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 "hashmap.h"
   7 #include "lockfile.h"
   8 #include "refs.h"
   9 #include "refs/refs-internal.h"
  10 #include "object.h"
  11 #include "tag.h"
  12
  13 /*
  14  * List of all available backends
  15  */
  16 static struct ref_storage_be *refs_backends = &refs_be_files;
  17
  18 static struct ref_storage_be *find_ref_storage_backend(const char *name)
  19 {
  20         struct ref_storage_be *be;
  21         for (be = refs_backends; be; be = be->next)
  22                 if (!strcmp(be->name, name))
  23                         return be;
  24         return NULL;
  25 }
  26
  27 int ref_storage_backend_exists(const char *name)
  28 {
  29         return find_ref_storage_backend(name) != NULL;
  30 }
  31
  32 /*
  33  * How to handle various characters in refnames:
  34  * 0: An acceptable character for refs
  35  * 1: End-of-component
  36  * 2: ., look for a preceding . to reject .. in refs
  37  * 3: {, look for a preceding @ to reject @{ in refs
  38  * 4: A bad character: ASCII control characters, and
  39  *    ":", "?", "[", "\", "^", "~", SP, or TAB
  40  * 5: *, reject unless REFNAME_REFSPEC_PATTERN is set
  41  */
  42 static unsigned char refname_disposition[256] = {
  43         1, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
  44         4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
  45         4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 2, 1,
  46         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 4,
  47         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  48         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 0, 4, 0,
  49         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  50         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 4, 4
  51 };
  52
  53 /*
  54  * Try to read one refname component from the front of refname.
  55  * Return the length of the component found, or -1 if the component is
  56  * not legal.  It is legal if it is something reasonable to have under
  57  * ".git/refs/"; We do not like it if:
  58  *
  59  * - any path component of it begins with ".", or
  60  * - it has double dots "..", or
  61  * - it has ASCII control characters, or
  62  * - it has ":", "?", "[", "\", "^", "~", SP, or TAB anywhere, or
  63  * - it has "*" anywhere unless REFNAME_REFSPEC_PATTERN is set, or
  64  * - it ends with a "/", or
  65  * - it ends with ".lock", or
  66  * - it contains a "@{" portion
  67  */
  68 static int check_refname_component(const char *refname, int *flags)
  69 {
  70         const char *cp;
  71         char last = '\0';
  72
  73         for (cp = refname; ; cp++) {
  74                 int ch = *cp & 255;
  75                 unsigned char disp = refname_disposition[ch];
  76                 switch (disp) {
  77                 case 1:
  78                         goto out;
  79                 case 2:
  80                         if (last == '.')
  81                                 return -1; /* Refname contains "..". */
  82                         break;
  83                 case 3:
  84                         if (last == '@')
  85                                 return -1; /* Refname contains "@{". */
  86                         break;
  87                 case 4:
  88                         return -1;
  89                 case 5:
  90                         if (!(*flags & REFNAME_REFSPEC_PATTERN))
  91                                 return -1; /* refspec can't be a pattern */
  92
  93                         /*
  94                          * Unset the pattern flag so that we only accept
  95                          * a single asterisk for one side of refspec.
  96                          */
  97                         *flags &= ~ REFNAME_REFSPEC_PATTERN;
  98                         break;
  99                 }
 100                 last = ch;
 101         }
 102 out:
 103         if (cp == refname)
 104                 return 0; /* Component has zero length. */
 105         if (refname[0] == '.')
 106                 return -1; /* Component starts with '.'. */
 107         if (cp - refname >= LOCK_SUFFIX_LEN &&
 108             !memcmp(cp - LOCK_SUFFIX_LEN, LOCK_SUFFIX, LOCK_SUFFIX_LEN))
 109                 return -1; /* Refname ends with ".lock". */
 110         return cp - refname;
 111 }
 112
 113 int check_refname_format(const char *refname, int flags)
 114 {
 115         int component_len, component_count = 0;
 116
 117         if (!strcmp(refname, "@"))
 118                 /* Refname is a single character '@'. */
 119                 return -1;
 120
 121         while (1) {
 122                 /* We are at the start of a path component. */
 123                 component_len = check_refname_component(refname, &flags);
 124                 if (component_len <= 0)
 125                         return -1;
 126
 127                 component_count++;
 128                 if (refname[component_len] == '\0')
 129                         break;
 130                 /* Skip to next component. */
 131                 refname += component_len + 1;
 132         }
 133
 134         if (refname[component_len - 1] == '.')
 135                 return -1; /* Refname ends with '.'. */
 136         if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
 137                 return -1; /* Refname has only one component. */
 138         return 0;
 139 }
 140
 141 int refname_is_safe(const char *refname)
 142 {
 143         const char *rest;
 144
 145         if (skip_prefix(refname, "refs/", &rest)) {
 146                 char *buf;
 147                 int result;
 148                 size_t restlen = strlen(rest);
 149
 150                 /* rest must not be empty, or start or end with "/" */
 151                 if (!restlen || *rest == '/' || rest[restlen - 1] == '/')
 152                         return 0;
 153
 154                 /*
 155                  * Does the refname try to escape refs/?
 156                  * For example: refs/foo/../bar is safe but refs/foo/../../bar
 157                  * is not.
