit_lock_file(&lock);
 795         ret = 0;
 796 done:
 797         strbuf_release(&buf);
 798         return ret;
 799 }
 800
 801 static int delete_pseudoref(const char *pseudoref, const struct object_id *old_oid)
 802 {
 803         const char *filename;
 804
 805         filename = git_path("%s", pseudoref);
 806
 807         if (old_oid && !is_null_oid(old_oid)) {
 808                 struct lock_file lock = LOCK_INIT;
 809                 int fd;
 810                 struct object_id actual_old_oid;
 811
 812                 fd = hold_lock_file_for_update_timeout(
 813                                 &lock, filename, 0,
 814                                 get_files_ref_lock_timeout_ms());
 815                 if (fd < 0) {
 816                         error_errno(_("could not open '%s' for writing"),
 817                                     filename);
 818                         return -1;
 819                 }
 820                 if (read_ref(pseudoref, &actual_old_oid))
 821                         die(_("could not read ref '%s'"), pseudoref);
 822                 if (!oideq(&actual_old_oid, old_oid)) {
 823                         error(_("unexpected object ID when deleting '%s'"),
 824                               pseudoref);
 825                         rollback_lock_file(&lock);
 826                         return -1;
 827                 }
 828
 829                 unlink(filename);
 830                 rollback_lock_file(&lock);
 831         } else {
 832                 unlink(filename);
 833         }
 834
 835         return 0;
 836 }
 837
 838 int refs_delete_ref(struct ref_store *refs, const char *msg,
 839                     const char *refname,
 840                     const struct object_id *old_oid,
 841                     unsigned int flags)
 842 {
 843         struct ref_transaction *transaction;
 844         struct strbuf err = STRBUF_INIT;
 845
 846         if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
 847                 assert(refs == get_main_ref_store(the_repository));
 848                 return delete_pseudoref(refname, old_oid);
 849         }
 850
 851         transaction = ref_store_transaction_begin(refs, &err);
 852         if (!transaction ||
 853             ref_transaction_delete(transaction, refname, old_oid,
 854                                    flags, msg, &err) ||
 855             ref_transaction_commit(transaction, &err)) {
 856                 error("%s", err.buf);
 857                 ref_transaction_free(transaction);
 858                 strbuf_release(&err);
 859                 return 1;
 860         }
 861         ref_transaction_free(transaction);
 862         strbuf_release(&err);
 863         return 0;
 864 }
 865
 866 int delete_ref(const char *msg, const char *refname,
 867                const struct object_id *old_oid, unsigned int flags)
 868 {
 869         return refs_delete_ref(get_main_ref_store(the_repository), msg, refname,
 870                                old_oid, flags);
 871 }
 872
 873 void copy_reflog_msg(struct strbuf *sb, const char *msg)
 874 {
 875         char c;
 876         int wasspace = 1;
 877
 878         strbuf_addch(sb, '\t');
 879         while ((c = *msg++)) {
 880                 if (wasspace && isspace(c))
 881                         continue;
 882                 wasspace = isspace(c);
 883                 if (wasspace)
 884                         c = ' ';
 885                 strbuf_addch(sb, c);
 886         }
 887         strbuf_rtrim(sb);
 888 }
 889
 890 int should_autocreate_reflog(const char *refname)
 891 {
 892         switch (log_all_ref_updates) {
 893         case LOG_REFS_ALWAYS:
 894                 return 1;
 895         case LOG_REFS_NORMAL:
 896                 return starts_with(refname, "refs/heads/") ||
 897                         starts_with(refname, "refs/remotes/") ||
 898                         starts_with(refname, "refs/notes/") ||
 899                         !strcmp(refname, "HEAD");
 900         default:
 901                 return 0;
 902         }
 903 }
 904
 905 int is_branch(const char *refname)
 906 {
 907         return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
 908 }
 909
 910 struct read_ref_at_cb {
 911         const char *refname;
 912         timestamp_t at_time;
 913         int cnt;
 914         int reccnt;
 915         struct object_id *oid;
 916         int found_it;
 917
 918         struct object_id ooid;
 919         struct object_id noid;
 920         int tz;
 921         timestamp_t date;
 922         char **msg;
 923         timestamp_t *cutoff_time;
 924         int *cutoff_tz;
 925         int *cutoff_cnt;
 926 };
 927
 928 static int read_ref_at_ent(struct object_id *ooid, struct object_id *noid,
 929                 const char *email, timestamp_t timestamp, int tz,
 930                 const char *message, void *cb_data)
 931 {
 932         struct read_ref_at_cb *cb = cb_data;
 933
 934         cb->reccnt++;
 935         cb->tz = tz;
 936         cb->date = timestamp;
 937
 938         if (timestamp <= cb->at_time || cb->cnt == 0) {
 939                 if (cb->msg)
 940                         *cb->msg = xstrdup(message);
 941                 if (cb->cutoff_time)
 942                         *cb->cutoff_time = timestamp;
 943                 if (cb->cutoff_tz)
 944                         *cb->cutoff_tz = tz;
 945                 if (cb->cutoff_cnt)
 946                         *cb->cutoff_cnt = cb->reccnt - 1;
 947                 /*
 948                  * we have not yet updated cb->[n|o]oid so they still
 949                  * hold the values for the previous record.
