refs.con commit refs: update some more docs to use "oid" rather than "sha1" (78fb457)
   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 */
  20static struct ref_storage_be *refs_backends = &refs_be_files;
  21
  22static 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
  31int 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 */
  46static 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 */
  72static 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        }
 106out:
 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
 117int 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
 145int 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 */
 182int 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
 195char *refs_resolve_refdup(struct ref_store *refs,
 196                          const char *refname, int resolve_flags,
 197                          struct object_id *oid, int *flags)
 198{
 199        const char *result;
 200
 201        result = refs_resolve_ref_unsafe(refs, refname, resolve_flags,
 202                                         oid, flags);
 203        return xstrdup_or_null(result);
 204}
 205
 206char *resolve_refdup(const char *refname, int resolve_flags,
 207                     struct object_id *oid, int *flags)
 208{
 209        return refs_resolve_refdup(get_main_ref_store(),
 210                                   refname, resolve_flags,
 211                                   oid, flags);
 212}
 213
 214/* The argument to filter_refs */
 215struct ref_filter {
 216        const char *pattern;
 217        each_ref_fn *fn;
 218        void *cb_data;
 219};
 220
 221int refs_read_ref_full(struct ref_store *refs, const char *refname,
 222                       int resolve_flags, struct object_id *oid, int *flags)
 223{
 224        if (refs_resolve_ref_unsafe(refs, refname, resolve_flags, oid, flags))
 225                return 0;
 226        return -1;
 227}
 228
 229int read_ref_full(const char *refname, int resolve_flags, struct object_id *oid, int *flags)
 230{
 231        return refs_read_ref_full(get_main_ref_store(), refname,
 232                                  resolve_flags, oid, flags);
 233}
 234
 235int read_ref(const char *refname, struct object_id *oid)
 236{
 237        return read_ref_full(refname, RESOLVE_REF_READING, oid, NULL);
 238}
 239
 240int ref_exists(const char *refname)
 241{
 242        return !!resolve_ref_unsafe(refname, RESOLVE_REF_READING, NULL, NULL);
 243}
 244
 245static 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
 255enum peel_status peel_object(const struct object_id *name, struct object_id *oid)
 256{
 257        struct object *o = lookup_unknown_object(name->hash);
 258
 259        if (o->type == OBJ_NONE) {
 260                int type = sha1_object_info(name->hash, 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        oidcpy(oid, &o->oid);
 273        return PEEL_PEELED;
 274}
 275
 276struct warn_if_dangling_data {
 277        FILE *fp;
 278        const char *refname;
 279        const struct string_list *refnames;
 280        const char *msg_fmt;
 281};
 282
 283static 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
 305void 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
 316void 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
 327int 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
 332int 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
 337int 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
 342int 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
 347int 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
 352int 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
 357int 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, &flag))
 366                ret = fn(buf.buf, &oid, flag, cb_data);
 367        strbuf_release(&buf);
 368
 369        return ret;
 370}
 371
 372int 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
 401int 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
 406const 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
 415static 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
 425int 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 */
 444static 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
 459int dwim_ref(const char *str, int len, struct object_id *oid, char **ref)
 460{
 461        char *last_branch = substitute_branch_name(&str, &len);
 462        int   refs_found  = expand_ref(str, len, oid, ref);
 463        free(last_branch);
 464        return refs_found;
 465}
 466
 467int expand_ref(const char *str, int len, struct object_id *oid, 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                struct object_id oid_from_ref;
 476                struct object_id *this_result;
 477                int flag;
 478
 479                this_result = refs_found ? &oid_from_ref : oid;
 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
 499int dwim_log(const char *str, int len, struct object_id *oid, 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                struct object_id hash;
 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                        oidcpy(oid, &hash);
 526                }
 527                if (!warn_ambiguous_refs)
 528                        break;
 529        }
 530        strbuf_release(&path);
 531        free(last_branch);
 532        return logs_found;
 533}
 534
 535static int is_per_worktree_ref(const char *refname)
 536{
 537        return !strcmp(refname, "HEAD") ||
 538                starts_with(refname, "refs/bisect/");
 539}
 540
 541static 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
 553enum 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
 562long 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
 577static int write_pseudoref(const char *pseudoref, const struct object_id *oid,
 578                           const struct object_id *old_oid, 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        if (!oid)
 587                return 0;
 588
 589        strbuf_addf(&buf, "%s\n", oid_to_hex(oid));
 590
 591        filename = git_path("%s", pseudoref);
 592        fd = hold_lock_file_for_update_timeout(&lock, filename,
 593                                               LOCK_DIE_ON_ERROR,
 594                                               get_files_ref_lock_timeout_ms());
 595        if (fd < 0) {
 596                strbuf_addf(err, "could not open '%s' for writing: %s",
 597                            filename, strerror(errno));
 598                goto done;
 599        }
 600
 601        if (old_oid) {
 602                struct object_id actual_old_oid;
 603
 604                if (read_ref(pseudoref, &actual_old_oid))
 605                        die("could not read ref '%s'", pseudoref);
 606                if (oidcmp(&actual_old_oid, old_oid)) {
 607                        strbuf_addf(err, "unexpected sha1 when writing '%s'", pseudoref);
 608                        rollback_lock_file(&lock);
 609                        goto done;
 610                }
 611        }
 612
 613        if (write_in_full(fd, buf.buf, buf.len) < 0) {
 614                strbuf_addf(err, "could not write to '%s'", filename);
 615                rollback_lock_file(&lock);
 616                goto done;
 617        }
 618
 619        commit_lock_file(&lock);
 620        ret = 0;
 621done:
 622        strbuf_release(&buf);
 623        return ret;
 624}
 625
 626static int delete_pseudoref(const char *pseudoref, const struct object_id *old_oid)
 627{
 628        static struct lock_file lock;
 629        const char *filename;
 630
 631        filename = git_path("%s", pseudoref);
 632
 633        if (old_oid && !is_null_oid(old_oid)) {
 634                int fd;
 635                struct object_id actual_old_oid;
