45b89d9df00de3c31a39a74a0cc0e635b0095cbc
   1#include "cache.h"
   2#include "tag.h"
   3#include "commit.h"
   4#include "tree.h"
   5#include "blob.h"
   6#include "tree-walk.h"
   7#include "refs.h"
   8#include "remote.h"
   9
  10static int get_sha1_oneline(const char *, unsigned char *, struct commit_list *);
  11
  12typedef int (*disambiguate_hint_fn)(const unsigned char *, void *);
  13
  14struct disambiguate_state {
  15        disambiguate_hint_fn fn;
  16        void *cb_data;
  17        unsigned char candidate[20];
  18        unsigned candidate_exists:1;
  19        unsigned candidate_checked:1;
  20        unsigned candidate_ok:1;
  21        unsigned disambiguate_fn_used:1;
  22        unsigned ambiguous:1;
  23        unsigned always_call_fn:1;
  24};
  25
  26static void update_candidates(struct disambiguate_state *ds, const unsigned char *current)
  27{
  28        if (ds->always_call_fn) {
  29                ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
  30                return;
  31        }
  32        if (!ds->candidate_exists) {
  33                /* this is the first candidate */
  34                hashcpy(ds->candidate, current);
  35                ds->candidate_exists = 1;
  36                return;
  37        } else if (!hashcmp(ds->candidate, current)) {
  38                /* the same as what we already have seen */
  39                return;
  40        }
  41
  42        if (!ds->fn) {
  43                /* cannot disambiguate between ds->candidate and current */
  44                ds->ambiguous = 1;
  45                return;
  46        }
  47
  48        if (!ds->candidate_checked) {
  49                ds->candidate_ok = ds->fn(ds->candidate, ds->cb_data);
  50                ds->disambiguate_fn_used = 1;
  51                ds->candidate_checked = 1;
  52        }
  53
  54        if (!ds->candidate_ok) {
  55                /* discard the candidate; we know it does not satisify fn */
  56                hashcpy(ds->candidate, current);
  57                ds->candidate_checked = 0;
  58                return;
  59        }
  60
  61        /* if we reach this point, we know ds->candidate satisfies fn */
  62        if (ds->fn(current, ds->cb_data)) {
  63                /*
  64                 * if both current and candidate satisfy fn, we cannot
  65                 * disambiguate.
  66                 */
  67                ds->candidate_ok = 0;
  68                ds->ambiguous = 1;
  69        }
  70
  71        /* otherwise, current can be discarded and candidate is still good */
  72}
  73
  74static void find_short_object_filename(int len, const char *hex_pfx, struct disambiguate_state *ds)
  75{
  76        struct alternate_object_database *alt;
  77        char hex[40];
  78        static struct alternate_object_database *fakeent;
  79
  80        if (!fakeent) {
  81                /*
  82                 * Create a "fake" alternate object database that
  83                 * points to our own object database, to make it
  84                 * easier to get a temporary working space in
  85                 * alt->name/alt->base while iterating over the
  86                 * object databases including our own.
  87                 */
  88                const char *objdir = get_object_directory();
  89                int objdir_len = strlen(objdir);
  90                int entlen = objdir_len + 43;
  91                fakeent = xmalloc(sizeof(*fakeent) + entlen);
  92                memcpy(fakeent->base, objdir, objdir_len);
  93                fakeent->name = fakeent->base + objdir_len + 1;
  94                fakeent->name[-1] = '/';
  95        }
  96        fakeent->next = alt_odb_list;
  97
  98        sprintf(hex, "%.2s", hex_pfx);
  99        for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 100                struct dirent *de;
 101                DIR *dir;
 102                sprintf(alt->name, "%.2s/", hex_pfx);
 103                dir = opendir(alt->base);
 104                if (!dir)
 105                        continue;
 106
 107                while (!ds->ambiguous && (de = readdir(dir)) != NULL) {
 108                        unsigned char sha1[20];
 109
 110                        if (strlen(de->d_name) != 38)
 111                                continue;
 112                        if (memcmp(de->d_name, hex_pfx + 2, len - 2))
 113                                continue;
 114                        memcpy(hex + 2, de->d_name, 38);
 115                        if (!get_sha1_hex(hex, sha1))
 116                                update_candidates(ds, sha1);
 117                }
 118                closedir(dir);
 119        }
 120}
 121
 122static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 123{
 124        do {
 125                if (*a != *b)
 126                        return 0;
 127                a++;
 128                b++;
 129                len -= 2;
 130        } while (len > 1);
 131        if (len)
 132                if ((*a ^ *b) & 0xf0)
 133                        return 0;
 134        return 1;
 135}
 136
 137static void unique_in_pack(int len,
 138                          const unsigned char *bin_pfx,
 139                           struct packed_git *p,
 140                           struct disambiguate_state *ds)
 141{
 142        uint32_t num, last, i, first = 0;
 143        const unsigned char *current = NULL;
 144
 145        open_pack_index(p);
 146        num = p->num_objects;
 147        last = num;
 148        while (first < last) {
 149                uint32_t mid = (first + last) / 2;
 150                const unsigned char *current;
 151                int cmp;
 152
 153                current = nth_packed_object_sha1(p, mid);
 154                cmp = hashcmp(bin_pfx, current);
 155                if (!cmp) {
 156                        first = mid;
 157                        break;
 158                }
 159                if (cmp > 0) {
 160                        first = mid+1;
 161                        continue;
 162                }
 163                last = mid;
 164        }
 165
 166        /*
 167         * At this point, "first" is the location of the lowest object
 168         * with an object name that could match "bin_pfx".  See if we have
 169         * 0, 1 or more objects that actually match(es).