 158                  */
 159                 buf = xmallocz(restlen);
 160                 result = !normalize_path_copy(buf, rest) && !strcmp(buf, rest);
 161                 free(buf);
 162                 return result;
 163         }
 164
 165         do {
 166                 if (!isupper(*refname) && *refname != '_')
 167                         return 0;
 168                 refname++;
 169         } while (*refname);
 170         return 1;
 171 }
 172
 173 char *resolve_refdup(const char *refname, int resolve_flags,
 174                      unsigned char *sha1, int *flags)
 175 {
 176         return xstrdup_or_null(resolve_ref_unsafe(refname, resolve_flags,
 177                                                   sha1, flags));
 178 }
 179
 180 /* The argument to filter_refs */
 181 struct ref_filter {
 182         const char *pattern;
 183         each_ref_fn *fn;
 184         void *cb_data;
 185 };
 186
 187 int read_ref_full(const char *refname, int resolve_flags, unsigned char *sha1, int *flags)
 188 {
 189         if (resolve_ref_unsafe(refname, resolve_flags, sha1, flags))
 190                 return 0;
 191         return -1;
 192 }
 193
 194 int read_ref(const char *refname, unsigned char *sha1)
 195 {
 196         return read_ref_full(refname, RESOLVE_REF_READING, sha1, NULL);
 197 }
 198
 199 int ref_exists(const char *refname)
 200 {
 201         unsigned char sha1[20];
 202         return !!resolve_ref_unsafe(refname, RESOLVE_REF_READING, sha1, NULL);
 203 }
 204
 205 static int filter_refs(const char *refname, const struct object_id *oid,
 206                            int flags, void *data)
 207 {
 208         struct ref_filter *filter = (struct ref_filter *)data;
 209
 210         if (wildmatch(filter->pattern, refname, 0, NULL))
 211                 return 0;
 212         return filter->fn(refname, oid, flags, filter->cb_data);
 213 }
 214
 215 enum peel_status peel_object(const unsigned char *name, unsigned char *sha1)
 216 {
 217         struct object *o = lookup_unknown_object(name);
 218
 219         if (o->type == OBJ_NONE) {
 220                 int type = sha1_object_info(name, NULL);
 221                 if (type < 0 || !object_as_type(o, type, 0))
 222                         return PEEL_INVALID;
 223         }
 224
 225         if (o->type != OBJ_TAG)
 226                 return PEEL_NON_TAG;
 227
 228         o = deref_tag_noverify(o);
 229         if (!o)
 230                 return PEEL_INVALID;
 231
 232         hashcpy(sha1, o->oid.hash);
 233         return PEEL_PEELED;
 234 }
 235
 236 struct warn_if_dangling_data {
 237         FILE *fp;
 238         const char *refname;
 239         const struct string_list *refnames;
 240         const char *msg_fmt;
 241 };
 242
 243 static int warn_if_dangling_symref(const char *refname, const struct object_id *oid,
 244                                    int flags, void *cb_data)
 245 {
 246         struct warn_if_dangling_data *d = cb_data;
 247         const char *resolves_to;
 248         struct object_id junk;
 249
 250         if (!(flags & REF_ISSYMREF))
 251                 return 0;
 252
 253         resolves_to = resolve_ref_unsafe(refname, 0, junk.hash, NULL);
 254         if (!resolves_to
 255             || (d->refname
 256                 ? strcmp(resolves_to, d->refname)
 257                 : !string_list_has_string(d->refnames, resolves_to))) {
 258                 return 0;
 259         }
 260
 261         fprintf(d->fp, d->msg_fmt, refname);
 262         fputc('\n', d->fp);
 263         return 0;
 264 }
 265
 266 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 267 {
 268         struct warn_if_dangling_data data;
 269
 270         data.fp = fp;
 271         data.refname = refname;
 272         data.refnames = NULL;
 273         data.msg_fmt = msg_fmt;
 274         for_each_rawref(warn_if_dangling_symref, &data);
 275 }
 276
 277 void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames)
 278 {
 279         struct warn_if_dangling_data data;
 280
 281         data.fp = fp;
 282         data.refname = NULL;
 283         data.refnames = refnames;
 284         data.msg_fmt = msg_fmt;
 285         for_each_rawref(warn_if_dangling_symref, &data);
 286 }
 287
 288 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 289 {
 290         return for_each_ref_in("refs/tags/", fn, cb_data);
 291 }
 292
 293 int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 294 {
 295         return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
 296 }
 297
 298 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 299 {
 300         return for_each_ref_in("refs/heads/", fn, cb_data);
 301 }
 302
 303 int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 304 {
 305         return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
 306 }
 307
 308 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 309 {
 310         return for_each_ref_in("refs/remotes/", fn, cb_data);
 311 }
 312
 313 int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 314 {
 315         return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
 316 }
 317
 318 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
 319 {
 320         struct strbuf buf = STRBUF_INIT;
 321         int ret = 0;
 322         struct object_id oid;
 323         int flag;
 324
 325         strbuf_addf(&buf, "%sHEAD", get_git_namespace());
 326         if (!read_ref_full(buf.buf, RESOLVE_REF_READING, oid.hash, &flag))
 327                 ret = fn(buf.buf, &oid, flag, cb_data);
 328         strbuf_release(&buf);
 329
 330         return ret;
 331 }
 332
 333 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 334         const char *prefix, void *cb_data)
 335 {
 336         struct strbuf real_pattern = STRBUF_INIT;
 337         struct ref_filter filter;
 338         int ret;
 339
 340         if (!prefix && !starts_with(pattern, "refs/"))
 341                 strbuf_addstr(&real_pattern, "refs/");
 342         else if (prefix)
 343                 strbuf_addstr(&real_pattern, prefix);
 344         strbuf_addstr(&real_pattern, pattern);
 345
 346         if (!has_glob_specials(pattern)) {
 347                 /* Append implied '/' '*' if not present. */
 348                 strbuf_complete(&real_pattern, '/');
 349                 /* No need to check for '*', there is none. */
 350                 strbuf_addch(&real_pattern, '*');
 351         }
 352
 353         filter.pattern = real_pattern.buf;
 354         filter.fn = fn;
 355         filter.cb_data = cb_data;
 356         ret = for_each_ref(filter_refs, &filter);
 357
 358         strbuf_release(&real_pattern);
 359         return ret;
 360 }
 361
 362 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 363 {
 364         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
 365 }
 366
 367 const char *prettify_refname(const char *name)
 368 {
 369         return name + (
 370                 starts_with(name, "refs/heads/") ? 11 :
 371                 starts_with(name, "refs/tags/") ? 10 :
 372                 starts_with(name, "refs/remotes/") ? 13 :
 373                 0);
 374 }
 375
 376 static const char *ref_rev_parse_rules[] = {
 377         "%.*s",
 378         "refs/%.*s",
 379         "refs/tags/%.*s",
 380         "refs/heads/%.*s",
 381         "refs/remotes/%.*s",
 382         "refs/remotes/%.*s/HEAD",
 383         NULL
 384 };
 385
 386 int refname_match(const char *abbrev_name, const char *full_name)
 387 {
 388         const char **p;
 389         const int abbrev_name_len = strlen(abbrev_name);
 390
 391         for (p = ref_rev_parse_rules; *p; p++) {
 392                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
 393                         return 1;
 394                 }
 395         }
 396
 397         return 0;
 398 }
 399
 400 /*
 401  * *string and *len will only be substituted, and *string returned (for
 402  * later free()ing) if the string passed in is a magic short-hand form
 403  * to name a branch.