 950                  */
 951                 if (!is_null_oid(&cb->ooid)) {
 952                         oidcpy(cb->oid, noid);
 953                         if (!oideq(&cb->ooid, noid))
 954                                 warning(_("log for ref %s has gap after %s"),
 955                                         cb->refname, show_date(cb->date, cb->tz, DATE_MODE(RFC2822)));
 956                 }
 957                 else if (cb->date == cb->at_time)
 958                         oidcpy(cb->oid, noid);
 959                 else if (!oideq(noid, cb->oid))
 960                         warning(_("log for ref %s unexpectedly ended on %s"),
 961                                 cb->refname, show_date(cb->date, cb->tz,
 962                                                        DATE_MODE(RFC2822)));
 963                 oidcpy(&cb->ooid, ooid);
 964                 oidcpy(&cb->noid, noid);
 965                 cb->found_it = 1;
 966                 return 1;
 967         }
 968         oidcpy(&cb->ooid, ooid);
 969         oidcpy(&cb->noid, noid);
 970         if (cb->cnt > 0)
 971                 cb->cnt--;
 972         return 0;
 973 }
 974
 975 static int read_ref_at_ent_oldest(struct object_id *ooid, struct object_id *noid,
 976                                   const char *email, timestamp_t timestamp,
 977                                   int tz, const char *message, void *cb_data)
 978 {
 979         struct read_ref_at_cb *cb = cb_data;
 980
 981         if (cb->msg)
 982                 *cb->msg = xstrdup(message);
 983         if (cb->cutoff_time)
 984                 *cb->cutoff_time = timestamp;
 985         if (cb->cutoff_tz)
 986                 *cb->cutoff_tz = tz;
 987         if (cb->cutoff_cnt)
 988                 *cb->cutoff_cnt = cb->reccnt;
 989         oidcpy(cb->oid, ooid);
 990         if (is_null_oid(cb->oid))
 991                 oidcpy(cb->oid, noid);
 992         /* We just want the first entry */
 993         return 1;
 994 }
 995
 996 int read_ref_at(struct ref_store *refs, const char *refname,
 997                 unsigned int flags, timestamp_t at_time, int cnt,
 998                 struct object_id *oid, char **msg,
 999                 timestamp_t *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
1000 {
1001         struct read_ref_at_cb cb;
1002
1003         memset(&cb, 0, sizeof(cb));
1004         cb.refname = refname;
1005         cb.at_time = at_time;
1006         cb.cnt = cnt;
1007         cb.msg = msg;
1008         cb.cutoff_time = cutoff_time;
1009         cb.cutoff_tz = cutoff_tz;
1010         cb.cutoff_cnt = cutoff_cnt;
1011         cb.oid = oid;
1012
1013         refs_for_each_reflog_ent_reverse(refs, refname, read_ref_at_ent, &cb);
1014
1015         if (!cb.reccnt) {
1016                 if (flags & GET_OID_QUIETLY)
1017                         exit(128);
1018                 else
1019                         die(_("log for %s is empty"), refname);
1020         }
1021         if (cb.found_it)
1022                 return 0;
1023
1024         refs_for_each_reflog_ent(refs, refname, read_ref_at_ent_oldest, &cb);
1025
1026         return 1;
1027 }
1028
1029 struct ref_transaction *ref_store_transaction_begin(struct ref_store *refs,
1030                                                     struct strbuf *err)
1031 {
1032         struct ref_transaction *tr;
1033         assert(err);
1034
1035         tr = xcalloc(1, sizeof(struct ref_transaction));
1036         tr->ref_store = refs;
1037         return tr;
1038 }
1039
1040 struct ref_transaction *ref_transaction_begin(struct strbuf *err)
1041 {
1042         return ref_store_transaction_begin(get_main_ref_store(the_repository), err);
1043 }
1044
1045 void ref_transaction_free(struct ref_transaction *transaction)
1046 {
1047         size_t i;
1048
1049         if (!transaction)
1050                 return;
1051
1052         switch (transaction->state) {
1053         case REF_TRANSACTION_OPEN:
1054         case REF_TRANSACTION_CLOSED:
1055                 /* OK */
1056                 break;
1057         case REF_TRANSACTION_PREPARED:
1058                 BUG("free called on a prepared reference transaction");
1059                 break;
1060         default:
1061                 BUG("unexpected reference transaction state");
1062                 break;
1063         }
1064
1065         for (i = 0; i < transaction->nr; i++) {
1066                 free(transaction->updates[i]->msg);
1067                 free(transaction->updates[i]);
1068         }
1069         free(transaction->updates);
1070         free(transaction);
1071 }
1072
1073 struct ref_update *ref_transaction_add_update(
1074                 struct ref_transaction *transaction,
1075                 const char *refname, unsigned int flags,
1076                 const struct object_id *new_oid,
1077                 const struct object_id *old_oid,
1078                 const char *msg)
1079 {
1080         struct ref_update *update;
1081
1082         if (transaction->state != REF_TRANSACTION_OPEN)
1083                 BUG("update called for transaction that is not open");
1084
1085         FLEX_ALLOC_STR(update, refname, refname);
1086         ALLOC_GROW(transaction->updates, transaction->nr + 1, transaction->alloc);
1087         transaction->updates[transaction->nr++] = update;
1088
1089         update->flags = flags;
1090
1091         if (flags & REF_HAVE_NEW)
1092                 oidcpy(&update->new_oid, new_oid);
1093         if (flags & REF_HAVE_OLD)
1094                 oidcpy(&update->old_oid, old_oid);
1095         update->msg = xstrdup_or_null(msg);
1096         return update;
1097 }
1098
1099 int ref_transaction_update(struct ref_transaction *transaction,
1100                            const char *refname,
1101                            const struct object_id *new_oid,
1102                            const struct object_id *old_oid,
1103                            unsigned int flags, const char *msg,
1104                            struct strbuf *err)
1105 {
1106         assert(err);
1107
1108         if ((new_oid && !is_null_oid(new_oid)) ?
1109             check_refname_format(refname, REFNAME_ALLOW_ONELEVEL) :
1110             !refname_is_safe(refname)) {
1111                 strbuf_addf(err, _("refusing to update ref with bad name '%s'"),
1112                             refname);
1113                 return -1;
1114         }
1115
1116         if (flags & ~REF_TRANSACTION_UPDATE_ALLOWED_FLAGS)
1117                 BUG("illegal flags 0x%x passed to ref_transaction_update()", flags);
1118
1119         flags |= (new_oid ? REF_HAVE_NEW : 0) | (old_oid ? REF_HAVE_OLD : 0);
1120
1121         ref_transaction_add_update(transaction, refname, flags,
1122                                    new_oid, old_oid, msg);
1123         return 0;
1124 }
1125
1126 int ref_transaction_create(struct ref_transaction *transaction,
1127                            const char *refname,
1128                            const struct object_id *new_oid,
1129                            unsigned int flags, const char *msg,
1130                            struct strbuf *err)
1131 {
1132         if (!new_oid || is_null_oid(new_oid))
1133                 BUG("create called without valid new_oid");
1134         return ref_transaction_update(transaction, refname, new_oid,
1135                                       &null_oid, flags, msg, err);
1136 }
1137
1138 int ref_transaction_delete(struct ref_transaction *transaction,
1139                            const char *refname,
1140                            const struct object_id *old_oid,
1141                            unsigned int flags, const char *msg,
1142                            struct strbuf *err)
1143 {
1144         if (old_oid && is_null_oid(old_oid))
1145                 BUG("delete called with old_oid set to zeros");
1146         return ref_transaction_update(transaction, refname,
1147                                       &null_oid, old_oid,
1148                                       flags, msg, err);
1149 }
1150
1151 int ref_transaction_verify(struct ref_transaction *transaction,
1152                            const char *refname,
1153                            const struct object_id *old_oid,
1154                            unsigned int flags,
1155                            struct strbuf *err)
1156 {
1157         if (!old_oid)
1158                 BUG("verify called with old_oid set to NULL");
1159         return ref_transaction_update(transaction, refname,
1160                                       NULL, old_oid,
1161                                       flags, NULL, err);
1162 }
1163
1164 int refs_update_ref(struct ref_store *refs, const char *msg,
1165                     const char *refname, const struct object_id *new_oid,
1166                     const struct object_id *old_oid, unsigned int flags,
1167                     enum action_on_err onerr)
1168 {
1169         struct ref_transaction *t = NULL;
1170         struct strbuf err = STRBUF_INIT;