 170         */
 171        for (i = first; i < num && !ds->ambiguous; i++) {
 172                current = nth_packed_object_sha1(p, i);
 173                if (!match_sha(len, bin_pfx, current))
 174                        break;
 175                update_candidates(ds, current);
 176        }
 177}
 178
 179static void find_short_packed_object(int len, const unsigned char *bin_pfx,
 180                                     struct disambiguate_state *ds)
 181{
 182        struct packed_git *p;
 183
 184        prepare_packed_git();
 185        for (p = packed_git; p && !ds->ambiguous; p = p->next)
 186                unique_in_pack(len, bin_pfx, p, ds);
 187}
 188
 189#define SHORT_NAME_NOT_FOUND (-1)
 190#define SHORT_NAME_AMBIGUOUS (-2)
 191
 192static int finish_object_disambiguation(struct disambiguate_state *ds,
 193                                        unsigned char *sha1)
 194{
 195        if (ds->ambiguous)
 196                return SHORT_NAME_AMBIGUOUS;
 197
 198        if (!ds->candidate_exists)
 199                return SHORT_NAME_NOT_FOUND;
 200
 201        if (!ds->candidate_checked)
 202                /*
 203                 * If this is the only candidate, there is no point
 204                 * calling the disambiguation hint callback.
 205                 *
 206                 * On the other hand, if the current candidate
 207                 * replaced an earlier candidate that did _not_ pass
 208                 * the disambiguation hint callback, then we do have
 209                 * more than one objects that match the short name
 210                 * given, so we should make sure this one matches;
 211                 * otherwise, if we discovered this one and the one
 212                 * that we previously discarded in the reverse order,
 213                 * we would end up showing different results in the
 214                 * same repository!
 215                 */
 216                ds->candidate_ok = (!ds->disambiguate_fn_used ||
 217                                    ds->fn(ds->candidate, ds->cb_data));
 218
 219        if (!ds->candidate_ok)
 220                return SHORT_NAME_AMBIGUOUS;
 221
 222        hashcpy(sha1, ds->candidate);
 223        return 0;
 224}
 225
 226static int disambiguate_commit_only(const unsigned char *sha1, void *cb_data_unused)
 227{
 228        int kind = sha1_object_info(sha1, NULL);
 229        return kind == OBJ_COMMIT;
 230}
 231
 232static int disambiguate_committish_only(const unsigned char *sha1, void *cb_data_unused)
 233{
 234        struct object *obj;
 235        int kind;
 236
 237        kind = sha1_object_info(sha1, NULL);
 238        if (kind == OBJ_COMMIT)
 239                return 1;
 240        if (kind != OBJ_TAG)
 241                return 0;
 242
 243        /* We need to do this the hard way... */
 244        obj = deref_tag(lookup_object(sha1), NULL, 0);
 245        if (obj && obj->type == OBJ_COMMIT)
 246                return 1;
 247        return 0;
 248}
 249
 250static int disambiguate_tree_only(const unsigned char *sha1, void *cb_data_unused)
 251{
 252        int kind = sha1_object_info(sha1, NULL);
 253        return kind == OBJ_TREE;
 254}
 255
 256static int disambiguate_treeish_only(const unsigned char *sha1, void *cb_data_unused)
 257{
 258        struct object *obj;
 259        int kind;
 260
 261        kind = sha1_object_info(sha1, NULL);
 262        if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 263                return 1;
 264        if (kind != OBJ_TAG)
 265                return 0;
 266
 267        /* We need to do this the hard way... */
 268        obj = deref_tag(lookup_object(sha1), NULL, 0);
 269        if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 270                return 1;
 271        return 0;
 272}
 273
 274static int disambiguate_blob_only(const unsigned char *sha1, void *cb_data_unused)
 275{
 276        int kind = sha1_object_info(sha1, NULL);
 277        return kind == OBJ_BLOB;
 278}
 279
 280static int prepare_prefixes(const char *name, int len,
 281                            unsigned char *bin_pfx,
 282                            char *hex_pfx)
 283{
 284        int i;
 285
 286        hashclr(bin_pfx);
 287        memset(hex_pfx, 'x', 40);
 288        for (i = 0; i < len ;i++) {
 289                unsigned char c = name[i];
 290                unsigned char val;
 291                if (c >= '0' && c <= '9')
 292                        val = c - '0';
 293                else if (c >= 'a' && c <= 'f')
 294                        val = c - 'a' + 10;
 295                else if (c >= 'A' && c <='F') {
 296                        val = c - 'A' + 10;
 297                        c -= 'A' - 'a';
 298                }
 299                else
 300                        return -1;
 301                hex_pfx[i] = c;
 302                if (!(i & 1))
 303                        val <<= 4;
 304                bin_pfx[i >> 1] |= val;
 305        }
 306        return 0;
 307}
 308
 309static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 310                          unsigned flags)
 311{
 312        int status;
 313        char hex_pfx[40];
 314        unsigned char bin_pfx[20];
 315        struct disambiguate_state ds;
 316        int quietly = !!(flags & GET_SHA1_QUIETLY);
 317
 318        if (len < MINIMUM_ABBREV || len > 40)
 319                return -1;
 320        if (prepare_prefixes(name, len, bin_pfx, hex_pfx) < 0)
 321                return -1;
 322
 323        prepare_alt_odb();
 324
 325        memset(&ds, 0, sizeof(ds));
 326        if (flags & GET_SHA1_COMMIT)
 327                ds.fn = disambiguate_commit_only;
 328        else if (flags & GET_SHA1_COMMITTISH)
 329                ds.fn = disambiguate_committish_only;
 330        else if (flags & GET_SHA1_TREE)
 331                ds.fn = disambiguate_tree_only;
 332        else if (flags & GET_SHA1_TREEISH)
 333                ds.fn = disambiguate_treeish_only;
 334        else if (flags & GET_SHA1_BLOB)
 335                ds.fn = disambiguate_blob_only;
 336
 337        find_short_object_filename(len, hex_pfx, &ds);
 338        find_short_packed_object(len, bin_pfx, &ds);
 339        status = finish_object_disambiguation(&ds, sha1);
 340
 341        if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
 342                return error("short SHA1 %.*s is ambiguous.", len, hex_pfx);
 343        return status;
 344}
 345
 346
 347int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 348{
 349        char hex_pfx[40];
