sha1-name.con commit Merge branch 'is/parsing-line-range' (6566a91)
   1#include "cache.h"
   2#include "config.h"
   3#include "tag.h"
   4#include "commit.h"
   5#include "tree.h"
   6#include "blob.h"
   7#include "tree-walk.h"
   8#include "refs.h"
   9#include "remote.h"
  10#include "dir.h"
  11#include "sha1-array.h"
  12#include "packfile.h"
  13#include "object-store.h"
  14#include "repository.h"
  15
  16static int get_oid_oneline(const char *, struct object_id *, struct commit_list *);
  17
  18typedef int (*disambiguate_hint_fn)(const struct object_id *, void *);
  19
  20struct disambiguate_state {
  21        int len; /* length of prefix in hex chars */
  22        char hex_pfx[GIT_MAX_HEXSZ + 1];
  23        struct object_id bin_pfx;
  24
  25        disambiguate_hint_fn fn;
  26        void *cb_data;
  27        struct object_id candidate;
  28        unsigned candidate_exists:1;
  29        unsigned candidate_checked:1;
  30        unsigned candidate_ok:1;
  31        unsigned disambiguate_fn_used:1;
  32        unsigned ambiguous:1;
  33        unsigned always_call_fn:1;
  34};
  35
  36static void update_candidates(struct disambiguate_state *ds, const struct object_id *current)
  37{
  38        if (ds->always_call_fn) {
  39                ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
  40                return;
  41        }
  42        if (!ds->candidate_exists) {
  43                /* this is the first candidate */
  44                oidcpy(&ds->candidate, current);
  45                ds->candidate_exists = 1;
  46                return;
  47        } else if (!oidcmp(&ds->candidate, current)) {
  48                /* the same as what we already have seen */
  49                return;
  50        }
  51
  52        if (!ds->fn) {
  53                /* cannot disambiguate between ds->candidate and current */
  54                ds->ambiguous = 1;
  55                return;
  56        }
  57
  58        if (!ds->candidate_checked) {
  59                ds->candidate_ok = ds->fn(&ds->candidate, ds->cb_data);
  60                ds->disambiguate_fn_used = 1;
  61                ds->candidate_checked = 1;
  62        }
  63
  64        if (!ds->candidate_ok) {
  65                /* discard the candidate; we know it does not satisfy fn */
  66                oidcpy(&ds->candidate, current);
  67                ds->candidate_checked = 0;
  68                return;
  69        }
  70
  71        /* if we reach this point, we know ds->candidate satisfies fn */
  72        if (ds->fn(current, ds->cb_data)) {
  73                /*
  74                 * if both current and candidate satisfy fn, we cannot
  75                 * disambiguate.
  76                 */
  77                ds->candidate_ok = 0;
  78                ds->ambiguous = 1;
  79        }
  80
  81        /* otherwise, current can be discarded and candidate is still good */
  82}
  83
  84static int append_loose_object(const struct object_id *oid, const char *path,
  85                               void *data)
  86{
  87        oid_array_append(data, oid);
  88        return 0;
  89}
  90
  91static int match_sha(unsigned, const unsigned char *, const unsigned char *);
  92
  93static void find_short_object_filename(struct disambiguate_state *ds)
  94{
  95        int subdir_nr = ds->bin_pfx.hash[0];
  96        struct alternate_object_database *alt;
  97        static struct alternate_object_database *fakeent;
  98
  99        if (!fakeent) {
 100                /*
 101                 * Create a "fake" alternate object database that
 102                 * points to our own object database, to make it
 103                 * easier to get a temporary working space in
 104                 * alt->name/alt->base while iterating over the
 105                 * object databases including our own.
 106                 */
 107                fakeent = alloc_alt_odb(get_object_directory());
 108        }
 109        fakeent->next = the_repository->objects->alt_odb_list;
 110
 111        for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 112                int pos;
 113
 114                if (!alt->loose_objects_subdir_seen[subdir_nr]) {
 115                        struct strbuf *buf = alt_scratch_buf(alt);
 116                        for_each_file_in_obj_subdir(subdir_nr, buf,
 117                                                    append_loose_object,
 118                                                    NULL, NULL,
 119                                                    &alt->loose_objects_cache);
 120                        alt->loose_objects_subdir_seen[subdir_nr] = 1;
 121                }
 122
 123                pos = oid_array_lookup(&alt->loose_objects_cache, &ds->bin_pfx);
 124                if (pos < 0)
 125                        pos = -1 - pos;
 126                while (!ds->ambiguous && pos < alt->loose_objects_cache.nr) {
 127                        const struct object_id *oid;
 128                        oid = alt->loose_objects_cache.oid + pos;
 129                        if (!match_sha(ds->len, ds->bin_pfx.hash, oid->hash))
 130                                break;
 131                        update_candidates(ds, oid);
 132                        pos++;
 133                }
 134        }
 135}
 136
 137static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 138{
 139        do {
 140                if (*a != *b)
 141                        return 0;
 142                a++;
 143                b++;
 144                len -= 2;
 145        } while (len > 1);
 146        if (len)
 147                if ((*a ^ *b) & 0xf0)
 148                        return 0;
 149        return 1;
 150}
 151
 152static void unique_in_pack(struct packed_git *p,
 153                           struct disambiguate_state *ds)
 154{
 155        uint32_t num, i, first = 0;
 156        const struct object_id *current = NULL;
 157
 158        if (open_pack_index(p) || !p->num_objects)
 159                return;
 160
 161        num = p->num_objects;
 162        bsearch_pack(&ds->bin_pfx, p, &first);
 163
 164        /*
 165         * At this point, "first" is the location of the lowest object
 166         * with an object name that could match "bin_pfx".  See if we have
 167         * 0, 1 or more objects that actually match(es).
 168         */
 169        for (i = first; i < num && !ds->ambiguous; i++) {
 170                struct object_id oid;
 171                current = nth_packed_object_oid(&oid, p, i);
 172                if (!match_sha(ds->len, ds->bin_pfx.hash, current->hash))
 173                        break;
 174                update_candidates(ds, current);
 175        }
 176}
 177
 178static void find_short_packed_object(struct disambiguate_state *ds)
 179{
 180        struct packed_git *p;
 181
 182        for (p = get_packed_git(the_repository); p && !ds->ambiguous;
 183             p = p->next)
 184                unique_in_pack(p, ds);
 185}
 186
 187#define SHORT_NAME_NOT_FOUND (-1)
 188#define SHORT_NAME_AMBIGUOUS (-2)
 189
 190static int finish_object_disambiguation(struct disambiguate_state *ds,
 191                                        struct object_id *oid)
 192{
 193        if (ds->ambiguous)
 194                return SHORT_NAME_AMBIGUOUS;
 195
 196        if (!ds->candidate_exists)
 197                return SHORT_NAME_NOT_FOUND;
 198
 199        if (!ds->candidate_checked)
 200                /*
 201                 * If this is the only candidate, there is no point
 202                 * calling the disambiguation hint callback.
 203                 *
 204                 * On the other hand, if the current candidate
 205                 * replaced an earlier candidate that did _not_ pass
 206                 * the disambiguation hint callback, then we do have
 207                 * more than one objects that match the short name
 208                 * given, so we should make sure this one matches;
 209                 * otherwise, if we discovered this one and the one
 210                 * that we previously discarded in the reverse order,
 211                 * we would end up showing different results in the
 212                 * same repository!
