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.h"
  13 #include "tag.h"
  14 #include "submodule.h"
  15 #include "worktree.h"
  16
  17 /*
  18  * List of all available backends
  19  */
  20 static struct ref_storage_be *refs_backends = &refs_be_files;
  21
  22 static struct ref_storage_be *find_ref_storage_backend(const char *name)
  23 {
  24         struct ref_storage_be *be;
  25         for (be = refs_backends; be; be = be->next)
  26                 if (!strcmp(be->name, name))
  27                         return be;
  28         return NULL;
  29 }
  30
  31 int ref_storage_backend_exists(const char *name)
  32 {
  33         return find_ref_storage_backend(name) != NULL;
  34 }
  35
  36 /*
  37  * How to handle various characters in refnames:
  38  * 0: An acceptable character for refs
  39  * 1: End-of-component
  40  * 2: ., look for a preceding . to reject .. in refs
  41  * 3: {, look for a preceding @ to reject @{ in refs
  42  * 4: A bad character: ASCII control characters, and
  43  *    ":", "?", "[", "\", "^", "~", SP, or TAB
  44  * 5: *, reject unless REFNAME_REFSPEC_PATTERN is set
  45  */
  46 static unsigned char refname_disposition[256] = {
  47         1, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
  48         4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
  49         4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 2, 1,
  50         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 4,
  51         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  52         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 0, 4, 0,
  53         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  54         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 4, 4
  55 };
  56
  57 /*
  58  * Try to read one refname component from the front of refname.
  59  * Return the length of the component found, or -1 if the component is
  60  * not legal.  It is legal if it is something reasonable to have under
  61  * ".git/refs/"; We do not like it if:
  62  *
  63  * - any path component of it begins with ".", or
  64  * - it has double dots "..", or
  65  * - it has ASCII control characters, or
  66  * - it has ":", "?", "[", "\", "^", "~", SP, or TAB anywhere, or
  67  * - it has "*" anywhere unless REFNAME_REFSPEC_PATTERN is set, or
  68  * - it ends with a "/", or
  69  * - it ends with ".lock", or
  70  * - it contains a "@{" portion
  71  */
  72 static int check_refname_component(const char *refname, int *flags)
  73 {
  74         const char *cp;
  75         char last = '\0';
  76
  77         for (cp = refname; ; cp++) {
  78                 int ch = *cp & 255;
  79                 unsigned char disp = refname_disposition[ch];
  80                 switch (disp) {
  81                 case 1:
  82                         goto out;
  83                 case 2:
  84                         if (last == '.')
  85                                 return -1; /* Refname contains "..". */
  86                         break;
  87                 case 3:
  88                         if (last == '@')
  89                                 return -1; /* Refname contains "@{". */
  90                         break;
  91                 case 4:
  92                         return -1;
  93                 case 5:
  94                         if (!(*flags & REFNAME_REFSPEC_PATTERN))
  95                                 return -1; /* refspec can't be a pattern */
  96
  97                         /*
  98                          * Unset the pattern flag so that we only accept
  99                          * a single asterisk for one side of refspec.
 100                          */
 101                         *flags &= ~ REFNAME_REFSPEC_PATTERN;
 102                         break;
 103                 }
 104                 last = ch;
 105         }
 106 out:
 107         if (cp == refname)
 108                 return 0; /* Component has zero length. */
 109         if (refname[0] == '.')
 110                 return -1; /* Component starts with '.'. */
 111         if (cp - refname >= LOCK_SUFFIX_LEN &&
 112             !memcmp(cp - LOCK_SUFFIX_LEN, LOCK_SUFFIX, LOCK_SUFFIX_LEN))
 113                 return -1; /* Refname ends with ".lock". */
 114         return cp - refname;
 115 }
 116
 117 int check_refname_format(const char *refname, int flags)
 118 {
 119         int component_len, component_count = 0;
 120
 121         if (!strcmp(refname, "@"))
 122                 /* Refname is a single character '@'. */
 123                 return -1;
 124
 125         while (1) {
 126                 /* We are at the start of a path component. */
 127                 component_len = check_refname_component(refname, &flags);
 128                 if (component_len <= 0)
 129                         return -1;
 130
 131                 component_count++;
 132                 if (refname[component_len] == '\0')
 133                         break;
 134                 /* Skip to next component. */
 135                 refname += component_len + 1;
 136         }
 137
 138         if (refname[component_len - 1] == '.')
 139                 return -1; /* Refname ends with '.'. */
 140         if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
 141                 return -1; /* Refname has only one component. */
 142         return 0;
 143 }
 144
 145 int refname_is_safe(const char *refname)
 146 {
 147         const char *rest;
 148
 149         if (skip_prefix(refname, "refs/", &rest)) {
 150                 char *buf;
 151                 int result;
 152                 size_t restlen = strlen(rest);
 153
 154                 /* rest must not be empty, or start or end with "/" */
 155                 if (!restlen || *rest == '/' || rest[restlen - 1] == '/')
 156                         return 0;
 157
 158                 /*
 159                  * Does the refname try to escape refs/?
 160                  * For example: refs/foo/../bar is safe but refs/foo/../../bar
 161                  * is not.
 162                  */
 163                 buf = xmallocz(restlen);
 164                 result = !normalize_path_copy(buf, rest) && !strcmp(buf, rest);
 165                 free(buf);
 166                 return result;
 167         }
 168
 169         do {
 170                 if (!isupper(*refname) && *refname != '_')
 171                         return 0;
 172                 refname++;
 173         } while (*refname);
 174         return 1;
 175 }
 176
 177 /*
 178  * Return true if refname, which has the specified oid and flags, can
 179  * be resolved to an object in the database. If the referred-to object
 180  * does not exist, emit a warning and return false.
 181  */
 182 int ref_resolves_to_object(const char *refname,
 183                            const struct object_id *oid,
 184                            unsigned int flags)
 185 {
 186         if (flags & REF_ISBROKEN)
 187                 return 0;
 188         if (!has_sha1_file(oid->hash)) {
 189                 error("%s does not point to a valid object!", refname);
 190                 return 0;
 191         }
 192         return 1;
 193 }
 194
 195 char *refs_resolve_refdup(struct ref_store *refs,
 196                           const char *refname, int resolve_flags,
 197                           unsigned char *sha1, int *flags)
 198 {
 199         const char *result;
 200
 201         result = refs_resolve_ref_unsafe(refs, refname, resolve_flags,
 202                                          sha1, flags);
 203         return xstrdup_or_null(result);
 204 }
 205
 206 char *resolve_refdup(const char *refname, int resolve_flags,
 207                      unsigned char *sha1, int *flags)
 208 {
 209         return refs_resolve_refdup(get_main_ref_store(),
 210                                    refname, resolve_flags,
 211                                    sha1, flags);
 212 }
 213
 214 /* The argument to filter_refs */
 215 struct ref_filter {
 216         const char *pattern;
 217         each_ref_fn *fn;
 218         void *cb_data;
 219 };
 220
 221 int refs_read_ref_full(struct ref_store *refs, const char *refname,
 222                        int resolve_flags, unsigned char *sha1, int *flags)
 223 {
 224         if (refs_resolve_ref_unsafe(refs, refname, resolve_flags, sha1, flags))
 225                 return 0;
 226         return -1;
 227 }
 228
 229 int read_ref_full(const char *refname, int resolve_flags, unsigned char *sha1, int *flags)
 230 {
 231         return refs_read_ref_full(get_main_ref_store(), refname,
 232                                   resolve_flags, sha1, flags);
 233 }
 234
 235 int read_ref(const char *refname, unsigned char *sha1)
 236 {
 237         return read_ref_full(refname, RESOLVE_REF_READING, sha1, NULL);
 238 }
 239
 240 int ref_exists(const char *refname)
 241 {
 242         return !!resolve_ref_unsafe(refname, RESOLVE_REF_READING, NULL, NULL);
 243 }
 244
 245 static int filter_refs(const char *refname, const struct object_id *oid,
 246                            int flags, void *data)
 247 {
 248         struct ref_filter *filter = (struct ref_filter *)data;
 249