 636
 637                fd = hold_lock_file_for_update_timeout(
 638                                &lock, filename, LOCK_DIE_ON_ERROR,
 639                                get_files_ref_lock_timeout_ms());
 640                if (fd < 0)
 641                        die_errno(_("Could not open '%s' for writing"), filename);
 642                if (read_ref(pseudoref, &actual_old_oid))
 643                        die("could not read ref '%s'", pseudoref);
 644                if (oidcmp(&actual_old_oid, old_oid)) {
 645                        warning("Unexpected sha1 when deleting %s", pseudoref);
 646                        rollback_lock_file(&lock);
 647                        return -1;
 648                }
 649
 650                unlink(filename);
 651                rollback_lock_file(&lock);
 652        } else {
 653                unlink(filename);
 654        }
 655
 656        return 0;
 657}
 658
 659int refs_delete_ref(struct ref_store *refs, const char *msg,
 660                    const char *refname,
 661                    const struct object_id *old_oid,
 662                    unsigned int flags)
 663{
 664        struct ref_transaction *transaction;
 665        struct strbuf err = STRBUF_INIT;
 666
 667        if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
 668                assert(refs == get_main_ref_store());
 669                return delete_pseudoref(refname, old_oid);
 670        }
 671
 672        transaction = ref_store_transaction_begin(refs, &err);
 673        if (!transaction ||
 674            ref_transaction_delete(transaction, refname, old_oid,
 675                                   flags, msg, &err) ||
 676            ref_transaction_commit(transaction, &err)) {
 677                error("%s", err.buf);
 678                ref_transaction_free(transaction);
 679                strbuf_release(&err);
 680                return 1;
 681        }
 682        ref_transaction_free(transaction);
 683        strbuf_release(&err);
 684        return 0;
 685}
 686
 687int delete_ref(const char *msg, const char *refname,
 688               const struct object_id *old_oid, unsigned int flags)
 689{
 690        return refs_delete_ref(get_main_ref_store(), msg, refname,
 691                               old_oid, flags);
 692}
 693
 694int copy_reflog_msg(char *buf, const char *msg)
 695{
 696        char *cp = buf;
 697        char c;
 698        int wasspace = 1;
 699
 700        *cp++ = '\t';
 701        while ((c = *msg++)) {
 702                if (wasspace && isspace(c))
 703                        continue;
 704                wasspace = isspace(c);
 705                if (wasspace)
 706                        c = ' ';
 707                *cp++ = c;
 708        }
 709        while (buf < cp && isspace(cp[-1]))
 710                cp--;
 711        *cp++ = '\n';
 712        return cp - buf;
 713}
 714
 715int should_autocreate_reflog(const char *refname)
 716{
 717        switch (log_all_ref_updates) {
 718        case LOG_REFS_ALWAYS:
 719                return 1;
 720        case LOG_REFS_NORMAL:
 721                return starts_with(refname, "refs/heads/") ||
 722                        starts_with(refname, "refs/remotes/") ||
 723                        starts_with(refname, "refs/notes/") ||
 724                        !strcmp(refname, "HEAD");
 725        default:
 726                return 0;
 727        }
 728}
 729
 730int is_branch(const char *refname)
 731{
 732        return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
 733}
 734
 735struct read_ref_at_cb {
 736        const char *refname;
 737        timestamp_t at_time;
 738        int cnt;
 739        int reccnt;
 740        struct object_id *oid;
 741        int found_it;
 742
 743        struct object_id ooid;
 744        struct object_id noid;
 745        int tz;
 746        timestamp_t date;
 747        char **msg;
 748        timestamp_t *cutoff_time;
 749        int *cutoff_tz;
 750        int *cutoff_cnt;
 751};
 752
 753static int read_ref_at_ent(struct object_id *ooid, struct object_id *noid,
 754                const char *email, timestamp_t timestamp, int tz,
 755                const char *message, void *cb_data)
 756{
 757        struct read_ref_at_cb *cb = cb_data;
 758
 759        cb->reccnt++;
 760        cb->tz = tz;
 761        cb->date = timestamp;
 762
 763        if (timestamp <= cb->at_time || cb->cnt == 0) {
 764                if (cb->msg)
 765                        *cb->msg = xstrdup(message);
 766                if (cb->cutoff_time)
 767                        *cb->cutoff_time = timestamp;
 768                if (cb->cutoff_tz)
 769                        *cb->cutoff_tz = tz;
 770                if (cb->cutoff_cnt)
 771                        *cb->cutoff_cnt = cb->reccnt - 1;
 772                /*
 773                 * we have not yet updated cb->[n|o]oid so they still
 774                 * hold the values for the previous record.
 775                 */
 776                if (!is_null_oid(&cb->ooid)) {
 777                        oidcpy(cb->oid, noid);
 778                        if (oidcmp(&cb->ooid, noid))
 779                                warning("Log for ref %s has gap after %s.",
 780                                        cb->refname, show_date(cb->date, cb->tz, DATE_MODE(RFC2822)));
 781                }
 782                else if (cb->date == cb->at_time)
 783                        oidcpy(cb->oid, noid);
 784                else if (oidcmp(noid, cb->oid))
 785                        warning("Log for ref %s unexpectedly ended on %s.",
 786                                cb->refname, show_date(cb->date, cb->tz,
 787                                                       DATE_MODE(RFC2822)));
 788                oidcpy(&cb->ooid, ooid);
 789                oidcpy(&cb->noid, noid);
 790                cb->found_it = 1;
 791                return 1;
 792        }
 793        oidcpy(&cb->ooid, ooid);
 794        oidcpy(&cb->noid, noid);
 795        if (cb->cnt > 0)
 796                cb->cnt--;
 797        return 0;
 798}
 799
 800static int read_ref_at_ent_oldest(struct object_id *ooid, struct object_id *noid,
 801                                  const char *email, timestamp_t timestamp,
 802                                  int tz, const char *message, void *cb_data)
 803{
 804        struct read_ref_at_cb *cb = cb_data;
 805
 806        if (cb->msg)
 807                *cb->msg = xstrdup(message);
 808        if (cb->cutoff_time)
 809                *cb->cutoff_time = timestamp;
 810        if (cb->cutoff_tz)
 811                *cb->cutoff_tz = tz;
 812        if (cb->cutoff_cnt)
 813                *cb->cutoff_cnt = cb->reccnt;
 814        oidcpy(cb->oid, ooid);
 815        if (is_null_oid(cb->oid))
 816                oidcpy(cb->oid, noid);
 817        /* We just want the first entry */
 818        return 1;
 819}
 820
 821int read_ref_at(const char *refname, unsigned int flags, timestamp_t at_time, int cnt,
 822                struct object_id *oid, char **msg,
 823                timestamp_t *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
 824{
 825        struct read_ref_at_cb cb;
 826
 827        memset(&cb, 0, sizeof(cb));
 828        cb.refname = refname;
 829        cb.at_time = at_time;
 830        cb.cnt = cnt;
 831        cb.msg = msg;
 832        cb.cutoff_time = cutoff_time;
 833        cb.cutoff_tz = cutoff_tz;
 834        cb.cutoff_cnt = cutoff_cnt;
 835        cb.oid = oid;
 836
 837        for_each_reflog_ent_reverse(refname, read_ref_at_ent, &cb);
 838
 839        if (!cb.reccnt) {
 840                if (flags & GET_OID_QUIETLY)
 841                        exit(128);
 842                else
 843                        die("Log for %s is empty.", refname);
 844        }