 213                 */
 214                ds->candidate_ok = (!ds->disambiguate_fn_used ||
 215                                    ds->fn(&ds->candidate, ds->cb_data));
 216
 217        if (!ds->candidate_ok)
 218                return SHORT_NAME_AMBIGUOUS;
 219
 220        oidcpy(oid, &ds->candidate);
 221        return 0;
 222}
 223
 224static int disambiguate_commit_only(const struct object_id *oid, void *cb_data_unused)
 225{
 226        int kind = oid_object_info(the_repository, oid, NULL);
 227        return kind == OBJ_COMMIT;
 228}
 229
 230static int disambiguate_committish_only(const struct object_id *oid, void *cb_data_unused)
 231{
 232        struct object *obj;
 233        int kind;
 234
 235        kind = oid_object_info(the_repository, oid, NULL);
 236        if (kind == OBJ_COMMIT)
 237                return 1;
 238        if (kind != OBJ_TAG)
 239                return 0;
 240
 241        /* We need to do this the hard way... */
 242        obj = deref_tag(parse_object(oid), NULL, 0);
 243        if (obj && obj->type == OBJ_COMMIT)
 244                return 1;
 245        return 0;
 246}
 247
 248static int disambiguate_tree_only(const struct object_id *oid, void *cb_data_unused)
 249{
 250        int kind = oid_object_info(the_repository, oid, NULL);
 251        return kind == OBJ_TREE;
 252}
 253
 254static int disambiguate_treeish_only(const struct object_id *oid, void *cb_data_unused)
 255{
 256        struct object *obj;
 257        int kind;
 258
 259        kind = oid_object_info(the_repository, oid, NULL);
 260        if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 261                return 1;
 262        if (kind != OBJ_TAG)
 263                return 0;
 264
 265        /* We need to do this the hard way... */
 266        obj = deref_tag(parse_object(oid), NULL, 0);
 267        if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 268                return 1;
 269        return 0;
 270}
 271
 272static int disambiguate_blob_only(const struct object_id *oid, void *cb_data_unused)
 273{
 274        int kind = oid_object_info(the_repository, oid, NULL);
 275        return kind == OBJ_BLOB;
 276}
 277
 278static disambiguate_hint_fn default_disambiguate_hint;
 279
 280int set_disambiguate_hint_config(const char *var, const char *value)
 281{
 282        static const struct {
 283                const char *name;
 284                disambiguate_hint_fn fn;
 285        } hints[] = {
 286                { "none", NULL },
 287                { "commit", disambiguate_commit_only },
 288                { "committish", disambiguate_committish_only },
 289                { "tree", disambiguate_tree_only },
 290                { "treeish", disambiguate_treeish_only },
 291                { "blob", disambiguate_blob_only }
 292        };
 293        int i;
 294
 295        if (!value)
 296                return config_error_nonbool(var);
 297
 298        for (i = 0; i < ARRAY_SIZE(hints); i++) {
 299                if (!strcasecmp(value, hints[i].name)) {
 300                        default_disambiguate_hint = hints[i].fn;
 301                        return 0;
 302                }
 303        }
 304
 305        return error("unknown hint type for '%s': %s", var, value);
 306}
 307
 308static int init_object_disambiguation(const char *name, int len,
 309                                      struct disambiguate_state *ds)
 310{
 311        int i;
 312
 313        if (len < MINIMUM_ABBREV || len > the_hash_algo->hexsz)
 314                return -1;
 315
 316        memset(ds, 0, sizeof(*ds));
 317
 318        for (i = 0; i < len ;i++) {
 319                unsigned char c = name[i];
 320                unsigned char val;
 321                if (c >= '0' && c <= '9')
 322                        val = c - '0';
 323                else if (c >= 'a' && c <= 'f')
 324                        val = c - 'a' + 10;
 325                else if (c >= 'A' && c <='F') {
 326                        val = c - 'A' + 10;
 327                        c -= 'A' - 'a';
 328                }
 329                else
 330                        return -1;
 331                ds->hex_pfx[i] = c;
 332                if (!(i & 1))
 333                        val <<= 4;
 334                ds->bin_pfx.hash[i >> 1] |= val;
 335        }
 336
 337        ds->len = len;
 338        ds->hex_pfx[len] = '\0';
 339        prepare_alt_odb(the_repository);
 340        return 0;
 341}
 342
 343static int show_ambiguous_object(const struct object_id *oid, void *data)
 344{
 345        const struct disambiguate_state *ds = data;
 346        struct strbuf desc = STRBUF_INIT;
 347        int type;
 348
 349        if (ds->fn && !ds->fn(oid, ds->cb_data))
 350                return 0;
 351
 352        type = oid_object_info(the_repository, oid, NULL);
 353        if (type == OBJ_COMMIT) {
 354                struct commit *commit = lookup_commit(oid);
 355                if (commit) {
 356                        struct pretty_print_context pp = {0};
 357                        pp.date_mode.type = DATE_SHORT;
 358                        format_commit_message(commit, " %ad - %s", &desc, &pp);
 359                }
 360        } else if (type == OBJ_TAG) {
 361                struct tag *tag = lookup_tag(oid);
 362                if (!parse_tag(tag) && tag->tag)
 363                        strbuf_addf(&desc, " %s", tag->tag);
 364        }
 365
 366        advise("  %s %s%s",
 367               find_unique_abbrev(oid, DEFAULT_ABBREV),
 368               type_name(type) ? type_name(type) : "unknown type",
 369               desc.buf);
 370
 371        strbuf_release(&desc);
 372        return 0;
 373}
 374
 375static int collect_ambiguous(const struct object_id *oid, void *data)
 376{
 377        oid_array_append(data, oid);
 378        return 0;
 379}
 380
 381static int sort_ambiguous(const void *a, const void *b)
 382{
 383        int a_type = oid_object_info(the_repository, a, NULL);
 384        int b_type = oid_object_info(the_repository, b, NULL);
 385        int a_type_sort;
 386        int b_type_sort;
 387
 388        /*
 389         * Sorts by hash within the same object type, just as
 390         * oid_array_for_each_unique() would do.
 391         */
 392        if (a_type == b_type)
 393                return oidcmp(a, b);
 394
 395        /*
 396         * Between object types show tags, then commits, and finally
 397         * trees and blobs.
 398         *
 399         * The object_type enum is commit, tree, blob, tag, but we
 400         * want tag, commit, tree blob. Cleverly (perhaps too
 401         * cleverly) do that with modulus, since the enum assigns 1 to
 402         * commit, so tag becomes 0.
 403         */
 404        a_type_sort = a_type % 4;
 405        b_type_sort = b_type % 4;
 406        return a_type_sort > b_type_sort ? 1 : -1;
 407}
 408
 409static int get_short_oid(const char *name, int len, struct object_id *oid,
 410                          unsigned flags)
 411{
 412        int status;
 413        struct disambiguate_state ds;
 414        int quietly = !!(flags & GET_OID_QUIETLY);
 415
 416        if (init_object_disambiguation(name, len, &ds) < 0)
 417                return -1;
 418
 419        if (HAS_MULTI_BITS(flags & GET_OID_DISAMBIGUATORS))
 420                BUG("multiple get_short_oid disambiguator flags");
 421
 422        if (flags & GET_OID_COMMIT)
 423                ds.fn = disambiguate_commit_only;
 424        else if (flags & GET_OID_COMMITTISH)
 425                ds.fn = disambiguate_committish_only;
 426        else if (flags & GET_OID_TREE)
 427                ds.fn = disambiguate_tree_only;
 428        else if (flags & GET_OID_TREEISH)
 429                ds.fn = disambiguate_treeish_only;
 430        else if (flags & GET_OID_BLOB)
 431                ds.fn = disambiguate_blob_only;
 432        else
 433                ds.fn = default_disambiguate_hint;
 434
 435        find_short_object_filename(&ds);
 436        find_short_packed_object(&ds);
 437        status = finish_object_disambiguation(&ds, oid);
 438
 439        if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
 440                struct oid_array collect = OID_ARRAY_INIT;
 441
 442                error(_("short SHA1 %s is ambiguous"), ds.hex_pfx);
 443
 444                /*
 445                 * We may still have ambiguity if we simply saw a series of
 446                 * candidates that did not satisfy our hint function. In
 447                 * that case, we still want to show them, so disable the hint
 448                 * function entirely.