1171         int ret = 0;
1172
1173         if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
1174                 assert(refs == get_main_ref_store(the_repository));
1175                 ret = write_pseudoref(refname, new_oid, old_oid, &err);
1176         } else {
1177                 t = ref_store_transaction_begin(refs, &err);
1178                 if (!t ||
1179                     ref_transaction_update(t, refname, new_oid, old_oid,
1180                                            flags, msg, &err) ||
1181                     ref_transaction_commit(t, &err)) {
1182                         ret = 1;
1183                         ref_transaction_free(t);
1184                 }
1185         }
1186         if (ret) {
1187                 const char *str = _("update_ref failed for ref '%s': %s");
1188
1189                 switch (onerr) {
1190                 case UPDATE_REFS_MSG_ON_ERR:
1191                         error(str, refname, err.buf);
1192                         break;
1193                 case UPDATE_REFS_DIE_ON_ERR:
1194                         die(str, refname, err.buf);
1195                         break;
1196                 case UPDATE_REFS_QUIET_ON_ERR:
1197                         break;
1198                 }
1199                 strbuf_release(&err);
1200                 return 1;
1201         }
1202         strbuf_release(&err);
1203         if (t)
1204                 ref_transaction_free(t);
1205         return 0;
1206 }
1207
1208 int update_ref(const char *msg, const char *refname,
1209                const struct object_id *new_oid,
1210                const struct object_id *old_oid,
1211                unsigned int flags, enum action_on_err onerr)
1212 {
1213         return refs_update_ref(get_main_ref_store(the_repository), msg, refname, new_oid,
1214                                old_oid, flags, onerr);
1215 }
1216
1217 char *refs_shorten_unambiguous_ref(struct ref_store *refs,
1218                                    const char *refname, int strict)
1219 {
1220         int i;
1221         static char **scanf_fmts;
1222         static int nr_rules;
1223         char *short_name;
1224         struct strbuf resolved_buf = STRBUF_INIT;
1225
1226         if (!nr_rules) {
1227                 /*
1228                  * Pre-generate scanf formats from ref_rev_parse_rules[].
1229                  * Generate a format suitable for scanf from a
1230                  * ref_rev_parse_rules rule by interpolating "%s" at the
1231                  * location of the "%.*s".
1232                  */
1233                 size_t total_len = 0;
1234                 size_t offset = 0;
1235
1236                 /* the rule list is NULL terminated, count them first */
1237                 for (nr_rules = 0; ref_rev_parse_rules[nr_rules]; nr_rules++)
1238                         /* -2 for strlen("%.*s") - strlen("%s"); +1 for NUL */
1239                         total_len += strlen(ref_rev_parse_rules[nr_rules]) - 2 + 1;
1240
1241                 scanf_fmts = xmalloc(st_add(st_mult(sizeof(char *), nr_rules), total_len));
1242
1243                 offset = 0;
1244                 for (i = 0; i < nr_rules; i++) {
1245                         assert(offset < total_len);
1246                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules] + offset;
1247                         offset += xsnprintf(scanf_fmts[i], total_len - offset,
1248                                             ref_rev_parse_rules[i], 2, "%s") + 1;
1249                 }
1250         }
1251
1252         /* bail out if there are no rules */
1253         if (!nr_rules)
1254                 return xstrdup(refname);
1255
1256         /* buffer for scanf result, at most refname must fit */
1257         short_name = xstrdup(refname);
1258
1259         /* skip first rule, it will always match */
1260         for (i = nr_rules - 1; i > 0 ; --i) {
1261                 int j;
1262                 int rules_to_fail = i;
1263                 int short_name_len;
1264
1265                 if (1 != sscanf(refname, scanf_fmts[i], short_name))
1266                         continue;
1267
1268                 short_name_len = strlen(short_name);
1269
1270                 /*
1271                  * in strict mode, all (except the matched one) rules
1272                  * must fail to resolve to a valid non-ambiguous ref
1273                  */
1274                 if (strict)
1275                         rules_to_fail = nr_rules;
1276
1277                 /*
1278                  * check if the short name resolves to a valid ref,
1279                  * but use only rules prior to the matched one
1280                  */
1281                 for (j = 0; j < rules_to_fail; j++) {
1282                         const char *rule = ref_rev_parse_rules[j];
1283
1284                         /* skip matched rule */
1285                         if (i == j)
1286                                 continue;
1287
1288                         /*
1289                          * the short name is ambiguous, if it resolves
1290                          * (with this previous rule) to a valid ref
1291                          * read_ref() returns 0 on success
1292                          */
1293                         strbuf_reset(&resolved_buf);
1294                         strbuf_addf(&resolved_buf, rule,
1295                                     short_name_len, short_name);
1296                         if (refs_ref_exists(refs, resolved_buf.buf))
1297                                 break;
1298                 }
1299
1300                 /*
1301                  * short name is non-ambiguous if all previous rules
1302                  * haven't resolved to a valid ref
1303                  */
1304                 if (j == rules_to_fail) {
1305                         strbuf_release(&resolved_buf);
1306                         return short_name;
1307                 }
1308         }
1309
1310         strbuf_release(&resolved_buf);
1311         free(short_name);
1312         return xstrdup(refname);
1313 }
1314
1315 char *shorten_unambiguous_ref(const char *refname, int strict)
1316 {
1317         return refs_shorten_unambiguous_ref(get_main_ref_store(the_repository),
1318                                             refname, strict);
1319 }
1320
1321 static struct string_list *hide_refs;
1322
1323 int parse_hide_refs_config(const char *var, const char *value, const char *section)
1324 {
1325         const char *key;
1326         if (!strcmp("transfer.hiderefs", var) ||
1327             (!parse_config_key(var, section, NULL, NULL, &key) &&
1328              !strcmp(key, "hiderefs"))) {
1329                 char *ref;
1330                 int len;
1331
1332                 if (!value)
1333                         return config_error_nonbool(var);
1334                 ref = xstrdup(value);
1335                 len = strlen(ref);
1336                 while (len && ref[len - 1] == '/')
1337                         ref[--len] = '\0';
1338                 if (!hide_refs) {
1339                         hide_refs = xcalloc(1, sizeof(*hide_refs));
1340                         hide_refs->strdup_strings = 1;
1341                 }
1342                 string_list_append(hide_refs, ref);
1343         }
1344         return 0;
1345 }
1346
1347 int ref_is_hidden(const char *refname, const char *refname_full)
1348 {
1349         int i;
1350
1351         if (!hide_refs)
1352                 return 0;
1353         for (i = hide_refs->nr - 1; i >= 0; i--) {
1354                 const char *match = hide_refs->items[i].string;
1355                 const char *subject;
1356                 int neg = 0;
1357                 const char *p;
1358
1359                 if (*match == '!') {
1360                         neg = 1;
1361                         match++;
1362                 }
1363
1364                 if (*match == '^') {
1365                         subject = refname_full;
1366                         match++;
1367                 } else {
1368                         subject = refname;
1369                 }
1370
1371                 /* refname can be NULL when namespaces are used. */
1372                 if (subject &&
1373                     skip_prefix(subject, match, &p) &&
1374                     (!*p || *p == '/'))
1375                         return !neg;
1376         }
1377         return 0;
1378 }
1379
1380 const char *find_descendant_ref(const char *dirname,
1381                                 const struct string_list *extras,
1382                                 const struct string_list *skip)
1383 {
1384         int pos;
1385
1386         if (!extras)
1387                 return NULL;
1388
1389         /*
1390          * Look at the place where dirname would be inserted into
1391          * extras. If there is an entry at that position that starts
1392          * with dirname (remember, dirname includes the trailing
1393          * slash) and is not in skip, then we have a conflict.