 404  */
 405 static char *substitute_branch_name(const char **string, int *len)
 406 {
 407         struct strbuf buf = STRBUF_INIT;
 408         int ret = interpret_branch_name(*string, *len, &buf);
 409
 410         if (ret == *len) {
 411                 size_t size;
 412                 *string = strbuf_detach(&buf, &size);
 413                 *len = size;
 414                 return (char *)*string;
 415         }
 416
 417         return NULL;
 418 }
 419
 420 int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
 421 {
 422         char *last_branch = substitute_branch_name(&str, &len);
 423         int   refs_found  = expand_ref(str, len, sha1, ref);
 424         free(last_branch);
 425         return refs_found;
 426 }
 427
 428 int expand_ref(const char *str, int len, unsigned char *sha1, char **ref)
 429 {
 430         const char **p, *r;
 431         int refs_found = 0;
 432
 433         *ref = NULL;
 434         for (p = ref_rev_parse_rules; *p; p++) {
 435                 char fullref[PATH_MAX];
 436                 unsigned char sha1_from_ref[20];
 437                 unsigned char *this_result;
 438                 int flag;
 439
 440                 this_result = refs_found ? sha1_from_ref : sha1;
 441                 mksnpath(fullref, sizeof(fullref), *p, len, str);
 442                 r = resolve_ref_unsafe(fullref, RESOLVE_REF_READING,
 443                                        this_result, &flag);
 444                 if (r) {
 445                         if (!refs_found++)
 446                                 *ref = xstrdup(r);
 447                         if (!warn_ambiguous_refs)
 448                                 break;
 449                 } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD")) {
 450                         warning("ignoring dangling symref %s.", fullref);
 451                 } else if ((flag & REF_ISBROKEN) && strchr(fullref, '/')) {
 452                         warning("ignoring broken ref %s.", fullref);
 453                 }
 454         }
 455         return refs_found;
 456 }
 457
 458 int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
 459 {
 460         char *last_branch = substitute_branch_name(&str, &len);
 461         const char **p;
 462         int logs_found = 0;
 463
 464         *log = NULL;
 465         for (p = ref_rev_parse_rules; *p; p++) {
 466                 unsigned char hash[20];
 467                 char path[PATH_MAX];
 468                 const char *ref, *it;
 469
 470                 mksnpath(path, sizeof(path), *p, len, str);
 471                 ref = resolve_ref_unsafe(path, RESOLVE_REF_READING,
 472                                          hash, NULL);
 473                 if (!ref)
 474                         continue;
 475                 if (reflog_exists(path))
 476                         it = path;
 477                 else if (strcmp(ref, path) && reflog_exists(ref))
 478                         it = ref;
 479                 else
 480                         continue;
 481                 if (!logs_found++) {
 482                         *log = xstrdup(it);
 483                         hashcpy(sha1, hash);
 484                 }
 485                 if (!warn_ambiguous_refs)
 486                         break;
 487         }
 488         free(last_branch);
 489         return logs_found;
 490 }
 491
 492 static int is_per_worktree_ref(const char *refname)
 493 {
 494         return !strcmp(refname, "HEAD") ||
 495                 starts_with(refname, "refs/bisect/");
 496 }
 497
 498 static int is_pseudoref_syntax(const char *refname)
 499 {
 500         const char *c;
 501
 502         for (c = refname; *c; c++) {
 503                 if (!isupper(*c) && *c != '-' && *c != '_')
 504                         return 0;
 505         }
 506
 507         return 1;
 508 }
 509
 510 enum ref_type ref_type(const char *refname)
 511 {
 512         if (is_per_worktree_ref(refname))
 513                 return REF_TYPE_PER_WORKTREE;
 514         if (is_pseudoref_syntax(refname))
 515                 return REF_TYPE_PSEUDOREF;
 516        return REF_TYPE_NORMAL;
 517 }
 518
 519 static int write_pseudoref(const char *pseudoref, const unsigned char *sha1,
 520                            const unsigned char *old_sha1, struct strbuf *err)
 521 {
 522         const char *filename;
 523         int fd;
 524         static struct lock_file lock;
 525         struct strbuf buf = STRBUF_INIT;
 526         int ret = -1;
 527
 528         strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
 529
 530         filename = git_path("%s", pseudoref);
 531         fd = hold_lock_file_for_update(&lock, filename, LOCK_DIE_ON_ERROR);
 532         if (fd < 0) {
 533                 strbuf_addf(err, "could not open '%s' for writing: %s",
 534                             filename, strerror(errno));
 535                 return -1;
 536         }
 537
 538         if (old_sha1) {
 539                 unsigned char actual_old_sha1[20];
 540
 541                 if (read_ref(pseudoref, actual_old_sha1))
 542                         die("could not read ref '%s'", pseudoref);
 543                 if (hashcmp(actual_old_sha1, old_sha1)) {
 544                         strbuf_addf(err, "unexpected sha1 when writing '%s'", pseudoref);
 545                         rollback_lock_file(&lock);
 546                         goto done;
 547                 }
 548         }
 549
 550         if (write_in_full(fd, buf.buf, buf.len) != buf.len) {
 551                 strbuf_addf(err, "could not write to '%s'", filename);
 552                 rollback_lock_file(&lock);
 553                 goto done;
 554         }
 555
 556         commit_lock_file(&lock);
 557         ret = 0;
 558 done:
 559         strbuf_release(&buf);
 560         return ret;
 561 }
 562
 563 static int delete_pseudoref(const char *pseudoref, const unsigned char *old_sha1)
 564 {
 565         static struct lock_file lock;
 566         const char *filename;
 567
 568         filename = git_path("%s", pseudoref);
 569
 570         if (old_sha1 && !is_null_sha1(old_sha1)) {
 571                 int fd;
 572                 unsigned char actual_old_sha1[20];
 573
 574                 fd = hold_lock_file_for_update(&lock, filename,
 575                                                LOCK_DIE_ON_ERROR);
 576                 if (fd < 0)
 577                         die_errno(_("Could not open '%s' for writing"), filename);
 578                 if (read_ref(pseudoref, actual_old_sha1))
 579                         die("could not read ref '%s'", pseudoref);
 580                 if (hashcmp(actual_old_sha1, old_sha1)) {
 581                         warning("Unexpected sha1 when deleting %s", pseudoref);
 582                         rollback_lock_file(&lock);
 583                         return -1;
 584                 }
 585
 586                 unlink(filename);
 587                 rollback_lock_file(&lock);
 588         } else {
 589                 unlink(filename);
 590         }
 591
 592         return 0;
 593 }
 594
 595 int delete_ref(const char *refname, const unsigned char *old_sha1,
 596                unsigned int flags)
 597 {
 598         struct ref_transaction *transaction;
 599         struct strbuf err = STRBUF_INIT;
 600
 601         if (ref_type(refname) == REF_TYPE_PSEUDOREF)
 602                 return delete_pseudoref(refname, old_sha1);
 603
 604         transaction = ref_transaction_begin(&err);
 605         if (!transaction ||
 606             ref_transaction_delete(transaction, refname, old_sha1,
 607                                    flags, NULL, &err) ||
 608             ref_transaction_commit(transaction, &err)) {
 609                 error("%s", err.buf);
 610                 ref_transaction_free(transaction);
 611                 strbuf_release(&err);
 612                 return 1;
 613         }
 614         ref_transaction_free(transaction);
 615         strbuf_release(&err);
