2e2dbb866431eb6f604559daae2d5cdc4cb38d04
   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};
  24
  25static void update_candidates(struct disambiguate_state *ds, const unsigned char *current)
  26{
  27        if (!ds->candidate_exists) {
  28                /* this is the first candidate */
  29                hashcpy(ds->candidate, current);
  30                ds->candidate_exists = 1;
  31                return;
  32        } else if (!hashcmp(ds->candidate, current)) {
  33                /* the same as what we already have seen */
  34                return;
  35        }
  36
  37        if (!ds->fn) {
  38                /* cannot disambiguate between ds->candidate and current */
  39                ds->ambiguous = 1;
  40                return;
  41        }
  42
  43        if (!ds->candidate_checked) {
  44                ds->candidate_ok = ds->fn(ds->candidate, ds->cb_data);
  45                ds->disambiguate_fn_used = 1;
  46                ds->candidate_checked = 1;
  47        }
  48
  49        if (!ds->candidate_ok) {
  50                /* discard the candidate; we know it does not satisify fn */
  51                hashcpy(ds->candidate, current);
  52                ds->candidate_checked = 0;
  53                return;
  54        }
  55
  56        /* if we reach this point, we know ds->candidate satisfies fn */
  57        if (ds->fn(current, ds->cb_data)) {
  58                /*
  59                 * if both current and candidate satisfy fn, we cannot
  60                 * disambiguate.
  61                 */
  62                ds->candidate_ok = 0;
  63                ds->ambiguous = 1;
  64        }
  65
  66        /* otherwise, current can be discarded and candidate is still good */
  67}
  68
  69static void find_short_object_filename(int len, const char *hex_pfx, struct disambiguate_state *ds)
  70{
  71        struct alternate_object_database *alt;
  72        char hex[40];
  73        static struct alternate_object_database *fakeent;
  74
  75        if (!fakeent) {
  76                /*
  77                 * Create a "fake" alternate object database that
  78                 * points to our own object database, to make it
  79                 * easier to get a temporary working space in
  80                 * alt->name/alt->base while iterating over the
  81                 * object databases including our own.
  82                 */
  83                const char *objdir = get_object_directory();
  84                int objdir_len = strlen(objdir);
  85                int entlen = objdir_len + 43;
  86                fakeent = xmalloc(sizeof(*fakeent) + entlen);
  87                memcpy(fakeent->base, objdir, objdir_len);
  88                fakeent->name = fakeent->base + objdir_len + 1;
  89                fakeent->name[-1] = '/';
  90        }
  91        fakeent->next = alt_odb_list;
  92
  93        sprintf(hex, "%.2s", hex_pfx);
  94        for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
  95                struct dirent *de;
  96                DIR *dir;
  97                sprintf(alt->name, "%.2s/", hex_pfx);
  98                dir = opendir(alt->base);
  99                if (!dir)
 100                        continue;
 101
 102                while (!ds->ambiguous && (de = readdir(dir)) != NULL) {
 103                        unsigned char sha1[20];
 104
 105                        if (strlen(de->d_name) != 38)
 106                                continue;
 107                        if (memcmp(de->d_name, hex_pfx + 2, len - 2))
 108                                continue;
 109                        memcpy(hex + 2, de->d_name, 38);
 110                        if (!get_sha1_hex(hex, sha1))
 111                                update_candidates(ds, sha1);
 112                }
 113                closedir(dir);
 114        }
 115}
 116
 117static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 118{
 119        do {
 120                if (*a != *b)
 121                        return 0;
 122                a++;
 123                b++;
 124                len -= 2;
 125        } while (len > 1);
 126        if (len)
 127                if ((*a ^ *b) & 0xf0)
 128                        return 0;
 129        return 1;
 130}
 131
 132static void unique_in_pack(int len,
 133                          const unsigned char *bin_pfx,
 134                           struct packed_git *p,
 135                           struct disambiguate_state *ds)
 136{
 137        uint32_t num, last, i, first = 0;
 138        const unsigned char *current = NULL;
 139
 140        open_pack_index(p);
 141        num = p->num_objects;
 142        last = num;
 143        while (first < last) {
 144                uint32_t mid = (first + last) / 2;
 145                const unsigned char *current;
 146                int cmp;
 147
 148                current = nth_packed_object_sha1(p, mid);
 149                cmp = hashcmp(bin_pfx, current);
 150                if (!cmp) {
 151                        first = mid;
 152                        break;
 153                }
 154                if (cmp > 0) {
 155                        first = mid+1;
 156                        continue;
 157                }
 158                last = mid;
 159        }
 160
 161        /*
 162         * At this point, "first" is the location of the lowest object
 163         * with an object name that could match "bin_pfx".  See if we have
 164         * 0, 1 or more objects that actually match(es).