 350        unsigned char bin_pfx[20];
 351        struct disambiguate_state ds;
 352        int len = strlen(prefix);
 353
 354        if (len < MINIMUM_ABBREV || len > 40)
 355                return -1;
 356        if (prepare_prefixes(prefix, len, bin_pfx, hex_pfx) < 0)
 357                return -1;
 358
 359        prepare_alt_odb();
 360
 361        memset(&ds, 0, sizeof(ds));
 362        ds.always_call_fn = 1;
 363        ds.cb_data = cb_data;
 364        ds.fn = fn;
 365
 366        find_short_object_filename(len, hex_pfx, &ds);
 367        find_short_packed_object(len, bin_pfx, &ds);
 368        return ds.ambiguous;
 369}
 370
 371const char *find_unique_abbrev(const unsigned char *sha1, int len)
 372{
 373        int status, exists;
 374        static char hex[41];
 375
 376        exists = has_sha1_file(sha1);
 377        memcpy(hex, sha1_to_hex(sha1), 40);
 378        if (len == 40 || !len)
 379                return hex;
 380        while (len < 40) {
 381                unsigned char sha1_ret[20];
 382                status = get_short_sha1(hex, len, sha1_ret, GET_SHA1_QUIETLY);
 383                if (exists
 384                    ? !status
 385                    : status == SHORT_NAME_NOT_FOUND) {
 386                        hex[len] = 0;
 387                        return hex;
 388                }
 389                len++;
 390        }
 391        return hex;
 392}
 393
 394static int ambiguous_path(const char *path, int len)
 395{
 396        int slash = 1;
 397        int cnt;
 398
 399        for (cnt = 0; cnt < len; cnt++) {
 400                switch (*path++) {
 401                case '\0':
 402                        break;
 403                case '/':
 404                        if (slash)
 405                                break;
 406                        slash = 1;
 407                        continue;
 408                case '.':
 409                        continue;
 410                default:
 411                        slash = 0;
 412                        continue;
 413                }
 414                break;
 415        }
 416        return slash;
 417}
 418
 419static inline int upstream_mark(const char *string, int len)
 420{
 421        const char *suffix[] = { "@{upstream}", "@{u}" };
 422        int i;
 423
 424        for (i = 0; i < ARRAY_SIZE(suffix); i++) {
 425                int suffix_len = strlen(suffix[i]);
 426                if (suffix_len <= len
 427                    && !memcmp(string, suffix[i], suffix_len))
 428                        return suffix_len;
 429        }
 430        return 0;
 431}
 432
 433static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 434static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf);
 435
 436static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 437{
 438        static const char *warn_msg = "refname '%.*s' is ambiguous.";
 439        char *real_ref = NULL;
 440        int refs_found = 0;
 441        int at, reflog_len, nth_prior = 0;
 442
 443        if (len == 40 && !get_sha1_hex(str, sha1))
 444                return 0;
 445
 446        /* basic@{time or number or -number} format to query ref-log */
 447        reflog_len = at = 0;
 448        if (len && str[len-1] == '}') {
 449                for (at = len-4; at >= 0; at--) {
 450                        if (str[at] == '@' && str[at+1] == '{') {
 451                                if (at == 0 && str[2] == '-') {
 452                                        nth_prior = 1;
 453                                        continue;
 454                                }
 455                                if (!upstream_mark(str + at, len - at)) {
 456                                        reflog_len = (len-1) - (at+2);
 457                                        len = at;
 458                                }
 459                                break;
 460                        }
 461                }
 462        }
 463
 464        /* Accept only unambiguous ref paths. */
 465        if (len && ambiguous_path(str, len))
 466                return -1;
 467
 468        if (nth_prior) {
 469                struct strbuf buf = STRBUF_INIT;
 470                int detached;
 471
 472                if (interpret_nth_prior_checkout(str, &buf) > 0) {
 473                        detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 474                        strbuf_release(&buf);
 475                        if (detached)
 476                                return 0;
 477                }
 478        }
 479
 480        if (!len && reflog_len)
 481                /* allow "@{...}" to mean the current branch reflog */
 482                refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 483        else if (reflog_len)
 484                refs_found = dwim_log(str, len, sha1, &real_ref);
 485        else
 486                refs_found = dwim_ref(str, len, sha1, &real_ref);
 487
 488        if (!refs_found)
 489                return -1;
 490
 491        if (warn_ambiguous_refs && refs_found > 1)
 492                warning(warn_msg, len, str);
 493
 494        if (reflog_len) {
 495                int nth, i;
 496                unsigned long at_time;
 497                unsigned long co_time;
 498                int co_tz, co_cnt;
 499
 500                /* a @{-N} placed anywhere except the start is an error */
 501                if (str[at+2] == '-')
 502                        return -1;
 503
 504                /* Is it asking for N-th entry, or approxidate? */
 505                for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 506                        char ch = str[at+2+i];
 507                        if ('0' <= ch && ch <= '9')
 508                                nth = nth * 10 + ch - '0';
 509                        else
 510                                nth = -1;
 511                }
 512                if (100000000 <= nth) {
 513                        at_time = nth;
 514                        nth = -1;
 515                } else if (0 <= nth)
 516                        at_time = 0;
 517                else {
 518                        int errors = 0;
 519                        char *tmp = xstrndup(str + at + 2, reflog_len);
 520                        at_time = approxidate_careful(tmp, &errors);
 521                        free(tmp);
 522                        if (errors)
 523                                return -1;
 524                }
 525                if (read_ref_at(real_ref, at_time, nth, sha1, NULL,
 526                                &co_time, &co_tz, &co_cnt)) {