 616         return 0;
 617 }
 618
 619 int copy_reflog_msg(char *buf, const char *msg)
 620 {
 621         char *cp = buf;
 622         char c;
 623         int wasspace = 1;
 624
 625         *cp++ = '\t';
 626         while ((c = *msg++)) {
 627                 if (wasspace && isspace(c))
 628                         continue;
 629                 wasspace = isspace(c);
 630                 if (wasspace)
 631                         c = ' ';
 632                 *cp++ = c;
 633         }
 634         while (buf < cp && isspace(cp[-1]))
 635                 cp--;
 636         *cp++ = '\n';
 637         return cp - buf;
 638 }
 639
 640 int should_autocreate_reflog(const char *refname)
 641 {
 642         if (!log_all_ref_updates)
 643                 return 0;
 644         return starts_with(refname, "refs/heads/") ||
 645                 starts_with(refname, "refs/remotes/") ||
 646                 starts_with(refname, "refs/notes/") ||
 647                 !strcmp(refname, "HEAD");
 648 }
 649
 650 int is_branch(const char *refname)
 651 {
 652         return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
 653 }
 654
 655 struct read_ref_at_cb {
 656         const char *refname;
 657         unsigned long at_time;
 658         int cnt;
 659         int reccnt;
 660         unsigned char *sha1;
 661         int found_it;
 662
 663         unsigned char osha1[20];
 664         unsigned char nsha1[20];
 665         int tz;
 666         unsigned long date;
 667         char **msg;
 668         unsigned long *cutoff_time;
 669         int *cutoff_tz;
 670         int *cutoff_cnt;
 671 };
 672
 673 static int read_ref_at_ent(unsigned char *osha1, unsigned char *nsha1,
 674                 const char *email, unsigned long timestamp, int tz,
 675                 const char *message, void *cb_data)
 676 {
 677         struct read_ref_at_cb *cb = cb_data;
 678
 679         cb->reccnt++;
 680         cb->tz = tz;
 681         cb->date = timestamp;
 682
 683         if (timestamp <= cb->at_time || cb->cnt == 0) {
 684                 if (cb->msg)
 685                         *cb->msg = xstrdup(message);
 686                 if (cb->cutoff_time)
 687                         *cb->cutoff_time = timestamp;
 688                 if (cb->cutoff_tz)
 689                         *cb->cutoff_tz = tz;
 690                 if (cb->cutoff_cnt)
 691                         *cb->cutoff_cnt = cb->reccnt - 1;
 692                 /*
 693                  * we have not yet updated cb->[n|o]sha1 so they still
 694                  * hold the values for the previous record.
 695                  */
 696                 if (!is_null_sha1(cb->osha1)) {
 697                         hashcpy(cb->sha1, nsha1);
 698                         if (hashcmp(cb->osha1, nsha1))
 699                                 warning("Log for ref %s has gap after %s.",
 700                                         cb->refname, show_date(cb->date, cb->tz, DATE_MODE(RFC2822)));
 701                 }
 702                 else if (cb->date == cb->at_time)
 703                         hashcpy(cb->sha1, nsha1);
 704                 else if (hashcmp(nsha1, cb->sha1))
 705                         warning("Log for ref %s unexpectedly ended on %s.",
 706                                 cb->refname, show_date(cb->date, cb->tz,
 707                                                        DATE_MODE(RFC2822)));
 708                 hashcpy(cb->osha1, osha1);
 709                 hashcpy(cb->nsha1, nsha1);
 710                 cb->found_it = 1;
 711                 return 1;
 712         }
 713         hashcpy(cb->osha1, osha1);
 714         hashcpy(cb->nsha1, nsha1);
 715         if (cb->cnt > 0)
 716                 cb->cnt--;
 717         return 0;
 718 }
 719
 720 static int read_ref_at_ent_oldest(unsigned char *osha1, unsigned char *nsha1,
 721                                   const char *email, unsigned long timestamp,
 722                                   int tz, const char *message, void *cb_data)
 723 {
 724         struct read_ref_at_cb *cb = cb_data;
 725
 726         if (cb->msg)
 727                 *cb->msg = xstrdup(message);
 728         if (cb->cutoff_time)
 729                 *cb->cutoff_time = timestamp;
 730         if (cb->cutoff_tz)
 731                 *cb->cutoff_tz = tz;
 732         if (cb->cutoff_cnt)
 733                 *cb->cutoff_cnt = cb->reccnt;
 734         hashcpy(cb->sha1, osha1);
 735         if (is_null_sha1(cb->sha1))
 736                 hashcpy(cb->sha1, nsha1);
 737         /* We just want the first entry */
 738         return 1;
 739 }
 740
 741 int read_ref_at(const char *refname, unsigned int flags, unsigned long at_time, int cnt,
 742                 unsigned char *sha1, char **msg,
 743                 unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
 744 {
 745         struct read_ref_at_cb cb;
 746
 747         memset(&cb, 0, sizeof(cb));
 748         cb.refname = refname;
 749         cb.at_time = at_time;
 750         cb.cnt = cnt;
 751         cb.msg = msg;
 752         cb.cutoff_time = cutoff_time;
 753         cb.cutoff_tz = cutoff_tz;
 754         cb.cutoff_cnt = cutoff_cnt;
 755         cb.sha1 = sha1;
 756
 757         for_each_reflog_ent_reverse(refname, read_ref_at_ent, &cb);
 758
 759         if (!cb.reccnt) {
 760                 if (flags & GET_SHA1_QUIETLY)
 761                         exit(128);
 762                 else
 763                         die("Log for %s is empty.", refname);
 764         }
 765         if (cb.found_it)
 766                 return 0;
 767
 768         for_each_reflog_ent(refname, read_ref_at_ent_oldest, &cb);
 769
 770         return 1;
 771 }
 772
 773 struct ref_transaction *ref_transaction_begin(struct strbuf *err)
 774 {
 775         assert(err);
 776
 777         return xcalloc(1, sizeof(struct ref_transaction));
 778 }
 779
 780 void ref_transaction_free(struct ref_transaction *transaction)
 781 {
 782         int i;
 783
 784         if (!transaction)
 785                 return;
 786
 787         for (i = 0; i < transaction->nr; i++) {
 788                 free(transaction->updates[i]->msg);
 789                 free(transaction->updates[i]);
 790         }
 791         free(transaction->updates);
 792         free(transaction);
 793 }
 794
 795 struct ref_update *ref_transaction_add_update(
 796                 struct ref_transaction *transaction,
 797                 const char *refname, unsigned int flags,
 798                 const unsigned char *new_sha1,
 799                 const unsigned char *old_sha1,
 800                 const char *msg)
 801 {
 802         struct ref_update *update;
 803
 804         if (transaction->state != REF_TRANSACTION_OPEN)
 805                 die("BUG: update called for transaction that is not open");
 806
 807         if ((flags & REF_ISPRUNING) && !(flags & REF_NODEREF))
 808                 die("BUG: REF_ISPRUNING set without REF_NODEREF");
 809
 810         FLEX_ALLOC_STR(update, refname, refname);
 811         ALLOC_GROW(transaction->updates, transaction->nr + 1, transaction->alloc);
 812         transaction->updates[transaction->nr++] = update;
 813
 814         update->flags = flags;
 815
 816         if (flags & REF_HAVE_NEW)
 817                 hashcpy(update->new_sha1, new_sha1);
 818         if (flags & REF_HAVE_OLD)
 819                 hashcpy(update->old_sha1, old_sha1);
 820         update->msg = xstrdup_or_null(msg);
 821         return update;
 822 }
 823
 824 int ref_transaction_update(struct ref_transaction *transaction,
 825                            const char *refname,
 826                            const unsigned char *new_sha1,
 827                            const unsigned char *old_sha1,
 828                            unsigned int flags, const char *msg,
 829                            struct strbuf *err)
 830 {
 831         assert(err);
 832
 833         if ((new_sha1 && !is_null_sha1(new_sha1)) ?