 165         */
 166        for (i = first; i < num && !ds->ambiguous; i++) {
 167                current = nth_packed_object_sha1(p, i);
 168                if (!match_sha(len, bin_pfx, current))
 169                        break;
 170                update_candidates(ds, current);
 171        }
 172}
 173
 174static void find_short_packed_object(int len, const unsigned char *bin_pfx,
 175                                     struct disambiguate_state *ds)
 176{
 177        struct packed_git *p;
 178
 179        prepare_packed_git();
 180        for (p = packed_git; p && !ds->ambiguous; p = p->next)
 181                unique_in_pack(len, bin_pfx, p, ds);
 182}
 183
 184#define SHORT_NAME_NOT_FOUND (-1)
 185#define SHORT_NAME_AMBIGUOUS (-2)
 186
 187static int finish_object_disambiguation(struct disambiguate_state *ds,
 188                                        unsigned char *sha1)
 189{
 190        if (ds->ambiguous)
 191                return SHORT_NAME_AMBIGUOUS;
 192
 193        if (!ds->candidate_exists)
 194                return SHORT_NAME_NOT_FOUND;
 195
 196        if (!ds->candidate_checked)
 197                /*
 198                 * If this is the only candidate, there is no point
 199                 * calling the disambiguation hint callback.
 200                 *
 201                 * On the other hand, if the current candidate
 202                 * replaced an earlier candidate that did _not_ pass
 203                 * the disambiguation hint callback, then we do have
 204                 * more than one objects that match the short name
 205                 * given, so we should make sure this one matches;
 206                 * otherwise, if we discovered this one and the one
 207                 * that we previously discarded in the reverse order,
 208                 * we would end up showing different results in the
 209                 * same repository!
 210                 */
 211                ds->candidate_ok = (!ds->disambiguate_fn_used ||
 212                                    ds->fn(ds->candidate, ds->cb_data));
 213
 214        if (!ds->candidate_ok)
 215                return SHORT_NAME_NOT_FOUND;
 216
 217        hashcpy(sha1, ds->candidate);
 218        return 0;
 219}
 220
 221static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 222                          int quietly)
 223{
 224        int i, status;
 225        char hex_pfx[40];
 226        unsigned char bin_pfx[20];
 227        struct disambiguate_state ds;
 228
 229        if (len < MINIMUM_ABBREV || len > 40)
 230                return -1;
 231        hashclr(bin_pfx);
 232        memset(hex_pfx, 'x', 40);
 233        for (i = 0; i < len ;i++) {
 234                unsigned char c = name[i];
 235                unsigned char val;
 236                if (c >= '0' && c <= '9')
 237                        val = c - '0';
 238                else if (c >= 'a' && c <= 'f')
 239                        val = c - 'a' + 10;
 240                else if (c >= 'A' && c <='F') {
 241                        val = c - 'A' + 10;
 242                        c -= 'A' - 'a';
 243                }
 244                else
 245                        return -1;
 246                hex_pfx[i] = c;
 247                if (!(i & 1))
 248                        val <<= 4;
 249                bin_pfx[i >> 1] |= val;
 250        }
 251
 252        prepare_alt_odb();
 253
 254        memset(&ds, 0, sizeof(ds));
 255        find_short_object_filename(len, hex_pfx, &ds);
 256        find_short_packed_object(len, bin_pfx, &ds);
 257        status = finish_object_disambiguation(&ds, sha1);
 258
 259        if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
 260                return error("short SHA1 %.*s is ambiguous.", len, hex_pfx);
 261        return status;
 262}
 263
 264const char *find_unique_abbrev(const unsigned char *sha1, int len)
 265{
 266        int status, exists;
 267        static char hex[41];
 268
 269        exists = has_sha1_file(sha1);
 270        memcpy(hex, sha1_to_hex(sha1), 40);
 271        if (len == 40 || !len)
 272                return hex;
 273        while (len < 40) {
 274                unsigned char sha1_ret[20];
 275                status = get_short_sha1(hex, len, sha1_ret, 1);
 276                if (exists
 277                    ? !status
 278                    : status == SHORT_NAME_NOT_FOUND) {
 279                        hex[len] = 0;
 280                        return hex;
 281                }
 282                len++;
