refs.con commit timestamp_t: a new data type for timestamps (dddbad7)
   1/*
   2 * The backend-independent part of the reference module.
   3 */
   4
   5#include "cache.h"
   6#include "hashmap.h"
   7#include "lockfile.h"
   8#include "refs.h"
   9#include "refs/refs-internal.h"
  10#include "object.h"
  11#include "tag.h"
  12#include "submodule.h"
  13
  14/*
  15 * List of all available backends
  16 */
  17static struct ref_storage_be *refs_backends = &refs_be_files;
  18
  19static struct ref_storage_be *find_ref_storage_backend(const char *name)
  20{
  21        struct ref_storage_be *be;
  22        for (be = refs_backends; be; be = be->next)
  23                if (!strcmp(be->name, name))
  24                        return be;
  25        return NULL;
  26}
  27
  28int ref_storage_backend_exists(const char *name)
  29{
  30        return find_ref_storage_backend(name) != NULL;
  31}
  32
  33/*
  34 * How to handle various characters in refnames:
  35 * 0: An acceptable character for refs
  36 * 1: End-of-component
  37 * 2: ., look for a preceding . to reject .. in refs
  38 * 3: {, look for a preceding @ to reject @{ in refs
  39 * 4: A bad character: ASCII control characters, and
  40 *    ":", "?", "[", "\", "^", "~", SP, or TAB
  41 * 5: *, reject unless REFNAME_REFSPEC_PATTERN is set
  42 */
  43static unsigned char refname_disposition[256] = {
  44        1, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
  45        4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
  46        4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 2, 1,
  47        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 4,
  48        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  49        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 0, 4, 0,
  50        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  51        0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 4, 4
  52};
  53
  54/*
  55 * Try to read one refname component from the front of refname.
  56 * Return the length of the component found, or -1 if the component is
  57 * not legal.  It is legal if it is something reasonable to have under
  58 * ".git/refs/"; We do not like it if:
  59 *
  60 * - any path component of it begins with ".", or
  61 * - it has double dots "..", or
  62 * - it has ASCII control characters, or
  63 * - it has ":", "?", "[", "\", "^", "~", SP, or TAB anywhere, or
  64 * - it has "*" anywhere unless REFNAME_REFSPEC_PATTERN is set, or
  65 * - it ends with a "/", or
  66 * - it ends with ".lock", or
  67 * - it contains a "@{" portion
  68 */
  69static int check_refname_component(const char *refname, int *flags)
  70{
  71        const char *cp;
  72        char last = '\0';
  73
  74        for (cp = refname; ; cp++) {
  75                int ch = *cp & 255;
  76                unsigned char disp = refname_disposition[ch];
  77                switch (disp) {
  78                case 1:
  79                        goto out;
  80                case 2:
  81                        if (last == '.')
  82                                return -1; /* Refname contains "..". */
  83                        break;
  84                case 3:
  85                        if (last == '@')
  86                                return -1; /* Refname contains "@{". */
  87                        break;
  88                case 4:
  89                        return -1;
  90                case 5:
  91                        if (!(*flags & REFNAME_REFSPEC_PATTERN))
  92                                return -1; /* refspec can't be a pattern */
  93
  94                        /*
  95                         * Unset the pattern flag so that we only accept
  96                         * a single asterisk for one side of refspec.
  97                         */
  98                        *flags &= ~ REFNAME_REFSPEC_PATTERN;
  99                        break;
 100                }
 101                last = ch;
 102        }
 103out:
 104        if (cp == refname)
 105                return 0; /* Component has zero length. */
 106        if (refname[0] == '.')
 107                return -1; /* Component starts with '.'. */
 108        if (cp - refname >= LOCK_SUFFIX_LEN &&
 109            !memcmp(cp - LOCK_SUFFIX_LEN, LOCK_SUFFIX, LOCK_SUFFIX_LEN))
 110                return -1; /* Refname ends with ".lock". */
 111        return cp - refname;
 112}
 113
 114int check_refname_format(const char *refname, int flags)
 115{
 116        int component_len, component_count = 0;
 117
 118        if (!strcmp(refname, "@"))
 119                /* Refname is a single character '@'. */
 120                return -1;
 121
 122        while (1) {
 123                /* We are at the start of a path component. */
 124                component_len = check_refname_component(refname, &flags);
 125                if (component_len <= 0)
 126                        return -1;
 127
 128                component_count++;
 129                if (refname[component_len] == '\0')
 130                        break;
 131                /* Skip to next component. */
 132                refname += component_len + 1;
 133        }
 134
 135        if (refname[component_len - 1] == '.')
 136                return -1; /* Refname ends with '.'. */
 137        if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
 138                return -1; /* Refname has only one component. */
 139        return 0;
 140}
 141
 142int refname_is_safe(const char *refname)
 143{
 144        const char *rest;
 145
 146        if (skip_prefix(refname, "refs/", &rest)) {
 147                char *buf;
 148                int result;
 149                size_t restlen = strlen(rest);
 150
 151                /* rest must not be empty, or start or end with "/" */
 152                if (!restlen || *rest == '/' || rest[restlen - 1] == '/')
 153                        return 0;
 154
 155                /*
 156                 * Does the refname try to escape refs/?
 157                 * For example: refs/foo/../bar is safe but refs/foo/../../bar
 158                 * is not.
 159                 */
 160                buf = xmallocz(restlen);
 161                result = !normalize_path_copy(buf, rest) && !strcmp(buf, rest);
 162                free(buf);
 163                return result;
 164        }
 165
 166        do {
 167                if (!isupper(*refname) && *refname != '_')
 168                        return 0;
 169                refname++;
 170        } while (*refname);
 171        return 1;
 172}
 173
 174char *refs_resolve_refdup(struct ref_store *refs,
 175                          const char *refname, int resolve_flags,
 176                          unsigned char *sha1, int *flags)
 177{
 178        const char *result;
 179
 180        result = refs_resolve_ref_unsafe(refs, refname, resolve_flags,
 181                                         sha1, flags);
 182        return xstrdup_or_null(result);
 183}
 184
 185char *resolve_refdup(const char *refname, int resolve_flags,
 186                     unsigned char *sha1, int *flags)
 187{
 188        return refs_resolve_refdup(get_main_ref_store(),
 189                                   refname, resolve_flags,
 190                                   sha1, flags);
 191}
 192
 193/* The argument to filter_refs */
 194struct ref_filter {
 195        const char *pattern;
 196        each_ref_fn *fn;
 197        void *cb_data;
 198};
 199
 200int refs_read_ref_full(struct ref_store *refs, const char *refname,
 201                       int resolve_flags, unsigned char *sha1, int *flags)
 202{
 203        if (refs_resolve_ref_unsafe(refs, refname, resolve_flags, sha1, flags))