 845        if (cb.found_it)
 846                return 0;
 847
 848        for_each_reflog_ent(refname, read_ref_at_ent_oldest, &cb);
 849
 850        return 1;
 851}
 852
 853struct ref_transaction *ref_store_transaction_begin(struct ref_store *refs,
 854                                                    struct strbuf *err)
 855{
 856        struct ref_transaction *tr;
 857        assert(err);
 858
 859        tr = xcalloc(1, sizeof(struct ref_transaction));
 860        tr->ref_store = refs;
 861        return tr;
 862}
 863
 864struct ref_transaction *ref_transaction_begin(struct strbuf *err)
 865{
 866        return ref_store_transaction_begin(get_main_ref_store(), err);
 867}
 868
 869void ref_transaction_free(struct ref_transaction *transaction)
 870{
 871        size_t i;
 872
 873        if (!transaction)
 874                return;
 875
 876        switch (transaction->state) {
 877        case REF_TRANSACTION_OPEN:
 878        case REF_TRANSACTION_CLOSED:
 879                /* OK */
 880                break;
 881        case REF_TRANSACTION_PREPARED:
 882                die("BUG: free called on a prepared reference transaction");
 883                break;
 884        default:
 885                die("BUG: unexpected reference transaction state");
 886                break;
 887        }
 888
 889        for (i = 0; i < transaction->nr; i++) {
 890                free(transaction->updates[i]->msg);
 891                free(transaction->updates[i]);
 892        }
 893        free(transaction->updates);
 894        free(transaction);
 895}
 896
 897struct ref_update *ref_transaction_add_update(
 898                struct ref_transaction *transaction,
 899                const char *refname, unsigned int flags,
 900                const struct object_id *new_oid,
 901                const struct object_id *old_oid,
 902                const char *msg)
 903{
 904        struct ref_update *update;
 905
 906        if (transaction->state != REF_TRANSACTION_OPEN)
 907                die("BUG: update called for transaction that is not open");
 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                oidcpy(&update->new_oid, new_oid);
 917        if (flags & REF_HAVE_OLD)
 918                oidcpy(&update->old_oid, old_oid);
 919        update->msg = xstrdup_or_null(msg);
 920        return update;
 921}
 922
 923int ref_transaction_update(struct ref_transaction *transaction,
 924                           const char *refname,
 925                           const struct object_id *new_oid,
 926                           const struct object_id *old_oid,
 927                           unsigned int flags, const char *msg,
 928                           struct strbuf *err)
 929{
 930        assert(err);
 931
 932        if ((new_oid && !is_null_oid(new_oid)) ?
 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        if (flags & ~REF_TRANSACTION_UPDATE_ALLOWED_FLAGS)
 941                BUG("illegal flags 0x%x passed to ref_transaction_update()", flags);
 942
 943        flags |= (new_oid ? REF_HAVE_NEW : 0) | (old_oid ? REF_HAVE_OLD : 0);
 944
 945        ref_transaction_add_update(transaction, refname, flags,
 946                                   new_oid, old_oid, msg);
 947        return 0;
 948}
 949
 950int ref_transaction_create(struct ref_transaction *transaction,
 951                           const char *refname,
 952                           const struct object_id *new_oid,
 953                           unsigned int flags, const char *msg,
 954                           struct strbuf *err)
 955{
 956        if (!new_oid || is_null_oid(new_oid))
 957                die("BUG: create called without valid new_oid");
 958        return ref_transaction_update(transaction, refname, new_oid,
 959                                      &null_oid, flags, msg, err);
 960}
 961
 962int ref_transaction_delete(struct ref_transaction *transaction,
 963                           const char *refname,
 964                           const struct object_id *old_oid,
 965                           unsigned int flags, const char *msg,
 966                           struct strbuf *err)
 967{
 968        if (old_oid && is_null_oid(old_oid))
 969                die("BUG: delete called with old_oid set to zeros");
 970        return ref_transaction_update(transaction, refname,
 971                                      &null_oid, old_oid,
 972                                      flags, msg, err);
 973}
 974
 975int ref_transaction_verify(struct ref_transaction *transaction,
 976                           const char *refname,
 977                           const struct object_id *old_oid,
 978                           unsigned int flags,
 979                           struct strbuf *err)
 980{
 981        if (!old_oid)
 982                die("BUG: verify called with old_oid set to NULL");
 983        return ref_transaction_update(transaction, refname,
 984                                      NULL, old_oid,
 985                                      flags, NULL, err);
 986}
 987
 988int refs_update_ref(struct ref_store *refs, const char *msg,
 989                    const char *refname, const struct object_id *new_oid,
 990                    const struct object_id *old_oid, unsigned int flags,
 991                    enum action_on_err onerr)
 992{
 993        struct ref_transaction *t = NULL;
 994        struct strbuf err = STRBUF_INIT;
 995        int ret = 0;
 996
 997        if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
 998                assert(refs == get_main_ref_store());
 999                ret = write_pseudoref(refname, new_oid, old_oid, &err);
1000        } else {
1001                t = ref_store_transaction_begin(refs, &err);
1002                if (!t ||
1003                    ref_transaction_update(t, refname, new_oid, old_oid,
1004                                           flags, msg, &err) ||
1005                    ref_transaction_commit(t, &err)) {
1006                        ret = 1;
1007                        ref_transaction_free(t);
1008                }
1009        }
1010        if (ret) {
1011                const char *str = "update_ref failed for ref '%s': %s";
1012
1013                switch (onerr) {
1014                case UPDATE_REFS_MSG_ON_ERR:
1015                        error(str, refname, err.buf);
1016                        break;
1017                case UPDATE_REFS_DIE_ON_ERR:
1018                        die(str, refname, err.buf);
1019                        break;
1020                case UPDATE_REFS_QUIET_ON_ERR:
1021                        break;
1022                }
1023                strbuf_release(&err);
1024                return 1;
1025        }
1026        strbuf_release(&err);
1027        if (t)
1028                ref_transaction_free(t);
1029        return 0;
1030}
1031
1032int update_ref(const char *msg, const char *refname,
1033               const struct object_id *new_oid,
1034               const struct object_id *old_oid,
1035               unsigned int flags, enum action_on_err onerr)
1036{
1037        return refs_update_ref(get_main_ref_store(), msg, refname, new_oid,
1038                               old_oid, flags, onerr);
1039}
1040
1041char *shorten_unambiguous_ref(const char *refname, int strict)
1042{
1043        int i;
1044        static char **scanf_fmts;
1045        static int nr_rules;
1046        char *short_name;
1047        struct strbuf resolved_buf = STRBUF_INIT;
1048
1049        if (!nr_rules) {
1050                /*
1051                 * Pre-generate scanf formats from ref_rev_parse_rules[].
1052                 * Generate a format suitable for scanf from a
1053                 * ref_rev_parse_rules rule by interpolating "%s" at the
1054                 * location of the "%.*s".