1394          */
1395         for (pos = string_list_find_insert_index(extras, dirname, 0);
1396              pos < extras->nr; pos++) {
1397                 const char *extra_refname = extras->items[pos].string;
1398
1399                 if (!starts_with(extra_refname, dirname))
1400                         break;
1401
1402                 if (!skip || !string_list_has_string(skip, extra_refname))
1403                         return extra_refname;
1404         }
1405         return NULL;
1406 }
1407
1408 int refs_rename_ref_available(struct ref_store *refs,
1409                               const char *old_refname,
1410                               const char *new_refname)
1411 {
1412         struct string_list skip = STRING_LIST_INIT_NODUP;
1413         struct strbuf err = STRBUF_INIT;
1414         int ok;
1415
1416         string_list_insert(&skip, old_refname);
1417         ok = !refs_verify_refname_available(refs, new_refname,
1418                                             NULL, &skip, &err);
1419         if (!ok)
1420                 error("%s", err.buf);
1421
1422         string_list_clear(&skip, 0);
1423         strbuf_release(&err);
1424         return ok;
1425 }
1426
1427 int refs_head_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1428 {
1429         struct object_id oid;
1430         int flag;
1431
1432         if (!refs_read_ref_full(refs, "HEAD", RESOLVE_REF_READING,
1433                                 &oid, &flag))
1434                 return fn("HEAD", &oid, flag, cb_data);
1435
1436         return 0;
1437 }
1438
1439 int head_ref(each_ref_fn fn, void *cb_data)
1440 {
1441         return refs_head_ref(get_main_ref_store(the_repository), fn, cb_data);
1442 }
1443
1444 struct ref_iterator *refs_ref_iterator_begin(
1445                 struct ref_store *refs,
1446                 const char *prefix, int trim, int flags)
1447 {
1448         struct ref_iterator *iter;
1449
1450         if (ref_paranoia < 0)
1451                 ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
1452         if (ref_paranoia)
1453                 flags |= DO_FOR_EACH_INCLUDE_BROKEN;
1454
1455         iter = refs->be->iterator_begin(refs, prefix, flags);
1456
1457         /*
1458          * `iterator_begin()` already takes care of prefix, but we
1459          * might need to do some trimming:
1460          */
1461         if (trim)
1462                 iter = prefix_ref_iterator_begin(iter, "", trim);
1463
1464         /* Sanity check for subclasses: */
1465         if (!iter->ordered)
1466                 BUG("reference iterator is not ordered");
1467
1468         return iter;
1469 }
1470
1471 /*
1472  * Call fn for each reference in the specified submodule for which the
1473  * refname begins with prefix. If trim is non-zero, then trim that
1474  * many characters off the beginning of each refname before passing
1475  * the refname to fn. flags can be DO_FOR_EACH_INCLUDE_BROKEN to
1476  * include broken references in the iteration. If fn ever returns a
1477  * non-zero value, stop the iteration and return that value;
1478  * otherwise, return 0.
1479  */
1480 static int do_for_each_repo_ref(struct repository *r, const char *prefix,
1481                                 each_repo_ref_fn fn, int trim, int flags,
1482                                 void *cb_data)
1483 {
1484         struct ref_iterator *iter;
1485         struct ref_store *refs = get_main_ref_store(r);
1486
1487         if (!refs)
1488                 return 0;
1489
1490         iter = refs_ref_iterator_begin(refs, prefix, trim, flags);
1491
1492         return do_for_each_repo_ref_iterator(r, iter, fn, cb_data);
1493 }
1494
1495 struct do_for_each_ref_help {
1496         each_ref_fn *fn;
1497         void *cb_data;
1498 };
1499
1500 static int do_for_each_ref_helper(struct repository *r,
1501                                   const char *refname,
1502                                   const struct object_id *oid,
1503                                   int flags,
1504                                   void *cb_data)
1505 {
1506         struct do_for_each_ref_help *hp = cb_data;
1507
1508         return hp->fn(refname, oid, flags, hp->cb_data);
1509 }
1510
1511 static int do_for_each_ref(struct ref_store *refs, const char *prefix,
1512                            each_ref_fn fn, int trim, int flags, void *cb_data)
1513 {
1514         struct ref_iterator *iter;
1515         struct do_for_each_ref_help hp = { fn, cb_data };
1516
1517         if (!refs)
1518                 return 0;
1519
1520         iter = refs_ref_iterator_begin(refs, prefix, trim, flags);
1521
1522         return do_for_each_repo_ref_iterator(the_repository, iter,
1523                                         do_for_each_ref_helper, &hp);
1524 }
1525
1526 int refs_for_each_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1527 {
1528         return do_for_each_ref(refs, "", fn, 0, 0, cb_data);
1529 }
1530
1531 int for_each_ref(each_ref_fn fn, void *cb_data)
1532 {
1533         return refs_for_each_ref(get_main_ref_store(the_repository), fn, cb_data);
1534 }
1535
1536 int refs_for_each_ref_in(struct ref_store *refs, const char *prefix,
1537                          each_ref_fn fn, void *cb_data)
1538 {
1539         return do_for_each_ref(refs, prefix, fn, strlen(prefix), 0, cb_data);
1540 }
1541
1542 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
1543 {
1544         return refs_for_each_ref_in(get_main_ref_store(the_repository), prefix, fn, cb_data);
1545 }
1546
1547 int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data, unsigned int broken)
1548 {
1549         unsigned int flag = 0;
1550
1551         if (broken)
1552                 flag = DO_FOR_EACH_INCLUDE_BROKEN;
1553         return do_for_each_ref(get_main_ref_store(the_repository),
1554                                prefix, fn, 0, flag, cb_data);
1555 }
1556
1557 int refs_for_each_fullref_in(struct ref_store *refs, const char *prefix,
1558                              each_ref_fn fn, void *cb_data,
1559                              unsigned int broken)
1560 {
1561         unsigned int flag = 0;
1562
1563         if (broken)
1564                 flag = DO_FOR_EACH_INCLUDE_BROKEN;
1565         return do_for_each_ref(refs, prefix, fn, 0, flag, cb_data);
1566 }
1567
1568 int for_each_replace_ref(struct repository *r, each_repo_ref_fn fn, void *cb_data)
1569 {
1570         return do_for_each_repo_ref(r, git_replace_ref_base, fn,
1571                                     strlen(git_replace_ref_base),
1572                                     DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1573 }
1574
1575 int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
1576 {
1577         struct strbuf buf = STRBUF_INIT;
1578         int ret;
1579         strbuf_addf(&buf, "%srefs/", get_git_namespace());
1580         ret = do_for_each_ref(get_main_ref_store(the_repository),
1581                               buf.buf, fn, 0, 0, cb_data);
1582         strbuf_release(&buf);
1583         return ret;
1584 }
1585
1586 int refs_for_each_rawref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1587 {