 204                return 0;
 205        return -1;
 206}
 207
 208int read_ref_full(const char *refname, int resolve_flags, unsigned char *sha1, int *flags)
 209{
 210        return refs_read_ref_full(get_main_ref_store(), refname,
 211                                  resolve_flags, sha1, flags);
 212}
 213
 214int read_ref(const char *refname, unsigned char *sha1)
 215{
 216        return read_ref_full(refname, RESOLVE_REF_READING, sha1, NULL);
 217}
 218
 219int ref_exists(const char *refname)
 220{
 221        unsigned char sha1[20];
 222        return !!resolve_ref_unsafe(refname, RESOLVE_REF_READING, sha1, NULL);
 223}
 224
 225static int filter_refs(const char *refname, const struct object_id *oid,
 226                           int flags, void *data)
 227{
 228        struct ref_filter *filter = (struct ref_filter *)data;
 229
 230        if (wildmatch(filter->pattern, refname, 0, NULL))
 231                return 0;
 232        return filter->fn(refname, oid, flags, filter->cb_data);
 233}
 234
 235enum peel_status peel_object(const unsigned char *name, unsigned char *sha1)
 236{
 237        struct object *o = lookup_unknown_object(name);
 238
 239        if (o->type == OBJ_NONE) {
 240                int type = sha1_object_info(name, NULL);
 241                if (type < 0 || !object_as_type(o, type, 0))
 242                        return PEEL_INVALID;
 243        }
 244
 245        if (o->type != OBJ_TAG)
 246                return PEEL_NON_TAG;
 247
 248        o = deref_tag_noverify(o);
 249        if (!o)
 250                return PEEL_INVALID;
 251
 252        hashcpy(sha1, o->oid.hash);
 253        return PEEL_PEELED;
 254}
 255
 256struct warn_if_dangling_data {
 257        FILE *fp;
 258        const char *refname;
 259        const struct string_list *refnames;
 260        const char *msg_fmt;
 261};
 262
 263static int warn_if_dangling_symref(const char *refname, const struct object_id *oid,
 264                                   int flags, void *cb_data)
 265{
 266        struct warn_if_dangling_data *d = cb_data;
 267        const char *resolves_to;
 268        struct object_id junk;
 269
 270        if (!(flags & REF_ISSYMREF))
 271                return 0;
 272
 273        resolves_to = resolve_ref_unsafe(refname, 0, junk.hash, NULL);
 274        if (!resolves_to
 275            || (d->refname
 276                ? strcmp(resolves_to, d->refname)
 277                : !string_list_has_string(d->refnames, resolves_to))) {
 278                return 0;
 279        }
 280
 281        fprintf(d->fp, d->msg_fmt, refname);
 282        fputc('\n', d->fp);
 283        return 0;
 284}
 285
 286void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 287{
 288        struct warn_if_dangling_data data;
 289
 290        data.fp = fp;
 291        data.refname = refname;
 292        data.refnames = NULL;
 293        data.msg_fmt = msg_fmt;
 294        for_each_rawref(warn_if_dangling_symref, &data);
 295}
 296
 297void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames)
 298{
 299        struct warn_if_dangling_data data;
 300
 301        data.fp = fp;
 302        data.refname = NULL;
 303        data.refnames = refnames;
 304        data.msg_fmt = msg_fmt;
 305        for_each_rawref(warn_if_dangling_symref, &data);
 306}
 307
 308int refs_for_each_tag_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 309{
 310        return refs_for_each_ref_in(refs, "refs/tags/", fn, cb_data);
 311}
 312
 313int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 314{
 315        return refs_for_each_tag_ref(get_main_ref_store(), fn, cb_data);
 316}
 317
 318int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 319{
 320        return refs_for_each_tag_ref(get_submodule_ref_store(submodule),
 321                                     fn, cb_data);
 322}
 323
 324int refs_for_each_branch_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 325{
 326        return refs_for_each_ref_in(refs, "refs/heads/", fn, cb_data);
 327}
 328
 329int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 330{
 331        return refs_for_each_branch_ref(get_main_ref_store(), fn, cb_data);
 332}
 333
 334int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 335{
 336        return refs_for_each_branch_ref(get_submodule_ref_store(submodule),
 337                                        fn, cb_data);
 338}
 339
 340int refs_for_each_remote_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
 341{
 342        return refs_for_each_ref_in(refs, "refs/remotes/", fn, cb_data);
 343}
 344
 345int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 346{
 347        return refs_for_each_remote_ref(get_main_ref_store(), fn, cb_data);
 348}
 349
 350int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 351{
 352        return refs_for_each_remote_ref(get_submodule_ref_store(submodule),
 353                                        fn, cb_data);
 354}
 355
 356int head_ref_namespaced(each_ref_fn fn, void *cb_data)
 357{
 358        struct strbuf buf = STRBUF_INIT;
 359        int ret = 0;
 360        struct object_id oid;
 361        int flag;
 362
 363        strbuf_addf(&buf, "%sHEAD", get_git_namespace());
 364        if (!read_ref_full(buf.buf, RESOLVE_REF_READING, oid.hash, &flag))
 365                ret = fn(buf.buf, &oid, flag, cb_data);
 366        strbuf_release(&buf);
 367
 368        return ret;
 369}
 370
 371int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 372        const char *prefix, void *cb_data)
 373{
 374        struct strbuf real_pattern = STRBUF_INIT;
 375        struct ref_filter filter;
 376        int ret;
 377
 378        if (!prefix && !starts_with(pattern, "refs/"))
 379                strbuf_addstr(&real_pattern, "refs/");
 380        else if (prefix)
 381                strbuf_addstr(&real_pattern, prefix);
 382        strbuf_addstr(&real_pattern, pattern);
 383
 384        if (!has_glob_specials(pattern)) {
 385                /* Append implied '/' '*' if not present. */
 386                strbuf_complete(&real_pattern, '/');
 387                /* No need to check for '*', there is none. */
 388                strbuf_addch(&real_pattern, '*');
 389        }
 390
 391        filter.pattern = real_pattern.buf;
 392        filter.fn = fn;
 393        filter.cb_data = cb_data;
 394        ret = for_each_ref(filter_refs, &filter);
 395
 396        strbuf_release(&real_pattern);
 397        return ret;
 398}
 399
 400int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 401{
 402        return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
 403}
 404
 405const char *prettify_refname(const char *name)
 406{
 407        if (skip_prefix(name, "refs/heads/", &name) ||
 408            skip_prefix(name, "refs/tags/", &name) ||
 409            skip_prefix(name, "refs/remotes/", &name))
 410                ; /* nothing */
 411        return name;
 412}
 413
 414static const char *ref_rev_parse_rules[] = {
 415        "%.*s",
 416        "refs/%.*s",
 417        "refs/tags/%.*s",
 418        "refs/heads/%.*s",
 419        "refs/remotes/%.*s",
 420        "refs/remotes/%.*s/HEAD",
 421        NULL
 422};
 423
 424int refname_match(const char *abbrev_name, const char *full_name)
 425{
 426        const char **p;
 427        const int abbrev_name_len = strlen(abbrev_name);
 428
 429        for (p = ref_rev_parse_rules; *p; p++) {
 430                if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
 431                        return 1;
 432                }
 433        }
 434
 435        return 0;
 436}
 437
 438/*
 439 * *string and *len will only be substituted, and *string returned (for
 440 * later free()ing) if the string passed in is a magic short-hand form
 441 * to name a branch.