 449                 */
 450                if (!ds.ambiguous)
 451                        ds.fn = NULL;
 452
 453                advise(_("The candidates are:"));
 454                for_each_abbrev(ds.hex_pfx, collect_ambiguous, &collect);
 455                QSORT(collect.oid, collect.nr, sort_ambiguous);
 456
 457                if (oid_array_for_each(&collect, show_ambiguous_object, &ds))
 458                        BUG("show_ambiguous_object shouldn't return non-zero");
 459                oid_array_clear(&collect);
 460        }
 461
 462        return status;
 463}
 464
 465int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 466{
 467        struct oid_array collect = OID_ARRAY_INIT;
 468        struct disambiguate_state ds;
 469        int ret;
 470
 471        if (init_object_disambiguation(prefix, strlen(prefix), &ds) < 0)
 472                return -1;
 473
 474        ds.always_call_fn = 1;
 475        ds.fn = collect_ambiguous;
 476        ds.cb_data = &collect;
 477        find_short_object_filename(&ds);
 478        find_short_packed_object(&ds);
 479
 480        ret = oid_array_for_each_unique(&collect, fn, cb_data);
 481        oid_array_clear(&collect);
 482        return ret;
 483}
 484
 485/*
 486 * Return the slot of the most-significant bit set in "val". There are various
 487 * ways to do this quickly with fls() or __builtin_clzl(), but speed is
 488 * probably not a big deal here.
 489 */
 490static unsigned msb(unsigned long val)
 491{
 492        unsigned r = 0;
 493        while (val >>= 1)
 494                r++;
 495        return r;
 496}
 497
 498struct min_abbrev_data {
 499        unsigned int init_len;
 500        unsigned int cur_len;
 501        char *hex;
 502        const struct object_id *oid;
 503};
 504
 505static inline char get_hex_char_from_oid(const struct object_id *oid,
 506                                         unsigned int pos)
 507{
 508        static const char hex[] = "0123456789abcdef";
 509
 510        if ((pos & 1) == 0)
 511                return hex[oid->hash[pos >> 1] >> 4];
 512        else
 513                return hex[oid->hash[pos >> 1] & 0xf];
 514}
 515
 516static int extend_abbrev_len(const struct object_id *oid, void *cb_data)
 517{
 518        struct min_abbrev_data *mad = cb_data;
 519
 520        unsigned int i = mad->init_len;
 521        while (mad->hex[i] && mad->hex[i] == get_hex_char_from_oid(oid, i))
 522                i++;
 523
 524        if (i < GIT_MAX_RAWSZ && i >= mad->cur_len)
 525                mad->cur_len = i + 1;
 526
 527        return 0;
 528}
 529
 530static void find_abbrev_len_for_pack(struct packed_git *p,
 531                                     struct min_abbrev_data *mad)
 532{
 533        int match = 0;
 534        uint32_t num, first = 0;
 535        struct object_id oid;
 536        const struct object_id *mad_oid;
 537
 538        if (open_pack_index(p) || !p->num_objects)
 539                return;
 540
 541        num = p->num_objects;
 542        mad_oid = mad->oid;
 543        match = bsearch_pack(mad_oid, p, &first);
 544
 545        /*
 546         * first is now the position in the packfile where we would insert
 547         * mad->hash if it does not exist (or the position of mad->hash if
 548         * it does exist). Hence, we consider a maximum of two objects
 549         * nearby for the abbreviation length.
 550         */
 551        mad->init_len = 0;
 552        if (!match) {
 553                if (nth_packed_object_oid(&oid, p, first))
 554                        extend_abbrev_len(&oid, mad);
 555        } else if (first < num - 1) {
 556                if (nth_packed_object_oid(&oid, p, first + 1))
 557                        extend_abbrev_len(&oid, mad);
 558        }
 559        if (first > 0) {
 560                if (nth_packed_object_oid(&oid, p, first - 1))
 561                        extend_abbrev_len(&oid, mad);
 562        }
 563        mad->init_len = mad->cur_len;
 564}
 565
 566static void find_abbrev_len_packed(struct min_abbrev_data *mad)
 567{
 568        struct packed_git *p;
 569
 570        for (p = get_packed_git(the_repository); p; p = p->next)
 571                find_abbrev_len_for_pack(p, mad);
 572}
 573
 574int find_unique_abbrev_r(char *hex, const struct object_id *oid, int len)
 575{
 576        struct disambiguate_state ds;
 577        struct min_abbrev_data mad;
 578        struct object_id oid_ret;
 579        const unsigned hexsz = the_hash_algo->hexsz;
 580
 581        if (len < 0) {
 582                unsigned long count = approximate_object_count();
 583                /*
 584                 * Add one because the MSB only tells us the highest bit set,
 585                 * not including the value of all the _other_ bits (so "15"
 586                 * is only one off of 2^4, but the MSB is the 3rd bit.
 587                 */
 588                len = msb(count) + 1;
 589                /*
 590                 * We now know we have on the order of 2^len objects, which
 591                 * expects a collision at 2^(len/2). But we also care about hex
 592                 * chars, not bits, and there are 4 bits per hex. So all
 593                 * together we need to divide by 2 and round up.
 594                 */
 595                len = DIV_ROUND_UP(len, 2);
 596                /*
 597                 * For very small repos, we stick with our regular fallback.