 834             check_refname_format(refname, REFNAME_ALLOW_ONELEVEL) :
 835             !refname_is_safe(refname)) {
 836                 strbuf_addf(err, "refusing to update ref with bad name '%s'",
 837                             refname);
 838                 return -1;
 839         }
 840
 841         flags |= (new_sha1 ? REF_HAVE_NEW : 0) | (old_sha1 ? REF_HAVE_OLD : 0);
 842
 843         ref_transaction_add_update(transaction, refname, flags,
 844                                    new_sha1, old_sha1, msg);
 845         return 0;
 846 }
 847
 848 int ref_transaction_create(struct ref_transaction *transaction,
 849                            const char *refname,
 850                            const unsigned char *new_sha1,
 851                            unsigned int flags, const char *msg,
 852                            struct strbuf *err)
 853 {
 854         if (!new_sha1 || is_null_sha1(new_sha1))
 855                 die("BUG: create called without valid new_sha1");
 856         return ref_transaction_update(transaction, refname, new_sha1,
 857                                       null_sha1, flags, msg, err);
 858 }
 859
 860 int ref_transaction_delete(struct ref_transaction *transaction,
 861                            const char *refname,
 862                            const unsigned char *old_sha1,
 863                            unsigned int flags, const char *msg,
 864                            struct strbuf *err)
 865 {
 866         if (old_sha1 && is_null_sha1(old_sha1))
 867                 die("BUG: delete called with old_sha1 set to zeros");
 868         return ref_transaction_update(transaction, refname,
 869                                       null_sha1, old_sha1,
 870                                       flags, msg, err);
 871 }
 872
 873 int ref_transaction_verify(struct ref_transaction *transaction,
 874                            const char *refname,
 875                            const unsigned char *old_sha1,
 876                            unsigned int flags,
 877                            struct strbuf *err)
 878 {
 879         if (!old_sha1)
 880                 die("BUG: verify called with old_sha1 set to NULL");
 881         return ref_transaction_update(transaction, refname,
 882                                       NULL, old_sha1,
 883                                       flags, NULL, err);
 884 }
 885
 886 int update_ref_oid(const char *msg, const char *refname,
 887                const struct object_id *new_oid, const struct object_id *old_oid,
 888                unsigned int flags, enum action_on_err onerr)
 889 {
 890         return update_ref(msg, refname, new_oid ? new_oid->hash : NULL,
 891                 old_oid ? old_oid->hash : NULL, flags, onerr);
 892 }
 893
 894 int update_ref(const char *msg, const char *refname,
 895                const unsigned char *new_sha1, const unsigned char *old_sha1,
 896                unsigned int flags, enum action_on_err onerr)
 897 {
 898         struct ref_transaction *t = NULL;
 899         struct strbuf err = STRBUF_INIT;
 900         int ret = 0;
 901
 902         if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
 903                 ret = write_pseudoref(refname, new_sha1, old_sha1, &err);
 904         } else {
 905                 t = ref_transaction_begin(&err);
 906                 if (!t ||
 907                     ref_transaction_update(t, refname, new_sha1, old_sha1,
 908                                            flags, msg, &err) ||
 909                     ref_transaction_commit(t, &err)) {
 910                         ret = 1;
 911                         ref_transaction_free(t);
 912                 }
 913         }
 914         if (ret) {
 915                 const char *str = "update_ref failed for ref '%s': %s";
 916
 917                 switch (onerr) {
 918                 case UPDATE_REFS_MSG_ON_ERR:
 919                         error(str, refname, err.buf);
 920                         break;
 921                 case UPDATE_REFS_DIE_ON_ERR:
 922                         die(str, refname, err.buf);
 923                         break;
 924                 case UPDATE_REFS_QUIET_ON_ERR:
 925                         break;
 926                 }
 927                 strbuf_release(&err);
 928                 return 1;
 929         }
 930         strbuf_release(&err);
 931         if (t)
 932                 ref_transaction_free(t);
 933         return 0;
 934 }
 935
 936 char *shorten_unambiguous_ref(const char *refname, int strict)
 937 {
 938         int i;
 939         static char **scanf_fmts;
 940         static int nr_rules;
 941         char *short_name;
 942
 943         if (!nr_rules) {
 944                 /*
 945                  * Pre-generate scanf formats from ref_rev_parse_rules[].
 946                  * Generate a format suitable for scanf from a
 947                  * ref_rev_parse_rules rule by interpolating "%s" at the
 948                  * location of the "%.*s".