 442 */
 443static char *substitute_branch_name(const char **string, int *len)
 444{
 445        struct strbuf buf = STRBUF_INIT;
 446        int ret = interpret_branch_name(*string, *len, &buf, 0);
 447
 448        if (ret == *len) {
 449                size_t size;
 450                *string = strbuf_detach(&buf, &size);
 451                *len = size;
 452                return (char *)*string;
 453        }
 454
 455        return NULL;
 456}
 457
 458int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
 459{
 460        char *last_branch = substitute_branch_name(&str, &len);
 461        int   refs_found  = expand_ref(str, len, sha1, ref);
 462        free(last_branch);
 463        return refs_found;
 464}
 465
 466int expand_ref(const char *str, int len, unsigned char *sha1, char **ref)
 467{
 468        const char **p, *r;
 469        int refs_found = 0;
 470        struct strbuf fullref = STRBUF_INIT;
 471
 472        *ref = NULL;
 473        for (p = ref_rev_parse_rules; *p; p++) {
 474                unsigned char sha1_from_ref[20];
 475                unsigned char *this_result;
 476                int flag;
 477
 478                this_result = refs_found ? sha1_from_ref : sha1;
 479                strbuf_reset(&fullref);
 480                strbuf_addf(&fullref, *p, len, str);
 481                r = resolve_ref_unsafe(fullref.buf, RESOLVE_REF_READING,
 482                                       this_result, &flag);
 483                if (r) {
 484                        if (!refs_found++)
 485                                *ref = xstrdup(r);
 486                        if (!warn_ambiguous_refs)
 487                                break;
 488                } else if ((flag & REF_ISSYMREF) && strcmp(fullref.buf, "HEAD")) {
 489                        warning("ignoring dangling symref %s.", fullref.buf);
 490                } else if ((flag & REF_ISBROKEN) && strchr(fullref.buf, '/')) {
 491                        warning("ignoring broken ref %s.", fullref.buf);
 492                }
 493        }
 494        strbuf_release(&fullref);
 495        return refs_found;
 496}
 497
 498int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
 499{
 500        char *last_branch = substitute_branch_name(&str, &len);
 501        const char **p;
 502        int logs_found = 0;
 503        struct strbuf path = STRBUF_INIT;
 504
 505        *log = NULL;
 506        for (p = ref_rev_parse_rules; *p; p++) {
 507                unsigned char hash[20];
 508                const char *ref, *it;
 509
 510                strbuf_reset(&path);
 511                strbuf_addf(&path, *p, len, str);
 512                ref = resolve_ref_unsafe(path.buf, RESOLVE_REF_READING,
 513                                         hash, NULL);
 514                if (!ref)
 515                        continue;
 516                if (reflog_exists(path.buf))
 517                        it = path.buf;
 518                else if (strcmp(ref, path.buf) && reflog_exists(ref))
 519                        it = ref;
 520                else
 521                        continue;
 522                if (!logs_found++) {
 523                        *log = xstrdup(it);
 524                        hashcpy(sha1, hash);
 525                }
 526                if (!warn_ambiguous_refs)
 527                        break;
 528        }
 529        strbuf_release(&path);
 530        free(last_branch);
 531        return logs_found;
 532}
 533
 534static int is_per_worktree_ref(const char *refname)
 535{
 536        return !strcmp(refname, "HEAD") ||
 537                starts_with(refname, "refs/bisect/");
 538}
 539
 540static int is_pseudoref_syntax(const char *refname)
 541{
 542        const char *c;
 543
 544        for (c = refname; *c; c++) {
 545                if (!isupper(*c) && *c != '-' && *c != '_')
 546                        return 0;
 547        }
 548
 549        return 1;
 550}
 551
 552enum ref_type ref_type(const char *refname)
 553{
 554        if (is_per_worktree_ref(refname))
 555                return REF_TYPE_PER_WORKTREE;
 556        if (is_pseudoref_syntax(refname))
 557                return REF_TYPE_PSEUDOREF;
 558       return REF_TYPE_NORMAL;
 559}
 560
 561static int write_pseudoref(const char *pseudoref, const unsigned char *sha1,
 562                           const unsigned char *old_sha1, struct strbuf *err)
 563{
 564        const char *filename;
 565        int fd;
 566        static struct lock_file lock;
 567        struct strbuf buf = STRBUF_INIT;
 568        int ret = -1;
 569
 570        strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
 571
 572        filename = git_path("%s", pseudoref);
 573        fd = hold_lock_file_for_update(&lock, filename, LOCK_DIE_ON_ERROR);
 574        if (fd < 0) {
 575                strbuf_addf(err, "could not open '%s' for writing: %s",
 576                            filename, strerror(errno));
 577                return -1;
 578        }
 579
 580        if (old_sha1) {
 581                unsigned char actual_old_sha1[20];
 582
 583                if (read_ref(pseudoref, actual_old_sha1))
 584                        die("could not read ref '%s'", pseudoref);
 585                if (hashcmp(actual_old_sha1, old_sha1)) {
 586                        strbuf_addf(err, "unexpected sha1 when writing '%s'", pseudoref);
 587                        rollback_lock_file(&lock);
 588                        goto done;
 589                }
 590        }
 591
 592        if (write_in_full(fd, buf.buf, buf.len) != buf.len) {
 593                strbuf_addf(err, "could not write to '%s'", filename);
 594                rollback_lock_file(&lock);
 595                goto done;
 596        }
 597
 598        commit_lock_file(&lock);
 599        ret = 0;
 600done:
 601        strbuf_release(&buf);
 602        return ret;
 603}
 604
 605static int delete_pseudoref(const char *pseudoref, const unsigned char *old_sha1)
 606{
 607        static struct lock_file lock;
 608        const char *filename;
 609
 610        filename = git_path("%s", pseudoref);
 611
 612        if (old_sha1 && !is_null_sha1(old_sha1)) {
 613                int fd;
 614                unsigned char actual_old_sha1[20];
 615
 616                fd = hold_lock_file_for_update(&lock, filename,
 617                                               LOCK_DIE_ON_ERROR);
 618                if (fd < 0)
 619                        die_errno(_("Could not open '%s' for writing"), filename);
 620                if (read_ref(pseudoref, actual_old_sha1))
 621                        die("could not read ref '%s'", pseudoref);
 622                if (hashcmp(actual_old_sha1, old_sha1)) {
 623                        warning("Unexpected sha1 when deleting %s", pseudoref);
 624                        rollback_lock_file(&lock);
 625                        return -1;
 626                }
 627
 628                unlink(filename);
 629                rollback_lock_file(&lock);
 630        } else {
 631                unlink(filename);
 632        }
 633
 634        return 0;
 635}
 636
 637int refs_delete_ref(struct ref_store *refs, const char *msg,
 638                    const char *refname,
 639                    const unsigned char *old_sha1,
 640                    unsigned int flags)
 641{
 642        struct ref_transaction *transaction;
 643        struct strbuf err = STRBUF_INIT;
 644
 645        if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
 646                assert(refs == get_main_ref_store());
 647                return delete_pseudoref(refname, old_sha1);
 648        }
 649
 650        transaction = ref_store_transaction_begin(refs, &err);
 651        if (!transaction ||
 652            ref_transaction_delete(transaction, refname, old_sha1,
 653                                   flags, msg, &err) ||
 654            ref_transaction_commit(transaction, &err)) {
 655                error("%s", err.buf);
 656                ref_transaction_free(transaction);
 657                strbuf_release(&err);
 658                return 1;
 659        }
 660        ref_transaction_free(transaction);
 661        strbuf_release(&err);
 662        return 0;
 663}
 664
 665int delete_ref(const char *msg, const char *refname,
 666               const unsigned char *old_sha1, unsigned int flags)
 667{
 668        return refs_delete_ref(get_main_ref_store(), msg, refname,
 669                               old_sha1, flags);
 670}
 671
 672int copy_reflog_msg(char *buf, const char *msg)
 673{
 674        char *cp = buf;
 675        char c;
 676        int wasspace = 1;
 677
 678        *cp++ = '\t';
 679        while ((c = *msg++)) {
 680                if (wasspace && isspace(c))
 681                        continue;
 682                wasspace = isspace(c);
 683                if (wasspace)
 684                        c = ' ';
 685                *cp++ = c;
 686        }
 687        while (buf < cp && isspace(cp[-1]))
 688                cp--;
 689        *cp++ = '\n';
 690        return cp - buf;
 691}
 692
 693int should_autocreate_reflog(const char *refname)
 694{
 695        switch (log_all_ref_updates) {
 696        case LOG_REFS_ALWAYS:
 697                return 1;
 698        case LOG_REFS_NORMAL:
 699                return starts_with(refname, "refs/heads/") ||
 700                        starts_with(refname, "refs/remotes/") ||
 701                        starts_with(refname, "refs/notes/") ||
 702                        !strcmp(refname, "HEAD");
 703        default:
 704                return 0;
 705        }
 706}
 707
 708int is_branch(const char *refname)
 709{
 710        return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
 711}
 712
 713struct read_ref_at_cb {
 714        const char *refname;
 715        timestamp_t at_time;
 716        int cnt;
 717        int reccnt;
 718        unsigned char *sha1;
 719        int found_it;
 720
 721        unsigned char osha1[20];
 722        unsigned char nsha1[20];
 723        int tz;
 724        timestamp_t date;
 725        char **msg;
 726        timestamp_t *cutoff_time;
 727        int *cutoff_tz;
 728        int *cutoff_cnt;
 729};
 730
 731static int read_ref_at_ent(struct object_id *ooid, struct object_id *noid,
 732                const char *email, timestamp_t timestamp, int tz,
 733                const char *message, void *cb_data)
 734{
 735        struct read_ref_at_cb *cb = cb_data;
 736
 737        cb->reccnt++;
 738        cb->tz = tz;
 739        cb->date = timestamp;
 740
 741        if (timestamp <= cb->at_time || cb->cnt == 0) {
 742                if (cb->msg)
 743                        *cb->msg = xstrdup(message);
 744                if (cb->cutoff_time)
 745                        *cb->cutoff_time = timestamp;
 746                if (cb->cutoff_tz)
 747                        *cb->cutoff_tz = tz;
 748                if (cb->cutoff_cnt)
 749                        *cb->cutoff_cnt = cb->reccnt - 1;
 750                /*
 751                 * we have not yet updated cb->[n|o]sha1 so they still
 752                 * hold the values for the previous record.