 598                 */
 599                if (len < FALLBACK_DEFAULT_ABBREV)
 600                        len = FALLBACK_DEFAULT_ABBREV;
 601        }
 602
 603        oid_to_hex_r(hex, oid);
 604        if (len == hexsz || !len)
 605                return hexsz;
 606
 607        mad.init_len = len;
 608        mad.cur_len = len;
 609        mad.hex = hex;
 610        mad.oid = oid;
 611
 612        find_abbrev_len_packed(&mad);
 613
 614        if (init_object_disambiguation(hex, mad.cur_len, &ds) < 0)
 615                return -1;
 616
 617        ds.fn = extend_abbrev_len;
 618        ds.always_call_fn = 1;
 619        ds.cb_data = (void *)&mad;
 620
 621        find_short_object_filename(&ds);
 622        (void)finish_object_disambiguation(&ds, &oid_ret);
 623
 624        hex[mad.cur_len] = 0;
 625        return mad.cur_len;
 626}
 627
 628const char *find_unique_abbrev(const struct object_id *oid, int len)
 629{
 630        static int bufno;
 631        static char hexbuffer[4][GIT_MAX_HEXSZ + 1];
 632        char *hex = hexbuffer[bufno];
 633        bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
 634        find_unique_abbrev_r(hex, oid, len);
 635        return hex;
 636}
 637
 638static int ambiguous_path(const char *path, int len)
 639{
 640        int slash = 1;
 641        int cnt;
 642
 643        for (cnt = 0; cnt < len; cnt++) {
 644                switch (*path++) {
 645                case '\0':
 646                        break;
 647                case '/':
 648                        if (slash)
 649                                break;
 650                        slash = 1;
 651                        continue;
 652                case '.':
 653                        continue;
 654                default:
 655                        slash = 0;
 656                        continue;
 657                }
 658                break;
 659        }
 660        return slash;
 661}
 662
 663static inline int at_mark(const char *string, int len,
 664                          const char **suffix, int nr)
 665{
 666        int i;
 667
 668        for (i = 0; i < nr; i++) {
 669                int suffix_len = strlen(suffix[i]);
 670                if (suffix_len <= len
 671                    && !strncasecmp(string, suffix[i], suffix_len))
 672                        return suffix_len;
 673        }
 674        return 0;
 675}
 676
 677static inline int upstream_mark(const char *string, int len)
 678{
 679        const char *suffix[] = { "@{upstream}", "@{u}" };
 680        return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 681}
 682
 683static inline int push_mark(const char *string, int len)
 684{
 685        const char *suffix[] = { "@{push}" };
 686        return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 687}
 688
 689static int get_oid_1(const char *name, int len, struct object_id *oid, unsigned lookup_flags);
 690static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 691
 692static int get_oid_basic(const char *str, int len, struct object_id *oid,
 693                          unsigned int flags)
 694{
 695        static const char *warn_msg = "refname '%.*s' is ambiguous.";
 696        static const char *object_name_msg = N_(
 697        "Git normally never creates a ref that ends with 40 hex characters\n"
 698        "because it will be ignored when you just specify 40-hex. These refs\n"
 699        "may be created by mistake. For example,\n"
 700        "\n"
 701        "  git checkout -b $br $(git rev-parse ...)\n"
 702        "\n"
 703        "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 704        "examine these refs and maybe delete them. Turn this message off by\n"
 705        "running \"git config advice.objectNameWarning false\"");
 706        struct object_id tmp_oid;
 707        char *real_ref = NULL;
 708        int refs_found = 0;
 709        int at, reflog_len, nth_prior = 0;
 710
 711        if (len == the_hash_algo->hexsz && !get_oid_hex(str, oid)) {
 712                if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 713                        refs_found = dwim_ref(str, len, &tmp_oid, &real_ref);
 714                        if (refs_found > 0) {
 715                                warning(warn_msg, len, str);
 716                                if (advice_object_name_warning)
 717                                        fprintf(stderr, "%s\n", _(object_name_msg));
 718                        }
 719                        free(real_ref);
 720                }
 721                return 0;
 722        }
 723
 724        /* basic@{time or number or -number} format to query ref-log */
 725        reflog_len = at = 0;
 726        if (len && str[len-1] == '}') {
 727                for (at = len-4; at >= 0; at--) {
 728                        if (str[at] == '@' && str[at+1] == '{') {
 729                                if (str[at+2] == '-') {
 730                                        if (at != 0)
 731                                                /* @{-N} not at start */
 732                                                return -1;
 733                                        nth_prior = 1;
 734                                        continue;
 735                                }
 736                                if (!upstream_mark(str + at, len - at) &&
 737                                    !push_mark(str + at, len - at)) {
 738                                        reflog_len = (len-1) - (at+2);
 739                                        len = at;
 740                                }
 741                                break;
 742                        }
 743                }
 744        }
 745
 746        /* Accept only unambiguous ref paths. */
 747        if (len && ambiguous_path(str, len))
 748                return -1;
 749
 750        if (nth_prior) {
 751                struct strbuf buf = STRBUF_INIT;
 752                int detached;
 753
 754                if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 755                        detached = (buf.len == the_hash_algo->hexsz && !get_oid_hex(buf.buf, oid));
 756                        strbuf_release(&buf);
 757                        if (detached)
 758                                return 0;
 759                }
 760        }
 761
 762        if (!len && reflog_len)
 763                /* allow "@{...}" to mean the current branch reflog */
 764                refs_found = dwim_ref("HEAD", 4, oid, &real_ref);
 765        else if (reflog_len)
 766                refs_found = dwim_log(str, len, oid, &real_ref);
 767        else
 768                refs_found = dwim_ref(str, len, oid, &real_ref);
 769
 770        if (!refs_found)
 771                return -1;
 772
 773        if (warn_ambiguous_refs && !(flags & GET_OID_QUIETLY) &&
 774            (refs_found > 1 ||
 775             !get_short_oid(str, len, &tmp_oid, GET_OID_QUIETLY)))
 776                warning(warn_msg, len, str);
 777
 778        if (reflog_len) {
 779                int nth, i;
 780                timestamp_t at_time;
 781                timestamp_t co_time;
 782                int co_tz, co_cnt;
 783
 784                /* Is it asking for N-th entry, or approxidate? */
 785                for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 786                        char ch = str[at+2+i];
 787                        if ('0' <= ch && ch <= '9')
 788                                nth = nth * 10 + ch - '0';
 789                        else
 790                                nth = -1;
 791                }
 792                if (100000000 <= nth) {
 793                        at_time = nth;
 794                        nth = -1;
 795                } else if (0 <= nth)
 796                        at_time = 0;
 797                else {
 798                        int errors = 0;
 799                        char *tmp = xstrndup(str + at + 2, reflog_len);
 800                        at_time = approxidate_careful(tmp, &errors);
 801                        free(tmp);
 802                        if (errors) {
 803                                free(real_ref);
 804                                return -1;
 805                        }
 806                }
 807                if (read_ref_at(real_ref, flags, at_time, nth, oid, NULL,
 808                                &co_time, &co_tz, &co_cnt)) {
 809                        if (!len) {
 810                                if (starts_with(real_ref, "refs/heads/")) {
 811                                        str = real_ref + 11;
 812                                        len = strlen(real_ref + 11);
 813                                } else {
 814                                        /* detached HEAD */
 815                                        str = "HEAD";
 816                                        len = 4;
 817                                }
 818                        }
 819                        if (at_time) {
 820                                if (!(flags & GET_OID_QUIETLY)) {
 821                                        warning("Log for '%.*s' only goes "
 822                                                "back to %s.", len, str,
 823                                                show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 824                                }
 825                        } else {
 826                                if (flags & GET_OID_QUIETLY) {
 827                                        exit(128);
 828                                }
 829                                die("Log for '%.*s' only has %d entries.",
 830                                    len, str, co_cnt);
 831                        }
 832                }
 833        }
 834
 835        free(real_ref);
 836        return 0;
 837}
 838
 839static int get_parent(const char *name, int len,
 840                      struct object_id *result, int idx)
 841{
 842        struct object_id oid;
 843        int ret = get_oid_1(name, len, &oid, GET_OID_COMMITTISH);
 844        struct commit *commit;
 845        struct commit_list *p;
 846
 847        if (ret)
 848                return ret;
 849        commit = lookup_commit_reference(&oid);
 850        if (parse_commit(commit))
 851                return -1;
 852        if (!idx) {
 853                oidcpy(result, &commit->object.oid);
 854                return 0;
 855        }
 856        p = commit->parents;
 857        while (p) {
 858                if (!--idx) {
 859                        oidcpy(result, &p->item->object.oid);
 860                        return 0;
 861                }
 862                p = p->next;
 863        }
 864        return -1;
 865}
 866
 867static int get_nth_ancestor(const char *name, int len,
 868                            struct object_id *result, int generation)
 869{
 870        struct object_id oid;
 871        struct commit *commit;
 872        int ret;
 873
 874        ret = get_oid_1(name, len, &oid, GET_OID_COMMITTISH);
 875        if (ret)
 876                return ret;
 877        commit = lookup_commit_reference(&oid);
 878        if (!commit)
 879                return -1;
 880
 881        while (generation--) {
 882                if (parse_commit(commit) || !commit->parents)
 883                        return -1;
 884                commit = commit->parents->item;
 885        }
 886        oidcpy(result, &commit->object.oid);
 887        return 0;
 888}
 889
 890struct object *peel_to_type(const char *name, int namelen,
 891                            struct object *o, enum object_type expected_type)
 892{
 893        if (name && !namelen)
 894                namelen = strlen(name);
 895        while (1) {
 896                if (!o || (!o->parsed && !parse_object(&o->oid)))
 897                        return NULL;
 898                if (expected_type == OBJ_ANY || o->type == expected_type)
 899                        return o;
 900                if (o->type == OBJ_TAG)
 901                        o = ((struct tag*) o)->tagged;
 902                else if (o->type == OBJ_COMMIT)
 903                        o = &(get_commit_tree(((struct commit *)o))->object);
 904                else {
 905                        if (name)
 906                                error("%.*s: expected %s type, but the object "
 907                                      "dereferences to %s type",
 908                                      namelen, name, type_name(expected_type),
 909                                      type_name(o->type));
 910                        return NULL;
 911                }
 912        }
 913}
 914
 915static int peel_onion(const char *name, int len, struct object_id *oid,
 916                      unsigned lookup_flags)
 917{
 918        struct object_id outer;
 919        const char *sp;
 920        unsigned int expected_type = 0;
 921        struct object *o;
 922
 923        /*
 924         * "ref^{type}" dereferences ref repeatedly until you cannot
 925         * dereference anymore, or you get an object of given type,
 926         * whichever comes first.  "ref^{}" means just dereference
 927         * tags until you get a non-tag.  "ref^0" is a shorthand for
 928         * "ref^{commit}".  "commit^{tree}" could be used to find the
 929         * top-level tree of the given commit.