1588         return do_for_each_ref(refs, "", fn, 0,
1589                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1590 }
1591
1592 int for_each_rawref(each_ref_fn fn, void *cb_data)
1593 {
1594         return refs_for_each_rawref(get_main_ref_store(the_repository), fn, cb_data);
1595 }
1596
1597 int refs_read_raw_ref(struct ref_store *ref_store,
1598                       const char *refname, struct object_id *oid,
1599                       struct strbuf *referent, unsigned int *type)
1600 {
1601         return ref_store->be->read_raw_ref(ref_store, refname, oid, referent, type);
1602 }
1603
1604 /* This function needs to return a meaningful errno on failure */
1605 const char *refs_resolve_ref_unsafe(struct ref_store *refs,
1606                                     const char *refname,
1607                                     int resolve_flags,
1608                                     struct object_id *oid, int *flags)
1609 {
1610         static struct strbuf sb_refname = STRBUF_INIT;
1611         struct object_id unused_oid;
1612         int unused_flags;
1613         int symref_count;
1614
1615         if (!oid)
1616                 oid = &unused_oid;
1617         if (!flags)
1618                 flags = &unused_flags;
1619
1620         *flags = 0;
1621
1622         if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1623                 if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1624                     !refname_is_safe(refname)) {
1625                         errno = EINVAL;
1626                         return NULL;
1627                 }
1628
1629                 /*
1630                  * dwim_ref() uses REF_ISBROKEN to distinguish between
1631                  * missing refs and refs that were present but invalid,
1632                  * to complain about the latter to stderr.
1633                  *
1634                  * We don't know whether the ref exists, so don't set
1635                  * REF_ISBROKEN yet.
1636                  */
1637                 *flags |= REF_BAD_NAME;
1638         }
1639
1640         for (symref_count = 0; symref_count < SYMREF_MAXDEPTH; symref_count++) {
1641                 unsigned int read_flags = 0;
1642
1643                 if (refs_read_raw_ref(refs, refname,
1644                                       oid, &sb_refname, &read_flags)) {
1645                         *flags |= read_flags;
1646
1647                         /* In reading mode, refs must eventually resolve */
1648                         if (resolve_flags & RESOLVE_REF_READING)
1649                                 return NULL;
1650
1651                         /*
1652                          * Otherwise a missing ref is OK. But the files backend
1653                          * may show errors besides ENOENT if there are
1654                          * similarly-named refs.
1655                          */
1656                         if (errno != ENOENT &&
1657                             errno != EISDIR &&
1658                             errno != ENOTDIR)
1659                                 return NULL;
1660
1661                         oidclr(oid);
1662                         if (*flags & REF_BAD_NAME)
1663                                 *flags |= REF_ISBROKEN;
1664                         return refname;
1665                 }
1666
1667                 *flags |= read_flags;
1668
1669                 if (!(read_flags & REF_ISSYMREF)) {
1670                         if (*flags & REF_BAD_NAME) {
1671                                 oidclr(oid);
1672                                 *flags |= REF_ISBROKEN;
1673                         }
1674                         return refname;
1675                 }
1676
1677                 refname = sb_refname.buf;
1678                 if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
1679                         oidclr(oid);
1680                         return refname;
1681                 }
1682                 if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1683                         if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1684                             !refname_is_safe(refname)) {
1685                                 errno = EINVAL;
1686                                 return NULL;
1687                         }
1688
1689                         *flags |= REF_ISBROKEN | REF_BAD_NAME;
1690                 }
1691         }
1692
1693         errno = ELOOP;
1694         return NULL;
1695 }
1696
1697 /* backend functions */
1698 int refs_init_db(struct strbuf *err)
1699 {
1700         struct ref_store *refs = get_main_ref_store(the_repository);
1701
1702         return refs->be->init_db(refs, err);
1703 }
1704
1705 const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
1706                                struct object_id *oid, int *flags)
1707 {
1708         return refs_resolve_ref_unsafe(get_main_ref_store(the_repository), refname,
1709                                        resolve_flags, oid, flags);
1710 }
1711
1712 int resolve_gitlink_ref(const char *submodule, const char *refname,
1713                         struct object_id *oid)
1714 {
1715         struct ref_store *refs;
1716         int flags;
1717
1718         refs = get_submodule_ref_store(submodule);
1719
1720         if (!refs)
1721                 return -1;
1722
1723         if (!refs_resolve_ref_unsafe(refs, refname, 0, oid, &flags) ||
1724             is_null_oid(oid))
1725                 return -1;
1726         return 0;
1727 }
1728
1729 struct ref_store_hash_entry
1730 {
1731         struct hashmap_entry ent;
1732
1733         struct ref_store *refs;
1734
1735         /* NUL-terminated identifier of the ref store: */
1736         char name[FLEX_ARRAY];
1737 };
1738
1739 static int ref_store_hash_cmp(const void *unused_cmp_data,
1740                               const struct hashmap_entry *eptr,
1741                               const struct hashmap_entry *entry_or_key,
1742                               const void *keydata)
1743 {
1744         const struct ref_store_hash_entry *e1, *e2;
1745         const char *name;
1746
1747         e1 = container_of(eptr, const struct ref_store_hash_entry, ent);
1748         e2 = container_of(entry_or_key, const struct ref_store_hash_entry, ent);
1749         name = keydata ? keydata : e2->name;
1750
1751         return strcmp(e1->name, name);
1752 }
1753
1754 static struct ref_store_hash_entry *alloc_ref_store_hash_entry(
1755                 const char *name, struct ref_store *refs)
1756 {
1757         struct ref_store_hash_entry *entry;
1758
1759         FLEX_ALLOC_STR(entry, name, name);
1760         hashmap_entry_init(&entry->ent, strhash(name));
1761         entry->refs = refs;
1762         return entry;
1763 }
1764
1765 /* A hashmap of ref_stores, stored by submodule name: */
1766 static struct hashmap submodule_ref_stores;
1767
1768 /* A hashmap of ref_stores, stored by worktree id: */
1769 static struct hashmap worktree_ref_stores;
1770
1771 /*
1772  * Look up a ref store by name. If that ref_store hasn't been
1773  * registered yet, return NULL.