 250         if (wildmatch(filter->pattern, refname, 0))
 251                 return 0;
 252         return filter->fn(refname, oid, flags, filter->cb_data);
 253 }
 254
 255 enum peel_status peel_object(const unsigned char *name, unsigned char *sha1)
 256 {
 257         struct object *o = lookup_unknown_object(name);
 258
 259         if (o->type == OBJ_NONE) {
 260                 int type = sha1_object_info(name, NULL);
 261                 if (type < 0 || !object_as_type(o, type, 0))
 262                         return PEEL_INVALID;
 263         }
 264
 265         if (o->type != OBJ_TAG)
 266                 return PEEL_NON_TAG;
 267
 268         o = deref_tag_noverify(o);
 269         if (!o)
 270                 return PEEL_INVALID;
 271
 272         hashcpy(sha1, o->oid.hash);
 273         return PEEL_PEELED;
 274 }
 275
 276 struct warn_if_dangling_data {
 277         FILE *fp;
 278         const char *refname;
 279         const struct string_list *refnames;
 280         const char *msg_fmt;
 281 };
 282
 283 static int warn_if_dangling_symref(const char *refname, const struct object_id *oid,
 284                                    int flags, void *cb_data)
 285 {
 286         struct warn_if_dangling_data *d = cb_data;
 287         const char *resolves_to;
 288
 289         if (!(flags & REF_ISSYMREF))
 290                 return 0;
 291
 292         resolves_to = resolve_ref_unsafe(refname, 0, NULL, NULL);
 293         if (!resolves_to
 294             || (d->refname
 295                 ? strcmp(resolves_to, d->refname)
 296                 : !string_list_has_string(d->refnames, resolves_to))) {
 297                 return 0;
 298         }
 299
 300         fprintf(d->fp, d->msg_fmt, refname);
 301         fputc('\n', d->fp);
 302         return 0;
 303 }
 304
 305 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 306 {
 307         struct warn_if_dangling_data data;
 308
 309         data.fp = fp;
 310         data.refname = refname;
 311         data.refnames = NULL;
 312         data.msg_fmt = msg_fmt;
 313         for_each_rawref(warn_if_dangling_symref, &data);
 314 }
 315
 316 void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames)
 317 {
 318         struct warn_if_dangling_data data;
 319
 320         data.fp = fp;
 321         data.refname = NULL;
 322         data.refnames = refnames;
 323         data.msg_fmt = msg_fmt;
 324         for_each_rawref(warn_if_dangling_symref, &data);
 325 }
 326
 327 int refs_for_each_tag_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 328 {
 329         return refs_for_each_ref_in(refs, "refs/tags/", fn, cb_data);
 330 }
 331
 332 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 333 {
 334         return refs_for_each_tag_ref(get_main_ref_store(), fn, cb_data);
 335 }
 336
 337 int refs_for_each_branch_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 338 {
 339         return refs_for_each_ref_in(refs, "refs/heads/", fn, cb_data);
 340 }
 341
 342 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 343 {
 344         return refs_for_each_branch_ref(get_main_ref_store(), fn, cb_data);
 345 }
 346
 347 int refs_for_each_remote_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 348 {
 349         return refs_for_each_ref_in(refs, "refs/remotes/", fn, cb_data);
 350 }
 351
 352 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 353 {
 354         return refs_for_each_remote_ref(get_main_ref_store(), fn, cb_data);
 355 }
 356
 357 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
 358 {
 359         struct strbuf buf = STRBUF_INIT;
 360         int ret = 0;
 361         struct object_id oid;
 362         int flag;
 363
 364         strbuf_addf(&buf, "%sHEAD", get_git_namespace());
 365         if (!read_ref_full(buf.buf, RESOLVE_REF_READING, oid.hash, &flag))
 366                 ret = fn(buf.buf, &oid, flag, cb_data);
 367         strbuf_release(&buf);
 368
 369         return ret;
 370 }
 371
 372 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 373         const char *prefix, void *cb_data)
 374 {
 375         struct strbuf real_pattern = STRBUF_INIT;
 376         struct ref_filter filter;
 377         int ret;
 378
 379         if (!prefix && !starts_with(pattern, "refs/"))
 380                 strbuf_addstr(&real_pattern, "refs/");
 381         else if (prefix)
 382                 strbuf_addstr(&real_pattern, prefix);
 383         strbuf_addstr(&real_pattern, pattern);
 384
 385         if (!has_glob_specials(pattern)) {
 386                 /* Append implied '/' '*' if not present. */
 387                 strbuf_complete(&real_pattern, '/');
 388                 /* No need to check for '*', there is none. */
 389                 strbuf_addch(&real_pattern, '*');
 390         }
 391
 392         filter.pattern = real_pattern.buf;
 393         filter.fn = fn;
 394         filter.cb_data = cb_data;
 395         ret = for_each_ref(filter_refs, &filter);
 396
 397         strbuf_release(&real_pattern);
 398         return ret;
 399 }
 400
 401 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 402 {
 403         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
 404 }
 405
 406 const char *prettify_refname(const char *name)
 407 {
 408         if (skip_prefix(name, "refs/heads/", &name) ||
 409             skip_prefix(name, "refs/tags/", &name) ||
 410             skip_prefix(name, "refs/remotes/", &name))
 411                 ; /* nothing */
 412         return name;
 413 }
 414
 415 static const char *ref_rev_parse_rules[] = {
 416         "%.*s",
 417         "refs/%.*s",
 418         "refs/tags/%.*s",
 419         "refs/heads/%.*s",
 420         "refs/remotes/%.*s",
 421         "refs/remotes/%.*s/HEAD",
 422         NULL
 423 };
 424
 425 int refname_match(const char *abbrev_name, const char *full_name)
 426 {
 427         const char **p;
 428         const int abbrev_name_len = strlen(abbrev_name);
 429
 430         for (p = ref_rev_parse_rules; *p; p++) {
 431                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
 432                         return 1;
 433                 }
 434         }
 435
 436         return 0;
 437 }
 438
 439 /*
 440  * *string and *len will only be substituted, and *string returned (for
 441  * later free()ing) if the string passed in is a magic short-hand form
 442  * to name a branch.
 443  */
 444 static char *substitute_branch_name(const char **string, int *len)
 445 {
 446         struct strbuf buf = STRBUF_INIT;
 447         int ret = interpret_branch_name(*string, *len, &buf, 0);
 448
 449         if (ret == *len) {
 450                 size_t size;
 451                 *string = strbuf_detach(&buf, &size);
 452                 *len = size;
 453                 return (char *)*string;
 454         }
 455
 456         return NULL;
 457 }
 458
 459 int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
 460 {
 461         char *last_branch = substitute_branch_name(&str, &len);
 462         int   refs_found  = expand_ref(str, len, sha1, ref);
 463         free(last_branch);
 464         return refs_found;
 465 }
 466
 467 int expand_ref(const char *str, int len, unsigned char *sha1, char **ref)
 468 {
 469         const char **p, *r;
 470         int refs_found = 0;
 471         struct strbuf fullref = STRBUF_INIT;
 472
 473         *ref = NULL;
 474         for (p = ref_rev_parse_rules; *p; p++) {
 475                 unsigned char sha1_from_ref[20];
 476                 unsigned char *this_result;
 477                 int flag;
 478
 479                 this_result = refs_found ? sha1_from_ref : sha1;
 480                 strbuf_reset(&fullref);
 481                 strbuf_addf(&fullref, *p, len, str);
 482                 r = resolve_ref_unsafe(fullref.buf, RESOLVE_REF_READING,
 483                                        this_result, &flag);
 484                 if (r) {
 485                         if (!refs_found++)
 486                                 *ref = xstrdup(r);
 487                         if (!warn_ambiguous_refs)
 488                                 break;
 489                 } else if ((flag & REF_ISSYMREF) && strcmp(fullref.buf, "HEAD")) {
 490                         warning("ignoring dangling symref %s.", fullref.buf);
 491                 } else if ((flag & REF_ISBROKEN) && strchr(fullref.buf, '/')) {
 492                         warning("ignoring broken ref %s.", fullref.buf);
 493                 }
 494         }
 495         strbuf_release(&fullref);
 496         return refs_found;
 497 }
 498
 499 int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
 500 {
 501         char *last_branch = substitute_branch_name(&str, &len);
 502         const char **p;
 503         int logs_found = 0;
 504         struct strbuf path = STRBUF_INIT;
 505
 506         *log = NULL;
 507         for (p = ref_rev_parse_rules; *p; p++) {
 508                 unsigned char hash[20];
 509                 const char *ref, *it;
 510
 511                 strbuf_reset(&path);
 512                 strbuf_addf(&path, *p, len, str);
 513                 ref = resolve_ref_unsafe(path.buf, RESOLVE_REF_READING,
 514                                          hash, NULL);