1055                 */
1056                size_t total_len = 0;
1057                size_t offset = 0;
1058
1059                /* the rule list is NULL terminated, count them first */
1060                for (nr_rules = 0; ref_rev_parse_rules[nr_rules]; nr_rules++)
1061                        /* -2 for strlen("%.*s") - strlen("%s"); +1 for NUL */
1062                        total_len += strlen(ref_rev_parse_rules[nr_rules]) - 2 + 1;
1063
1064                scanf_fmts = xmalloc(st_add(st_mult(sizeof(char *), nr_rules), total_len));
1065
1066                offset = 0;
1067                for (i = 0; i < nr_rules; i++) {
1068                        assert(offset < total_len);
1069                        scanf_fmts[i] = (char *)&scanf_fmts[nr_rules] + offset;
1070                        offset += snprintf(scanf_fmts[i], total_len - offset,
1071                                           ref_rev_parse_rules[i], 2, "%s") + 1;
1072                }
1073        }
1074
1075        /* bail out if there are no rules */
1076        if (!nr_rules)
1077                return xstrdup(refname);
1078
1079        /* buffer for scanf result, at most refname must fit */
1080        short_name = xstrdup(refname);
1081
1082        /* skip first rule, it will always match */
1083        for (i = nr_rules - 1; i > 0 ; --i) {
1084                int j;
1085                int rules_to_fail = i;
1086                int short_name_len;
1087
1088                if (1 != sscanf(refname, scanf_fmts[i], short_name))
1089                        continue;
1090
1091                short_name_len = strlen(short_name);
1092
1093                /*
1094                 * in strict mode, all (except the matched one) rules
1095                 * must fail to resolve to a valid non-ambiguous ref
1096                 */
1097                if (strict)
1098                        rules_to_fail = nr_rules;
1099
1100                /*
1101                 * check if the short name resolves to a valid ref,
1102                 * but use only rules prior to the matched one
1103                 */
1104                for (j = 0; j < rules_to_fail; j++) {
1105                        const char *rule = ref_rev_parse_rules[j];
1106
1107                        /* skip matched rule */
1108                        if (i == j)
1109                                continue;
1110
1111                        /*
1112                         * the short name is ambiguous, if it resolves
1113                         * (with this previous rule) to a valid ref
1114                         * read_ref() returns 0 on success
1115                         */
1116                        strbuf_reset(&resolved_buf);
1117                        strbuf_addf(&resolved_buf, rule,
1118                                    short_name_len, short_name);
1119                        if (ref_exists(resolved_buf.buf))
1120                                break;
1121                }
1122
1123                /*
1124                 * short name is non-ambiguous if all previous rules
1125                 * haven't resolved to a valid ref
1126                 */
1127                if (j == rules_to_fail) {
1128                        strbuf_release(&resolved_buf);
1129                        return short_name;
1130                }
1131        }
1132
1133        strbuf_release(&resolved_buf);
1134        free(short_name);
1135        return xstrdup(refname);
1136}
1137
1138static struct string_list *hide_refs;
1139
1140int parse_hide_refs_config(const char *var, const char *value, const char *section)
1141{
1142        const char *key;
1143        if (!strcmp("transfer.hiderefs", var) ||
1144            (!parse_config_key(var, section, NULL, NULL, &key) &&
1145             !strcmp(key, "hiderefs"))) {
1146                char *ref;
1147                int len;
1148
1149                if (!value)
1150                        return config_error_nonbool(var);
1151                ref = xstrdup(value);
1152                len = strlen(ref);
1153                while (len && ref[len - 1] == '/')
1154                        ref[--len] = '\0';
1155                if (!hide_refs) {
1156                        hide_refs = xcalloc(1, sizeof(*hide_refs));
1157                        hide_refs->strdup_strings = 1;
1158                }
1159                string_list_append(hide_refs, ref);
1160        }
1161        return 0;
1162}
1163
1164int ref_is_hidden(const char *refname, const char *refname_full)
1165{
1166        int i;
1167
1168        if (!hide_refs)
1169                return 0;
1170        for (i = hide_refs->nr - 1; i >= 0; i--) {
1171                const char *match = hide_refs->items[i].string;
1172                const char *subject;
1173                int neg = 0;
1174                const char *p;
1175
1176                if (*match == '!') {
1177                        neg = 1;
1178                        match++;
1179                }
1180
1181                if (*match == '^') {
1182                        subject = refname_full;
1183                        match++;
1184                } else {
1185                        subject = refname;
1186                }
1187
1188                /* refname can be NULL when namespaces are used. */
1189                if (subject &&
1190                    skip_prefix(subject, match, &p) &&
1191                    (!*p || *p == '/'))
1192                        return !neg;
1193        }
1194        return 0;
1195}
1196
1197const char *find_descendant_ref(const char *dirname,
1198                                const struct string_list *extras,
1199                                const struct string_list *skip)
1200{
1201        int pos;
1202
1203        if (!extras)
1204                return NULL;
1205
1206        /*
1207         * Look at the place where dirname would be inserted into
1208         * extras. If there is an entry at that position that starts
1209         * with dirname (remember, dirname includes the trailing
1210         * slash) and is not in skip, then we have a conflict.
1211         */
1212        for (pos = string_list_find_insert_index(extras, dirname, 0);
1213             pos < extras->nr; pos++) {
1214                const char *extra_refname = extras->items[pos].string;
1215
1216                if (!starts_with(extra_refname, dirname))
1217                        break;
1218
1219                if (!skip || !string_list_has_string(skip, extra_refname))
1220                        return extra_refname;
1221        }
1222        return NULL;
1223}
1224
1225int refs_rename_ref_available(struct ref_store *refs,
1226                              const char *old_refname,
1227                              const char *new_refname)
1228{
1229        struct string_list skip = STRING_LIST_INIT_NODUP;
1230        struct strbuf err = STRBUF_INIT;
1231        int ok;
1232
1233        string_list_insert(&skip, old_refname);
1234        ok = !refs_verify_refname_available(refs, new_refname,
1235                                            NULL, &skip, &err);
1236        if (!ok)
1237                error("%s", err.buf);
1238
1239        string_list_clear(&skip, 0);
1240        strbuf_release(&err);
1241        return ok;
1242}
1243
1244int refs_head_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1245{
1246        struct object_id oid;
1247        int flag;
1248
1249        if (!refs_read_ref_full(refs, "HEAD", RESOLVE_REF_READING,
1250                                &oid, &flag))
1251                return fn("HEAD", &oid, flag, cb_data);
1252
1253        return 0;
1254}
1255
1256int head_ref(each_ref_fn fn, void *cb_data)
1257{
1258        return refs_head_ref(get_main_ref_store(), fn, cb_data);
1259}
1260
1261struct ref_iterator *refs_ref_iterator_begin(
1262                struct ref_store *refs,
1263                const char *prefix, int trim, int flags)
1264{
1265        struct ref_iterator *iter;
1266
1267        if (ref_paranoia < 0)
1268                ref_paranoia = git_env_bool("GIT_REF_PARANOIA", 0);
1269        if (ref_paranoia)
1270                flags |= DO_FOR_EACH_INCLUDE_BROKEN;
1271
1272        iter = refs->be->iterator_begin(refs, prefix, flags);
1273
1274        /*
1275         * `iterator_begin()` already takes care of prefix, but we
1276         * might need to do some trimming:
1277         */
1278        if (trim)
1279                iter = prefix_ref_iterator_begin(iter, "", trim);
1280
1281        /* Sanity check for subclasses: */
1282        if (!iter->ordered)
1283                BUG("reference iterator is not ordered");
1284
1285        return iter;
1286}
1287
1288/*
1289 * Call fn for each reference in the specified submodule for which the
1290 * refname begins with prefix. If trim is non-zero, then trim that
1291 * many characters off the beginning of each refname before passing
1292 * the refname to fn. flags can be DO_FOR_EACH_INCLUDE_BROKEN to
1293 * include broken references in the iteration. If fn ever returns a
1294 * non-zero value, stop the iteration and return that value;
1295 * otherwise, return 0.