1774  */
1775 static struct ref_store *lookup_ref_store_map(struct hashmap *map,
1776                                               const char *name)
1777 {
1778         struct ref_store_hash_entry *entry;
1779         unsigned int hash;
1780
1781         if (!map->tablesize)
1782                 /* It's initialized on demand in register_ref_store(). */
1783                 return NULL;
1784
1785         hash = strhash(name);
1786         entry = hashmap_get_entry_from_hash(map, hash, name,
1787                                         struct ref_store_hash_entry, ent);
1788         return entry ? entry->refs : NULL;
1789 }
1790
1791 /*
1792  * Create, record, and return a ref_store instance for the specified
1793  * gitdir.
1794  */
1795 static struct ref_store *ref_store_init(const char *gitdir,
1796                                         unsigned int flags)
1797 {
1798         const char *be_name = "files";
1799         struct ref_storage_be *be = find_ref_storage_backend(be_name);
1800         struct ref_store *refs;
1801
1802         if (!be)
1803                 BUG("reference backend %s is unknown", be_name);
1804
1805         refs = be->init(gitdir, flags);
1806         return refs;
1807 }
1808
1809 struct ref_store *get_main_ref_store(struct repository *r)
1810 {
1811         if (r->refs_private)
1812                 return r->refs_private;
1813
1814         if (!r->gitdir)
1815                 BUG("attempting to get main_ref_store outside of repository");
1816
1817         r->refs_private = ref_store_init(r->gitdir, REF_STORE_ALL_CAPS);
1818         return r->refs_private;
1819 }
1820
1821 /*
1822  * Associate a ref store with a name. It is a fatal error to call this
1823  * function twice for the same name.
1824  */
1825 static void register_ref_store_map(struct hashmap *map,
1826                                    const char *type,
1827                                    struct ref_store *refs,
1828                                    const char *name)
1829 {
1830         struct ref_store_hash_entry *entry;
1831
1832         if (!map->tablesize)
1833                 hashmap_init(map, ref_store_hash_cmp, NULL, 0);
1834
1835         entry = alloc_ref_store_hash_entry(name, refs);
1836         if (hashmap_put(map, &entry->ent))
1837                 BUG("%s ref_store '%s' initialized twice", type, name);
1838 }
1839
1840 struct ref_store *get_submodule_ref_store(const char *submodule)
1841 {
1842         struct strbuf submodule_sb = STRBUF_INIT;
1843         struct ref_store *refs;
1844         char *to_free = NULL;
1845         size_t len;
1846
1847         if (!submodule)
1848                 return NULL;
1849
1850         len = strlen(submodule);
1851         while (len && is_dir_sep(submodule[len - 1]))
1852                 len--;
1853         if (!len)
1854                 return NULL;
1855
1856         if (submodule[len])
1857                 /* We need to strip off one or more trailing slashes */
1858                 submodule = to_free = xmemdupz(submodule, len);
1859
1860         refs = lookup_ref_store_map(&submodule_ref_stores, submodule);
1861         if (refs)
1862                 goto done;
1863
1864         strbuf_addstr(&submodule_sb, submodule);
1865         if (!is_nonbare_repository_dir(&submodule_sb))
1866                 goto done;
1867
1868         if (submodule_to_gitdir(&submodule_sb, submodule))
1869                 goto done;
1870
1871         /* assume that add_submodule_odb() has been called */
1872         refs = ref_store_init(submodule_sb.buf,
1873                               REF_STORE_READ | REF_STORE_ODB);
1874         register_ref_store_map(&submodule_ref_stores, "submodule",
1875                                refs, submodule);
1876
1877 done:
1878         strbuf_release(&submodule_sb);
1879         free(to_free);
1880
1881         return refs;
1882 }
1883
1884 struct ref_store *get_worktree_ref_store(const struct worktree *wt)
1885 {
1886         struct ref_store *refs;
1887         const char *id;
1888
1889         if (wt->is_current)
1890                 return get_main_ref_store(the_repository);
1891
1892         id = wt->id ? wt->id : "/";
1893         refs = lookup_ref_store_map(&worktree_ref_stores, id);
1894         if (refs)
1895                 return refs;
1896
1897         if (wt->id)
1898                 refs = ref_store_init(git_common_path("worktrees/%s", wt->id),
1899                                       REF_STORE_ALL_CAPS);
1900         else
1901                 refs = ref_store_init(get_git_common_dir(),
1902                                       REF_STORE_ALL_CAPS);
1903
1904         if (refs)
1905                 register_ref_store_map(&worktree_ref_stores, "worktree",
1906                                        refs, id);
1907         return refs;
1908 }
1909
1910 void base_ref_store_init(struct ref_store *refs,
1911                          const struct ref_storage_be *be)
1912 {
1913         refs->be = be;
1914 }
1915
1916 /* backend functions */
1917 int refs_pack_refs(struct ref_store *refs, unsigned int flags)
1918 {
1919         return refs->be->pack_refs(refs, flags);
1920 }
1921
1922 int refs_peel_ref(struct ref_store *refs, const char *refname,
1923                   struct object_id *oid)
1924 {
1925         int flag;
1926         struct object_id base;
1927
1928         if (current_ref_iter && current_ref_iter->refname == refname) {
1929                 struct object_id peeled;
1930
1931                 if (ref_iterator_peel(current_ref_iter, &peeled))
1932                         return -1;
1933                 oidcpy(oid, &peeled);
1934                 return 0;
1935         }
1936
1937         if (refs_read_ref_full(refs, refname,
1938                                RESOLVE_REF_READING, &base, &flag))
1939                 return -1;
1940
1941         return peel_object(&base, oid);
1942 }
1943
1944 int peel_ref(const char *refname, struct object_id *oid)
1945 {
1946         return refs_peel_ref(get_main_ref_store(the_repository), refname, oid);
1947 }
1948
1949 int refs_create_symref(struct ref_store *refs,
1950                        const char *ref_target,
1951                        const char *refs_heads_master,
1952                        const char *logmsg)
1953 {
1954         return refs->be->create_symref(refs, ref_target,
1955                                        refs_heads_master,
1956                                        logmsg);
1957 }
1958
1959 int create_symref(const char *ref_target, const char *refs_heads_master,
1960                   const char *logmsg)
1961 {
1962         return refs_create_symref(get_main_ref_store(the_repository), ref_target,