 283        }
 284        return hex;
 285}
 286
 287static int ambiguous_path(const char *path, int len)
 288{
 289        int slash = 1;
 290        int cnt;
 291
 292        for (cnt = 0; cnt < len; cnt++) {
 293                switch (*path++) {
 294                case '\0':
 295                        break;
 296                case '/':
 297                        if (slash)
 298                                break;
 299                        slash = 1;
 300                        continue;
 301                case '.':
 302                        continue;
 303                default:
 304                        slash = 0;
 305                        continue;
 306                }
 307                break;
 308        }
 309        return slash;
 310}
 311
 312static inline int upstream_mark(const char *string, int len)
 313{
 314        const char *suffix[] = { "@{upstream}", "@{u}" };
 315        int i;
 316
 317        for (i = 0; i < ARRAY_SIZE(suffix); i++) {
 318                int suffix_len = strlen(suffix[i]);
 319                if (suffix_len <= len
 320                    && !memcmp(string, suffix[i], suffix_len))
 321                        return suffix_len;
 322        }
 323        return 0;
 324}
 325
 326static int get_sha1_1(const char *name, int len, unsigned char *sha1);
 327
 328static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 329{
 330        static const char *warn_msg = "refname '%.*s' is ambiguous.";
 331        char *real_ref = NULL;
 332        int refs_found = 0;
 333        int at, reflog_len;
 334
 335        if (len == 40 && !get_sha1_hex(str, sha1))
 336                return 0;
 337
 338        /* basic@{time or number or -number} format to query ref-log */
 339        reflog_len = at = 0;
 340        if (len && str[len-1] == '}') {
 341                for (at = len-2; at >= 0; at--) {
 342                        if (str[at] == '@' && str[at+1] == '{') {
 343                                if (!upstream_mark(str + at, len - at)) {
 344                                        reflog_len = (len-1) - (at+2);
 345                                        len = at;
 346                                }
 347                                break;
 348                        }
 349                }
 350        }
 351
 352        /* Accept only unambiguous ref paths. */
 353        if (len && ambiguous_path(str, len))
 354                return -1;
 355
 356        if (!len && reflog_len) {
 357                struct strbuf buf = STRBUF_INIT;
 358                int ret;
 359                /* try the @{-N} syntax for n-th checkout */
 360                ret = interpret_branch_name(str+at, &buf);
 361                if (ret > 0) {
 362                        /* substitute this branch name and restart */
 363                        return get_sha1_1(buf.buf, buf.len, sha1);
 364                } else if (ret == 0) {
 365                        return -1;
 366                }
 367                /* allow "@{...}" to mean the current branch reflog */
 368                refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 369        } else if (reflog_len)
 370                refs_found = dwim_log(str, len, sha1, &real_ref);
 371        else
 372                refs_found = dwim_ref(str, len, sha1, &real_ref);
 373
 374        if (!refs_found)
 375                return -1;
 376
 377        if (warn_ambiguous_refs && refs_found > 1)
 378                warning(warn_msg, len, str);
 379
 380        if (reflog_len) {
 381                int nth, i;
 382                unsigned long at_time;
 383                unsigned long co_time;
 384                int co_tz, co_cnt;
 385
 386                /* a @{-N} placed anywhere except the start is an error */
 387                if (str[at+2] == '-')
 388                        return -1;
 389
 390                /* Is it asking for N-th entry, or approxidate? */
 391                for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 392                        char ch = str[at+2+i];
 393                        if ('0' <= ch && ch <= '9')
 394                                nth = nth * 10 + ch - '0';
 395                        else
 396                                nth = -1;
 397                }
 398                if (100000000 <= nth) {
 399                        at_time = nth;
 400                        nth = -1;
 401                } else if (0 <= nth)
 402                        at_time = 0;
 403                else {
 404                        int errors = 0;