 515                 if (!ref)
 516                         continue;
 517                 if (reflog_exists(path.buf))
 518                         it = path.buf;
 519                 else if (strcmp(ref, path.buf) && reflog_exists(ref))
 520                         it = ref;
 521                 else
 522                         continue;
 523                 if (!logs_found++) {
 524                         *log = xstrdup(it);
 525                         hashcpy(sha1, hash);
 526                 }
 527                 if (!warn_ambiguous_refs)
 528                         break;
 529         }
 530         strbuf_release(&path);
 531         free(last_branch);
 532         return logs_found;
 533 }
 534
 535 static int is_per_worktree_ref(const char *refname)
 536 {
 537         return !strcmp(refname, "HEAD") ||
 538                 starts_with(refname, "refs/bisect/");
 539 }
 540
 541 static int is_pseudoref_syntax(const char *refname)
 542 {
 543         const char *c;
 544
 545         for (c = refname; *c; c++) {
 546                 if (!isupper(*c) && *c != '-' && *c != '_')
 547                         return 0;
 548         }
 549
 550         return 1;
 551 }
 552
 553 enum ref_type ref_type(const char *refname)
 554 {
 555         if (is_per_worktree_ref(refname))
 556                 return REF_TYPE_PER_WORKTREE;
 557         if (is_pseudoref_syntax(refname))
 558                 return REF_TYPE_PSEUDOREF;
 559        return REF_TYPE_NORMAL;
 560 }
 561
 562 long get_files_ref_lock_timeout_ms(void)
 563 {
 564         static int configured = 0;
 565
 566         /* The default timeout is 100 ms: */
 567         static int timeout_ms = 100;
 568
 569         if (!configured) {
 570                 git_config_get_int("core.filesreflocktimeout", &timeout_ms);
 571                 configured = 1;
 572         }
 573
 574         return timeout_ms;
 575 }
 576
 577 static int write_pseudoref(const char *pseudoref, const unsigned char *sha1,
 578                            const unsigned char *old_sha1, struct strbuf *err)
 579 {
 580         const char *filename;
 581         int fd;
 582         static struct lock_file lock;
 583         struct strbuf buf = STRBUF_INIT;
 584         int ret = -1;
 585
 586         strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
 587
 588         filename = git_path("%s", pseudoref);
 589         fd = hold_lock_file_for_update_timeout(&lock, filename,
 590                                                LOCK_DIE_ON_ERROR,
 591                                                get_files_ref_lock_timeout_ms());
 592         if (fd < 0) {
 593                 strbuf_addf(err, "could not open '%s' for writing: %s",
 594                             filename, strerror(errno));
 595                 goto done;
 596         }
 597
 598         if (old_sha1) {
 599                 unsigned char actual_old_sha1[20];
 600
 601                 if (read_ref(pseudoref, actual_old_sha1))
 602                         die("could not read ref '%s'", pseudoref);
 603                 if (hashcmp(actual_old_sha1, old_sha1)) {
 604                         strbuf_addf(err, "unexpected sha1 when writing '%s'", pseudoref);
 605                         rollback_lock_file(&lock);
 606                         goto done;
 607                 }
 608         }
 609
 610         if (write_in_full(fd, buf.buf, buf.len) < 0) {
 611                 strbuf_addf(err, "could not write to '%s'", filename);
 612                 rollback_lock_file(&lock);
 613                 goto done;
 614         }
 615
 616         commit_lock_file(&lock);
 617         ret = 0;
 618 done:
 619         strbuf_release(&buf);
 620         return ret;
 621 }
 622
 623 static int delete_pseudoref(const char *pseudoref, const unsigned char *old_sha1)
 624 {
 625         static struct lock_file lock;
 626         const char *filename;
 627
 628         filename = git_path("%s", pseudoref);
 629
 630         if (old_sha1 && !is_null_sha1(old_sha1)) {
 631                 int fd;
 632                 unsigned char actual_old_sha1[20];
 633
 634                 fd = hold_lock_file_for_update_timeout(
 635                                 &lock, filename, LOCK_DIE_ON_ERROR,
 636                                 get_files_ref_lock_timeout_ms());
 637                 if (fd < 0)
 638                         die_errno(_("Could not open '%s' for writing"), filename);
 639                 if (read_ref(pseudoref, actual_old_sha1))
 640                         die("could not read ref '%s'", pseudoref);
 641                 if (hashcmp(actual_old_sha1, old_sha1)) {
 642                         warning("Unexpected sha1 when deleting %s", pseudoref);
 643                         rollback_lock_file(&lock);
 644                         return -1;
 645                 }
 646
 647                 unlink(filename);
 648                 rollback_lock_file(&lock);
 649         } else {
 650                 unlink(filename);
 651         }
 652
 653         return 0;
 654 }
 655
 656 int refs_delete_ref(struct ref_store *refs, const char *msg,
 657                     const char *refname,
 658                     const unsigned char *old_sha1,
 659                     unsigned int flags)
 660 {
 661         struct ref_transaction *transaction;
 662         struct strbuf err = STRBUF_INIT;
 663
 664         if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
 665                 assert(refs == get_main_ref_store());
 666                 return delete_pseudoref(refname, old_sha1);
 667         }
 668
 669         transaction = ref_store_transaction_begin(refs, &err);
 670         if (!transaction ||
 671             ref_transaction_delete(transaction, refname, old_sha1,
 672                                    flags, msg, &err) ||
 673             ref_transaction_commit(transaction, &err)) {
 674                 error("%s", err.buf);
 675                 ref_transaction_free(transaction);
 676                 strbuf_release(&err);
 677                 return 1;
 678         }
 679         ref_transaction_free(transaction);
 680         strbuf_release(&err);
 681         return 0;
 682 }
 683
 684 int delete_ref(const char *msg, const char *refname,
 685                const unsigned char *old_sha1, unsigned int flags)
 686 {
 687         return refs_delete_ref(get_main_ref_store(), msg, refname,
 688                                old_sha1, flags);
 689 }
 690
 691 int copy_reflog_msg(char *buf, const char *msg)
 692 {
 693         char *cp = buf;
 694         char c;
 695         int wasspace = 1;
 696
 697         *cp++ = '\t';
 698         while ((c = *msg++)) {
 699                 if (wasspace && isspace(c))
 700                         continue;
 701                 wasspace = isspace(c);
 702                 if (wasspace)
 703                         c = ' ';
 704                 *cp++ = c;
 705         }
 706         while (buf < cp && isspace(cp[-1]))
 707                 cp--;
 708         *cp++ = '\n';
 709         return cp - buf;
 710 }
 711
 712 int should_autocreate_reflog(const char *refname)
 713 {
 714         switch (log_all_ref_updates) {
 715         case LOG_REFS_ALWAYS:
 716                 return 1;
 717         case LOG_REFS_NORMAL:
 718                 return starts_with(refname, "refs/heads/") ||
 719                         starts_with(refname, "refs/remotes/") ||
 720                         starts_with(refname, "refs/notes/") ||
 721                         !strcmp(refname, "HEAD");
 722         default:
 723                 return 0;
 724         }
 725 }
 726
 727 int is_branch(const char *refname)
 728 {
 729         return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
 730 }
 731
 732 struct read_ref_at_cb {
 733         const char *refname;
 734         timestamp_t at_time;
 735         int cnt;
 736         int reccnt;
 737         unsigned char *sha1;
 738         int found_it;
 739
 740         unsigned char osha1[20];
 741         unsigned char nsha1[20];
 742         int tz;
 743         timestamp_t date;
 744         char **msg;
 745         timestamp_t *cutoff_time;
 746         int *cutoff_tz;
 747         int *cutoff_cnt;
 748 };
 749
 750 static int read_ref_at_ent(struct object_id *ooid, struct object_id *noid,
 751                 const char *email, timestamp_t timestamp, int tz,
 752                 const char *message, void *cb_data)
 753 {
 754         struct read_ref_at_cb *cb = cb_data;
 755
 756         cb->reccnt++;
 757         cb->tz = tz;
 758         cb->date = timestamp;
 759
 760         if (timestamp <= cb->at_time || cb->cnt == 0) {
 761                 if (cb->msg)
 762                         *cb->msg = xstrdup(message);
 763                 if (cb->cutoff_time)
 764                         *cb->cutoff_time = timestamp;
 765                 if (cb->cutoff_tz)
 766                         *cb->cutoff_tz = tz;
 767                 if (cb->cutoff_cnt)
 768                         *cb->cutoff_cnt = cb->reccnt - 1;
 769                 /*
 770                  * we have not yet updated cb->[n|o]sha1 so they still
 771                  * hold the values for the previous record.