1963                                   refs_heads_master, logmsg);
1964 }
1965
1966 int ref_update_reject_duplicates(struct string_list *refnames,
1967                                  struct strbuf *err)
1968 {
1969         size_t i, n = refnames->nr;
1970
1971         assert(err);
1972
1973         for (i = 1; i < n; i++) {
1974                 int cmp = strcmp(refnames->items[i - 1].string,
1975                                  refnames->items[i].string);
1976
1977                 if (!cmp) {
1978                         strbuf_addf(err,
1979                                     _("multiple updates for ref '%s' not allowed"),
1980                                     refnames->items[i].string);
1981                         return 1;
1982                 } else if (cmp > 0) {
1983                         BUG("ref_update_reject_duplicates() received unsorted list");
1984                 }
1985         }
1986         return 0;
1987 }
1988
1989 int ref_transaction_prepare(struct ref_transaction *transaction,
1990                             struct strbuf *err)
1991 {
1992         struct ref_store *refs = transaction->ref_store;
1993
1994         switch (transaction->state) {
1995         case REF_TRANSACTION_OPEN:
1996                 /* Good. */
1997                 break;
1998         case REF_TRANSACTION_PREPARED:
1999                 BUG("prepare called twice on reference transaction");
2000                 break;
2001         case REF_TRANSACTION_CLOSED:
2002                 BUG("prepare called on a closed reference transaction");
2003                 break;
2004         default:
2005                 BUG("unexpected reference transaction state");
2006                 break;
2007         }
2008
2009         if (getenv(GIT_QUARANTINE_ENVIRONMENT)) {
2010                 strbuf_addstr(err,
2011                               _("ref updates forbidden inside quarantine environment"));
2012                 return -1;
2013         }
2014
2015         return refs->be->transaction_prepare(refs, transaction, err);
2016 }
2017
2018 int ref_transaction_abort(struct ref_transaction *transaction,
2019                           struct strbuf *err)
2020 {
2021         struct ref_store *refs = transaction->ref_store;
2022         int ret = 0;
2023
2024         switch (transaction->state) {
2025         case REF_TRANSACTION_OPEN:
2026                 /* No need to abort explicitly. */
2027                 break;
2028         case REF_TRANSACTION_PREPARED:
2029                 ret = refs->be->transaction_abort(refs, transaction, err);
2030                 break;
2031         case REF_TRANSACTION_CLOSED:
2032                 BUG("abort called on a closed reference transaction");
2033                 break;
2034         default:
2035                 BUG("unexpected reference transaction state");
2036                 break;
2037         }
2038
2039         ref_transaction_free(transaction);
2040         return ret;
2041 }
2042
2043 int ref_transaction_commit(struct ref_transaction *transaction,
2044                            struct strbuf *err)
2045 {
2046         struct ref_store *refs = transaction->ref_store;
2047         int ret;
2048
2049         switch (transaction->state) {
2050         case REF_TRANSACTION_OPEN:
2051                 /* Need to prepare first. */
2052                 ret = ref_transaction_prepare(transaction, err);
2053                 if (ret)
2054                         return ret;
2055                 break;
2056         case REF_TRANSACTION_PREPARED:
2057                 /* Fall through to finish. */
2058                 break;
2059         case REF_TRANSACTION_CLOSED:
2060                 BUG("commit called on a closed reference transaction");
2061                 break;
2062         default:
2063                 BUG("unexpected reference transaction state");
2064                 break;
2065         }
2066
2067         return refs->be->transaction_finish(refs, transaction, err);
2068 }
2069
2070 int refs_verify_refname_available(struct ref_store *refs,
2071                                   const char *refname,
2072                                   const struct string_list *extras,
2073                                   const struct string_list *skip,
2074                                   struct strbuf *err)
2075 {
2076         const char *slash;
2077         const char *extra_refname;
2078         struct strbuf dirname = STRBUF_INIT;
2079         struct strbuf referent = STRBUF_INIT;
2080         struct object_id oid;
2081         unsigned int type;
2082         struct ref_iterator *iter;
2083         int ok;
2084         int ret = -1;
2085
2086         /*
2087          * For the sake of comments in this function, suppose that
2088          * refname is "refs/foo/bar".
2089          */
2090
2091         assert(err);
2092
2093         strbuf_grow(&dirname, strlen(refname) + 1);
2094         for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
2095                 /* Expand dirname to the new prefix, not including the trailing slash: */
2096                 strbuf_add(&dirname, refname + dirname.len, slash - refname - dirname.len);
2097
2098                 /*
2099                  * We are still at a leading dir of the refname (e.g.,
2100                  * "refs/foo"; if there is a reference with that name,
2101                  * it is a conflict, *unless* it is in skip.
2102                  */
2103                 if (skip && string_list_has_string(skip, dirname.buf))
2104                         continue;
2105
2106                 if (!refs_read_raw_ref(refs, dirname.buf, &oid, &referent, &type)) {
2107                         strbuf_addf(err, _("'%s' exists; cannot create '%s'"),
2108                                     dirname.buf, refname);
2109                         goto cleanup;
2110                 }
2111
2112                 if (extras && string_list_has_string(extras, dirname.buf)) {
2113                         strbuf_addf(err, _("cannot process '%s' and '%s' at the same time"),
2114                                     refname, dirname.buf);
2115                         goto cleanup;
2116                 }
2117         }
2118
2119         /*
2120          * We are at the leaf of our refname (e.g., "refs/foo/bar").
2121          * There is no point in searching for a reference with that
2122          * name, because a refname isn't considered to conflict with
2123          * itself. But we still need to check for references whose
2124          * names are in the "refs/foo/bar/" namespace, because they
2125          * *do* conflict.