 753                 */
 754                if (!is_null_sha1(cb->osha1)) {
 755                        hashcpy(cb->sha1, noid->hash);
 756                        if (hashcmp(cb->osha1, noid->hash))
 757                                warning("Log for ref %s has gap after %s.",
 758                                        cb->refname, show_date(cb->date, cb->tz, DATE_MODE(RFC2822)));
 759                }
 760                else if (cb->date == cb->at_time)
 761                        hashcpy(cb->sha1, noid->hash);
 762                else if (hashcmp(noid->hash, cb->sha1))
 763                        warning("Log for ref %s unexpectedly ended on %s.",
 764                                cb->refname, show_date(cb->date, cb->tz,
 765                                                       DATE_MODE(RFC2822)));
 766                hashcpy(cb->osha1, ooid->hash);
 767                hashcpy(cb->nsha1, noid->hash);
 768                cb->found_it = 1;
 769                return 1;
 770        }
 771        hashcpy(cb->osha1, ooid->hash);
 772        hashcpy(cb->nsha1, noid->hash);
 773        if (cb->cnt > 0)
 774                cb->cnt--;
 775        return 0;
 776}
 777
 778static int read_ref_at_ent_oldest(struct object_id *ooid, struct object_id *noid,
 779                                  const char *email, timestamp_t timestamp,
 780                                  int tz, const char *message, void *cb_data)
 781{
 782        struct read_ref_at_cb *cb = cb_data;
 783
 784        if (cb->msg)
 785                *cb->msg = xstrdup(message);
 786        if (cb->cutoff_time)
 787                *cb->cutoff_time = timestamp;
 788        if (cb->cutoff_tz)
 789                *cb->cutoff_tz = tz;
 790        if (cb->cutoff_cnt)
 791                *cb->cutoff_cnt = cb->reccnt;
 792        hashcpy(cb->sha1, ooid->hash);
 793        if (is_null_sha1(cb->sha1))
 794                hashcpy(cb->sha1, noid->hash);
 795        /* We just want the first entry */
 796        return 1;
 797}
 798
 799int read_ref_at(const char *refname, unsigned int flags, timestamp_t at_time, int cnt,
 800                unsigned char *sha1, char **msg,
 801                timestamp_t *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
 802{
 803        struct read_ref_at_cb cb;
 804
 805        memset(&cb, 0, sizeof(cb));
 806        cb.refname = refname;
 807        cb.at_time = at_time;
 808        cb.cnt = cnt;
 809        cb.msg = msg;
 810        cb.cutoff_time = cutoff_time;
 811        cb.cutoff_tz = cutoff_tz;
 812        cb.cutoff_cnt = cutoff_cnt;
 813        cb.sha1 = sha1;
 814
 815        for_each_reflog_ent_reverse(refname, read_ref_at_ent, &cb);
 816
 817        if (!cb.reccnt) {
 818                if (flags & GET_SHA1_QUIETLY)
 819                        exit(128);
 820                else
 821                        die("Log for %s is empty.", refname);
 822        }
 823        if (cb.found_it)
 824                return 0;
 825
 826        for_each_reflog_ent(refname, read_ref_at_ent_oldest, &cb);
 827
 828        return 1;
 829}
 830
 831struct ref_transaction *ref_store_transaction_begin(struct ref_store *refs,
 832                                                    struct strbuf *err)
 833{
 834        struct ref_transaction *tr;
 835        assert(err);
 836
 837        tr = xcalloc(1, sizeof(struct ref_transaction));
 838        tr->ref_store = refs;
 839        return tr;
 840}
 841
 842struct ref_transaction *ref_transaction_begin(struct strbuf *err)
 843{
 844        return ref_store_transaction_begin(get_main_ref_store(), err);
 845}
 846
 847void ref_transaction_free(struct ref_transaction *transaction)
 848{
 849        int i;
 850
 851        if (!transaction)
 852                return;
 853
 854        for (i = 0; i < transaction->nr; i++) {
 855                free(transaction->updates[i]->msg);
 856                free(transaction->updates[i]);
 857        }
 858        free(transaction->updates);
 859        free(transaction);
 860}
 861
 862struct ref_update *ref_transaction_add_update(
 863                struct ref_transaction *transaction,
 864                const char *refname, unsigned int flags,
 865                const unsigned char *new_sha1,
 866                const unsigned char *old_sha1,
 867                const char *msg)
 868{
 869        struct ref_update *update;
 870
 871        if (transaction->state != REF_TRANSACTION_OPEN)
 872                die("BUG: update called for transaction that is not open");
 873
 874        if ((flags & REF_ISPRUNING) && !(flags & REF_NODEREF))
 875                die("BUG: REF_ISPRUNING set without REF_NODEREF");
 876
 877        FLEX_ALLOC_STR(update, refname, refname);
 878        ALLOC_GROW(transaction->updates, transaction->nr + 1, transaction->alloc);
 879        transaction->updates[transaction->nr++] = update;
 880
 881        update->flags = flags;
 882
 883        if (flags & REF_HAVE_NEW)
 884                hashcpy(update->new_sha1, new_sha1);
 885        if (flags & REF_HAVE_OLD)
 886                hashcpy(update->old_sha1, old_sha1);
 887        update->msg = xstrdup_or_null(msg);
 888        return update;
 889}
 890
 891int ref_transaction_update(struct ref_transaction *transaction,
 892                           const char *refname,
 893                           const unsigned char *new_sha1,
 894                           const unsigned char *old_sha1,
 895                           unsigned int flags, const char *msg,
 896                           struct strbuf *err)
 897{
 898        assert(err);
 899
 900        if ((new_sha1 && !is_null_sha1(new_sha1)) ?