 405                        char *tmp = xstrndup(str + at + 2, reflog_len);
 406                        at_time = approxidate_careful(tmp, &errors);
 407                        free(tmp);
 408                        if (errors)
 409                                return -1;
 410                }
 411                if (read_ref_at(real_ref, at_time, nth, sha1, NULL,
 412                                &co_time, &co_tz, &co_cnt)) {
 413                        if (at_time)
 414                                warning("Log for '%.*s' only goes "
 415                                        "back to %s.", len, str,
 416                                        show_date(co_time, co_tz, DATE_RFC2822));
 417                        else {
 418                                free(real_ref);
 419                                die("Log for '%.*s' only has %d entries.",
 420                                    len, str, co_cnt);
 421                        }
 422                }
 423        }
 424
 425        free(real_ref);
 426        return 0;
 427}
 428
 429static int get_parent(const char *name, int len,
 430                      unsigned char *result, int idx)
 431{
 432        unsigned char sha1[20];
 433        int ret = get_sha1_1(name, len, sha1);
 434        struct commit *commit;
 435        struct commit_list *p;
 436
 437        if (ret)
 438                return ret;
 439        commit = lookup_commit_reference(sha1);
 440        if (!commit)
 441                return -1;
 442        if (parse_commit(commit))
 443                return -1;
 444        if (!idx) {
 445                hashcpy(result, commit->object.sha1);
 446                return 0;
 447        }
 448        p = commit->parents;
 449        while (p) {
 450                if (!--idx) {
 451                        hashcpy(result, p->item->object.sha1);
 452                        return 0;
 453                }
 454                p = p->next;
 455        }
 456        return -1;
 457}
 458
 459static int get_nth_ancestor(const char *name, int len,
 460                            unsigned char *result, int generation)
 461{
 462        unsigned char sha1[20];
 463        struct commit *commit;
 464        int ret;
 465
 466        ret = get_sha1_1(name, len, sha1);
 467        if (ret)
 468                return ret;
 469        commit = lookup_commit_reference(sha1);
 470        if (!commit)
 471                return -1;
 472
 473        while (generation--) {
 474                if (parse_commit(commit) || !commit->parents)
 475                        return -1;
 476                commit = commit->parents->item;
 477        }
 478        hashcpy(result, commit->object.sha1);
 479        return 0;
 480}
 481
 482struct object *peel_to_type(const char *name, int namelen,
 483                            struct object *o, enum object_type expected_type)
 484{
 485        if (name && !namelen)
 486                namelen = strlen(name);
 487        while (1) {
 488                if (!o || (!o->parsed && !parse_object(o->sha1)))
 489                        return NULL;
 490                if (o->type == expected_type)
 491                        return o;
 492                if (o->type == OBJ_TAG)
 493                        o = ((struct tag*) o)->tagged;
 494                else if (o->type == OBJ_COMMIT)
 495                        o = &(((struct commit *) o)->tree->object);
 496                else {
 497                        if (name)
 498                                error("%.*s: expected %s type, but the object "
 499                                      "dereferences to %s type",
 500                                      namelen, name, typename(expected_type),
 501                                      typename(o->type));
 502                        return NULL;
 503                }
 504        }
 505}
 506
 507static int peel_onion(const char *name, int len, unsigned char *sha1)
 508{
 509        unsigned char outer[20];
 510        const char *sp;
 511        unsigned int expected_type = 0;
 512        struct object *o;
 513
 514        /*
 515         * "ref^{type}" dereferences ref repeatedly until you cannot
 516         * dereference anymore, or you get an object of given type,
 517         * whichever comes first.  "ref^{}" means just dereference
 518         * tags until you get a non-tag.  "ref^0" is a shorthand for
 519         * "ref^{commit}".  "commit^{tree}" could be used to find the
 520         * top-level tree of the given commit.