 527                        if (at_time)
 528                                warning("Log for '%.*s' only goes "
 529                                        "back to %s.", len, str,
 530                                        show_date(co_time, co_tz, DATE_RFC2822));
 531                        else {
 532                                free(real_ref);
 533                                die("Log for '%.*s' only has %d entries.",
 534                                    len, str, co_cnt);
 535                        }
 536                }
 537        }
 538
 539        free(real_ref);
 540        return 0;
 541}
 542
 543static int get_parent(const char *name, int len,
 544                      unsigned char *result, int idx)
 545{
 546        unsigned char sha1[20];
 547        int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 548        struct commit *commit;
 549        struct commit_list *p;
 550
 551        if (ret)
 552                return ret;
 553        commit = lookup_commit_reference(sha1);
 554        if (!commit)
 555                return -1;
 556        if (parse_commit(commit))
 557                return -1;
 558        if (!idx) {
 559                hashcpy(result, commit->object.sha1);
 560                return 0;
 561        }
 562        p = commit->parents;
 563        while (p) {
 564                if (!--idx) {
 565                        hashcpy(result, p->item->object.sha1);
 566                        return 0;
 567                }
 568                p = p->next;
 569        }
 570        return -1;
 571}
 572
 573static int get_nth_ancestor(const char *name, int len,
 574                            unsigned char *result, int generation)
 575{
 576        unsigned char sha1[20];
 577        struct commit *commit;
 578        int ret;
 579
 580        ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 581        if (ret)
 582                return ret;
 583        commit = lookup_commit_reference(sha1);
 584        if (!commit)
 585                return -1;
 586
 587        while (generation--) {
 588                if (parse_commit(commit) || !commit->parents)
 589                        return -1;
 590                commit = commit->parents->item;
 591        }
 592        hashcpy(result, commit->object.sha1);
 593        return 0;
 594}
 595
 596struct object *peel_to_type(const char *name, int namelen,
 597                            struct object *o, enum object_type expected_type)
 598{
 599        if (name && !namelen)
 600                namelen = strlen(name);
 601        while (1) {
 602                if (!o || (!o->parsed && !parse_object(o->sha1)))
 603                        return NULL;
 604                if (expected_type == OBJ_ANY || o->type == expected_type)
 605                        return o;
 606                if (o->type == OBJ_TAG)
 607                        o = ((struct tag*) o)->tagged;
 608                else if (o->type == OBJ_COMMIT)
 609                        o = &(((struct commit *) o)->tree->object);
 610                else {
 611                        if (name)
 612                                error("%.*s: expected %s type, but the object "
 613                                      "dereferences to %s type",
 614                                      namelen, name, typename(expected_type),
 615                                      typename(o->type));
 616                        return NULL;
 617                }
 618        }
 619}
 620
 621static int peel_onion(const char *name, int len, unsigned char *sha1)
 622{
 623        unsigned char outer[20];
 624        const char *sp;
 625        unsigned int expected_type = 0;
 626        unsigned lookup_flags = 0;
 627        struct object *o;
 628
 629        /*
 630         * "ref^{type}" dereferences ref repeatedly until you cannot
 631         * dereference anymore, or you get an object of given type,
 632         * whichever comes first.  "ref^{}" means just dereference
 633         * tags until you get a non-tag.  "ref^0" is a shorthand for
 634         * "ref^{commit}".  "commit^{tree}" could be used to find the
 635         * top-level tree of the given commit.
 636         */
 637        if (len < 4 || name[len-1] != '}')
 638                return -1;
 639
 640        for (sp = name + len - 1; name <= sp; sp--) {
 641                int ch = *sp;
 642                if (ch == '{' && name < sp && sp[-1] == '^')
 643                        break;
 644        }
 645        if (sp <= name)
 646                return -1;
 647
 648        sp++; /* beginning of type name, or closing brace for empty */
 649        if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
 650                expected_type = OBJ_COMMIT;
 651        else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
 652                expected_type = OBJ_TREE;
 653        else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
 654                expected_type = OBJ_BLOB;
 655        else if (!prefixcmp(sp, "object}"))
 656                expected_type = OBJ_ANY;
 657        else if (sp[0] == '}')
 658                expected_type = OBJ_NONE;
 659        else if (sp[0] == '/')
 660                expected_type = OBJ_COMMIT;
 661        else
 662                return -1;
 663
 664        if (expected_type == OBJ_COMMIT)
 665                lookup_flags = GET_SHA1_COMMITTISH;
 666        else if (expected_type == OBJ_TREE)
 667                lookup_flags = GET_SHA1_TREEISH;
 668
 669        if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 670                return -1;
 671
 672        o = parse_object(outer);
 673        if (!o)
 674                return -1;
 675        if (!expected_type) {
 676                o = deref_tag(o, name, sp - name - 2);
 677                if (!o || (!o->parsed && !parse_object(o->sha1)))
 678                        return -1;
 679                hashcpy(sha1, o->sha1);
 680                return 0;
 681        }
 682
 683        /*
 684         * At this point, the syntax look correct, so
 685         * if we do not get the needed object, we should
 686         * barf.
 687         */
 688        o = peel_to_type(name, len, o, expected_type);
 689        if (!o)
 690                return -1;
 691
 692        hashcpy(sha1, o->sha1);
 693        if (sp[0] == '/') {
 694                /* "$commit^{/foo}" */
 695                char *prefix;
 696                int ret;
 697                struct commit_list *list = NULL;
 698
 699                /*
 700                 * $commit^{/}. Some regex implementation may reject.