 949                  */
 950                 size_t total_len = 0;
 951                 size_t offset = 0;
 952
 953                 /* the rule list is NULL terminated, count them first */
 954                 for (nr_rules = 0; ref_rev_parse_rules[nr_rules]; nr_rules++)
 955                         /* -2 for strlen("%.*s") - strlen("%s"); +1 for NUL */
 956                         total_len += strlen(ref_rev_parse_rules[nr_rules]) - 2 + 1;
 957
 958                 scanf_fmts = xmalloc(st_add(st_mult(sizeof(char *), nr_rules), total_len));
 959
 960                 offset = 0;
 961                 for (i = 0; i < nr_rules; i++) {
 962                         assert(offset < total_len);
 963                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules] + offset;
 964                         offset += snprintf(scanf_fmts[i], total_len - offset,
 965                                            ref_rev_parse_rules[i], 2, "%s") + 1;
 966                 }
 967         }
 968
 969         /* bail out if there are no rules */
 970         if (!nr_rules)
 971                 return xstrdup(refname);
 972
 973         /* buffer for scanf result, at most refname must fit */
 974         short_name = xstrdup(refname);
 975
 976         /* skip first rule, it will always match */
 977         for (i = nr_rules - 1; i > 0 ; --i) {
 978                 int j;
 979                 int rules_to_fail = i;
 980                 int short_name_len;
 981
 982                 if (1 != sscanf(refname, scanf_fmts[i], short_name))
 983                         continue;
 984
 985                 short_name_len = strlen(short_name);
 986
 987                 /*
 988                  * in strict mode, all (except the matched one) rules
 989                  * must fail to resolve to a valid non-ambiguous ref
 990                  */
 991                 if (strict)
 992                         rules_to_fail = nr_rules;
 993
 994                 /*
 995                  * check if the short name resolves to a valid ref,
 996                  * but use only rules prior to the matched one
 997                  */
 998                 for (j = 0; j < rules_to_fail; j++) {
 999                         const char *rule = ref_rev_parse_rules[j];
1000                         char refname[PATH_MAX];
1001
1002                         /* skip matched rule */
1003                         if (i == j)
1004                                 continue;
1005
1006                         /*
1007                          * the short name is ambiguous, if it resolves
1008                          * (with this previous rule) to a valid ref
1009                          * read_ref() returns 0 on success
1010                          */
1011                         mksnpath(refname, sizeof(refname),
1012                                  rule, short_name_len, short_name);
1013                         if (ref_exists(refname))
1014                                 break;
1015                 }
1016
1017                 /*
1018                  * short name is non-ambiguous if all previous rules
1019                  * haven't resolved to a valid ref
1020                  */
1021                 if (j == rules_to_fail)
1022                         return short_name;
1023         }
1024
1025         free(short_name);
1026         return xstrdup(refname);
1027 }
1028
1029 static struct string_list *hide_refs;
1030
1031 int parse_hide_refs_config(const char *var, const char *value, const char *section)
1032 {
1033         if (!strcmp("transfer.hiderefs", var) ||
1034             /* NEEDSWORK: use parse_config_key() once both are merged */
1035             (starts_with(var, section) && var[strlen(section)] == '.' &&
1036              !strcmp(var + strlen(section), ".hiderefs"))) {
1037                 char *ref;
1038                 int len;
1039
1040                 if (!value)
1041                         return config_error_nonbool(var);
1042                 ref = xstrdup(value);
1043                 len = strlen(ref);
1044                 while (len && ref[len - 1] == '/')
1045                         ref[--len] = '\0';
1046                 if (!hide_refs) {
1047                         hide_refs = xcalloc(1, sizeof(*hide_refs));
1048                         hide_refs->strdup_strings = 1;
1049                 }
1050                 string_list_append(hide_refs, ref);
1051         }
1052         return 0;
1053 }
1054
1055 int ref_is_hidden(const char *refname, const char *refname_full)
1056 {
1057         int i;
1058
1059         if (!hide_refs)
1060                 return 0;
1061         for (i = hide_refs->nr - 1; i >= 0; i--) {
1062                 const char *match = hide_refs->items[i].string;
1063                 const char *subject;
1064                 int neg = 0;
1065                 int len;
1066
1067                 if (*match == '!') {
1068                         neg = 1;
1069                         match++;
1070                 }
1071
1072                 if (*match == '^') {
1073                         subject = refname_full;
1074                         match++;
1075                 } else {
1076                         subject = refname;
1077                 }
1078
1079                 /* refname can be NULL when namespaces are used. */
1080                 if (!subject || !starts_with(subject, match))
1081                         continue;
1082                 len = strlen(match);
1083                 if (!subject[len] || subject[len] == '/')
1084                         return !neg;
1085         }
1086         return 0;
1087 }
1088
1089 const char *find_descendant_ref(const char *dirname,
1090                                 const struct string_list *extras,
1091                                 const struct string_list *skip)
1092 {
1093         int pos;
1094
1095         if (!extras)
1096                 return NULL;
1097
1098         /*
1099          * Look at the place where dirname would be inserted into
1100          * extras. If there is an entry at that position that starts
1101          * with dirname (remember, dirname includes the trailing
1102          * slash) and is not in skip, then we have a conflict.
1103          */
1104         for (pos = string_list_find_insert_index(extras, dirname, 0);
1105              pos < extras->nr; pos++) {
1106                 const char *extra_refname = extras->items[pos].string;
1107
1108                 if (!starts_with(extra_refname, dirname))
1109                         break;
1110
1111                 if (!skip || !string_list_has_string(skip, extra_refname))
1112                         return extra_refname;
1113         }
1114         return NULL;
1115 }
1116
1117 int rename_ref_available(const char *old_refname, const char *new_refname)
1118 {
1119         struct string_list skip = STRING_LIST_INIT_NODUP;
1120         struct strbuf err = STRBUF_INIT;
1121         int ok;
1122
1123         string_list_insert(&skip, old_refname);
1124         ok = !verify_refname_available(new_refname, NULL, &skip, &err);
1125         if (!ok)
1126                 error("%s", err.buf);
1127
1128         string_list_clear(&skip, 0);
1129         strbuf_release(&err);
1130         return ok;
1131 }
1132
1133 int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1134 {
1135         struct object_id oid;
1136         int flag;
1137
1138         if (submodule) {
1139                 if (resolve_gitlink_ref(submodule, "HEAD", oid.hash) == 0)
1140                         return fn("HEAD", &oid, 0, cb_data);
1141
1142                 return 0;
1143         }
1144
1145         if (!read_ref_full("HEAD", RESOLVE_REF_READING, oid.hash, &flag))
1146                 return fn("HEAD", &oid, flag, cb_data);
1147
1148         return 0;
1149 }
1150
1151 int head_ref(each_ref_fn fn, void *cb_data)
1152 {
1153         return head_ref_submodule(NULL, fn, cb_data);
1154 }
1155
1156 /*
1157  * Call fn for each reference in the specified submodule for which the
1158  * refname begins with prefix. If trim is non-zero, then trim that
1159  * many characters off the beginning of each refname before passing
1160  * the refname to fn. flags can be DO_FOR_EACH_INCLUDE_BROKEN to
1161  * include broken references in the iteration. If fn ever returns a
1162  * non-zero value, stop the iteration and return that value;
1163  * otherwise, return 0.