 901            check_refname_format(refname, REFNAME_ALLOW_ONELEVEL) :
 902            !refname_is_safe(refname)) {
 903                strbuf_addf(err, "refusing to update ref with bad name '%s'",
 904                            refname);
 905                return -1;
 906        }
 907
 908        flags |= (new_sha1 ? REF_HAVE_NEW : 0) | (old_sha1 ? REF_HAVE_OLD : 0);
 909
 910        ref_transaction_add_update(transaction, refname, flags,
 911                                   new_sha1, old_sha1, msg);
 912        return 0;
 913}
 914
 915int ref_transaction_create(struct ref_transaction *transaction,
 916                           const char *refname,
 917                           const unsigned char *new_sha1,
 918                           unsigned int flags, const char *msg,
 919                           struct strbuf *err)
 920{
 921        if (!new_sha1 || is_null_sha1(new_sha1))
 922                die("BUG: create called without valid new_sha1");
 923        return ref_transaction_update(transaction, refname, new_sha1,
 924                                      null_sha1, flags, msg, err);
 925}
 926
 927int ref_transaction_delete(struct ref_transaction *transaction,
 928                           const char *refname,
 929                           const unsigned char *old_sha1,
 930                           unsigned int flags, const char *msg,
 931                           struct strbuf *err)
 932{
 933        if (old_sha1 && is_null_sha1(old_sha1))
 934                die("BUG: delete called with old_sha1 set to zeros");
 935        return ref_transaction_update(transaction, refname,
 936                                      null_sha1, old_sha1,
 937                                      flags, msg, err);
 938}
 939
 940int ref_transaction_verify(struct ref_transaction *transaction,
 941                           const char *refname,
 942                           const unsigned char *old_sha1,
 943                           unsigned int flags,
 944                           struct strbuf *err)
 945{
 946        if (!old_sha1)
 947                die("BUG: verify called with old_sha1 set to NULL");
 948        return ref_transaction_update(transaction, refname,
 949                                      NULL, old_sha1,
 950                                      flags, NULL, err);
 951}
 952
 953int update_ref_oid(const char *msg, const char *refname,
 954               const struct object_id *new_oid, const struct object_id *old_oid,
 955               unsigned int flags, enum action_on_err onerr)
 956{
 957        return update_ref(msg, refname, new_oid ? new_oid->hash : NULL,
 958                old_oid ? old_oid->hash : NULL, flags, onerr);
 959}
 960
 961int refs_update_ref(struct ref_store *refs, const char *msg,
 962                    const char *refname, const unsigned char *new_sha1,
 963                    const unsigned char *old_sha1, unsigned int flags,
 964                    enum action_on_err onerr)
 965{
 966        struct ref_transaction *t = NULL;
 967        struct strbuf err = STRBUF_INIT;
 968        int ret = 0;
 969
 970        if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
 971                assert(refs == get_main_ref_store());
 972                ret = write_pseudoref(refname, new_sha1, old_sha1, &err);
 973        } else {
 974                t = ref_store_transaction_begin(refs, &err);
 975                if (!t ||
 976                    ref_transaction_update(t, refname, new_sha1, old_sha1,
 977                                           flags, msg, &err) ||
 978                    ref_transaction_commit(t, &err)) {
 979                        ret = 1;
 980                        ref_transaction_free(t);
 981                }
 982        }
 983        if (ret) {
 984                const char *str = "update_ref failed for ref '%s': %s";
 985
 986                switch (onerr) {
 987                case UPDATE_REFS_MSG_ON_ERR:
 988                        error(str, refname, err.buf);
 989                        break;
 990                case UPDATE_REFS_DIE_ON_ERR:
 991                        die(str, refname, err.buf);
 992                        break;
 993                case UPDATE_REFS_QUIET_ON_ERR:
 994                        break;
 995                }
 996                strbuf_release(&err);
 997                return 1;
 998        }
 999        strbuf_release(&err);
1000        if (t)
1001                ref_transaction_free(t);
1002        return 0;
1003}
1004
1005int update_ref(const char *msg, const char *refname,
1006               const unsigned char *new_sha1,
1007               const unsigned char *old_sha1,
1008               unsigned int flags, enum action_on_err onerr)
1009{
1010        return refs_update_ref(get_main_ref_store(), msg, refname, new_sha1,
1011                               old_sha1, flags, onerr);
1012}
1013
1014char *shorten_unambiguous_ref(const char *refname, int strict)
1015{
1016        int i;
1017        static char **scanf_fmts;
1018        static int nr_rules;
1019        char *short_name;
1020        struct strbuf resolved_buf = STRBUF_INIT;
1021
1022        if (!nr_rules) {
1023                /*
1024                 * Pre-generate scanf formats from ref_rev_parse_rules[].
1025                 * Generate a format suitable for scanf from a
1026                 * ref_rev_parse_rules rule by interpolating "%s" at the
1027                 * location of the "%.*s".
1028                 */
1029                size_t total_len = 0;
1030                size_t offset = 0;
1031
1032                /* the rule list is NULL terminated, count them first */
1033                for (nr_rules = 0; ref_rev_parse_rules[nr_rules]; nr_rules++)
1034                        /* -2 for strlen("%.*s") - strlen("%s"); +1 for NUL */
1035                        total_len += strlen(ref_rev_parse_rules[nr_rules]) - 2 + 1;
1036
1037                scanf_fmts = xmalloc(st_add(st_mult(sizeof(char *), nr_rules), total_len));
1038
1039                offset = 0;
1040                for (i = 0; i < nr_rules; i++) {
1041                        assert(offset < total_len);
1042                        scanf_fmts[i] = (char *)&scanf_fmts[nr_rules] + offset;
1043                        offset += snprintf(scanf_fmts[i], total_len - offset,
1044                                           ref_rev_parse_rules[i], 2, "%s") + 1;
1045                }
1046        }
1047
1048        /* bail out if there are no rules */
1049        if (!nr_rules)
1050                return xstrdup(refname);
1051
1052        /* buffer for scanf result, at most refname must fit */
1053        short_name = xstrdup(refname);
1054
1055        /* skip first rule, it will always match */
1056        for (i = nr_rules - 1; i > 0 ; --i) {
1057                int j;
1058                int rules_to_fail = i;
1059                int short_name_len;
1060
1061                if (1 != sscanf(refname, scanf_fmts[i], short_name))
1062                        continue;
1063
1064                short_name_len = strlen(short_name);
1065
1066                /*
1067                 * in strict mode, all (except the matched one) rules
1068                 * must fail to resolve to a valid non-ambiguous ref
1069                 */
1070                if (strict)
1071                        rules_to_fail = nr_rules;
1072
1073                /*
1074                 * check if the short name resolves to a valid ref,
1075                 * but use only rules prior to the matched one
1076                 */
1077                for (j = 0; j < rules_to_fail; j++) {
1078                        const char *rule = ref_rev_parse_rules[j];
1079
1080                        /* skip matched rule */
1081                        if (i == j)
1082                                continue;
1083
1084                        /*
1085                         * the short name is ambiguous, if it resolves
1086                         * (with this previous rule) to a valid ref
1087                         * read_ref() returns 0 on success
1088                         */
1089                        strbuf_reset(&resolved_buf);
1090                        strbuf_addf(&resolved_buf, rule,
1091                                    short_name_len, short_name);
1092                        if (ref_exists(resolved_buf.buf))
1093                                break;
1094                }
1095
1096                /*
1097                 * short name is non-ambiguous if all previous rules
1098                 * haven't resolved to a valid ref
1099                 */
1100                if (j == rules_to_fail) {
1101                        strbuf_release(&resolved_buf);
1102                        return short_name;
1103                }
1104        }
1105
1106        strbuf_release(&resolved_buf);
1107        free(short_name);
1108        return xstrdup(refname);
1109}
1110
1111static struct string_list *hide_refs;
1112
1113int parse_hide_refs_config(const char *var, const char *value, const char *section)