 701                 * We don't need regex anyway. '' pattern always matches.
 702                 */
 703                if (sp[1] == '}')
 704                        return 0;
 705
 706                prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 707                commit_list_insert((struct commit *)o, &list);
 708                ret = get_sha1_oneline(prefix, sha1, list);
 709                free(prefix);
 710                return ret;
 711        }
 712        return 0;
 713}
 714
 715static int get_describe_name(const char *name, int len, unsigned char *sha1)
 716{
 717        const char *cp;
 718        unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 719
 720        for (cp = name + len - 1; name + 2 <= cp; cp--) {
 721                char ch = *cp;
 722                if (hexval(ch) & ~0377) {
 723                        /* We must be looking at g in "SOMETHING-g"
 724                         * for it to be describe output.
 725                         */
 726                        if (ch == 'g' && cp[-1] == '-') {
 727                                cp++;
 728                                len -= cp - name;
 729                                return get_short_sha1(cp, len, sha1, flags);
 730                        }
 731                }
 732        }
 733        return -1;
 734}
 735
 736static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 737{
 738        int ret, has_suffix;
 739        const char *cp;
 740
 741        /*
 742         * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 743         */
 744        has_suffix = 0;
 745        for (cp = name + len - 1; name <= cp; cp--) {
 746                int ch = *cp;
 747                if ('0' <= ch && ch <= '9')
 748                        continue;
 749                if (ch == '~' || ch == '^')
 750                        has_suffix = ch;
 751                break;
 752        }
 753
 754        if (has_suffix) {
 755                int num = 0;
 756                int len1 = cp - name;
 757                cp++;
 758                while (cp < name + len)
 759                        num = num * 10 + *cp++ - '0';
 760                if (!num && len1 == len - 1)
 761                        num = 1;
 762                if (has_suffix == '^')
 763                        return get_parent(name, len1, sha1, num);
 764                /* else if (has_suffix == '~') -- goes without saying */
 765                return get_nth_ancestor(name, len1, sha1, num);
 766        }
 767
 768        ret = peel_onion(name, len, sha1);
 769        if (!ret)
 770                return 0;
 771
 772        ret = get_sha1_basic(name, len, sha1);
 773        if (!ret)
 774                return 0;
 775
 776        /* It could be describe output that is "SOMETHING-gXXXX" */
 777        ret = get_describe_name(name, len, sha1);
 778        if (!ret)
 779                return 0;
 780
 781        return get_short_sha1(name, len, sha1, lookup_flags);
 782}
 783
 784/*
 785 * This interprets names like ':/Initial revision of "git"' by searching
 786 * through history and returning the first commit whose message starts
 787 * the given regular expression.
 788 *
 789 * For future extension, ':/!' is reserved. If you want to match a message
 790 * beginning with a '!', you have to repeat the exclamation mark.
 791 */
 792#define ONELINE_SEEN (1u<<20)
 793
 794static int handle_one_ref(const char *path,
 795                const unsigned char *sha1, int flag, void *cb_data)
 796{
 797        struct commit_list **list = cb_data;
 798        struct object *object = parse_object(sha1);
 799        if (!object)
 800                return 0;
 801        if (object->type == OBJ_TAG) {
 802                object = deref_tag(object, path, strlen(path));
 803                if (!object)
 804                        return 0;
 805        }
 806        if (object->type != OBJ_COMMIT)
 807                return 0;
 808        commit_list_insert_by_date((struct commit *)object, list);
 809        return 0;
 810}
 811
 812static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 813                            struct commit_list *list)
 814{
 815        struct commit_list *backup = NULL, *l;
 816        int found = 0;
 817        regex_t regex;
 818
 819        if (prefix[0] == '!') {
 820                if (prefix[1] != '!')
 821                        die ("Invalid search pattern: %s", prefix);
 822                prefix++;
 823        }
 824
 825        if (regcomp(&regex, prefix, REG_EXTENDED))
 826                die("Invalid search pattern: %s", prefix);
 827
 828        for (l = list; l; l = l->next) {
 829                l->item->object.flags |= ONELINE_SEEN;
 830                commit_list_insert(l->item, &backup);
 831        }
 832        while (list) {
 833                char *p, *to_free = NULL;
 834                struct commit *commit;
 835                enum object_type type;
 836                unsigned long size;
 837                int matches;
 838
 839                commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 840                if (!parse_object(commit->object.sha1))
 841                        continue;
 842                if (commit->buffer)
 843                        p = commit->buffer;
 844                else {
 845                        p = read_sha1_file(commit->object.sha1, &type, &size);
 846                        if (!p)
 847                                continue;
 848                        to_free = p;
 849                }
 850
 851                p = strstr(p, "\n\n");
 852                matches = p && !regexec(&regex, p + 2, 0, NULL, 0);
 853                free(to_free);
 854
 855                if (matches) {
 856                        hashcpy(sha1, commit->object.sha1);
 857                        found = 1;
 858                        break;
 859                }
 860        }
 861        regfree(&regex);
 862        free_commit_list(list);
 863        for (l = backup; l; l = l->next)
 864                clear_commit_marks(l->item, ONELINE_SEEN);
 865        free_commit_list(backup);
 866        return found ? 0 : -1;
 867}
 868
 869struct grab_nth_branch_switch_cbdata {
 870        int remaining;
 871        struct strbuf buf;
 872};
 873
 874static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 875                                  const char *email, unsigned long timestamp, int tz,
 876                                  const char *message, void *cb_data)
 877{
 878        struct grab_nth_branch_switch_cbdata *cb = cb_data;
 879        const char *match = NULL, *target = NULL;
 880        size_t len;
 881
 882        if (!prefixcmp(message, "checkout: moving from ")) {
 883                match = message + strlen("checkout: moving from ");
 884                target = strstr(match, " to ");
 885        }
 886
 887        if (!match || !target)
 888                return 0;
 889        if (--(cb->remaining) == 0) {
 890                len = target - match;
 891                strbuf_reset(&cb->buf);
 892                strbuf_add(&cb->buf, match, len);
 893                return 1; /* we are done */
 894        }
 895        return 0;
 896}
 897
 898/*
 899 * Parse @{-N} syntax, return the number of characters parsed
 900 * if successful; otherwise signal an error with negative value.