2126          */
2127         strbuf_addstr(&dirname, refname + dirname.len);
2128         strbuf_addch(&dirname, '/');
2129
2130         iter = refs_ref_iterator_begin(refs, dirname.buf, 0,
2131                                        DO_FOR_EACH_INCLUDE_BROKEN);
2132         while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
2133                 if (skip &&
2134                     string_list_has_string(skip, iter->refname))
2135                         continue;
2136
2137                 strbuf_addf(err, _("'%s' exists; cannot create '%s'"),
2138                             iter->refname, refname);
2139                 ref_iterator_abort(iter);
2140                 goto cleanup;
2141         }
2142
2143         if (ok != ITER_DONE)
2144                 BUG("error while iterating over references");
2145
2146         extra_refname = find_descendant_ref(dirname.buf, extras, skip);
2147         if (extra_refname)
2148                 strbuf_addf(err, _("cannot process '%s' and '%s' at the same time"),
2149                             refname, extra_refname);
2150         else
2151                 ret = 0;
2152
2153 cleanup:
2154         strbuf_release(&referent);
2155         strbuf_release(&dirname);
2156         return ret;
2157 }
2158
2159 int refs_for_each_reflog(struct ref_store *refs, each_ref_fn fn, void *cb_data)
2160 {
2161         struct ref_iterator *iter;
2162         struct do_for_each_ref_help hp = { fn, cb_data };
2163
2164         iter = refs->be->reflog_iterator_begin(refs);
2165
2166         return do_for_each_repo_ref_iterator(the_repository, iter,
2167                                              do_for_each_ref_helper, &hp);
2168 }
2169
2170 int for_each_reflog(each_ref_fn fn, void *cb_data)
2171 {
2172         return refs_for_each_reflog(get_main_ref_store(the_repository), fn, cb_data);
2173 }
2174
2175 int refs_for_each_reflog_ent_reverse(struct ref_store *refs,
2176                                      const char *refname,
2177                                      each_reflog_ent_fn fn,
2178                                      void *cb_data)
2179 {
2180         return refs->be->for_each_reflog_ent_reverse(refs, refname,
2181                                                      fn, cb_data);
2182 }
2183
2184 int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn,
2185                                 void *cb_data)
2186 {
2187         return refs_for_each_reflog_ent_reverse(get_main_ref_store(the_repository),
2188                                                 refname, fn, cb_data);
2189 }
2190
2191 int refs_for_each_reflog_ent(struct ref_store *refs, const char *refname,
2192                              each_reflog_ent_fn fn, void *cb_data)
2193 {
2194         return refs->be->for_each_reflog_ent(refs, refname, fn, cb_data);
2195 }
2196
2197 int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn,
2198                         void *cb_data)
2199 {
2200         return refs_for_each_reflog_ent(get_main_ref_store(the_repository), refname,
2201                                         fn, cb_data);
2202 }
2203
2204 int refs_reflog_exists(struct ref_store *refs, const char *refname)
2205 {
2206         return refs->be->reflog_exists(refs, refname);
2207 }
2208
2209 int reflog_exists(const char *refname)
2210 {
2211         return refs_reflog_exists(get_main_ref_store(the_repository), refname);
2212 }
2213
2214 int refs_create_reflog(struct ref_store *refs, const char *refname,
2215                        int force_create, struct strbuf *err)
2216 {
2217         return refs->be->create_reflog(refs, refname, force_create, err);
2218 }
2219
2220 int safe_create_reflog(const char *refname, int force_create,
2221                        struct strbuf *err)
2222 {
2223         return refs_create_reflog(get_main_ref_store(the_repository), refname,
2224                                   force_create, err);
2225 }
2226
2227 int refs_delete_reflog(struct ref_store *refs, const char *refname)
2228 {
2229         return refs->be->delete_reflog(refs, refname);
2230 }
2231
2232 int delete_reflog(const char *refname)
2233 {
2234         return refs_delete_reflog(get_main_ref_store(the_repository), refname);
2235 }
2236
2237 int refs_reflog_expire(struct ref_store *refs,
2238                        const char *refname, const struct object_id *oid,
2239                        unsigned int flags,
2240                        reflog_expiry_prepare_fn prepare_fn,
2241                        reflog_expiry_should_prune_fn should_prune_fn,
2242                        reflog_expiry_cleanup_fn cleanup_fn,
2243                        void *policy_cb_data)
2244 {
2245         return refs->be->reflog_expire(refs, refname, oid, flags,
2246                                        prepare_fn, should_prune_fn,
2247                                        cleanup_fn, policy_cb_data);
2248 }
2249
2250 int reflog_expire(const char *refname, const struct object_id *oid,
2251                   unsigned int flags,
2252                   reflog_expiry_prepare_fn prepare_fn,
2253                   reflog_expiry_should_prune_fn should_prune_fn,
2254                   reflog_expiry_cleanup_fn cleanup_fn,
2255                   void *policy_cb_data)
2256 {
2257         return refs_reflog_expire(get_main_ref_store(the_repository),
2258                                   refname, oid, flags,
2259                                   prepare_fn, should_prune_fn,
2260                                   cleanup_fn, policy_cb_data);
2261 }
2262
2263 int initial_ref_transaction_commit(struct ref_transaction *transaction,
2264                                    struct strbuf *err)
2265 {
2266         struct ref_store *refs = transaction->ref_store;
2267
2268         return refs->be->initial_transaction_commit(refs, transaction, err);
2269 }
2270
2271 int refs_delete_refs(struct ref_store *refs, const char *msg,
2272                      struct string_list *refnames, unsigned int flags)
2273 {
2274         return refs->be->delete_refs(refs, msg, refnames, flags);
2275 }
2276
2277 int delete_refs(const char *msg, struct string_list *refnames,
2278                 unsigned int flags)
2279 {
2280         return refs_delete_refs(get_main_ref_store(the_repository), msg, refnames, flags);
2281 }
2282
2283 int refs_rename_ref(struct ref_store *refs, const char *oldref,
2284                     const char *newref, const char *logmsg)
2285 {
2286         return refs->be->rename_ref(refs, oldref, newref, logmsg);
2287 }
2288
2289 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
2290 {
2291         return refs_rename_ref(get_main_ref_store(the_repository), oldref, newref, logmsg);
2292 }
2293
2294 int refs_copy_existing_ref(struct ref_store *refs, const char *oldref,
2295                     const char *newref, const char *logmsg)
2296 {
2297         return refs->be->copy_ref(refs, oldref, newref, logmsg);
2298 }
2299
2300 int copy_existing_ref(const char *oldref, const char *newref, const char *logmsg)
2301 {
2302         return refs_copy_existing_ref(get_main_ref_store(the_repository), oldref, newref, logmsg);
2303 }