1114{
1115        const char *key;
1116        if (!strcmp("transfer.hiderefs", var) ||
1117            (!parse_config_key(var, section, NULL, NULL, &key) &&
1118             !strcmp(key, "hiderefs"))) {
1119                char *ref;
1120                int len;
1121
1122                if (!value)
1123                        return config_error_nonbool(var);
1124                ref = xstrdup(value);
1125                len = strlen(ref);
1126                while (len && ref[len - 1] == '/')
1127                        ref[--len] = '\0';
1128                if (!hide_refs) {
1129                        hide_refs = xcalloc(1, sizeof(*hide_refs));
1130                        hide_refs->strdup_strings = 1;
1131                }
1132                string_list_append(hide_refs, ref);
1133        }
1134        return 0;
1135}
1136
1137int ref_is_hidden(const char *refname, const char *refname_full)
1138{
1139        int i;
1140
1141        if (!hide_refs)
1142                return 0;
1143        for (i = hide_refs->nr - 1; i >= 0; i--) {
1144                const char *match = hide_refs->items[i].string;
1145                const char *subject;
1146                int neg = 0;
1147                int len;
1148
1149                if (*match == '!') {
1150                        neg = 1;
1151                        match++;
1152                }
1153
1154                if (*match == '^') {
1155                        subject = refname_full;
1156                        match++;
1157                } else {
1158                        subject = refname;
1159                }
1160
1161                /* refname can be NULL when namespaces are used. */
1162                if (!subject || !starts_with(subject, match))
1163                        continue;
1164                len = strlen(match);
1165                if (!subject[len] || subject[len] == '/')
1166                        return !neg;
1167        }
1168        return 0;
1169}
1170
1171const char *find_descendant_ref(const char *dirname,
1172                                const struct string_list *extras,
1173                                const struct string_list *skip)
1174{
1175        int pos;
1176
1177        if (!extras)
1178                return NULL;
1179
1180        /*
1181         * Look at the place where dirname would be inserted into
1182         * extras. If there is an entry at that position that starts
1183         * with dirname (remember, dirname includes the trailing
1184         * slash) and is not in skip, then we have a conflict.
1185         */
1186        for (pos = string_list_find_insert_index(extras, dirname, 0);
1187             pos < extras->nr; pos++) {
1188                const char *extra_refname = extras->items[pos].string;
1189
1190                if (!starts_with(extra_refname, dirname))
1191                        break;
1192
1193                if (!skip || !string_list_has_string(skip, extra_refname))
1194                        return extra_refname;
1195        }
1196        return NULL;
1197}
1198
1199int refs_rename_ref_available(struct ref_store *refs,
1200                              const char *old_refname,
1201                              const char *new_refname)
1202{
1203        struct string_list skip = STRING_LIST_INIT_NODUP;
1204        struct strbuf err = STRBUF_INIT;
1205        int ok;
1206
1207        string_list_insert(&skip, old_refname);
1208        ok = !refs_verify_refname_available(refs, new_refname,
1209                                            NULL, &skip, &err);
1210        if (!ok)
1211                error("%s", err.buf);
1212
1213        string_list_clear(&skip, 0);
1214        strbuf_release(&err);
1215        return ok;
1216}
1217
1218int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1219{
1220        struct object_id oid;
1221        int flag;
1222
1223        if (submodule) {
1224                if (resolve_gitlink_ref(submodule, "HEAD", oid.hash) == 0)
1225                        return fn("HEAD", &oid, 0, cb_data);
1226
1227                return 0;
1228        }
1229
1230        if (!read_ref_full("HEAD", RESOLVE_REF_READING, oid.hash, &flag))
1231                return fn("HEAD", &oid, flag, cb_data);
1232
1233        return 0;
1234}
1235
1236int head_ref(each_ref_fn fn, void *cb_data)
1237{
1238        return head_ref_submodule(NULL, fn, cb_data);
1239}
1240
1241/*
1242 * Call fn for each reference in the specified submodule for which the
1243 * refname begins with prefix. If trim is non-zero, then trim that
1244 * many characters off the beginning of each refname before passing
1245 * the refname to fn. flags can be DO_FOR_EACH_INCLUDE_BROKEN to
1246 * include broken references in the iteration. If fn ever returns a
1247 * non-zero value, stop the iteration and return that value;
1248 * otherwise, return 0.
1249 */
1250static int do_for_each_ref(struct ref_store *refs, const char *prefix,
1251                           each_ref_fn fn, int trim, int flags, void *cb_data)
1252{
1253        struct ref_iterator *iter;
1254
1255        if (!refs)
1256                return 0;
1257
1258        iter = refs->be->iterator_begin(refs, prefix, flags);
1259        iter = prefix_ref_iterator_begin(iter, prefix, trim);
1260
1261        return do_for_each_ref_iterator(iter, fn, cb_data);
1262}
1263
1264int refs_for_each_ref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1265{
1266        return do_for_each_ref(refs, "", fn, 0, 0, cb_data);
1267}
1268
1269int for_each_ref(each_ref_fn fn, void *cb_data)
1270{
1271        return refs_for_each_ref(get_main_ref_store(), fn, cb_data);
1272}
1273
1274int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1275{
1276        return refs_for_each_ref(get_submodule_ref_store(submodule), fn, cb_data);
1277}
1278
1279int refs_for_each_ref_in(struct ref_store *refs, const char *prefix,
1280                         each_ref_fn fn, void *cb_data)
1281{
1282        return do_for_each_ref(refs, prefix, fn, strlen(prefix), 0, cb_data);
1283}
1284
1285int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
1286{
1287        return refs_for_each_ref_in(get_main_ref_store(), prefix, fn, cb_data);
1288}
1289
1290int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data, unsigned int broken)
1291{
1292        unsigned int flag = 0;
1293
1294        if (broken)
1295                flag = DO_FOR_EACH_INCLUDE_BROKEN;
1296        return do_for_each_ref(get_main_ref_store(),
1297                               prefix, fn, 0, flag, cb_data);
1298}
1299
1300int for_each_ref_in_submodule(const char *submodule, const char *prefix,
1301                              each_ref_fn fn, void *cb_data)
1302{
1303        return refs_for_each_ref_in(get_submodule_ref_store(submodule),
1304                                    prefix, fn, cb_data);
1305}
1306
1307int for_each_replace_ref(each_ref_fn fn, void *cb_data)
1308{
1309        return do_for_each_ref(get_main_ref_store(),
1310                               git_replace_ref_base, fn,
1311                               strlen(git_replace_ref_base),
1312                               0, cb_data);
1313}
1314
1315int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
1316{
1317        struct strbuf buf = STRBUF_INIT;
1318        int ret;
1319        strbuf_addf(&buf, "%srefs/", get_git_namespace());
1320        ret = do_for_each_ref(get_main_ref_store(),
1321                              buf.buf, fn, 0, 0, cb_data);
1322        strbuf_release(&buf);
1323        return ret;
1324}
1325
1326int refs_for_each_rawref(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1327{
1328        return do_for_each_ref(refs, "", fn, 0,
1329                               DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1330}
1331
1332int for_each_rawref(each_ref_fn fn, void *cb_data)
1333{
1334        return refs_for_each_rawref(get_main_ref_store(), fn, cb_data);
1335}
1336
1337/* This function needs to return a meaningful errno on failure */
1338const char *refs_resolve_ref_unsafe(struct ref_store *refs,
1339                                    const char *refname,
1340                                    int resolve_flags,
1341                                    unsigned char *sha1, int *flags)
1342{
1343        static struct strbuf sb_refname = STRBUF_INIT;
1344        int unused_flags;
1345        int symref_count;
1346
1347        if (!flags)
1348                flags = &unused_flags;
1349
1350        *flags = 0;
1351
1352        if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1353                if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1354                    !refname_is_safe(refname)) {
1355                        errno = EINVAL;
1356                        return NULL;
1357                }
1358
1359                /*
1360                 * dwim_ref() uses REF_ISBROKEN to distinguish between
1361                 * missing refs and refs that were present but invalid,
1362                 * to complain about the latter to stderr.