 772                  */
 773                 if (!is_null_sha1(cb->osha1)) {
 774                         hashcpy(cb->sha1, noid->hash);
 775                         if (hashcmp(cb->osha1, noid->hash))
 776                                 warning("Log for ref %s has gap after %s.",
 777                                         cb->refname, show_date(cb->date, cb->tz, DATE_MODE(RFC2822)));
 778                 }
 779                 else if (cb->date == cb->at_time)
 780                         hashcpy(cb->sha1, noid->hash);
 781                 else if (hashcmp(noid->hash, cb->sha1))
 782                         warning("Log for ref %s unexpectedly ended on %s.",
 783                                 cb->refname, show_date(cb->date, cb->tz,
 784                                                        DATE_MODE(RFC2822)));
 785                 hashcpy(cb->osha1, ooid->hash);
 786                 hashcpy(cb->nsha1, noid->hash);
 787                 cb->found_it = 1;
 788                 return 1;
 789         }
 790         hashcpy(cb->osha1, ooid->hash);
 791         hashcpy(cb->nsha1, noid->hash);
 792         if (cb->cnt > 0)
 793                 cb->cnt--;
 794         return 0;
 795 }
 796
 797 static int read_ref_at_ent_oldest(struct object_id *ooid, struct object_id *noid,
 798                                   const char *email, timestamp_t timestamp,
 799                                   int tz, const char *message, void *cb_data)
 800 {
 801         struct read_ref_at_cb *cb = cb_data;
 802
 803         if (cb->msg)
 804                 *cb->msg = xstrdup(message);
 805         if (cb->cutoff_time)
 806                 *cb->cutoff_time = timestamp;
 807         if (cb->cutoff_tz)
 808                 *cb->cutoff_tz = tz;
 809         if (cb->cutoff_cnt)
 810                 *cb->cutoff_cnt = cb->reccnt;
 811         hashcpy(cb->sha1, ooid->hash);
 812         if (is_null_sha1(cb->sha1))
 813                 hashcpy(cb->sha1, noid->hash);
 814         /* We just want the first entry */
 815         return 1;
 816 }
 817
 818 int read_ref_at(const char *refname, unsigned int flags, timestamp_t at_time, int cnt,
 819                 unsigned char *sha1, char **msg,
 820                 timestamp_t *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
 821 {
 822         struct read_ref_at_cb cb;
 823
 824         memset(&cb, 0, sizeof(cb));
 825         cb.refname = refname;
 826         cb.at_time = at_time;
 827         cb.cnt = cnt;
 828         cb.msg = msg;
 829         cb.cutoff_time = cutoff_time;
 830         cb.cutoff_tz = cutoff_tz;
 831         cb.cutoff_cnt = cutoff_cnt;
 832         cb.sha1 = sha1;
 833
 834         for_each_reflog_ent_reverse(refname, read_ref_at_ent, &cb);
 835
 836         if (!cb.reccnt) {
 837                 if (flags & GET_OID_QUIETLY)
 838                         exit(128);
 839                 else
 840                         die("Log for %s is empty.", refname);
 841         }
 842         if (cb.found_it)
 843                 return 0;
 844
 845         for_each_reflog_ent(refname, read_ref_at_ent_oldest, &cb);
 846
 847         return 1;
 848 }
 849
 850 struct ref_transaction *ref_store_transaction_begin(struct ref_store *refs,
 851                                                     struct strbuf *err)
 852 {
 853         struct ref_transaction *tr;
 854         assert(err);
 855
 856         tr = xcalloc(1, sizeof(struct ref_transaction));
 857         tr->ref_store = refs;
 858         return tr;
 859 }
 860
 861 struct ref_transaction *ref_transaction_begin(struct strbuf *err)
 862 {
 863         return ref_store_transaction_begin(get_main_ref_store(), err);
 864 }
 865
 866 void ref_transaction_free(struct ref_transaction *transaction)
 867 {
 868         size_t i;
 869
 870         if (!transaction)
 871                 return;
 872
 873         switch (transaction->state) {
 874         case REF_TRANSACTION_OPEN:
 875         case REF_TRANSACTION_CLOSED:
 876                 /* OK */
 877                 break;
 878         case REF_TRANSACTION_PREPARED:
 879                 die("BUG: free called on a prepared reference transaction");
 880                 break;
 881         default:
 882                 die("BUG: unexpected reference transaction state");
 883                 break;
 884         }
 885
 886         for (i = 0; i < transaction->nr; i++) {
 887                 free(transaction->updates[i]->msg);
 888                 free(transaction->updates[i]);
 889         }
 890         free(transaction->updates);
 891         free(transaction);
 892 }
 893
 894 struct ref_update *ref_transaction_add_update(
 895                 struct ref_transaction *transaction,
 896                 const char *refname, unsigned int flags,
 897                 const unsigned char *new_sha1,
 898                 const unsigned char *old_sha1,
 899                 const char *msg)
 900 {
 901         struct ref_update *update;
 902
 903         if (transaction->state != REF_TRANSACTION_OPEN)
 904                 die("BUG: update called for transaction that is not open");
 905
 906         if ((flags & REF_ISPRUNING) && !(flags & REF_NODEREF))
 907                 die("BUG: REF_ISPRUNING set without REF_NODEREF");
 908
 909         FLEX_ALLOC_STR(update, refname, refname);
 910         ALLOC_GROW(transaction->updates, transaction->nr + 1, transaction->alloc);
 911         transaction->updates[transaction->nr++] = update;
 912
 913         update->flags = flags;
 914
 915         if (flags & REF_HAVE_NEW)
 916                 hashcpy(update->new_oid.hash, new_sha1);
 917         if (flags & REF_HAVE_OLD)
 918                 hashcpy(update->old_oid.hash, old_sha1);
 919         update->msg = xstrdup_or_null(msg);
 920         return update;
 921 }
 922
 923 int ref_transaction_update(struct ref_transaction *transaction,
 924                            const char *refname,
 925                            const unsigned char *new_sha1,
 926                            const unsigned char *old_sha1,
 927                            unsigned int flags, const char *msg,
 928                            struct strbuf *err)
 929 {
 930         assert(err);
 931
 932         if ((new_sha1 && !is_null_sha1(new_sha1)) ?
 933             check_refname_format(refname, REFNAME_ALLOW_ONELEVEL) :
 934             !refname_is_safe(refname)) {
 935                 strbuf_addf(err, "refusing to update ref with bad name '%s'",
 936                             refname);
 937                 return -1;
 938         }
 939
 940         flags &= REF_TRANSACTION_UPDATE_ALLOWED_FLAGS;
 941
 942         flags |= (new_sha1 ? REF_HAVE_NEW : 0) | (old_sha1 ? REF_HAVE_OLD : 0);
 943
 944         ref_transaction_add_update(transaction, refname, flags,
 945                                    new_sha1, old_sha1, msg);
 946         return 0;
 947 }
 948
 949 int ref_transaction_create(struct ref_transaction *transaction,
 950                            const char *refname,
 951                            const unsigned char *new_sha1,
 952                            unsigned int flags, const char *msg,
 953                            struct strbuf *err)
 954 {
 955         if (!new_sha1 || is_null_sha1(new_sha1))
 956                 die("BUG: create called without valid new_sha1");
 957         return ref_transaction_update(transaction, refname, new_sha1,
 958                                       null_sha1, flags, msg, err);
 959 }
 960
 961 int ref_transaction_delete(struct ref_transaction *transaction,
 962                            const char *refname,
 963                            const unsigned char *old_sha1,
 964                            unsigned int flags, const char *msg,
 965                            struct strbuf *err)
 966 {
 967         if (old_sha1 && is_null_sha1(old_sha1))
 968                 die("BUG: delete called with old_sha1 set to zeros");
 969         return ref_transaction_update(transaction, refname,
 970                                       null_sha1, old_sha1,
 971                                       flags, msg, err);
 972 }
 973
 974 int ref_transaction_verify(struct ref_transaction *transaction,
 975                            const char *refname,
 976                            const unsigned char *old_sha1,
 977                            unsigned int flags,
 978                            struct strbuf *err)
 979 {
 980         if (!old_sha1)
 981                 die("BUG: verify called with old_sha1 set to NULL");
 982         return ref_transaction_update(transaction, refname,
 983                                       NULL, old_sha1,
 984                                       flags, NULL, err);
 985 }
 986
 987 int update_ref_oid(const char *msg, const char *refname,
 988                const struct object_id *new_oid, const struct object_id *old_oid,
 989                unsigned int flags, enum action_on_err onerr)
 990 {
 991         return update_ref(msg, refname, new_oid ? new_oid->hash : NULL,
 992                 old_oid ? old_oid->hash : NULL, flags, onerr);
 993 }
 994
 995 int refs_update_ref(struct ref_store *refs, const char *msg,
 996                     const char *refname, const unsigned char *new_sha1,
 997                     const unsigned char *old_sha1, unsigned int flags,
 998                     enum action_on_err onerr)
 999 {
1000         struct ref_transaction *t = NULL;
1001         struct strbuf err = STRBUF_INIT;
1002         int ret = 0;
1003
1004         if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
1005                 assert(refs == get_main_ref_store());
1006                 ret = write_pseudoref(refname, new_sha1, old_sha1, &err);
1007         } else {
1008                 t = ref_store_transaction_begin(refs, &err);
1009                 if (!t ||
1010                     ref_transaction_update(t, refname, new_sha1, old_sha1,
1011                                            flags, msg, &err) ||
1012                     ref_transaction_commit(t, &err)) {
1013                         ret = 1;
1014                         ref_transaction_free(t);
1015                 }
1016         }
1017         if (ret) {
1018                 const char *str = "update_ref failed for ref '%s': %s";
1019
1020                 switch (onerr) {
1021                 case UPDATE_REFS_MSG_ON_ERR:
1022                         error(str, refname, err.buf);
1023                         break;
1024                 case UPDATE_REFS_DIE_ON_ERR:
1025                         die(str, refname, err.buf);
1026                         break;
1027                 case UPDATE_REFS_QUIET_ON_ERR:
1028                         break;
1029                 }
1030                 strbuf_release(&err);
1031                 return 1;
1032         }
1033         strbuf_release(&err);
1034         if (t)
1035                 ref_transaction_free(t);
1036         return 0;
1037 }
1038
1039 int update_ref(const char *msg, const char *refname,
1040                const unsigned char *new_sha1,
1041                const unsigned char *old_sha1,
1042                unsigned int flags, enum action_on_err onerr)
1043 {
1044         return refs_update_ref(get_main_ref_store(), msg, refname, new_sha1,
1045                                old_sha1, flags, onerr);
1046 }
1047
1048 char *shorten_unambiguous_ref(const char *refname, int strict)
1049 {
1050         int i;
1051         static char **scanf_fmts;
1052         static int nr_rules;
1053         char *short_name;
1054         struct strbuf resolved_buf = STRBUF_INIT;
1055
1056         if (!nr_rules) {
1057                 /*
1058                  * Pre-generate scanf formats from ref_rev_parse_rules[].