1296 */
1297static int do_for_each_ref(struct ref_store *refs, const char *prefix,
1298                           each_ref_fn fn, int trim, int flags, void *cb_data)
1299{
1300        struct ref_iterator *iter;
1301
1302        if (!refs)
1303                return 0;
1304
1305        iter = refs_ref_iterator_begin(refs, prefix, trim, flags);
1306
1307        return do_for_each_ref_iterator(iter, fn, cb_data);
1308}
1309
1310int refs_for_each_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1311{
1312        return do_for_each_ref(refs, "", fn, 0, 0, cb_data);
1313}
1314
1315int for_each_ref(each_ref_fn fn, void *cb_data)
1316{
1317        return refs_for_each_ref(get_main_ref_store(), fn, cb_data);
1318}
1319
1320int refs_for_each_ref_in(struct ref_store *refs, const char *prefix,
1321                         each_ref_fn fn, void *cb_data)
1322{
1323        return do_for_each_ref(refs, prefix, fn, strlen(prefix), 0, cb_data);
1324}
1325
1326int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
1327{
1328        return refs_for_each_ref_in(get_main_ref_store(), prefix, fn, cb_data);
1329}
1330
1331int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data, unsigned int broken)
1332{
1333        unsigned int flag = 0;
1334
1335        if (broken)
1336                flag = DO_FOR_EACH_INCLUDE_BROKEN;
1337        return do_for_each_ref(get_main_ref_store(),
1338                               prefix, fn, 0, flag, cb_data);
1339}
1340
1341int refs_for_each_fullref_in(struct ref_store *refs, const char *prefix,
1342                             each_ref_fn fn, void *cb_data,
1343                             unsigned int broken)
1344{
1345        unsigned int flag = 0;
1346
1347        if (broken)
1348                flag = DO_FOR_EACH_INCLUDE_BROKEN;
1349        return do_for_each_ref(refs, prefix, fn, 0, flag, cb_data);
1350}
1351
1352int for_each_replace_ref(each_ref_fn fn, void *cb_data)
1353{
1354        return do_for_each_ref(get_main_ref_store(),
1355                               git_replace_ref_base, fn,
1356                               strlen(git_replace_ref_base),
1357                               DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1358}
1359
1360int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
1361{
1362        struct strbuf buf = STRBUF_INIT;
1363        int ret;
1364        strbuf_addf(&buf, "%srefs/", get_git_namespace());
1365        ret = do_for_each_ref(get_main_ref_store(),
1366                              buf.buf, fn, 0, 0, cb_data);
1367        strbuf_release(&buf);
1368        return ret;
1369}
1370
1371int refs_for_each_rawref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1372{
1373        return do_for_each_ref(refs, "", fn, 0,
1374                               DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1375}
1376
1377int for_each_rawref(each_ref_fn fn, void *cb_data)
1378{
1379        return refs_for_each_rawref(get_main_ref_store(), fn, cb_data);
1380}
1381
1382int refs_read_raw_ref(struct ref_store *ref_store,
1383                      const char *refname, struct object_id *oid,
1384                      struct strbuf *referent, unsigned int *type)
1385{
1386        return ref_store->be->read_raw_ref(ref_store, refname, oid, referent, type);
1387}
1388
1389/* This function needs to return a meaningful errno on failure */
1390const char *refs_resolve_ref_unsafe(struct ref_store *refs,
1391                                    const char *refname,
1392                                    int resolve_flags,
1393                                    struct object_id *oid, int *flags)
1394{
1395        static struct strbuf sb_refname = STRBUF_INIT;
1396        struct object_id unused_oid;
1397        int unused_flags;
1398        int symref_count;
1399
1400        if (!oid)
1401                oid = &unused_oid;
1402        if (!flags)
1403                flags = &unused_flags;
1404
1405        *flags = 0;
1406
1407        if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1408                if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1409                    !refname_is_safe(refname)) {
1410                        errno = EINVAL;
1411                        return NULL;
1412                }
1413
1414                /*
1415                 * dwim_ref() uses REF_ISBROKEN to distinguish between
1416                 * missing refs and refs that were present but invalid,
1417                 * to complain about the latter to stderr.
1418                 *
1419                 * We don't know whether the ref exists, so don't set
1420                 * REF_ISBROKEN yet.
1421                 */
1422                *flags |= REF_BAD_NAME;
1423        }
1424
1425        for (symref_count = 0; symref_count < SYMREF_MAXDEPTH; symref_count++) {
1426                unsigned int read_flags = 0;
1427
1428                if (refs_read_raw_ref(refs, refname,
1429                                      oid, &sb_refname, &read_flags)) {
1430                        *flags |= read_flags;
1431
1432                        /* In reading mode, refs must eventually resolve */
1433                        if (resolve_flags & RESOLVE_REF_READING)
1434                                return NULL;
1435
1436                        /*
1437                         * Otherwise a missing ref is OK. But the files backend
1438                         * may show errors besides ENOENT if there are
1439                         * similarly-named refs.