1164  */
1165 static int do_for_each_ref(const char *submodule, const char *prefix,
1166                            each_ref_fn fn, int trim, int flags, void *cb_data)
1167 {
1168         struct ref_store *refs = get_ref_store(submodule);
1169         struct ref_iterator *iter;
1170
1171         if (!refs)
1172                 return 0;
1173
1174         iter = refs->be->iterator_begin(refs, prefix, flags);
1175         iter = prefix_ref_iterator_begin(iter, prefix, trim);
1176
1177         return do_for_each_ref_iterator(iter, fn, cb_data);
1178 }
1179
1180 int for_each_ref(each_ref_fn fn, void *cb_data)
1181 {
1182         return do_for_each_ref(NULL, "", fn, 0, 0, cb_data);
1183 }
1184
1185 int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1186 {
1187         return do_for_each_ref(submodule, "", fn, 0, 0, cb_data);
1188 }
1189
1190 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
1191 {
1192         return do_for_each_ref(NULL, prefix, fn, strlen(prefix), 0, cb_data);
1193 }
1194
1195 int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data, unsigned int broken)
1196 {
1197         unsigned int flag = 0;
1198
1199         if (broken)
1200                 flag = DO_FOR_EACH_INCLUDE_BROKEN;
1201         return do_for_each_ref(NULL, prefix, fn, 0, flag, cb_data);
1202 }
1203
1204 int for_each_ref_in_submodule(const char *submodule, const char *prefix,
1205                 each_ref_fn fn, void *cb_data)
1206 {
1207         return do_for_each_ref(submodule, prefix, fn, strlen(prefix), 0, cb_data);
1208 }
1209
1210 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
1211 {
1212         return do_for_each_ref(NULL, git_replace_ref_base, fn,
1213                                strlen(git_replace_ref_base), 0, cb_data);
1214 }
1215
1216 int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
1217 {
1218         struct strbuf buf = STRBUF_INIT;
1219         int ret;
1220         strbuf_addf(&buf, "%srefs/", get_git_namespace());
1221         ret = do_for_each_ref(NULL, buf.buf, fn, 0, 0, cb_data);
1222         strbuf_release(&buf);
1223         return ret;
1224 }
1225
1226 int for_each_rawref(each_ref_fn fn, void *cb_data)
1227 {
1228         return do_for_each_ref(NULL, "", fn, 0,
1229                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1230 }
1231
1232 /* This function needs to return a meaningful errno on failure */
1233 const char *resolve_ref_recursively(struct ref_store *refs,
1234                                     const char *refname,
1235                                     int resolve_flags,
1236                                     unsigned char *sha1, int *flags)
1237 {
1238         static struct strbuf sb_refname = STRBUF_INIT;
1239         int unused_flags;
1240         int symref_count;
1241
1242         if (!flags)
1243                 flags = &unused_flags;
1244
1245         *flags = 0;
1246
1247         if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1248                 if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1249                     !refname_is_safe(refname)) {
1250                         errno = EINVAL;
1251                         return NULL;
1252                 }
1253
1254                 /*
1255                  * dwim_ref() uses REF_ISBROKEN to distinguish between
1256                  * missing refs and refs that were present but invalid,
1257                  * to complain about the latter to stderr.
1258                  *
1259                  * We don't know whether the ref exists, so don't set
1260                  * REF_ISBROKEN yet.
1261                  */
1262                 *flags |= REF_BAD_NAME;
1263         }
1264
1265         for (symref_count = 0; symref_count < SYMREF_MAXDEPTH; symref_count++) {
1266                 unsigned int read_flags = 0;
1267
1268                 if (refs->be->read_raw_ref(refs, refname,
1269                                            sha1, &sb_refname, &read_flags)) {
1270                         *flags |= read_flags;
1271                         if (errno != ENOENT || (resolve_flags & RESOLVE_REF_READING))
1272                                 return NULL;
1273                         hashclr(sha1);
1274                         if (*flags & REF_BAD_NAME)
1275                                 *flags |= REF_ISBROKEN;
1276                         return refname;
1277                 }
1278
1279                 *flags |= read_flags;
1280
1281                 if (!(read_flags & REF_ISSYMREF)) {
1282                         if (*flags & REF_BAD_NAME) {
1283                                 hashclr(sha1);
1284                                 *flags |= REF_ISBROKEN;
1285                         }
1286                         return refname;
1287                 }
1288
1289                 refname = sb_refname.buf;
1290                 if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
1291                         hashclr(sha1);
1292                         return refname;
1293                 }
1294                 if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1295                         if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1296                             !refname_is_safe(refname)) {
1297                                 errno = EINVAL;
1298                                 return NULL;
1299                         }
1300
1301                         *flags |= REF_ISBROKEN | REF_BAD_NAME;
1302                 }
1303         }
1304
1305         errno = ELOOP;
1306         return NULL;
1307 }
1308
1309 /* backend functions */
1310 int refs_init_db(struct strbuf *err)
1311 {
1312         struct ref_store *refs = get_ref_store(NULL);
1313
1314         return refs->be->init_db(refs, err);
1315 }
1316
1317 const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
1318                                unsigned char *sha1, int *flags)
1319 {
1320         return resolve_ref_recursively(get_ref_store(NULL), refname,
1321                                        resolve_flags, sha1, flags);
1322 }
1323
1324 int resolve_gitlink_ref(const char *submodule, const char *refname,
1325                         unsigned char *sha1)
1326 {
1327         size_t len = strlen(submodule);
1328         struct ref_store *refs;
1329         int flags;
1330
1331         while (len && submodule[len - 1] == '/')
1332                 len--;
1333
1334         if (!len)
1335                 return -1;
1336
1337         if (submodule[len]) {
1338                 /* We need to strip off one or more trailing slashes */
1339                 char *stripped = xmemdupz(submodule, len);
1340
1341                 refs = get_ref_store(stripped);
1342                 free(stripped);
1343         } else {
1344                 refs = get_ref_store(submodule);
1345         }
1346
1347         if (!refs)
1348                 return -1;
1349
1350         if (!resolve_ref_recursively(refs, refname, 0, sha1, &flags) ||
1351             is_null_sha1(sha1))
1352                 return -1;
1353         return 0;
1354 }
1355
1356 struct submodule_hash_entry
1357 {
1358         struct hashmap_entry ent; /* must be the first member! */
1359
1360         struct ref_store *refs;
1361
1362         /* NUL-terminated name of submodule: */
1363         char submodule[FLEX_ARRAY];
1364 };
1365
1366 static int submodule_hash_cmp(const void *entry, const void *entry_or_key,
1367                               const void *keydata)
1368 {
1369         const struct submodule_hash_entry *e1 = entry, *e2 = entry_or_key;
1370         const char *submodule = keydata ? keydata : e2->submodule;
1371
1372         return strcmp(e1->submodule, submodule);
1373 }
1374
1375 static struct submodule_hash_entry *alloc_submodule_hash_entry(
1376                 const char *submodule, struct ref_store *refs)
1377 {
1378         struct submodule_hash_entry *entry;
1379
1380         FLEX_ALLOC_STR(entry, submodule, submodule);
1381         hashmap_entry_init(entry, strhash(submodule));
1382         entry->refs = refs;
1383         return entry;
1384 }
1385
1386 /* A pointer to the ref_store for the main repository: */
1387 static struct ref_store *main_ref_store;
1388
1389 /* A hashmap of ref_stores, stored by submodule name: */
1390 static struct hashmap submodule_ref_stores;
1391
1392 /*
1393  * Return the ref_store instance for the specified submodule (or the
1394  * main repository if submodule is NULL). If that ref_store hasn't
1395  * been initialized yet, return NULL.
1396  */
1397 static struct ref_store *lookup_ref_store(const char *submodule)
1398 {
1399         struct submodule_hash_entry *entry;
1400
1401         if (!submodule)
1402                 return main_ref_store;
1403
1404         if (!submodule_ref_stores.tablesize)
1405                 /* It's initialized on demand in register_ref_store(). */
1406                 return NULL;
1407
1408         entry = hashmap_get_from_hash(&submodule_ref_stores,
1409                                       strhash(submodule), submodule);
1410         return entry ? entry->refs : NULL;
1411 }
1412
1413 /*
1414  * Register the specified ref_store to be the one that should be used
1415  * for submodule (or the main repository if submodule is NULL). It is
1416  * a fatal error to call this function twice for the same submodule.