1059                  * Generate a format suitable for scanf from a
1060                  * ref_rev_parse_rules rule by interpolating "%s" at the
1061                  * location of the "%.*s".
1062                  */
1063                 size_t total_len = 0;
1064                 size_t offset = 0;
1065
1066                 /* the rule list is NULL terminated, count them first */
1067                 for (nr_rules = 0; ref_rev_parse_rules[nr_rules]; nr_rules++)
1068                         /* -2 for strlen("%.*s") - strlen("%s"); +1 for NUL */
1069                         total_len += strlen(ref_rev_parse_rules[nr_rules]) - 2 + 1;
1070
1071                 scanf_fmts = xmalloc(st_add(st_mult(sizeof(char *), nr_rules), total_len));
1072
1073                 offset = 0;
1074                 for (i = 0; i < nr_rules; i++) {
1075                         assert(offset < total_len);
1076                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules] + offset;
1077                         offset += snprintf(scanf_fmts[i], total_len - offset,
1078                                            ref_rev_parse_rules[i], 2, "%s") + 1;
1079                 }
1080         }
1081
1082         /* bail out if there are no rules */
1083         if (!nr_rules)
1084                 return xstrdup(refname);
1085
1086         /* buffer for scanf result, at most refname must fit */
1087         short_name = xstrdup(refname);
1088
1089         /* skip first rule, it will always match */
1090         for (i = nr_rules - 1; i > 0 ; --i) {
1091                 int j;
1092                 int rules_to_fail = i;
1093                 int short_name_len;
1094
1095                 if (1 != sscanf(refname, scanf_fmts[i], short_name))
1096                         continue;
1097
1098                 short_name_len = strlen(short_name);
1099
1100                 /*
1101                  * in strict mode, all (except the matched one) rules
1102                  * must fail to resolve to a valid non-ambiguous ref
1103                  */
1104                 if (strict)
1105                         rules_to_fail = nr_rules;
1106
1107                 /*
1108                  * check if the short name resolves to a valid ref,
1109                  * but use only rules prior to the matched one
1110                  */
1111                 for (j = 0; j < rules_to_fail; j++) {
1112                         const char *rule = ref_rev_parse_rules[j];
1113
1114                         /* skip matched rule */
1115                         if (i == j)
1116                                 continue;
1117
1118                         /*
1119                          * the short name is ambiguous, if it resolves
1120                          * (with this previous rule) to a valid ref
1121                          * read_ref() returns 0 on success
1122                          */
1123                         strbuf_reset(&resolved_buf);
1124                         strbuf_addf(&resolved_buf, rule,
1125                                     short_name_len, short_name);
1126                         if (ref_exists(resolved_buf.buf))
1127                                 break;
1128                 }
1129
1130                 /*
1131                  * short name is non-ambiguous if all previous rules
1132                  * haven't resolved to a valid ref
1133                  */
1134                 if (j == rules_to_fail) {
1135                         strbuf_release(&resolved_buf);
1136                         return short_name;
1137                 }
1138         }
1139
1140         strbuf_release(&resolved_buf);
1141         free(short_name);
1142         return xstrdup(refname);
1143 }
1144
1145 static struct string_list *hide_refs;
1146
1147 int parse_hide_refs_config(const char *var, const char *value, const char *section)
1148 {
1149         const char *key;
1150         if (!strcmp("transfer.hiderefs", var) ||
1151             (!parse_config_key(var, section, NULL, NULL, &key) &&
1152              !strcmp(key, "hiderefs"))) {
1153                 char *ref;
1154                 int len;
1155
1156                 if (!value)
1157                         return config_error_nonbool(var);
1158                 ref = xstrdup(value);
1159                 len = strlen(ref);
1160                 while (len && ref[len - 1] == '/')
1161                         ref[--len] = '\0';
1162                 if (!hide_refs) {
1163                         hide_refs = xcalloc(1, sizeof(*hide_refs));
1164                         hide_refs->strdup_strings = 1;
1165                 }
1166                 string_list_append(hide_refs, ref);
1167         }
1168         return 0;
1169 }
1170
1171 int ref_is_hidden(const char *refname, const char *refname_full)
1172 {
1173         int i;
1174
1175         if (!hide_refs)
1176                 return 0;
1177         for (i = hide_refs->nr - 1; i >= 0; i--) {
1178                 const char *match = hide_refs->items[i].string;
1179                 const char *subject;
1180                 int neg = 0;
1181                 const char *p;
1182
1183                 if (*match == '!') {
1184                         neg = 1;
1185                         match++;
1186                 }
1187
1188                 if (*match == '^') {
1189                         subject = refname_full;
1190                         match++;
1191                 } else {
1192                         subject = refname;
1193                 }
1194
1195                 /* refname can be NULL when namespaces are used. */
1196                 if (subject &&
1197                     skip_prefix(subject, match, &p) &&
1198                     (!*p || *p == '/'))
1199                         return !neg;
1200         }
1201         return 0;
1202 }
1203
1204 const char *find_descendant_ref(const char *dirname,
1205                                 const struct string_list *extras,
1206                                 const struct string_list *skip)
1207 {
1208         int pos;
1209
1210         if (!extras)
1211                 return NULL;
1212
1213         /*
1214          * Look at the place where dirname would be inserted into
1215          * extras. If there is an entry at that position that starts
1216          * with dirname (remember, dirname includes the trailing
1217          * slash) and is not in skip, then we have a conflict.
1218          */
1219         for (pos = string_list_find_insert_index(extras, dirname, 0);
1220              pos < extras->nr; pos++) {
1221                 const char *extra_refname = extras->items[pos].string;
1222
1223                 if (!starts_with(extra_refname, dirname))
1224                         break;
1225
1226                 if (!skip || !string_list_has_string(skip, extra_refname))
1227                         return extra_refname;
1228         }
1229         return NULL;
1230 }
1231
1232 int refs_rename_ref_available(struct ref_store *refs,
1233                               const char *old_refname,
1234                               const char *new_refname)
1235 {
1236         struct string_list skip = STRING_LIST_INIT_NODUP;
1237         struct strbuf err = STRBUF_INIT;
1238         int ok;
1239
1240         string_list_insert(&skip, old_refname);
1241         ok = !refs_verify_refname_available(refs, new_refname,
1242                                             NULL, &skip, &err);
1243         if (!ok)
1244                 error("%s", err.buf);
1245
1246         string_list_clear(&skip, 0);
1247         strbuf_release(&err);
1248         return ok;
1249 }
1250
1251 int refs_head_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1252 {
1253         struct object_id oid;
1254         int flag;
1255
1256         if (!refs_read_ref_full(refs, "HEAD", RESOLVE_REF_READING,
1257                                 oid.hash, &flag))
1258                 return fn("HEAD", &oid, flag, cb_data);
1259
1260         return 0;
1261 }
1262
1263 int head_ref(each_ref_fn fn, void *cb_data)
1264 {
1265         return refs_head_ref(get_main_ref_store(), fn, cb_data);
1266 }
1267
1268 struct ref_iterator *refs_ref_iterator_begin(
1269                 struct ref_store *refs,
1270                 const char *prefix, int trim, int flags)
1271 {
1272         struct ref_iterator *iter;
1273
1274         if (ref_paranoia < 0)
1275                 ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
1276         if (ref_paranoia)
1277                 flags |= DO_FOR_EACH_INCLUDE_BROKEN;
1278
1279         iter = refs->be->iterator_begin(refs, prefix, flags);
1280
1281         /*
1282          * `iterator_begin()` already takes care of prefix, but we
1283          * might need to do some trimming:
1284          */
1285         if (trim)
1286                 iter = prefix_ref_iterator_begin(iter, "", trim);
1287
1288         return iter;
1289 }
1290
1291 /*
1292  * Call fn for each reference in the specified submodule for which the
1293  * refname begins with prefix. If trim is non-zero, then trim that
1294  * many characters off the beginning of each refname before passing
1295  * the refname to fn. flags can be DO_FOR_EACH_INCLUDE_BROKEN to
1296  * include broken references in the iteration. If fn ever returns a
1297  * non-zero value, stop the iteration and return that value;
1298  * otherwise, return 0.