1440                         */
1441                        if (errno != ENOENT &&
1442                            errno != EISDIR &&
1443                            errno != ENOTDIR)
1444                                return NULL;
1445
1446                        oidclr(oid);
1447                        if (*flags & REF_BAD_NAME)
1448                                *flags |= REF_ISBROKEN;
1449                        return refname;
1450                }
1451
1452                *flags |= read_flags;
1453
1454                if (!(read_flags & REF_ISSYMREF)) {
1455                        if (*flags & REF_BAD_NAME) {
1456                                oidclr(oid);
1457                                *flags |= REF_ISBROKEN;
1458                        }
1459                        return refname;
1460                }
1461
1462                refname = sb_refname.buf;
1463                if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
1464                        oidclr(oid);
1465                        return refname;
1466                }
1467                if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1468                        if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1469                            !refname_is_safe(refname)) {
1470                                errno = EINVAL;
1471                                return NULL;
1472                        }
1473
1474                        *flags |= REF_ISBROKEN | REF_BAD_NAME;
1475                }
1476        }
1477
1478        errno = ELOOP;
1479        return NULL;
1480}
1481
1482/* backend functions */
1483int refs_init_db(struct strbuf *err)
1484{
1485        struct ref_store *refs = get_main_ref_store();
1486
1487        return refs->be->init_db(refs, err);
1488}
1489
1490const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
1491                               struct object_id *oid, int *flags)
1492{
1493        return refs_resolve_ref_unsafe(get_main_ref_store(), refname,
1494                                       resolve_flags, oid, flags);
1495}
1496
1497int resolve_gitlink_ref(const char *submodule, const char *refname,
1498                        struct object_id *oid)
1499{
1500        struct ref_store *refs;
1501        int flags;
1502
1503        refs = get_submodule_ref_store(submodule);
1504
1505        if (!refs)
1506                return -1;
1507
1508        if (!refs_resolve_ref_unsafe(refs, refname, 0, oid, &flags) ||
1509            is_null_oid(oid))
1510                return -1;
1511        return 0;
1512}
1513
1514struct ref_store_hash_entry
1515{
1516        struct hashmap_entry ent; /* must be the first member! */
1517
1518        struct ref_store *refs;
1519
1520        /* NUL-terminated identifier of the ref store: */
1521        char name[FLEX_ARRAY];
1522};
1523
1524static int ref_store_hash_cmp(const void *unused_cmp_data,
1525                              const void *entry, const void *entry_or_key,
1526                              const void *keydata)
1527{
1528        const struct ref_store_hash_entry *e1 = entry, *e2 = entry_or_key;
1529        const char *name = keydata ? keydata : e2->name;
1530
1531        return strcmp(e1->name, name);
1532}
1533
1534static struct ref_store_hash_entry *alloc_ref_store_hash_entry(
1535                const char *name, struct ref_store *refs)
1536{
1537        struct ref_store_hash_entry *entry;
1538
1539        FLEX_ALLOC_STR(entry, name, name);
1540        hashmap_entry_init(entry, strhash(name));
1541        entry->refs = refs;
1542        return entry;
1543}
1544
1545/* A pointer to the ref_store for the main repository: */
1546static struct ref_store *main_ref_store;
1547
1548/* A hashmap of ref_stores, stored by submodule name: */
1549static struct hashmap submodule_ref_stores;
1550
1551/* A hashmap of ref_stores, stored by worktree id: */
1552static struct hashmap worktree_ref_stores;
1553
1554/*
1555 * Look up a ref store by name. If that ref_store hasn't been
1556 * registered yet, return NULL.
1557 */
1558static struct ref_store *lookup_ref_store_map(struct hashmap *map,
1559                                              const char *name)
1560{
1561        struct ref_store_hash_entry *entry;
1562
1563        if (!map->tablesize)
1564                /* It's initialized on demand in register_ref_store(). */
1565                return NULL;
1566
1567        entry = hashmap_get_from_hash(map, strhash(name), name);
1568        return entry ? entry->refs : NULL;
1569}
1570
1571/*
1572 * Create, record, and return a ref_store instance for the specified
1573 * gitdir.
1574 */
1575static struct ref_store *ref_store_init(const char *gitdir,
1576                                        unsigned int flags)
1577{
1578        const char *be_name = "files";
1579        struct ref_storage_be *be = find_ref_storage_backend(be_name);
1580        struct ref_store *refs;
1581
1582        if (!be)
1583                die("BUG: reference backend %s is unknown", be_name);
1584
1585        refs = be->init(gitdir, flags);
1586        return refs;
1587}
1588
1589struct ref_store *get_main_ref_store(void)
1590{
1591        if (main_ref_store)
1592                return main_ref_store;
1593
1594        main_ref_store = ref_store_init(get_git_dir(), REF_STORE_ALL_CAPS);
1595        return main_ref_store;
1596}
1597
1598/*
1599 * Associate a ref store with a name. It is a fatal error to call this
1600 * function twice for the same name.
1601 */
1602static void register_ref_store_map(struct hashmap *map,
1603                                   const char *type,
1604                                   struct ref_store *refs,
1605                                   const char *name)
1606{
1607        if (!map->tablesize)
1608                hashmap_init(map, ref_store_hash_cmp, NULL, 0);
1609
1610        if (hashmap_put(map, alloc_ref_store_hash_entry(name, refs)))
1611                die("BUG: %s ref_store '%s' initialized twice", type, name);
1612}
1613
1614struct ref_store *get_submodule_ref_store(const char *submodule)
1615{
1616        struct strbuf submodule_sb = STRBUF_INIT;
1617        struct ref_store *refs;
1618        char *to_free = NULL;
1619        size_t len;
1620
1621        if (!submodule)
1622                return NULL;
1623
1624        len = strlen(submodule);
1625        while (len && is_dir_sep(submodule[len - 1]))
1626                len--;
1627        if (!len)
1628                return NULL;
1629
1630        if (submodule[len])
1631                /* We need to strip off one or more trailing slashes */
1632                submodule = to_free = xmemdupz(submodule, len);
1633
1634        refs = lookup_ref_store_map(&submodule_ref_stores, submodule);
1635        if (refs)
1636                goto done;
1637
1638        strbuf_addstr(&submodule_sb, submodule);
1639        if (!is_nonbare_repository_dir(&submodule_sb))
1640                goto done;
1641
1642        if (submodule_to_gitdir(&submodule_sb, submodule))
1643                goto done;
1644
1645        /* assume that add_submodule_odb() has been called */
1646        refs = ref_store_init(submodule_sb.buf,
1647                              REF_STORE_READ | REF_STORE_ODB);
1648        register_ref_store_map(&submodule_ref_stores, "submodule",
1649                               refs, submodule);
1650
1651done:
1652        strbuf_release(&submodule_sb);
1653        free(to_free);
1654
1655        return refs;
1656}
1657
1658struct ref_store *get_worktree_ref_store(const struct worktree *wt)
1659{
1660        struct ref_store *refs;
1661        const char *id;
1662
1663        if (wt->is_current)
1664                return get_main_ref_store();
1665
1666        id = wt->id ? wt->id : "/";
1667        refs = lookup_ref_store_map(&worktree_ref_stores, id);
1668        if (refs)
1669                return refs;
1670
1671        if (wt->id)
1672                refs = ref_store_init(git_common_path("worktrees/%s", wt->id),
1673                                      REF_STORE_ALL_CAPS);
1674        else
1675                refs = ref_store_init(get_git_common_dir(),
1676                                      REF_STORE_ALL_CAPS);