1363                 *
1364                 * We don't know whether the ref exists, so don't set
1365                 * REF_ISBROKEN yet.
1366                 */
1367                *flags |= REF_BAD_NAME;
1368        }
1369
1370        for (symref_count = 0; symref_count < SYMREF_MAXDEPTH; symref_count++) {
1371                unsigned int read_flags = 0;
1372
1373                if (refs->be->read_raw_ref(refs, refname,
1374                                           sha1, &sb_refname, &read_flags)) {
1375                        *flags |= read_flags;
1376                        if (errno != ENOENT || (resolve_flags & RESOLVE_REF_READING))
1377                                return NULL;
1378                        hashclr(sha1);
1379                        if (*flags & REF_BAD_NAME)
1380                                *flags |= REF_ISBROKEN;
1381                        return refname;
1382                }
1383
1384                *flags |= read_flags;
1385
1386                if (!(read_flags & REF_ISSYMREF)) {
1387                        if (*flags & REF_BAD_NAME) {
1388                                hashclr(sha1);
1389                                *flags |= REF_ISBROKEN;
1390                        }
1391                        return refname;
1392                }
1393
1394                refname = sb_refname.buf;
1395                if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
1396                        hashclr(sha1);
1397                        return refname;
1398                }
1399                if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1400                        if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1401                            !refname_is_safe(refname)) {
1402                                errno = EINVAL;
1403                                return NULL;
1404                        }
1405
1406                        *flags |= REF_ISBROKEN | REF_BAD_NAME;
1407                }
1408        }
1409
1410        errno = ELOOP;
1411        return NULL;
1412}
1413
1414/* backend functions */
1415int refs_init_db(struct strbuf *err)
1416{
1417        struct ref_store *refs = get_main_ref_store();
1418
1419        return refs->be->init_db(refs, err);
1420}
1421
1422const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
1423                               unsigned char *sha1, int *flags)
1424{
1425        return refs_resolve_ref_unsafe(get_main_ref_store(), refname,
1426                                       resolve_flags, sha1, flags);
1427}
1428
1429int resolve_gitlink_ref(const char *submodule, const char *refname,
1430                        unsigned char *sha1)
1431{
1432        size_t len = strlen(submodule);
1433        struct ref_store *refs;
1434        int flags;
1435
1436        while (len && submodule[len - 1] == '/')
1437                len--;
1438
1439        if (!len)
1440                return -1;
1441
1442        if (submodule[len]) {
1443                /* We need to strip off one or more trailing slashes */
1444                char *stripped = xmemdupz(submodule, len);
1445
1446                refs = get_submodule_ref_store(stripped);
1447                free(stripped);
1448        } else {
1449                refs = get_submodule_ref_store(submodule);
1450        }
1451
1452        if (!refs)
1453                return -1;
1454
1455        if (!refs_resolve_ref_unsafe(refs, refname, 0, sha1, &flags) ||
1456            is_null_sha1(sha1))
1457                return -1;
1458        return 0;
1459}
1460
1461struct submodule_hash_entry
1462{
1463        struct hashmap_entry ent; /* must be the first member! */
1464
1465        struct ref_store *refs;
1466
1467        /* NUL-terminated name of submodule: */
1468        char submodule[FLEX_ARRAY];
1469};
1470
1471static int submodule_hash_cmp(const void *entry, const void *entry_or_key,
1472                              const void *keydata)
1473{
1474        const struct submodule_hash_entry *e1 = entry, *e2 = entry_or_key;
1475        const char *submodule = keydata ? keydata : e2->submodule;
1476
1477        return strcmp(e1->submodule, submodule);
1478}
1479
1480static struct submodule_hash_entry *alloc_submodule_hash_entry(
1481                const char *submodule, struct ref_store *refs)
1482{
1483        struct submodule_hash_entry *entry;
1484
1485        FLEX_ALLOC_STR(entry, submodule, submodule);
1486        hashmap_entry_init(entry, strhash(submodule));
1487        entry->refs = refs;
1488        return entry;
1489}
1490
1491/* A pointer to the ref_store for the main repository: */
1492static struct ref_store *main_ref_store;
1493
1494/* A hashmap of ref_stores, stored by submodule name: */
1495static struct hashmap submodule_ref_stores;
1496
1497/*
1498 * Return the ref_store instance for the specified submodule. If that
1499 * ref_store hasn't been initialized yet, return NULL.
1500 */
1501static struct ref_store *lookup_submodule_ref_store(const char *submodule)
1502{
1503        struct submodule_hash_entry *entry;
1504
1505        if (!submodule_ref_stores.tablesize)
1506                /* It's initialized on demand in register_ref_store(). */
1507                return NULL;
1508
1509        entry = hashmap_get_from_hash(&submodule_ref_stores,
1510                                      strhash(submodule), submodule);
1511        return entry ? entry->refs : NULL;
1512}
1513
1514/*
1515 * Create, record, and return a ref_store instance for the specified
1516 * gitdir.
1517 */
1518static struct ref_store *ref_store_init(const char *gitdir,
1519                                        unsigned int flags)
1520{
1521        const char *be_name = "files";
1522        struct ref_storage_be *be = find_ref_storage_backend(be_name);
1523        struct ref_store *refs;
1524
1525        if (!be)
1526                die("BUG: reference backend %s is unknown", be_name);
1527
1528        refs = be->init(gitdir, flags);
1529        return refs;
1530}
1531
1532struct ref_store *get_main_ref_store(void)
1533{
1534        if (main_ref_store)
1535                return main_ref_store;
1536
1537        main_ref_store = ref_store_init(get_git_dir(),
1538                                        (REF_STORE_READ |
1539                                         REF_STORE_WRITE |
1540                                         REF_STORE_ODB |
1541                                         REF_STORE_MAIN));
1542        return main_ref_store;
1543}
1544
1545/*
1546 * Register the specified ref_store to be the one that should be used
1547 * for submodule. It is a fatal error to call this function twice for
1548 * the same submodule.
1549 */
1550static void register_submodule_ref_store(struct ref_store *refs,
1551                                         const char *submodule)
1552{
1553        if (!submodule_ref_stores.tablesize)
1554                hashmap_init(&submodule_ref_stores, submodule_hash_cmp, 0);
1555
1556        if (hashmap_put(&submodule_ref_stores,
1557                        alloc_submodule_hash_entry(submodule, refs)))
1558                die("BUG: ref_store for submodule '%s' initialized twice",
1559                    submodule);
1560}
1561
1562struct ref_store *get_submodule_ref_store(const char *submodule)
1563{
1564        struct strbuf submodule_sb = STRBUF_INIT;
1565        struct ref_store *refs;
1566        int ret;
1567
1568        if (!submodule || !*submodule) {
1569                /*
1570                 * FIXME: This case is ideally not allowed. But that
1571                 * can't happen until we clean up all the callers.