 901 */
 902static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf)
 903{
 904        long nth;
 905        int retval;
 906        struct grab_nth_branch_switch_cbdata cb;
 907        const char *brace;
 908        char *num_end;
 909
 910        if (name[0] != '@' || name[1] != '{' || name[2] != '-')
 911                return -1;
 912        brace = strchr(name, '}');
 913        if (!brace)
 914                return -1;
 915        nth = strtol(name + 3, &num_end, 10);
 916        if (num_end != brace)
 917                return -1;
 918        if (nth <= 0)
 919                return -1;
 920        cb.remaining = nth;
 921        strbuf_init(&cb.buf, 20);
 922
 923        retval = 0;
 924        if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
 925                strbuf_reset(buf);
 926                strbuf_add(buf, cb.buf.buf, cb.buf.len);
 927                retval = brace - name + 1;
 928        }
 929
 930        strbuf_release(&cb.buf);
 931        return retval;
 932}
 933
 934int get_sha1_mb(const char *name, unsigned char *sha1)
 935{
 936        struct commit *one, *two;
 937        struct commit_list *mbs;
 938        unsigned char sha1_tmp[20];
 939        const char *dots;
 940        int st;
 941
 942        dots = strstr(name, "...");
 943        if (!dots)
 944                return get_sha1(name, sha1);
 945        if (dots == name)
 946                st = get_sha1("HEAD", sha1_tmp);
 947        else {
 948                struct strbuf sb;
 949                strbuf_init(&sb, dots - name);
 950                strbuf_add(&sb, name, dots - name);
 951                st = get_sha1_committish(sb.buf, sha1_tmp);
 952                strbuf_release(&sb);
 953        }
 954        if (st)
 955                return st;
 956        one = lookup_commit_reference_gently(sha1_tmp, 0);
 957        if (!one)
 958                return -1;
 959
 960        if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
 961                return -1;
 962        two = lookup_commit_reference_gently(sha1_tmp, 0);
 963        if (!two)
 964                return -1;
 965        mbs = get_merge_bases(one, two, 1);
 966        if (!mbs || mbs->next)
 967                st = -1;
 968        else {
 969                st = 0;
 970                hashcpy(sha1, mbs->item->object.sha1);
 971        }
 972        free_commit_list(mbs);
 973        return st;
 974}
 975
 976/*
 977 * This reads short-hand syntax that not only evaluates to a commit
 978 * object name, but also can act as if the end user spelled the name
 979 * of the branch from the command line.
 980 *
 981 * - "@{-N}" finds the name of the Nth previous branch we were on, and
 982 *   places the name of the branch in the given buf and returns the
 983 *   number of characters parsed if successful.
 984 *
 985 * - "<branch>@{upstream}" finds the name of the other ref that
 986 *   <branch> is configured to merge with (missing <branch> defaults
 987 *   to the current branch), and places the name of the branch in the
 988 *   given buf and returns the number of characters parsed if
 989 *   successful.
 990 *
 991 * If the input is not of the accepted format, it returns a negative
 992 * number to signal an error.
 993 *
 994 * If the input was ok but there are not N branch switches in the
 995 * reflog, it returns 0.
 996 */
 997int interpret_branch_name(const char *name, struct strbuf *buf)
 998{
 999        char *cp;
1000        struct branch *upstream;
1001        int namelen = strlen(name);
1002        int len = interpret_nth_prior_checkout(name, buf);
1003        int tmp_len;
1004
1005        if (!len)
1006                return len; /* syntax Ok, not enough switches */
1007        if (0 < len && len == namelen)
1008                return len; /* consumed all */
1009        else if (0 < len) {
1010                /* we have extra data, which might need further processing */
1011                struct strbuf tmp = STRBUF_INIT;
1012                int used = buf->len;
1013                int ret;
1014
1015                strbuf_add(buf, name + len, namelen - len);
1016                ret = interpret_branch_name(buf->buf, &tmp);
1017                /* that data was not interpreted, remove our cruft */
1018                if (ret < 0) {
1019                        strbuf_setlen(buf, used);
1020                        return len;
1021                }
1022                strbuf_reset(buf);
1023                strbuf_addbuf(buf, &tmp);
1024                strbuf_release(&tmp);
1025                /* tweak for size of {-N} versus expanded ref name */
1026                return ret - used + len;
1027        }
1028
1029        cp = strchr(name, '@');
1030        if (!cp)
1031                return -1;
1032        tmp_len = upstream_mark(cp, namelen - (cp - name));
1033        if (!tmp_len)
1034                return -1;
1035        len = cp + tmp_len - name;
1036        cp = xstrndup(name, cp - name);
1037        upstream = branch_get(*cp ? cp : NULL);
1038        /*
1039         * Upstream can be NULL only if cp refers to HEAD and HEAD
1040         * points to something different than a branch.