1677
1678        if (refs)
1679                register_ref_store_map(&worktree_ref_stores, "worktree",
1680                                       refs, id);
1681        return refs;
1682}
1683
1684void base_ref_store_init(struct ref_store *refs,
1685                         const struct ref_storage_be *be)
1686{
1687        refs->be = be;
1688}
1689
1690/* backend functions */
1691int refs_pack_refs(struct ref_store *refs, unsigned int flags)
1692{
1693        return refs->be->pack_refs(refs, flags);
1694}
1695
1696int refs_peel_ref(struct ref_store *refs, const char *refname,
1697                  struct object_id *oid)
1698{
1699        int flag;
1700        struct object_id base;
1701
1702        if (current_ref_iter && current_ref_iter->refname == refname) {
1703                struct object_id peeled;
1704
1705                if (ref_iterator_peel(current_ref_iter, &peeled))
1706                        return -1;
1707                oidcpy(oid, &peeled);
1708                return 0;
1709        }
1710
1711        if (refs_read_ref_full(refs, refname,
1712                               RESOLVE_REF_READING, &base, &flag))
1713                return -1;
1714
1715        return peel_object(&base, oid);
1716}
1717
1718int peel_ref(const char *refname, struct object_id *oid)
1719{
1720        return refs_peel_ref(get_main_ref_store(), refname, oid);
1721}
1722
1723int refs_create_symref(struct ref_store *refs,
1724                       const char *ref_target,
1725                       const char *refs_heads_master,
1726                       const char *logmsg)
1727{
1728        return refs->be->create_symref(refs, ref_target,
1729                                       refs_heads_master,
1730                                       logmsg);
1731}
1732
1733int create_symref(const char *ref_target, const char *refs_heads_master,
1734                  const char *logmsg)
1735{
1736        return refs_create_symref(get_main_ref_store(), ref_target,
1737                                  refs_heads_master, logmsg);
1738}
1739
1740int ref_update_reject_duplicates(struct string_list *refnames,
1741                                 struct strbuf *err)
1742{
1743        size_t i, n = refnames->nr;
1744
1745        assert(err);
1746
1747        for (i = 1; i < n; i++) {
1748                int cmp = strcmp(refnames->items[i - 1].string,
1749                                 refnames->items[i].string);
1750
1751                if (!cmp) {
1752                        strbuf_addf(err,
1753                                    "multiple updates for ref '%s' not allowed.",
1754                                    refnames->items[i].string);
1755                        return 1;
1756                } else if (cmp > 0) {
1757                        die("BUG: ref_update_reject_duplicates() received unsorted list");
1758                }
1759        }
1760        return 0;
1761}
1762
1763int ref_transaction_prepare(struct ref_transaction *transaction,
1764                            struct strbuf *err)
1765{
1766        struct ref_store *refs = transaction->ref_store;
1767
1768        switch (transaction->state) {
1769        case REF_TRANSACTION_OPEN:
1770                /* Good. */
1771                break;
1772        case REF_TRANSACTION_PREPARED:
1773                die("BUG: prepare called twice on reference transaction");
1774                break;
1775        case REF_TRANSACTION_CLOSED:
1776                die("BUG: prepare called on a closed reference transaction");
1777                break;
1778        default:
1779                die("BUG: unexpected reference transaction state");
1780                break;
1781        }
1782
1783        if (getenv(GIT_QUARANTINE_ENVIRONMENT)) {
1784                strbuf_addstr(err,
1785                              _("ref updates forbidden inside quarantine environment"));
1786                return -1;
1787        }
1788
1789        return refs->be->transaction_prepare(refs, transaction, err);
1790}
1791
1792int ref_transaction_abort(struct ref_transaction *transaction,
1793                          struct strbuf *err)
1794{
1795        struct ref_store *refs = transaction->ref_store;
1796        int ret = 0;
1797
1798        switch (transaction->state) {
1799        case REF_TRANSACTION_OPEN:
1800                /* No need to abort explicitly. */
1801                break;
1802        case REF_TRANSACTION_PREPARED:
1803                ret = refs->be->transaction_abort(refs, transaction, err);
1804                break;
1805        case REF_TRANSACTION_CLOSED:
1806                die("BUG: abort called on a closed reference transaction");
1807                break;
1808        default:
1809                die("BUG: unexpected reference transaction state");
1810                break;
1811        }
1812
1813        ref_transaction_free(transaction);
1814        return ret;
1815}
1816
1817int ref_transaction_commit(struct ref_transaction *transaction,
1818                           struct strbuf *err)
1819{
1820        struct ref_store *refs = transaction->ref_store;
1821        int ret;
1822
1823        switch (transaction->state) {
1824        case REF_TRANSACTION_OPEN:
1825                /* Need to prepare first. */
1826                ret = ref_transaction_prepare(transaction, err);
1827                if (ret)
1828                        return ret;
1829                break;
1830        case REF_TRANSACTION_PREPARED:
1831                /* Fall through to finish. */
1832                break;
1833        case REF_TRANSACTION_CLOSED:
1834                die("BUG: commit called on a closed reference transaction");
1835                break;
1836        default:
1837                die("BUG: unexpected reference transaction state");
1838                break;
1839        }
1840
1841        return refs->be->transaction_finish(refs, transaction, err);
1842}
1843
1844int refs_verify_refname_available(struct ref_store *refs,
1845                                  const char *refname,
1846                                  const struct string_list *extras,
1847                                  const struct string_list *skip,
1848                                  struct strbuf *err)
1849{
1850        const char *slash;
1851        const char *extra_refname;
1852        struct strbuf dirname = STRBUF_INIT;
1853        struct strbuf referent = STRBUF_INIT;
1854        struct object_id oid;
1855        unsigned int type;
1856        struct ref_iterator *iter;
1857        int ok;
1858        int ret = -1;
1859
1860        /*
1861         * For the sake of comments in this function, suppose that
1862         * refname is "refs/foo/bar".
1863         */
1864
1865        assert(err);
1866
1867        strbuf_grow(&dirname, strlen(refname) + 1);
1868        for (slash = strchr(refname, '/'); slash; slash = strchr(slash + 1, '/')) {
1869                /* Expand dirname to the new prefix, not including the trailing slash: */
1870                strbuf_add(&dirname, refname + dirname.len, slash - refname - dirname.len);
1871
1872                /*
1873                 * We are still at a leading dir of the refname (e.g.,
1874                 * "refs/foo"; if there is a reference with that name,
1875                 * it is a conflict, *unless* it is in skip.
1876                 */
1877                if (skip && string_list_has_string(skip, dirname.buf))
1878                        continue;
1879
1880                if (!refs_read_raw_ref(refs, dirname.buf, &oid, &referent, &type)) {
1881                        strbuf_addf(err, "'%s' exists; cannot create '%s'",
1882                                    dirname.buf, refname);
1883                        goto cleanup;
1884                }
1885
1886                if (extras && string_list_has_string(extras, dirname.buf)) {
1887                        strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
1888                                    refname, dirname.buf);
1889                        goto cleanup;
1890                }
1891        }
1892
1893        /*
1894         * We are at the leaf of our refname (e.g., "refs/foo/bar").