 930         */
 931        if (len < 4 || name[len-1] != '}')
 932                return -1;
 933
 934        for (sp = name + len - 1; name <= sp; sp--) {
 935                int ch = *sp;
 936                if (ch == '{' && name < sp && sp[-1] == '^')
 937                        break;
 938        }
 939        if (sp <= name)
 940                return -1;
 941
 942        sp++; /* beginning of type name, or closing brace for empty */
 943        if (starts_with(sp, "commit}"))
 944                expected_type = OBJ_COMMIT;
 945        else if (starts_with(sp, "tag}"))
 946                expected_type = OBJ_TAG;
 947        else if (starts_with(sp, "tree}"))
 948                expected_type = OBJ_TREE;
 949        else if (starts_with(sp, "blob}"))
 950                expected_type = OBJ_BLOB;
 951        else if (starts_with(sp, "object}"))
 952                expected_type = OBJ_ANY;
 953        else if (sp[0] == '}')
 954                expected_type = OBJ_NONE;
 955        else if (sp[0] == '/')
 956                expected_type = OBJ_COMMIT;
 957        else
 958                return -1;
 959
 960        lookup_flags &= ~GET_OID_DISAMBIGUATORS;
 961        if (expected_type == OBJ_COMMIT)
 962                lookup_flags |= GET_OID_COMMITTISH;
 963        else if (expected_type == OBJ_TREE)
 964                lookup_flags |= GET_OID_TREEISH;
 965
 966        if (get_oid_1(name, sp - name - 2, &outer, lookup_flags))
 967                return -1;
 968
 969        o = parse_object(&outer);
 970        if (!o)
 971                return -1;
 972        if (!expected_type) {
 973                o = deref_tag(o, name, sp - name - 2);
 974                if (!o || (!o->parsed && !parse_object(&o->oid)))
 975                        return -1;
 976                oidcpy(oid, &o->oid);
 977                return 0;
 978        }
 979
 980        /*
 981         * At this point, the syntax look correct, so
 982         * if we do not get the needed object, we should
 983         * barf.
 984         */
 985        o = peel_to_type(name, len, o, expected_type);
 986        if (!o)
 987                return -1;
 988
 989        oidcpy(oid, &o->oid);
 990        if (sp[0] == '/') {
 991                /* "$commit^{/foo}" */
 992                char *prefix;
 993                int ret;
 994                struct commit_list *list = NULL;
 995
 996                /*
 997                 * $commit^{/}. Some regex implementation may reject.
 998                 * We don't need regex anyway. '' pattern always matches.
 999                 */
1000                if (sp[1] == '}')
1001                        return 0;
1002
1003                prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
1004                commit_list_insert((struct commit *)o, &list);
1005                ret = get_oid_oneline(prefix, oid, list);
1006                free(prefix);
1007                return ret;
1008        }
1009        return 0;
1010}
1011
1012static int get_describe_name(const char *name, int len, struct object_id *oid)
1013{
1014        const char *cp;
1015        unsigned flags = GET_OID_QUIETLY | GET_OID_COMMIT;
1016
1017        for (cp = name + len - 1; name + 2 <= cp; cp--) {
1018                char ch = *cp;
1019                if (!isxdigit(ch)) {
1020                        /* We must be looking at g in "SOMETHING-g"
1021                         * for it to be describe output.
1022                         */
1023                        if (ch == 'g' && cp[-1] == '-') {
1024                                cp++;
1025                                len -= cp - name;
1026                                return get_short_oid(cp, len, oid, flags);
1027                        }
1028                }
1029        }
1030        return -1;
1031}
1032
1033static int get_oid_1(const char *name, int len, struct object_id *oid, unsigned lookup_flags)
1034{
1035        int ret, has_suffix;
1036        const char *cp;
1037
1038        /*
1039         * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
1040         */
1041        has_suffix = 0;
1042        for (cp = name + len - 1; name <= cp; cp--) {
1043                int ch = *cp;
1044                if ('0' <= ch && ch <= '9')
1045                        continue;
1046                if (ch == '~' || ch == '^')
1047                        has_suffix = ch;
1048                break;
1049        }
1050
1051        if (has_suffix) {
1052                int num = 0;
1053                int len1 = cp - name;
1054                cp++;
1055                while (cp < name + len)
1056                        num = num * 10 + *cp++ - '0';
1057                if (!num && len1 == len - 1)
1058                        num = 1;
1059                if (has_suffix == '^')
1060                        return get_parent(name, len1, oid, num);
1061                /* else if (has_suffix == '~') -- goes without saying */
1062                return get_nth_ancestor(name, len1, oid, num);
1063        }
1064
1065        ret = peel_onion(name, len, oid, lookup_flags);
1066        if (!ret)
1067                return 0;
1068
1069        ret = get_oid_basic(name, len, oid, lookup_flags);
1070        if (!ret)
1071                return 0;
1072
1073        /* It could be describe output that is "SOMETHING-gXXXX" */
1074        ret = get_describe_name(name, len, oid);
1075        if (!ret)
1076                return 0;
1077
1078        return get_short_oid(name, len, oid, lookup_flags);
1079}
1080
1081/*
1082 * This interprets names like ':/Initial revision of "git"' by searching
1083 * through history and returning the first commit whose message starts
1084 * the given regular expression.
1085 *
1086 * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
1087 *
1088 * For a literal '!' character at the beginning of a pattern, you have to repeat
1089 * that, like: ':/!!foo'
1090 *
1091 * For future extension, all other sequences beginning with ':/!' are reserved.