1299  */
1300 static int do_for_each_ref(struct ref_store *refs, const char *prefix,
1301                            each_ref_fn fn, int trim, int flags, void *cb_data)
1302 {
1303         struct ref_iterator *iter;
1304
1305         if (!refs)
1306                 return 0;
1307
1308         iter = refs_ref_iterator_begin(refs, prefix, trim, flags);
1309
1310         return do_for_each_ref_iterator(iter, fn, cb_data);
1311 }
1312
1313 int refs_for_each_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1314 {
1315         return do_for_each_ref(refs, "", fn, 0, 0, cb_data);
1316 }
1317
1318 int for_each_ref(each_ref_fn fn, void *cb_data)
1319 {
1320         return refs_for_each_ref(get_main_ref_store(), fn, cb_data);
1321 }
1322
1323 int refs_for_each_ref_in(struct ref_store *refs, const char *prefix,
1324                          each_ref_fn fn, void *cb_data)
1325 {
1326         return do_for_each_ref(refs, prefix, fn, strlen(prefix), 0, cb_data);
1327 }
1328
1329 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
1330 {
1331         return refs_for_each_ref_in(get_main_ref_store(), prefix, fn, cb_data);
1332 }
1333
1334 int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data, unsigned int broken)
1335 {
1336         unsigned int flag = 0;
1337
1338         if (broken)
1339                 flag = DO_FOR_EACH_INCLUDE_BROKEN;
1340         return do_for_each_ref(get_main_ref_store(),
1341                                prefix, fn, 0, flag, cb_data);
1342 }
1343
1344 int refs_for_each_fullref_in(struct ref_store *refs, const char *prefix,
1345                              each_ref_fn fn, void *cb_data,
1346                              unsigned int broken)
1347 {
1348         unsigned int flag = 0;
1349
1350         if (broken)
1351                 flag = DO_FOR_EACH_INCLUDE_BROKEN;
1352         return do_for_each_ref(refs, prefix, fn, 0, flag, cb_data);
1353 }
1354
1355 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
1356 {
1357         return do_for_each_ref(get_main_ref_store(),
1358                                git_replace_ref_base, fn,
1359                                strlen(git_replace_ref_base),
1360                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1361 }
1362
1363 int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
1364 {
1365         struct strbuf buf = STRBUF_INIT;
1366         int ret;
1367         strbuf_addf(&buf, "%srefs/", get_git_namespace());
1368         ret = do_for_each_ref(get_main_ref_store(),
1369                               buf.buf, fn, 0, 0, cb_data);
1370         strbuf_release(&buf);
1371         return ret;
1372 }
1373
1374 int refs_for_each_rawref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1375 {
1376         return do_for_each_ref(refs, "", fn, 0,
1377                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1378 }
1379
1380 int for_each_rawref(each_ref_fn fn, void *cb_data)
1381 {
1382         return refs_for_each_rawref(get_main_ref_store(), fn, cb_data);
1383 }
1384
1385 int refs_read_raw_ref(struct ref_store *ref_store,
1386                       const char *refname, unsigned char *sha1,
1387                       struct strbuf *referent, unsigned int *type)
1388 {
1389         return ref_store->be->read_raw_ref(ref_store, refname, sha1, referent, type);
1390 }
1391
1392 /* This function needs to return a meaningful errno on failure */
1393 const char *refs_resolve_ref_unsafe(struct ref_store *refs,
1394                                     const char *refname,
1395                                     int resolve_flags,
1396                                     unsigned char *sha1, int *flags)
1397 {
1398         static struct strbuf sb_refname = STRBUF_INIT;
1399         struct object_id unused_oid;
1400         int unused_flags;
1401         int symref_count;
1402
1403         if (!sha1)
1404                 sha1 = unused_oid.hash;
1405         if (!flags)
1406                 flags = &unused_flags;
1407
1408         *flags = 0;
1409
1410         if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1411                 if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1412                     !refname_is_safe(refname)) {
1413                         errno = EINVAL;
1414                         return NULL;
1415                 }
1416
1417                 /*
1418                  * dwim_ref() uses REF_ISBROKEN to distinguish between
1419                  * missing refs and refs that were present but invalid,
1420                  * to complain about the latter to stderr.
1421                  *
1422                  * We don't know whether the ref exists, so don't set
1423                  * REF_ISBROKEN yet.
1424                  */
1425                 *flags |= REF_BAD_NAME;
1426         }
1427
1428         for (symref_count = 0; symref_count < SYMREF_MAXDEPTH; symref_count++) {
1429                 unsigned int read_flags = 0;
1430
1431                 if (refs_read_raw_ref(refs, refname,
1432                                       sha1, &sb_refname, &read_flags)) {
1433                         *flags |= read_flags;
1434                         if (errno != ENOENT || (resolve_flags & RESOLVE_REF_READING))
1435                                 return NULL;
1436                         hashclr(sha1);
1437                         if (*flags & REF_BAD_NAME)
1438                                 *flags |= REF_ISBROKEN;
1439                         return refname;
1440                 }
1441
1442                 *flags |= read_flags;
1443
1444                 if (!(read_flags & REF_ISSYMREF)) {
1445                         if (*flags & REF_BAD_NAME) {
1446                                 hashclr(sha1);
1447                                 *flags |= REF_ISBROKEN;
1448                         }
1449                         return refname;
1450                 }
1451
1452                 refname = sb_refname.buf;
1453                 if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
1454                         hashclr(sha1);
1455                         return refname;
1456                 }
1457                 if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1458                         if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1459                             !refname_is_safe(refname)) {
1460                                 errno = EINVAL;
1461                                 return NULL;
1462                         }
1463
1464                         *flags |= REF_ISBROKEN | REF_BAD_NAME;
1465                 }
1466         }
1467
1468         errno = ELOOP;
1469         return NULL;
1470 }
1471
1472 /* backend functions */
1473 int refs_init_db(struct strbuf *err)
1474 {
1475         struct ref_store *refs = get_main_ref_store();
1476
1477         return refs->be->init_db(refs, err);
1478 }
1479
1480 const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
1481                                unsigned char *sha1, int *flags)
1482 {
1483         return refs_resolve_ref_unsafe(get_main_ref_store(), refname,
1484                                        resolve_flags, sha1, flags);
1485 }
1486
1487 int resolve_gitlink_ref(const char *submodule, const char *refname,
1488                         unsigned char *sha1)
1489 {
1490         struct ref_store *refs;
1491         int flags;
1492
1493         refs = get_submodule_ref_store(submodule);
1494
1495         if (!refs)
1496                 return -1;
1497
1498         if (!refs_resolve_ref_unsafe(refs, refname, 0, sha1, &flags) ||
1499             is_null_sha1(sha1))
1500                 return -1;
1501         return 0;
1502 }
1503
1504 struct ref_store_hash_entry
1505 {
1506         struct hashmap_entry ent; /* must be the first member! */
1507
1508         struct ref_store *refs;
1509
1510         /* NUL-terminated identifier of the ref store: */
1511         char name[FLEX_ARRAY];
1512 };
1513
1514 static int ref_store_hash_cmp(const void *unused_cmp_data,
1515                               const void *entry, const void *entry_or_key,
1516                               const void *keydata)
1517 {
1518         const struct ref_store_hash_entry *e1 = entry, *e2 = entry_or_key;
1519         const char *name = keydata ? keydata : e2->name;
1520
1521         return strcmp(e1->name, name);
1522 }
1523
1524 static struct ref_store_hash_entry *alloc_ref_store_hash_entry(
1525                 const char *name, struct ref_store *refs)
1526 {
1527         struct ref_store_hash_entry *entry;
1528
1529         FLEX_ALLOC_STR(entry, name, name);
1530         hashmap_entry_init(entry, strhash(name));
1531         entry->refs = refs;
1532         return entry;
1533 }
1534
1535 /* A pointer to the ref_store for the main repository: */
1536 static struct ref_store *main_ref_store;
1537
1538 /* A hashmap of ref_stores, stored by submodule name: */
1539 static struct hashmap submodule_ref_stores;
1540
1541 /* A hashmap of ref_stores, stored by worktree id: */
1542 static struct hashmap worktree_ref_stores;
1543
1544 /*
1545  * Look up a ref store by name. If that ref_store hasn't been
1546  * registered yet, return NULL.