1572                 */
1573                return get_main_ref_store();
1574        }
1575
1576        refs = lookup_submodule_ref_store(submodule);
1577        if (refs)
1578                return refs;
1579
1580        strbuf_addstr(&submodule_sb, submodule);
1581        ret = is_nonbare_repository_dir(&submodule_sb);
1582        strbuf_release(&submodule_sb);
1583        if (!ret)
1584                return NULL;
1585
1586        ret = submodule_to_gitdir(&submodule_sb, submodule);
1587        if (ret) {
1588                strbuf_release(&submodule_sb);
1589                return NULL;
1590        }
1591
1592        /* assume that add_submodule_odb() has been called */
1593        refs = ref_store_init(submodule_sb.buf,
1594                              REF_STORE_READ | REF_STORE_ODB);
1595        register_submodule_ref_store(refs, submodule);
1596
1597        strbuf_release(&submodule_sb);
1598        return refs;
1599}
1600
1601void base_ref_store_init(struct ref_store *refs,
1602                         const struct ref_storage_be *be)
1603{
1604        refs->be = be;
1605}
1606
1607/* backend functions */
1608int refs_pack_refs(struct ref_store *refs, unsigned int flags)
1609{
1610        return refs->be->pack_refs(refs, flags);
1611}
1612
1613int refs_peel_ref(struct ref_store *refs, const char *refname,
1614                  unsigned char *sha1)
1615{
1616        return refs->be->peel_ref(refs, refname, sha1);
1617}
1618
1619int peel_ref(const char *refname, unsigned char *sha1)
1620{
1621        return refs_peel_ref(get_main_ref_store(), refname, sha1);
1622}
1623
1624int refs_create_symref(struct ref_store *refs,
1625                       const char *ref_target,
1626                       const char *refs_heads_master,
1627                       const char *logmsg)
1628{
1629        return refs->be->create_symref(refs, ref_target,
1630                                       refs_heads_master,
1631                                       logmsg);
1632}
1633
1634int create_symref(const char *ref_target, const char *refs_heads_master,
1635                  const char *logmsg)
1636{
1637        return refs_create_symref(get_main_ref_store(), ref_target,
1638                                  refs_heads_master, logmsg);
1639}
1640
1641int ref_transaction_commit(struct ref_transaction *transaction,
1642                           struct strbuf *err)
1643{
1644        struct ref_store *refs = transaction->ref_store;
1645
1646        return refs->be->transaction_commit(refs, transaction, err);
1647}
1648
1649int refs_verify_refname_available(struct ref_store *refs,
1650                                  const char *refname,
1651                                  const struct string_list *extra,
1652                                  const struct string_list *skip,
1653                                  struct strbuf *err)
1654{
1655        return refs->be->verify_refname_available(refs, refname, extra, skip, err);
1656}
1657
1658int refs_for_each_reflog(struct ref_store *refs, each_ref_fn fn, void *cb_data)
1659{
1660        struct ref_iterator *iter;
1661
1662        iter = refs->be->reflog_iterator_begin(refs);
1663
1664        return do_for_each_ref_iterator(iter, fn, cb_data);
1665}
1666
1667int for_each_reflog(each_ref_fn fn, void *cb_data)
1668{
1669        return refs_for_each_reflog(get_main_ref_store(), fn, cb_data);
1670}
1671
1672int refs_for_each_reflog_ent_reverse(struct ref_store *refs,
1673                                     const char *refname,
1674                                     each_reflog_ent_fn fn,
1675                                     void *cb_data)
1676{
1677        return refs->be->for_each_reflog_ent_reverse(refs, refname,
1678                                                     fn, cb_data);
1679}
1680
1681int for_each_reflog_ent_reverse(const char *refname, each_reflog_ent_fn fn,
1682                                void *cb_data)
1683{
1684        return refs_for_each_reflog_ent_reverse(get_main_ref_store(),
1685                                                refname, fn, cb_data);
1686}
1687
1688int refs_for_each_reflog_ent(struct ref_store *refs, const char *refname,
1689                             each_reflog_ent_fn fn, void *cb_data)
1690{
1691        return refs->be->for_each_reflog_ent(refs, refname, fn, cb_data);
1692}
1693
1694int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn,
1695                        void *cb_data)
1696{
1697        return refs_for_each_reflog_ent(get_main_ref_store(), refname,
1698                                        fn, cb_data);
1699}
1700
1701int refs_reflog_exists(struct ref_store *refs, const char *refname)
1702{
1703        return refs->be->reflog_exists(refs, refname);
1704}
1705
1706int reflog_exists(const char *refname)
1707{
1708        return refs_reflog_exists(get_main_ref_store(), refname);
1709}
1710
1711int refs_create_reflog(struct ref_store *refs, const char *refname,
1712                       int force_create, struct strbuf *err)
1713{
1714        return refs->be->create_reflog(refs, refname, force_create, err);
1715}
1716
1717int safe_create_reflog(const char *refname, int force_create,
1718                       struct strbuf *err)
1719{
1720        return refs_create_reflog(get_main_ref_store(), refname,
1721                                  force_create, err);
1722}
1723
1724int refs_delete_reflog(struct ref_store *refs, const char *refname)
1725{
1726        return refs->be->delete_reflog(refs, refname);
1727}
1728
1729int delete_reflog(const char *refname)
1730{
1731        return refs_delete_reflog(get_main_ref_store(), refname);
1732}
1733
1734int refs_reflog_expire(struct ref_store *refs,
1735                       const char *refname, const unsigned char *sha1,
1736                       unsigned int flags,
1737                       reflog_expiry_prepare_fn prepare_fn,
1738                       reflog_expiry_should_prune_fn should_prune_fn,
1739                       reflog_expiry_cleanup_fn cleanup_fn,
1740                       void *policy_cb_data)
1741{
1742        return refs->be->reflog_expire(refs, refname, sha1, flags,
1743                                       prepare_fn, should_prune_fn,
1744                                       cleanup_fn, policy_cb_data);
1745}
1746
1747int reflog_expire(const char *refname, const unsigned char *sha1,
1748                  unsigned int flags,
1749                  reflog_expiry_prepare_fn prepare_fn,
1750                  reflog_expiry_should_prune_fn should_prune_fn,
1751                  reflog_expiry_cleanup_fn cleanup_fn,
1752                  void *policy_cb_data)
1753{
1754        return refs_reflog_expire(get_main_ref_store(),
1755                                  refname, sha1, flags,
1756                                  prepare_fn, should_prune_fn,
1757                                  cleanup_fn, policy_cb_data);
1758}
1759
1760int initial_ref_transaction_commit(struct ref_transaction *transaction,
1761                                   struct strbuf *err)
1762{
1763        struct ref_store *refs = transaction->ref_store;
1764
1765        return refs->be->initial_transaction_commit(refs, transaction, err);
1766}
1767
1768int refs_delete_refs(struct ref_store *refs, struct string_list *refnames,
1769                     unsigned int flags)
1770{
1771        return refs->be->delete_refs(refs, refnames, flags);
1772}
1773
1774int delete_refs(struct string_list *refnames, unsigned int flags)
1775{
1776        return refs_delete_refs(get_main_ref_store(), refnames, flags);
1777}
1778
1779int refs_rename_ref(struct ref_store *refs, const char *oldref,
1780                    const char *newref, const char *logmsg)
1781{
1782        return refs->be->rename_ref(refs, oldref, newref, logmsg);
1783}
1784
1785int rename_ref(const char *oldref, const char *newref, const char *logmsg)
1786{
1787        return refs_rename_ref(get_main_ref_store(), oldref, newref, logmsg);
1788}