1895         * There is no point in searching for a reference with that
1896         * name, because a refname isn't considered to conflict with
1897         * itself. But we still need to check for references whose
1898         * names are in the "refs/foo/bar/" namespace, because they
1899         * *do* conflict.
1900         */
1901        strbuf_addstr(&dirname, refname + dirname.len);
1902        strbuf_addch(&dirname, '/');
1903
1904        iter = refs_ref_iterator_begin(refs, dirname.buf, 0,
1905                                       DO_FOR_EACH_INCLUDE_BROKEN);
1906        while ((ok = ref_iterator_advance(iter)) == ITER_OK) {
1907                if (skip &&
1908                    string_list_has_string(skip, iter->refname))
1909                        continue;
1910
1911                strbuf_addf(err, "'%s' exists; cannot create '%s'",
1912                            iter->refname, refname);
1913                ref_iterator_abort(iter);
1914                goto cleanup;
1915        }
1916
1917        if (ok != ITER_DONE)
1918                die("BUG: error while iterating over references");
1919
1920        extra_refname = find_descendant_ref(dirname.buf, extras, skip);
1921        if (extra_refname)
1922                strbuf_addf(err, "cannot process '%s' and '%s' at the same time",
1923                            refname, extra_refname);
1924        else
1925                ret = 0;
1926
1927cleanup:
1928        strbuf_release(&referent);
1929        strbuf_release(&dirname);
1930        return ret;
1931}
1932
1933int refs_for_each_reflog(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1934{
1935        struct ref_iterator *iter;
1936
1937        iter = refs->be->reflog_iterator_begin(refs);
1938
1939        return do_for_each_ref_iterator(iter, fn, cb_data);
1940}
1941
1942int for_each_reflog(each_ref_fn fn, void *cb_data)
1943{
1944        return refs_for_each_reflog(get_main_ref_store(), fn, cb_data);
1945}
1946
1947int refs_for_each_reflog_ent_reverse(struct ref_store *refs,
1948                                     const char *refname,
1949                                     each_reflog_ent_fn fn,
1950                                     void *cb_data)
1951{
1952        return refs->be->for_each_reflog_ent_reverse(refs, refname,
1953                                                     fn, cb_data);
1954}
1955
1956int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn,
1957                                void *cb_data)
1958{
1959        return refs_for_each_reflog_ent_reverse(get_main_ref_store(),
1960                                                refname, fn, cb_data);
1961}
1962
1963int refs_for_each_reflog_ent(struct ref_store *refs, const char *refname,
1964                             each_reflog_ent_fn fn, void *cb_data)
1965{
1966        return refs->be->for_each_reflog_ent(refs, refname, fn, cb_data);
1967}
1968
1969int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn,
1970                        void *cb_data)
1971{
1972        return refs_for_each_reflog_ent(get_main_ref_store(), refname,
1973                                        fn, cb_data);
1974}
1975
1976int refs_reflog_exists(struct ref_store *refs, const char *refname)
1977{
1978        return refs->be->reflog_exists(refs, refname);
1979}
1980
1981int reflog_exists(const char *refname)
1982{
1983        return refs_reflog_exists(get_main_ref_store(), refname);
1984}
1985
1986int refs_create_reflog(struct ref_store *refs, const char *refname,
1987                       int force_create, struct strbuf *err)
1988{
1989        return refs->be->create_reflog(refs, refname, force_create, err);
1990}
1991
1992int safe_create_reflog(const char *refname, int force_create,
1993                       struct strbuf *err)
1994{
1995        return refs_create_reflog(get_main_ref_store(), refname,
1996                                  force_create, err);
1997}
1998
1999int refs_delete_reflog(struct ref_store *refs, const char *refname)
2000{
2001        return refs->be->delete_reflog(refs, refname);
2002}
2003
2004int delete_reflog(const char *refname)
2005{
2006        return refs_delete_reflog(get_main_ref_store(), refname);
2007}
2008
2009int refs_reflog_expire(struct ref_store *refs,
2010                       const char *refname, const struct object_id *oid,
2011                       unsigned int flags,
2012                       reflog_expiry_prepare_fn prepare_fn,
2013                       reflog_expiry_should_prune_fn should_prune_fn,
2014                       reflog_expiry_cleanup_fn cleanup_fn,
2015                       void *policy_cb_data)
2016{
2017        return refs->be->reflog_expire(refs, refname, oid, flags,
2018                                       prepare_fn, should_prune_fn,
2019                                       cleanup_fn, policy_cb_data);
2020}
2021
2022int reflog_expire(const char *refname, const struct object_id *oid,
2023                  unsigned int flags,
2024                  reflog_expiry_prepare_fn prepare_fn,
2025                  reflog_expiry_should_prune_fn should_prune_fn,
2026                  reflog_expiry_cleanup_fn cleanup_fn,
2027                  void *policy_cb_data)
2028{
2029        return refs_reflog_expire(get_main_ref_store(),
2030                                  refname, oid, flags,
2031                                  prepare_fn, should_prune_fn,
2032                                  cleanup_fn, policy_cb_data);
2033}
2034
2035int initial_ref_transaction_commit(struct ref_transaction *transaction,
2036                                   struct strbuf *err)
2037{
2038        struct ref_store *refs = transaction->ref_store;
2039
2040        return refs->be->initial_transaction_commit(refs, transaction, err);
2041}
2042
2043int refs_delete_refs(struct ref_store *refs, const char *msg,
2044                     struct string_list *refnames, unsigned int flags)
2045{
2046        return refs->be->delete_refs(refs, msg, refnames, flags);
2047}
2048
2049int delete_refs(const char *msg, struct string_list *refnames,
2050                unsigned int flags)
2051{
2052        return refs_delete_refs(get_main_ref_store(), msg, refnames, flags);
2053}
2054
2055int refs_rename_ref(struct ref_store *refs, const char *oldref,
2056                    const char *newref, const char *logmsg)
2057{
2058        return refs->be->rename_ref(refs, oldref, newref, logmsg);
2059}
2060
2061int rename_ref(const char *oldref, const char *newref, const char *logmsg)
2062{
2063        return refs_rename_ref(get_main_ref_store(), oldref, newref, logmsg);
2064}
2065
2066int refs_copy_existing_ref(struct ref_store *refs, const char *oldref,
2067                    const char *newref, const char *logmsg)
2068{
2069        return refs->be->copy_ref(refs, oldref, newref, logmsg);
2070}
2071
2072int copy_existing_ref(const char *oldref, const char *newref, const char *logmsg)
2073{
2074        return refs_copy_existing_ref(get_main_ref_store(), oldref, newref, logmsg);
2075}