1547  */
1548 static struct ref_store *lookup_ref_store_map(struct hashmap *map,
1549                                               const char *name)
1550 {
1551         struct ref_store_hash_entry *entry;
1552
1553         if (!map->tablesize)
1554                 /* It's initialized on demand in register_ref_store(). */
1555                 return NULL;
1556
1557         entry = hashmap_get_from_hash(map, strhash(name), name);
1558         return entry ? entry->refs : NULL;
1559 }
1560
1561 /*
1562  * Create, record, and return a ref_store instance for the specified
1563  * gitdir.
1564  */
1565 static struct ref_store *ref_store_init(const char *gitdir,
1566                                         unsigned int flags)
1567 {
1568         const char *be_name = "files";
1569         struct ref_storage_be *be = find_ref_storage_backend(be_name);
1570         struct ref_store *refs;
1571
1572         if (!be)
1573                 die("BUG: reference backend %s is unknown", be_name);
1574
1575         refs = be->init(gitdir, flags);
1576         return refs;
1577 }
1578
1579 struct ref_store *get_main_ref_store(void)
1580 {
1581         if (main_ref_store)
1582                 return main_ref_store;
1583
1584         main_ref_store = ref_store_init(get_git_dir(), REF_STORE_ALL_CAPS);
1585         return main_ref_store;
1586 }
1587
1588 /*
1589  * Associate a ref store with a name. It is a fatal error to call this
1590  * function twice for the same name.
1591  */
1592 static void register_ref_store_map(struct hashmap *map,
1593                                    const char *type,
1594                                    struct ref_store *refs,
1595                                    const char *name)
1596 {
1597         if (!map->tablesize)
1598                 hashmap_init(map, ref_store_hash_cmp, NULL, 0);
1599
1600         if (hashmap_put(map, alloc_ref_store_hash_entry(name, refs)))
1601                 die("BUG: %s ref_store '%s' initialized twice", type, name);
1602 }
1603
1604 struct ref_store *get_submodule_ref_store(const char *submodule)
1605 {
1606         struct strbuf submodule_sb = STRBUF_INIT;
1607         struct ref_store *refs;
1608         char *to_free = NULL;
1609         size_t len;
1610
1611         if (!submodule)
1612                 return NULL;
1613
1614         len = strlen(submodule);
1615         while (len && is_dir_sep(submodule[len - 1]))
1616                 len--;
1617         if (!len)
1618                 return NULL;
1619
1620         if (submodule[len])
1621                 /* We need to strip off one or more trailing slashes */
1622                 submodule = to_free = xmemdupz(submodule, len);
1623
1624         refs = lookup_ref_store_map(&submodule_ref_stores, submodule);
1625         if (refs)
1626                 goto done;
1627
1628         strbuf_addstr(&submodule_sb, submodule);
1629         if (!is_nonbare_repository_dir(&submodule_sb))
1630                 goto done;
1631
1632         if (submodule_to_gitdir(&submodule_sb, submodule))
1633                 goto done;
1634
1635         /* assume that add_submodule_odb() has been called */
1636         refs = ref_store_init(submodule_sb.buf,
1637                               REF_STORE_READ | REF_STORE_ODB);
1638         register_ref_store_map(&submodule_ref_stores, "submodule",
1639                                refs, submodule);
1640
1641 done:
1642         strbuf_release(&submodule_sb);
1643         free(to_free);
1644
1645         return refs;
1646 }
1647
1648 struct ref_store *get_worktree_ref_store(const struct worktree *wt)
1649 {
1650         struct ref_store *refs;
1651         const char *id;
1652
1653         if (wt->is_current)
1654                 return get_main_ref_store();
1655
1656         id = wt->id ? wt->id : "/";
1657         refs = lookup_ref_store_map(&worktree_ref_stores, id);
1658         if (refs)
1659                 return refs;
1660
1661         if (wt->id)
1662                 refs = ref_store_init(git_common_path("worktrees/%s", wt->id),
1663                                       REF_STORE_ALL_CAPS);
1664         else
1665                 refs = ref_store_init(get_git_common_dir(),
1666                                       REF_STORE_ALL_CAPS);
1667
1668         if (refs)
1669                 register_ref_store_map(&worktree_ref_stores, "worktree",
1670                                        refs, id);
1671         return refs;
1672 }
1673
1674 void base_ref_store_init(struct ref_store *refs,
1675                          const struct ref_storage_be *be)
1676 {
1677         refs->be = be;
1678 }
1679
1680 /* backend functions */
1681 int refs_pack_refs(struct ref_store *refs, unsigned int flags)
1682 {
1683         return refs->be->pack_refs(refs, flags);
1684 }
1685
1686 int refs_peel_ref(struct ref_store *refs, const char *refname,
1687                   unsigned char *sha1)
1688 {
1689         return refs->be->peel_ref(refs, refname, sha1);
1690 }
1691
1692 int peel_ref(const char *refname, unsigned char *sha1)
1693 {
1694         return refs_peel_ref(get_main_ref_store(), refname, sha1);
1695 }
1696
1697 int refs_create_symref(struct ref_store *refs,
1698                        const char *ref_target,
1699                        const char *refs_heads_master,
1700                        const char *logmsg)
1701 {
1702         return refs->be->create_symref(refs, ref_target,
1703                                        refs_heads_master,
1704                                        logmsg);
1705 }
1706
1707 int create_symref(const char *ref_target, const char *refs_heads_master,
1708                   const char *logmsg)
1709 {
1710         return refs_create_symref(get_main_ref_store(), ref_target,
1711                                   refs_heads_master, logmsg);
1712 }
1713
1714 int ref_update_reject_duplicates(struct string_list *refnames,
1715                                  struct strbuf *err)
1716 {
1717         size_t i, n = refnames->nr;
1718
1719         assert(err);
1720
1721         for (i = 1; i < n; i++) {
1722                 int cmp = strcmp(refnames->items[i - 1].string,
1723                                  refnames->items[i].string);
1724
1725                 if (!cmp) {
1726                         strbuf_addf(err,
1727                                     "multiple updates for ref '%s' not allowed.",
1728                                     refnames->items[i].string);
1729                         return 1;
1730                 } else if (cmp > 0) {
1731                         die("BUG: ref_update_reject_duplicates() received unsorted list");
1732                 }
1733         }
1734         return 0;
1735 }
1736
1737 int ref_transaction_prepare(struct ref_transaction *transaction,
1738                             struct strbuf *err)
1739 {
1740         struct ref_store *refs = transaction->ref_store;
1741
1742         switch (transaction->state) {
1743         case REF_TRANSACTION_OPEN:
1744                 /* Good. */
1745                 break;
1746         case REF_TRANSACTION_PREPARED:
1747                 die("BUG: prepare called twice on reference transaction");
1748                 break;
1749         case REF_TRANSACTION_CLOSED:
1750                 die("BUG: prepare called on a closed reference transaction");
1751                 break;
1752         default:
1753                 die("BUG: unexpected reference transaction state");
1754                 break;
1755         }
1756
1757         if (getenv(GIT_QUARANTINE_ENVIRONMENT)) {
1758                 strbuf_addstr(err,
1759                               _("ref updates forbidden inside quarantine environment"));
1760                 return -1;
1761         }
1762
1763         return refs->be->transaction_prepare(refs, transaction, err);
1764 }
1765
1766 int ref_transaction_abort(struct ref_transaction *transaction,
1767                           struct strbuf *err)
1768 {
1769         struct ref_store *refs = transaction->ref_store;
1770         int ret = 0;
1771
1772         switch (transaction->state) {
1773         case REF_TRANSACTION_OPEN:
1774                 /* No need to abort explicitly. */
1775                 break;
1776         case REF_TRANSACTION_PREPARED:
1777                 ret = refs->be->transaction_abort(refs, transaction, err);
1778                 break;
1779         case REF_TRANSACTION_CLOSED:
1780                 die("BUG: abort called on a closed reference transaction");
1781                 break;
1782         default:
1783                 die("BUG: unexpected reference transaction state");
1784                 break;
1785         }
1786
1787         ref_transaction_free(transaction);
1788         return ret;
1789 }
1790
1791 int ref_transaction_commit(struct ref_transaction *transaction,
1792                            struct strbuf *err)
1793 {
1794         struct ref_store *refs = transaction->ref_store;
1795         int ret;
1796
1797         switch (transaction->state) {
1798         case REF_TRANSACTION_OPEN:
1799                 /* Need to prepare first. */
1800                 ret = ref_transaction_prepare(transaction, err);
1801                 if (ret)
1802                         return ret;
1803                 break;
1804         case REF_TRANSACTION_PREPARED:
1805                 /* Fall through to finish. */
1806                 break;
1807         case REF_TRANSACTION_CLOSED:
1808                 die("BUG: commit called on a closed reference transaction");
1809                 break;
1810         default:
1811                 die("BUG: unexpected reference transaction state");
1812                 break;
1813         }
1814
1815         return refs->be->transaction_finish(refs, transaction, err);
1816 }
1817
1818 int refs_verify_refname_available(struct ref_store *refs,
1819                                   const char *refname,
1820                                   const struct string_list *extras,
1821                                   const struct string_list *skip,
1822                                   struct strbuf *err)
1823 {
1824         const char *slash;
1825         const char *extra_refname;
1826         struct strbuf dirname = STRBUF_INIT;
1827         struct strbuf referent = STRBUF_INIT;
1828         struct object_id oid;
1829         unsigned int type;
1830         struct ref_iterator *iter;
1831         int ok;
1832         int ret = -1;
1833
1834         /*
1835          * For the sake of comments in this function, suppose that
1836          * refname is "refs/foo/bar".