1041         */
1042        if (!upstream)
1043                return error(_("HEAD does not point to a branch"));
1044        if (!upstream->merge || !upstream->merge[0]->dst) {
1045                if (!ref_exists(upstream->refname))
1046                        return error(_("No such branch: '%s'"), cp);
1047                if (!upstream->merge)
1048                        return error(_("No upstream configured for branch '%s'"),
1049                                     upstream->name);
1050                return error(
1051                        _("Upstream branch '%s' not stored as a remote-tracking branch"),
1052                        upstream->merge[0]->src);
1053        }
1054        free(cp);
1055        cp = shorten_unambiguous_ref(upstream->merge[0]->dst, 0);
1056        strbuf_reset(buf);
1057        strbuf_addstr(buf, cp);
1058        free(cp);
1059        return len;
1060}
1061
1062int strbuf_branchname(struct strbuf *sb, const char *name)
1063{
1064        int len = strlen(name);
1065        if (interpret_branch_name(name, sb) == len)
1066                return 0;
1067        strbuf_add(sb, name, len);
1068        return len;
1069}
1070
1071int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1072{
1073        strbuf_branchname(sb, name);
1074        if (name[0] == '-')
1075                return -1;
1076        strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1077        return check_refname_format(sb->buf, 0);
1078}
1079
1080/*
1081 * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1082 * notably "xyz^" for "parent of xyz"
1083 */
1084int get_sha1(const char *name, unsigned char *sha1)
1085{
1086        struct object_context unused;
1087        return get_sha1_with_context(name, 0, sha1, &unused);
1088}
1089
1090/*
1091 * Many callers know that the user meant to name a committish by
1092 * syntactical positions where the object name appears.  Calling this
1093 * function allows the machinery to disambiguate shorter-than-unique
1094 * abbreviated object names between committish and others.
1095 *
1096 * Note that this does NOT error out when the named object is not a
1097 * committish. It is merely to give a hint to the disambiguation
1098 * machinery.
1099 */
1100int get_sha1_committish(const char *name, unsigned char *sha1)
1101{
1102        struct object_context unused;
1103        return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1104                                     sha1, &unused);
1105}
1106
1107int get_sha1_treeish(const char *name, unsigned char *sha1)
1108{
1109        struct object_context unused;
1110        return get_sha1_with_context(name, GET_SHA1_TREEISH,
1111                                     sha1, &unused);
1112}
1113
1114int get_sha1_commit(const char *name, unsigned char *sha1)
1115{
1116        struct object_context unused;
1117        return get_sha1_with_context(name, GET_SHA1_COMMIT,
1118                                     sha1, &unused);
1119}
1120
1121int get_sha1_tree(const char *name, unsigned char *sha1)
1122{
1123        struct object_context unused;
1124        return get_sha1_with_context(name, GET_SHA1_TREE,
1125                                     sha1, &unused);
1126}
1127
1128int get_sha1_blob(const char *name, unsigned char *sha1)
1129{
1130        struct object_context unused;
1131        return get_sha1_with_context(name, GET_SHA1_BLOB,
1132                                     sha1, &unused);
1133}
1134
1135/* Must be called only when object_name:filename doesn't exist. */
1136static void diagnose_invalid_sha1_path(const char *prefix,
1137                                       const char *filename,
1138                                       const unsigned char *tree_sha1,
1139                                       const char *object_name,
1140                                       int object_name_len)
1141{
1142        struct stat st;
1143        unsigned char sha1[20];
1144        unsigned mode;
1145
1146        if (!prefix)
1147                prefix = "";
1148
1149        if (!lstat(filename, &st))
1150                die("Path '%s' exists on disk, but not in '%.*s'.",
1151                    filename, object_name_len, object_name);
1152        if (errno == ENOENT || errno == ENOTDIR) {
1153                char *fullname = xmalloc(strlen(filename)
1154                                             + strlen(prefix) + 1);
1155                strcpy(fullname, prefix);
1156                strcat(fullname, filename);
1157
1158                if (!get_tree_entry(tree_sha1, fullname,
1159                                    sha1, &mode)) {
1160                        die("Path '%s' exists, but not '%s'.\n"
1161                            "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1162                            fullname,
1163                            filename,
1164                            object_name_len, object_name,
1165                            fullname,
1166                            object_name_len, object_name,
1167                            filename);
1168                }
1169                die("Path '%s' does not exist in '%.*s'",
1170                    filename, object_name_len, object_name);
1171        }
1172}
1173
1174/* Must be called only when :stage:filename doesn't exist. */
1175static void diagnose_invalid_index_path(int stage,
1176                                        const char *prefix,
1177                                        const char *filename)
1178{
1179        struct stat st;
1180        struct cache_entry *ce;
1181        int pos;
1182        unsigned namelen = strlen(filename);
1183        unsigned fullnamelen;
1184        char *fullname;
1185
1186        if (!prefix)
1187                prefix = "";
1188
1189        /* Wrong stage number? */
1190        pos = cache_name_pos(filename, namelen);
1191        if (pos < 0)
1192                pos = -pos - 1;
1193        if (pos < active_nr) {
1194                ce = active_cache[pos];
1195                if (ce_namelen(ce) == namelen &&
1196                    !memcmp(ce->name, filename, namelen))
1197                        die("Path '%s' is in the index, but not at stage %d.\n"
1198                            "Did you mean ':%d:%s'?",
1199                            filename, stage,
1200                            ce_stage(ce), filename);
1201        }
1202
1203        /* Confusion between relative and absolute filenames? */
1204        fullnamelen = namelen + strlen(prefix);
1205        fullname = xmalloc(fullnamelen + 1);
1206        strcpy(fullname, prefix);
1207        strcat(fullname, filename);
1208        pos = cache_name_pos(fullname, fullnamelen);
1209        if (pos < 0)
1210                pos = -pos - 1;
1211        if (pos < active_nr) {
1212                ce = active_cache[pos];
1213                if (ce_namelen(ce) == fullnamelen &&
1214                    !memcmp(ce->name, fullname, fullnamelen))
1215                        die("Path '%s' is in the index, but not '%s'.\n"
1216                            "Did you mean ':%d:%s' aka ':%d:./%s'?",