1092 */
1093
1094/* Remember to update object flag allocation in object.h */
1095#define ONELINE_SEEN (1u<<20)
1096
1097static int handle_one_ref(const char *path, const struct object_id *oid,
1098                          int flag, void *cb_data)
1099{
1100        struct commit_list **list = cb_data;
1101        struct object *object = parse_object(oid);
1102        if (!object)
1103                return 0;
1104        if (object->type == OBJ_TAG) {
1105                object = deref_tag(object, path, strlen(path));
1106                if (!object)
1107                        return 0;
1108        }
1109        if (object->type != OBJ_COMMIT)
1110                return 0;
1111        commit_list_insert((struct commit *)object, list);
1112        return 0;
1113}
1114
1115static int get_oid_oneline(const char *prefix, struct object_id *oid,
1116                            struct commit_list *list)
1117{
1118        struct commit_list *backup = NULL, *l;
1119        int found = 0;
1120        int negative = 0;
1121        regex_t regex;
1122
1123        if (prefix[0] == '!') {
1124                prefix++;
1125
1126                if (prefix[0] == '-') {
1127                        prefix++;
1128                        negative = 1;
1129                } else if (prefix[0] != '!') {
1130                        return -1;
1131                }
1132        }
1133
1134        if (regcomp(&regex, prefix, REG_EXTENDED))
1135                return -1;
1136
1137        for (l = list; l; l = l->next) {
1138                l->item->object.flags |= ONELINE_SEEN;
1139                commit_list_insert(l->item, &backup);
1140        }
1141        while (list) {
1142                const char *p, *buf;
1143                struct commit *commit;
1144                int matches;
1145
1146                commit = pop_most_recent_commit(&list, ONELINE_SEEN);
1147                if (!parse_object(&commit->object.oid))
1148                        continue;
1149                buf = get_commit_buffer(commit, NULL);
1150                p = strstr(buf, "\n\n");
1151                matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
1152                unuse_commit_buffer(commit, buf);
1153
1154                if (matches) {
1155                        oidcpy(oid, &commit->object.oid);
1156                        found = 1;
1157                        break;
1158                }
1159        }
1160        regfree(&regex);
1161        free_commit_list(list);
1162        for (l = backup; l; l = l->next)
1163                clear_commit_marks(l->item, ONELINE_SEEN);
1164        free_commit_list(backup);
1165        return found ? 0 : -1;
1166}
1167
1168struct grab_nth_branch_switch_cbdata {
1169        int remaining;
1170        struct strbuf buf;
1171};
1172
1173static int grab_nth_branch_switch(struct object_id *ooid, struct object_id *noid,
1174                                  const char *email, timestamp_t timestamp, int tz,
1175                                  const char *message, void *cb_data)
1176{
1177        struct grab_nth_branch_switch_cbdata *cb = cb_data;
1178        const char *match = NULL, *target = NULL;
1179        size_t len;
1180
1181        if (skip_prefix(message, "checkout: moving from ", &match))
1182                target = strstr(match, " to ");
1183
1184        if (!match || !target)
1185                return 0;
1186        if (--(cb->remaining) == 0) {
1187                len = target - match;
1188                strbuf_reset(&cb->buf);
1189                strbuf_add(&cb->buf, match, len);
1190                return 1; /* we are done */
1191        }
1192        return 0;
1193}
1194
1195/*
1196 * Parse @{-N} syntax, return the number of characters parsed
1197 * if successful; otherwise signal an error with negative value.
1198 */
1199static int interpret_nth_prior_checkout(const char *name, int namelen,
1200                                        struct strbuf *buf)
1201{
1202        long nth;
1203        int retval;
1204        struct grab_nth_branch_switch_cbdata cb;
1205        const char *brace;
1206        char *num_end;
1207
1208        if (namelen < 4)
1209                return -1;
1210        if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1211                return -1;
1212        brace = memchr(name, '}', namelen);
1213        if (!brace)
1214                return -1;
1215        nth = strtol(name + 3, &num_end, 10);
1216        if (num_end != brace)
1217                return -1;
1218        if (nth <= 0)
1219                return -1;
1220        cb.remaining = nth;
1221        strbuf_init(&cb.buf, 20);
1222
1223        retval = 0;
1224        if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1225                strbuf_reset(buf);
1226                strbuf_addbuf(buf, &cb.buf);
1227                retval = brace - name + 1;
1228        }
1229
1230        strbuf_release(&cb.buf);
1231        return retval;
1232}
1233
1234int get_oid_mb(const char *name, struct object_id *oid)
1235{
1236        struct commit *one, *two;
1237        struct commit_list *mbs;
1238        struct object_id oid_tmp;
1239        const char *dots;
1240        int st;
1241
1242        dots = strstr(name, "...");
1243        if (!dots)
1244                return get_oid(name, oid);
1245        if (dots == name)
1246                st = get_oid("HEAD", &oid_tmp);
1247        else {
1248                struct strbuf sb;
1249                strbuf_init(&sb, dots - name);
1250                strbuf_add(&sb, name, dots - name);
1251                st = get_oid_committish(sb.buf, &oid_tmp);
1252                strbuf_release(&sb);
1253        }
1254        if (st)
1255                return st;
1256        one = lookup_commit_reference_gently(&oid_tmp, 0);
1257        if (!one)
1258                return -1;
1259
1260        if (get_oid_committish(dots[3] ? (dots + 3) : "HEAD", &oid_tmp))
1261                return -1;
1262        two = lookup_commit_reference_gently(&oid_tmp, 0);
1263        if (!two)
1264                return -1;
1265        mbs = get_merge_bases(one, two);
1266        if (!mbs || mbs->next)
1267                st = -1;
1268        else {
1269                st = 0;
1270                oidcpy(oid, &mbs->item->object.oid);
1271        }
1272        free_commit_list(mbs);
1273        return st;
1274}
1275
1276/* parse @something syntax, when 'something' is not {.*} */
1277static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1278{
1279        const char *next;
1280
1281        if (len || name[1] == '{')
1282                return -1;
1283
1284        /* make sure it's a single @, or @@{.*}, not @foo */
1285        next = memchr(name + len + 1, '@', namelen - len - 1);
1286        if (next && next[1] != '{')
1287                return -1;
1288        if (!next)
1289                next = name + namelen;
1290        if (next != name + 1)
1291                return -1;
1292
1293        strbuf_reset(buf);
1294        strbuf_add(buf, "HEAD", 4);
1295        return 1;
1296}
1297
1298static int reinterpret(const char *name, int namelen, int len,
1299                       struct strbuf *buf, unsigned allowed)
1300{
1301        /* we have extra data, which might need further processing */
1302        struct strbuf tmp = STRBUF_INIT;
1303        int used = buf->len;
1304        int ret;
1305
1306        strbuf_add(buf, name + len, namelen - len);
1307        ret = interpret_branch_name(buf->buf, buf->len, &tmp, allowed);
1308        /* that data was not interpreted, remove our cruft */
1309        if (ret < 0) {
1310                strbuf_setlen(buf, used);
1311                return len;
1312        }
1313        strbuf_reset(buf);
1314        strbuf_addbuf(buf, &tmp);
1315        strbuf_release(&tmp);
1316        /* tweak for size of {-N} versus expanded ref name */
1317        return ret - used + len;
1318}
1319
1320static void set_shortened_ref(struct strbuf *buf, const char *ref)
1321{
1322        char *s = shorten_unambiguous_ref(ref, 0);
1323        strbuf_reset(buf);
1324        strbuf_addstr(buf, s);
1325        free(s);
1326}
1327
1328static int branch_interpret_allowed(const char *refname, unsigned allowed)
1329{
1330        if (!allowed)
1331                return 1;
1332
1333        if ((allowed & INTERPRET_BRANCH_LOCAL) &&
1334            starts_with(refname, "refs/heads/"))
1335                return 1;
1336        if ((allowed & INTERPRET_BRANCH_REMOTE) &&
1337            starts_with(refname, "refs/remotes/"))
1338                return 1;
1339
1340        return 0;
1341}
1342
1343static int interpret_branch_mark(const char *name, int namelen,
1344                                 int at, struct strbuf *buf,