1417  */
1418 static void register_ref_store(struct ref_store *refs, const char *submodule)
1419 {
1420         if (!submodule) {
1421                 if (main_ref_store)
1422                         die("BUG: main_ref_store initialized twice");
1423
1424                 main_ref_store = refs;
1425         } else {
1426                 if (!submodule_ref_stores.tablesize)
1427                         hashmap_init(&submodule_ref_stores, submodule_hash_cmp, 0);
1428
1429                 if (hashmap_put(&submodule_ref_stores,
1430                                 alloc_submodule_hash_entry(submodule, refs)))
1431                         die("BUG: ref_store for submodule '%s' initialized twice",
1432                             submodule);
1433         }
1434 }
1435
1436 /*
1437  * Create, record, and return a ref_store instance for the specified
1438  * submodule (or the main repository if submodule is NULL).
1439  */
1440 static struct ref_store *ref_store_init(const char *submodule)
1441 {
1442         const char *be_name = "files";
1443         struct ref_storage_be *be = find_ref_storage_backend(be_name);
1444         struct ref_store *refs;
1445
1446         if (!be)
1447                 die("BUG: reference backend %s is unknown", be_name);
1448
1449         refs = be->init(submodule);
1450         register_ref_store(refs, submodule);
1451         return refs;
1452 }
1453
1454 struct ref_store *get_ref_store(const char *submodule)
1455 {
1456         struct ref_store *refs;
1457
1458         if (!submodule || !*submodule) {
1459                 refs = lookup_ref_store(NULL);
1460
1461                 if (!refs)
1462                         refs = ref_store_init(NULL);
1463         } else {
1464                 refs = lookup_ref_store(submodule);
1465
1466                 if (!refs) {
1467                         struct strbuf submodule_sb = STRBUF_INIT;
1468
1469                         strbuf_addstr(&submodule_sb, submodule);
1470                         if (is_nonbare_repository_dir(&submodule_sb))
1471                                 refs = ref_store_init(submodule);
1472                         strbuf_release(&submodule_sb);
1473                 }
1474         }
1475
1476         return refs;
1477 }
1478
1479 void base_ref_store_init(struct ref_store *refs,
1480                          const struct ref_storage_be *be)
1481 {
1482         refs->be = be;
1483 }
1484
1485 /* backend functions */
1486 int pack_refs(unsigned int flags)
1487 {
1488         struct ref_store *refs = get_ref_store(NULL);
1489
1490         return refs->be->pack_refs(refs, flags);
1491 }
1492
1493 int peel_ref(const char *refname, unsigned char *sha1)
1494 {
1495         struct ref_store *refs = get_ref_store(NULL);
1496
1497         return refs->be->peel_ref(refs, refname, sha1);
1498 }
1499
1500 int create_symref(const char *ref_target, const char *refs_heads_master,
1501                   const char *logmsg)
1502 {
1503         struct ref_store *refs = get_ref_store(NULL);
1504
1505         return refs->be->create_symref(refs, ref_target, refs_heads_master,
1506                                        logmsg);
1507 }
1508
1509 int ref_transaction_commit(struct ref_transaction *transaction,
1510                            struct strbuf *err)
1511 {
1512         struct ref_store *refs = get_ref_store(NULL);
1513
1514         return refs->be->transaction_commit(refs, transaction, err);
1515 }
1516
1517 int verify_refname_available(const char *refname,
1518                              const struct string_list *extra,
1519                              const struct string_list *skip,
1520                              struct strbuf *err)
1521 {
1522         struct ref_store *refs = get_ref_store(NULL);
1523
1524         return refs->be->verify_refname_available(refs, refname, extra, skip, err);
1525 }
1526
1527 int for_each_reflog(each_ref_fn fn, void *cb_data)
1528 {
1529         struct ref_store *refs = get_ref_store(NULL);
1530         struct ref_iterator *iter;
1531
1532         iter = refs->be->reflog_iterator_begin(refs);
1533
1534         return do_for_each_ref_iterator(iter, fn, cb_data);
1535 }
1536
1537 int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn,
1538                                 void *cb_data)
1539 {
1540         struct ref_store *refs = get_ref_store(NULL);
1541
1542         return refs->be->for_each_reflog_ent_reverse(refs, refname,
1543                                                      fn, cb_data);
1544 }
1545
1546 int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn,
1547                         void *cb_data)
1548 {
1549         struct ref_store *refs = get_ref_store(NULL);
1550
1551         return refs->be->for_each_reflog_ent(refs, refname, fn, cb_data);
1552 }
1553
1554 int reflog_exists(const char *refname)
1555 {
1556         struct ref_store *refs = get_ref_store(NULL);
1557
1558         return refs->be->reflog_exists(refs, refname);
1559 }
1560
1561 int safe_create_reflog(const char *refname, int force_create,
1562                        struct strbuf *err)
1563 {
1564         struct ref_store *refs = get_ref_store(NULL);
1565
1566         return refs->be->create_reflog(refs, refname, force_create, err);
1567 }
1568
1569 int delete_reflog(const char *refname)
1570 {
1571         struct ref_store *refs = get_ref_store(NULL);
1572
1573         return refs->be->delete_reflog(refs, refname);
1574 }
1575
1576 int reflog_expire(const char *refname, const unsigned char *sha1,
1577                   unsigned int flags,
1578                   reflog_expiry_prepare_fn prepare_fn,
1579                   reflog_expiry_should_prune_fn should_prune_fn,
1580                   reflog_expiry_cleanup_fn cleanup_fn,
1581                   void *policy_cb_data)
1582 {
1583         struct ref_store *refs = get_ref_store(NULL);
1584
1585         return refs->be->reflog_expire(refs, refname, sha1, flags,
1586                                        prepare_fn, should_prune_fn,
1587                                        cleanup_fn, policy_cb_data);
1588 }
1589
1590 int initial_ref_transaction_commit(struct ref_transaction *transaction,
1591                                    struct strbuf *err)
1592 {
1593         struct ref_store *refs = get_ref_store(NULL);
1594
1595         return refs->be->initial_transaction_commit(refs, transaction, err);
1596 }
1597
1598 int delete_refs(struct string_list *refnames, unsigned int flags)
1599 {
1600         struct ref_store *refs = get_ref_store(NULL);
1601
1602         return refs->be->delete_refs(refs, refnames, flags);
1603 }
1604
1605 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
1606 {
1607         struct ref_store *refs = get_ref_store(NULL);
1608
1609         return refs->be->rename_ref(refs, oldref, newref, logmsg);
1610 }