1217                            fullname, filename,
1218                            ce_stage(ce), fullname,
1219                            ce_stage(ce), filename);
1220        }
1221
1222        if (!lstat(filename, &st))
1223                die("Path '%s' exists on disk, but not in the index.", filename);
1224        if (errno == ENOENT || errno == ENOTDIR)
1225                die("Path '%s' does not exist (neither on disk nor in the index).",
1226                    filename);
1227
1228        free(fullname);
1229}
1230
1231
1232static char *resolve_relative_path(const char *rel)
1233{
1234        if (prefixcmp(rel, "./") && prefixcmp(rel, "../"))
1235                return NULL;
1236
1237        if (!startup_info)
1238                die("BUG: startup_info struct is not initialized.");
1239
1240        if (!is_inside_work_tree())
1241                die("relative path syntax can't be used outside working tree.");
1242
1243        /* die() inside prefix_path() if resolved path is outside worktree */
1244        return prefix_path(startup_info->prefix,
1245                           startup_info->prefix ? strlen(startup_info->prefix) : 0,
1246                           rel);
1247}
1248
1249static int get_sha1_with_context_1(const char *name,
1250                                   unsigned flags,
1251                                   const char *prefix,
1252                                   unsigned char *sha1,
1253                                   struct object_context *oc)
1254{
1255        int ret, bracket_depth;
1256        int namelen = strlen(name);
1257        const char *cp;
1258        int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1259
1260        memset(oc, 0, sizeof(*oc));
1261        oc->mode = S_IFINVALID;
1262        ret = get_sha1_1(name, namelen, sha1, flags);
1263        if (!ret)
1264                return ret;
1265        /*
1266         * sha1:path --> object name of path in ent sha1
1267         * :path -> object name of absolute path in index
1268         * :./path -> object name of path relative to cwd in index
1269         * :[0-3]:path -> object name of path in index at stage
1270         * :/foo -> recent commit matching foo
1271         */
1272        if (name[0] == ':') {
1273                int stage = 0;
1274                struct cache_entry *ce;
1275                char *new_path = NULL;
1276                int pos;
1277                if (!only_to_die && namelen > 2 && name[1] == '/') {
1278                        struct commit_list *list = NULL;
1279                        for_each_ref(handle_one_ref, &list);
1280                        return get_sha1_oneline(name + 2, sha1, list);
1281                }
1282                if (namelen < 3 ||
1283                    name[2] != ':' ||
1284                    name[1] < '0' || '3' < name[1])
1285                        cp = name + 1;
1286                else {
1287                        stage = name[1] - '0';
1288                        cp = name + 3;
1289                }
1290                new_path = resolve_relative_path(cp);
1291                if (!new_path) {
1292                        namelen = namelen - (cp - name);
1293                } else {
1294                        cp = new_path;
1295                        namelen = strlen(cp);
1296                }
1297
1298                strncpy(oc->path, cp,
1299                        sizeof(oc->path));
1300                oc->path[sizeof(oc->path)-1] = '\0';
1301
1302                if (!active_cache)
1303                        read_cache();
1304                pos = cache_name_pos(cp, namelen);
1305                if (pos < 0)
1306                        pos = -pos - 1;
1307                while (pos < active_nr) {
1308                        ce = active_cache[pos];
1309                        if (ce_namelen(ce) != namelen ||
1310                            memcmp(ce->name, cp, namelen))
1311                                break;
1312                        if (ce_stage(ce) == stage) {
1313                                hashcpy(sha1, ce->sha1);
1314                                oc->mode = ce->ce_mode;
1315                                free(new_path);
1316                                return 0;
1317                        }
1318                        pos++;
1319                }
1320                if (only_to_die && name[1] && name[1] != '/')
1321                        diagnose_invalid_index_path(stage, prefix, cp);
1322                free(new_path);
1323                return -1;
1324        }
1325        for (cp = name, bracket_depth = 0; *cp; cp++) {
1326                if (*cp == '{')
1327                        bracket_depth++;
1328                else if (bracket_depth && *cp == '}')
1329                        bracket_depth--;
1330                else if (!bracket_depth && *cp == ':')
1331                        break;
1332        }
1333        if (*cp == ':') {
1334                unsigned char tree_sha1[20];
1335                int len = cp - name;
1336                if (!get_sha1_1(name, len, tree_sha1, GET_SHA1_TREEISH)) {
1337                        const char *filename = cp+1;
1338                        char *new_filename = NULL;
1339
1340                        new_filename = resolve_relative_path(filename);
1341                        if (new_filename)
1342                                filename = new_filename;
1343                        ret = get_tree_entry(tree_sha1, filename, sha1, &oc->mode);
1344                        if (ret && only_to_die) {
1345                                diagnose_invalid_sha1_path(prefix, filename,
1346                                                           tree_sha1,
1347                                                           name, len);
1348                        }
1349                        hashcpy(oc->tree, tree_sha1);
1350                        strncpy(oc->path, filename,
1351                                sizeof(oc->path));
1352                        oc->path[sizeof(oc->path)-1] = '\0';
1353
1354                        free(new_filename);
1355                        return ret;
1356                } else {
1357                        if (only_to_die)
1358                                die("Invalid object name '%.*s'.", len, name);
1359                }
1360        }
1361        return ret;
1362}
1363
1364/*
1365 * Call this function when you know "name" given by the end user must
1366 * name an object but it doesn't; the function _may_ die with a better
1367 * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1368 * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1369 * you have a chance to diagnose the error further.
1370 */
1371void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1372{
1373        struct object_context oc;
1374        unsigned char sha1[20];
1375        get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1376}
1377
1378int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1379{
1380        return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1381}