1345                                 int (*get_mark)(const char *, int),
1346                                 const char *(*get_data)(struct branch *,
1347                                                         struct strbuf *),
1348                                 unsigned allowed)
1349{
1350        int len;
1351        struct branch *branch;
1352        struct strbuf err = STRBUF_INIT;
1353        const char *value;
1354
1355        len = get_mark(name + at, namelen - at);
1356        if (!len)
1357                return -1;
1358
1359        if (memchr(name, ':', at))
1360                return -1;
1361
1362        if (at) {
1363                char *name_str = xmemdupz(name, at);
1364                branch = branch_get(name_str);
1365                free(name_str);
1366        } else
1367                branch = branch_get(NULL);
1368
1369        value = get_data(branch, &err);
1370        if (!value)
1371                die("%s", err.buf);
1372
1373        if (!branch_interpret_allowed(value, allowed))
1374                return -1;
1375
1376        set_shortened_ref(buf, value);
1377        return len + at;
1378}
1379
1380int interpret_branch_name(const char *name, int namelen, struct strbuf *buf,
1381                          unsigned allowed)
1382{
1383        char *at;
1384        const char *start;
1385        int len;
1386
1387        if (!namelen)
1388                namelen = strlen(name);
1389
1390        if (!allowed || (allowed & INTERPRET_BRANCH_LOCAL)) {
1391                len = interpret_nth_prior_checkout(name, namelen, buf);
1392                if (!len) {
1393                        return len; /* syntax Ok, not enough switches */
1394                } else if (len > 0) {
1395                        if (len == namelen)
1396                                return len; /* consumed all */
1397                        else
1398                                return reinterpret(name, namelen, len, buf, allowed);
1399                }
1400        }
1401
1402        for (start = name;
1403             (at = memchr(start, '@', namelen - (start - name)));
1404             start = at + 1) {
1405
1406                if (!allowed || (allowed & INTERPRET_BRANCH_HEAD)) {
1407                        len = interpret_empty_at(name, namelen, at - name, buf);
1408                        if (len > 0)
1409                                return reinterpret(name, namelen, len, buf,
1410                                                   allowed);
1411                }
1412
1413                len = interpret_branch_mark(name, namelen, at - name, buf,
1414                                            upstream_mark, branch_get_upstream,
1415                                            allowed);
1416                if (len > 0)
1417                        return len;
1418
1419                len = interpret_branch_mark(name, namelen, at - name, buf,
1420                                            push_mark, branch_get_push,
1421                                            allowed);
1422                if (len > 0)
1423                        return len;
1424        }
1425
1426        return -1;
1427}
1428
1429void strbuf_branchname(struct strbuf *sb, const char *name, unsigned allowed)
1430{
1431        int len = strlen(name);
1432        int used = interpret_branch_name(name, len, sb, allowed);
1433
1434        if (used < 0)
1435                used = 0;
1436        strbuf_add(sb, name + used, len - used);
1437}
1438
1439int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1440{
1441        if (startup_info->have_repository)
1442                strbuf_branchname(sb, name, INTERPRET_BRANCH_LOCAL);
1443        else
1444                strbuf_addstr(sb, name);
1445
1446        /*
1447         * This splice must be done even if we end up rejecting the
1448         * name; builtin/branch.c::copy_or_rename_branch() still wants
1449         * to see what the name expanded to so that "branch -m" can be
1450         * used as a tool to correct earlier mistakes.
1451         */
1452        strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1453
1454        if (*name == '-' ||
1455            !strcmp(sb->buf, "refs/heads/HEAD"))
1456                return -1;
1457
1458        return check_refname_format(sb->buf, 0);
1459}
1460
1461/*
1462 * This is like "get_oid_basic()", except it allows "object ID expressions",
1463 * notably "xyz^" for "parent of xyz"
1464 */
1465int get_oid(const char *name, struct object_id *oid)
1466{
1467        struct object_context unused;
1468        return get_oid_with_context(name, 0, oid, &unused);
1469}
1470
1471
1472/*
1473 * Many callers know that the user meant to name a commit-ish by
1474 * syntactical positions where the object name appears.  Calling this
1475 * function allows the machinery to disambiguate shorter-than-unique
1476 * abbreviated object names between commit-ish and others.
1477 *
1478 * Note that this does NOT error out when the named object is not a
1479 * commit-ish. It is merely to give a hint to the disambiguation
1480 * machinery.
1481 */
1482int get_oid_committish(const char *name, struct object_id *oid)
1483{
1484        struct object_context unused;
1485        return get_oid_with_context(name, GET_OID_COMMITTISH,
1486                                    oid, &unused);
1487}
1488
1489int get_oid_treeish(const char *name, struct object_id *oid)
1490{
1491        struct object_context unused;
1492        return get_oid_with_context(name, GET_OID_TREEISH,
1493                                    oid, &unused);
1494}
1495
1496int get_oid_commit(const char *name, struct object_id *oid)
1497{
1498        struct object_context unused;
1499        return get_oid_with_context(name, GET_OID_COMMIT,
1500                                    oid, &unused);
1501}
1502
1503int get_oid_tree(const char *name, struct object_id *oid)
1504{
1505        struct object_context unused;
1506        return get_oid_with_context(name, GET_OID_TREE,
1507                                    oid, &unused);
1508}
1509
1510int get_oid_blob(const char *name, struct object_id *oid)
1511{
1512        struct object_context unused;
1513        return get_oid_with_context(name, GET_OID_BLOB,
1514                                    oid, &unused);
1515}
1516
1517/* Must be called only when object_name:filename doesn't exist. */
1518static void diagnose_invalid_oid_path(const char *prefix,
1519                                      const char *filename,
1520                                      const struct object_id *tree_oid,
1521                                      const char *object_name,
1522                                      int object_name_len)
1523{
1524        struct object_id oid;
1525        unsigned mode;
1526
1527        if (!prefix)
1528                prefix = "";
1529
1530        if (file_exists(filename))
1531                die("Path '%s' exists on disk, but not in '%.*s'.",
1532                    filename, object_name_len, object_name);
1533        if (is_missing_file_error(errno)) {
1534                char *fullname = xstrfmt("%s%s", prefix, filename);
1535
1536                if (!get_tree_entry(tree_oid, fullname, &oid, &mode)) {
1537                        die("Path '%s' exists, but not '%s'.\n"
1538                            "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1539                            fullname,
1540                            filename,
1541                            object_name_len, object_name,
1542                            fullname,
1543                            object_name_len, object_name,
1544                            filename);
1545                }
1546                die("Path '%s' does not exist in '%.*s'",
1547                    filename, object_name_len, object_name);
1548        }
1549}
1550
1551/* Must be called only when :stage:filename doesn't exist. */
1552static void diagnose_invalid_index_path(int stage,
1553                                        const char *prefix,
1554                                        const char *filename)
1555{
1556        const struct cache_entry *ce;
1557        int pos;
1558        unsigned namelen = strlen(filename);
1559        struct strbuf fullname = STRBUF_INIT;
1560
1561        if (!prefix)
1562                prefix = "";
1563
1564        /* Wrong stage number? */
1565        pos = cache_name_pos(filename, namelen);
1566        if (pos < 0)
1567                pos = -pos - 1;
1568        if (pos < active_nr) {
1569                ce = active_cache[pos];
1570                if (ce_namelen(ce) == namelen &&
1571                    !memcmp(ce->name, filename, namelen))
1572                        die("Path '%s' is in the index, but not at stage %d.\n"
1573                            "Did you mean ':%d:%s'?",