1837          */
1838
1839         assert(err);
1840
1841         strbuf_grow(&dirname, strlen(refname) + 1);
1842         for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
1843                 /* Expand dirname to the new prefix, not including the trailing slash: */
1844                 strbuf_add(&dirname, refname + dirname.len, slash - refname - dirname.len);
1845
1846                 /*
1847                  * We are still at a leading dir of the refname (e.g.,
1848                  * "refs/foo"; if there is a reference with that name,
1849                  * it is a conflict, *unless* it is in skip.
1850                  */
1851                 if (skip && string_list_has_string(skip, dirname.buf))
1852                         continue;
1853
1854                 if (!refs_read_raw_ref(refs, dirname.buf, oid.hash, &referent, &type)) {
1855                         strbuf_addf(err, "'%s' exists; cannot create '%s'",
1856                                     dirname.buf, refname);
1857                         goto cleanup;
1858                 }
1859
1860                 if (extras && string_list_has_string(extras, dirname.buf)) {
1861                         strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
1862                                     refname, dirname.buf);
1863                         goto cleanup;
1864                 }
1865         }
1866
1867         /*
1868          * We are at the leaf of our refname (e.g., "refs/foo/bar").
1869          * There is no point in searching for a reference with that
1870          * name, because a refname isn't considered to conflict with
1871          * itself. But we still need to check for references whose
1872          * names are in the "refs/foo/bar/" namespace, because they
1873          * *do* conflict.
1874          */
1875         strbuf_addstr(&dirname, refname + dirname.len);
1876         strbuf_addch(&dirname, '/');
1877
1878         iter = refs_ref_iterator_begin(refs, dirname.buf, 0,
1879                                        DO_FOR_EACH_INCLUDE_BROKEN);
1880         while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
1881                 if (skip &&
1882                     string_list_has_string(skip, iter->refname))
1883                         continue;
1884
1885                 strbuf_addf(err, "'%s' exists; cannot create '%s'",
1886                             iter->refname, refname);
1887                 ref_iterator_abort(iter);
1888                 goto cleanup;
1889         }
1890
1891         if (ok != ITER_DONE)
1892                 die("BUG: error while iterating over references");
1893
1894         extra_refname = find_descendant_ref(dirname.buf, extras, skip);
1895         if (extra_refname)
1896                 strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
1897                             refname, extra_refname);
1898         else
1899                 ret = 0;
1900
1901 cleanup:
1902         strbuf_release(&referent);
1903         strbuf_release(&dirname);
1904         return ret;
1905 }
1906
1907 int refs_for_each_reflog(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1908 {
1909         struct ref_iterator *iter;
1910
1911         iter = refs->be->reflog_iterator_begin(refs);
1912
1913         return do_for_each_ref_iterator(iter, fn, cb_data);
1914 }
1915
1916 int for_each_reflog(each_ref_fn fn, void *cb_data)
1917 {
1918         return refs_for_each_reflog(get_main_ref_store(), fn, cb_data);
1919 }
1920
1921 int refs_for_each_reflog_ent_reverse(struct ref_store *refs,
1922                                      const char *refname,
1923                                      each_reflog_ent_fn fn,
1924                                      void *cb_data)
1925 {
1926         return refs->be->for_each_reflog_ent_reverse(refs, refname,
1927                                                      fn, cb_data);
1928 }
1929
1930 int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn,
1931                                 void *cb_data)
1932 {
1933         return refs_for_each_reflog_ent_reverse(get_main_ref_store(),
1934                                                 refname, fn, cb_data);
1935 }
1936
1937 int refs_for_each_reflog_ent(struct ref_store *refs, const char *refname,
1938                              each_reflog_ent_fn fn, void *cb_data)
1939 {
1940         return refs->be->for_each_reflog_ent(refs, refname, fn, cb_data);
1941 }
1942
1943 int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn,
1944                         void *cb_data)
1945 {
1946         return refs_for_each_reflog_ent(get_main_ref_store(), refname,
1947                                         fn, cb_data);
1948 }
1949
1950 int refs_reflog_exists(struct ref_store *refs, const char *refname)
1951 {
1952         return refs->be->reflog_exists(refs, refname);
1953 }
1954
1955 int reflog_exists(const char *refname)
1956 {
1957         return refs_reflog_exists(get_main_ref_store(), refname);
1958 }
1959
1960 int refs_create_reflog(struct ref_store *refs, const char *refname,
1961                        int force_create, struct strbuf *err)
1962 {
1963         return refs->be->create_reflog(refs, refname, force_create, err);
1964 }
1965
1966 int safe_create_reflog(const char *refname, int force_create,
1967                        struct strbuf *err)
1968 {
1969         return refs_create_reflog(get_main_ref_store(), refname,
1970                                   force_create, err);
1971 }
1972
1973 int refs_delete_reflog(struct ref_store *refs, const char *refname)
1974 {
1975         return refs->be->delete_reflog(refs, refname);
1976 }
1977
1978 int delete_reflog(const char *refname)
1979 {
1980         return refs_delete_reflog(get_main_ref_store(), refname);
1981 }
1982
1983 int refs_reflog_expire(struct ref_store *refs,
1984                        const char *refname, const unsigned char *sha1,
1985                        unsigned int flags,
1986                        reflog_expiry_prepare_fn prepare_fn,
1987                        reflog_expiry_should_prune_fn should_prune_fn,
1988                        reflog_expiry_cleanup_fn cleanup_fn,
1989                        void *policy_cb_data)
1990 {
1991         return refs->be->reflog_expire(refs, refname, sha1, flags,
1992                                        prepare_fn, should_prune_fn,
1993                                        cleanup_fn, policy_cb_data);
1994 }
1995
1996 int reflog_expire(const char *refname, const unsigned char *sha1,
1997                   unsigned int flags,
1998                   reflog_expiry_prepare_fn prepare_fn,
1999                   reflog_expiry_should_prune_fn should_prune_fn,
2000                   reflog_expiry_cleanup_fn cleanup_fn,
2001                   void *policy_cb_data)
2002 {
2003         return refs_reflog_expire(get_main_ref_store(),
2004                                   refname, sha1, flags,
2005                                   prepare_fn, should_prune_fn,
2006                                   cleanup_fn, policy_cb_data);
2007 }
2008
2009 int initial_ref_transaction_commit(struct ref_transaction *transaction,
2010                                    struct strbuf *err)
2011 {
2012         struct ref_store *refs = transaction->ref_store;
2013
2014         return refs->be->initial_transaction_commit(refs, transaction, err);
2015 }
2016
2017 int refs_delete_refs(struct ref_store *refs, const char *msg,
2018                      struct string_list *refnames, unsigned int flags)
2019 {
2020         return refs->be->delete_refs(refs, msg, refnames, flags);
2021 }
2022
2023 int delete_refs(const char *msg, struct string_list *refnames,
2024                 unsigned int flags)
2025 {
2026         return refs_delete_refs(get_main_ref_store(), msg, refnames, flags);
2027 }
2028
2029 int refs_rename_ref(struct ref_store *refs, const char *oldref,
2030                     const char *newref, const char *logmsg)
2031 {
2032         return refs->be->rename_ref(refs, oldref, newref, logmsg);
2033 }
2034
2035 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
2036 {
2037         return refs_rename_ref(get_main_ref_store(), oldref, newref, logmsg);
2038 }