1574                            filename, stage,
1575                            ce_stage(ce), filename);
1576        }
1577
1578        /* Confusion between relative and absolute filenames? */
1579        strbuf_addstr(&fullname, prefix);
1580        strbuf_addstr(&fullname, filename);
1581        pos = cache_name_pos(fullname.buf, fullname.len);
1582        if (pos < 0)
1583                pos = -pos - 1;
1584        if (pos < active_nr) {
1585                ce = active_cache[pos];
1586                if (ce_namelen(ce) == fullname.len &&
1587                    !memcmp(ce->name, fullname.buf, fullname.len))
1588                        die("Path '%s' is in the index, but not '%s'.\n"
1589                            "Did you mean ':%d:%s' aka ':%d:./%s'?",
1590                            fullname.buf, filename,
1591                            ce_stage(ce), fullname.buf,
1592                            ce_stage(ce), filename);
1593        }
1594
1595        if (file_exists(filename))
1596                die("Path '%s' exists on disk, but not in the index.", filename);
1597        if (is_missing_file_error(errno))
1598                die("Path '%s' does not exist (neither on disk nor in the index).",
1599                    filename);
1600
1601        strbuf_release(&fullname);
1602}
1603
1604
1605static char *resolve_relative_path(const char *rel)
1606{
1607        if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1608                return NULL;
1609
1610        if (!is_inside_work_tree())
1611                die("relative path syntax can't be used outside working tree.");
1612
1613        /* die() inside prefix_path() if resolved path is outside worktree */
1614        return prefix_path(startup_info->prefix,
1615                           startup_info->prefix ? strlen(startup_info->prefix) : 0,
1616                           rel);
1617}
1618
1619static int get_oid_with_context_1(const char *name,
1620                                  unsigned flags,
1621                                  const char *prefix,
1622                                  struct object_id *oid,
1623                                  struct object_context *oc)
1624{
1625        int ret, bracket_depth;
1626        int namelen = strlen(name);
1627        const char *cp;
1628        int only_to_die = flags & GET_OID_ONLY_TO_DIE;
1629
1630        if (only_to_die)
1631                flags |= GET_OID_QUIETLY;
1632
1633        memset(oc, 0, sizeof(*oc));
1634        oc->mode = S_IFINVALID;
1635        strbuf_init(&oc->symlink_path, 0);
1636        ret = get_oid_1(name, namelen, oid, flags);
1637        if (!ret)
1638                return ret;
1639        /*
1640         * sha1:path --> object name of path in ent sha1
1641         * :path -> object name of absolute path in index
1642         * :./path -> object name of path relative to cwd in index
1643         * :[0-3]:path -> object name of path in index at stage
1644         * :/foo -> recent commit matching foo
1645         */
1646        if (name[0] == ':') {
1647                int stage = 0;
1648                const struct cache_entry *ce;
1649                char *new_path = NULL;
1650                int pos;
1651                if (!only_to_die && namelen > 2 && name[1] == '/') {
1652                        struct commit_list *list = NULL;
1653
1654                        for_each_ref(handle_one_ref, &list);
1655                        head_ref(handle_one_ref, &list);
1656                        commit_list_sort_by_date(&list);
1657                        return get_oid_oneline(name + 2, oid, list);
1658                }
1659                if (namelen < 3 ||
1660                    name[2] != ':' ||
1661                    name[1] < '0' || '3' < name[1])
1662                        cp = name + 1;
1663                else {
1664                        stage = name[1] - '0';
1665                        cp = name + 3;
1666                }
1667                new_path = resolve_relative_path(cp);
1668                if (!new_path) {
1669                        namelen = namelen - (cp - name);
1670                } else {
1671                        cp = new_path;
1672                        namelen = strlen(cp);
1673                }
1674
1675                if (flags & GET_OID_RECORD_PATH)
1676                        oc->path = xstrdup(cp);
1677
1678                if (!active_cache)
1679                        read_cache();
1680                pos = cache_name_pos(cp, namelen);
1681                if (pos < 0)
1682                        pos = -pos - 1;
1683                while (pos < active_nr) {
1684                        ce = active_cache[pos];
1685                        if (ce_namelen(ce) != namelen ||
1686                            memcmp(ce->name, cp, namelen))
1687                                break;
1688                        if (ce_stage(ce) == stage) {
1689                                oidcpy(oid, &ce->oid);
1690                                oc->mode = ce->ce_mode;
1691                                free(new_path);
1692                                return 0;
1693                        }
1694                        pos++;
1695                }
1696                if (only_to_die && name[1] && name[1] != '/')
1697                        diagnose_invalid_index_path(stage, prefix, cp);
1698                free(new_path);
1699                return -1;
1700        }
1701        for (cp = name, bracket_depth = 0; *cp; cp++) {
1702                if (*cp == '{')
1703                        bracket_depth++;
1704                else if (bracket_depth && *cp == '}')
1705                        bracket_depth--;
1706                else if (!bracket_depth && *cp == ':')
1707                        break;
1708        }
1709        if (*cp == ':') {
1710                struct object_id tree_oid;
1711                int len = cp - name;
1712                unsigned sub_flags = flags;
1713
1714                sub_flags &= ~GET_OID_DISAMBIGUATORS;
1715                sub_flags |= GET_OID_TREEISH;
1716
1717                if (!get_oid_1(name, len, &tree_oid, sub_flags)) {
1718                        const char *filename = cp+1;
1719                        char *new_filename = NULL;
1720
1721                        new_filename = resolve_relative_path(filename);
1722                        if (new_filename)
1723                                filename = new_filename;
1724                        if (flags & GET_OID_FOLLOW_SYMLINKS) {
1725                                ret = get_tree_entry_follow_symlinks(&tree_oid,
1726                                        filename, oid, &oc->symlink_path,
1727                                        &oc->mode);
1728                        } else {
1729                                ret = get_tree_entry(&tree_oid, filename, oid,
1730                                                     &oc->mode);
1731                                if (ret && only_to_die) {
1732                                        diagnose_invalid_oid_path(prefix,
1733                                                                   filename,
1734                                                                   &tree_oid,
1735                                                                   name, len);
1736                                }
1737                        }
1738                        if (flags & GET_OID_RECORD_PATH)
1739                                oc->path = xstrdup(filename);
1740
1741                        free(new_filename);
1742                        return ret;
1743                } else {
1744                        if (only_to_die)
1745                                die("Invalid object name '%.*s'.", len, name);
1746                }
1747        }
1748        return ret;
1749}
1750
1751/*
1752 * Call this function when you know "name" given by the end user must
1753 * name an object but it doesn't; the function _may_ die with a better
1754 * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1755 * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1756 * you have a chance to diagnose the error further.
1757 */
1758void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1759{
1760        struct object_context oc;
1761        struct object_id oid;
1762        get_oid_with_context_1(name, GET_OID_ONLY_TO_DIE, prefix, &oid, &oc);
1763}
1764
1765int get_oid_with_context(const char *str, unsigned flags, struct object_id *oid, struct object_context *oc)
1766{
1767        if (flags & GET_OID_FOLLOW_SYMLINKS && flags & GET_OID_ONLY_TO_DIE)
1768                BUG("incompatible flags for get_sha1_with_context");
1769        return get_oid_with_context_1(str, flags, NULL, oid, oc);
1770}