 521         */
 522        if (len < 4 || name[len-1] != '}')
 523                return -1;
 524
 525        for (sp = name + len - 1; name <= sp; sp--) {
 526                int ch = *sp;
 527                if (ch == '{' && name < sp && sp[-1] == '^')
 528                        break;
 529        }
 530        if (sp <= name)
 531                return -1;
 532
 533        sp++; /* beginning of type name, or closing brace for empty */
 534        if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
 535                expected_type = OBJ_COMMIT;
 536        else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
 537                expected_type = OBJ_TREE;
 538        else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
 539                expected_type = OBJ_BLOB;
 540        else if (sp[0] == '}')
 541                expected_type = OBJ_NONE;
 542        else if (sp[0] == '/')
 543                expected_type = OBJ_COMMIT;
 544        else
 545                return -1;
 546
 547        if (get_sha1_1(name, sp - name - 2, outer))
 548                return -1;
 549
 550        o = parse_object(outer);
 551        if (!o)
 552                return -1;
 553        if (!expected_type) {
 554                o = deref_tag(o, name, sp - name - 2);
 555                if (!o || (!o->parsed && !parse_object(o->sha1)))
 556                        return -1;
 557                hashcpy(sha1, o->sha1);
 558                return 0;
 559        }
 560
 561        /*
 562         * At this point, the syntax look correct, so
 563         * if we do not get the needed object, we should
 564         * barf.
 565         */
 566        o = peel_to_type(name, len, o, expected_type);
 567        if (!o)
 568                return -1;
 569
 570        hashcpy(sha1, o->sha1);
 571        if (sp[0] == '/') {
 572                /* "$commit^{/foo}" */
 573                char *prefix;
 574                int ret;
 575                struct commit_list *list = NULL;
 576
 577                /*
 578                 * $commit^{/}. Some regex implementation may reject.
 579                 * We don't need regex anyway. '' pattern always matches.
 580                 */
 581                if (sp[1] == '}')
 582                        return 0;
 583
 584                prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 585                commit_list_insert((struct commit *)o, &list);
 586                ret = get_sha1_oneline(prefix, sha1, list);
 587                free(prefix);
 588                return ret;
 589        }
 590        return 0;
 591}
 592
 593static int get_describe_name(const char *name, int len, unsigned char *sha1)
 594{
 595        const char *cp;
 596
 597        for (cp = name + len - 1; name + 2 <= cp; cp--) {
 598                char ch = *cp;
 599                if (hexval(ch) & ~0377) {
 600                        /* We must be looking at g in "SOMETHING-g"
 601                         * for it to be describe output.
 602                         */
 603                        if (ch == 'g' && cp[-1] == '-') {
 604                                cp++;
 605                                len -= cp - name;
 606                                return get_short_sha1(cp, len, sha1, 1);
 607                        }
 608                }
 609        }
 610        return -1;
 611}
 612
 613static int get_sha1_1(const char *name, int len, unsigned char *sha1)
 614{
 615        int ret, has_suffix;
 616        const char *cp;
 617
 618        /*
 619         * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 620         */
 621        has_suffix = 0;
 622        for (cp = name + len - 1; name <= cp; cp--) {
 623                int ch = *cp;
 624                if ('0' <= ch && ch <= '9')
 625                        continue;
 626                if (ch == '~' || ch == '^')
 627                        has_suffix = ch;
 628                break;
 629        }
 630
 631        if (has_suffix) {
 632                int num = 0;
 633                int len1 = cp - name;
 634                cp++;
 635                while (cp < name + len)
 636                        num = num * 10 + *cp++ - '0';
 637                if (!num && len1 == len - 1)
 638                        num = 1;
 639                if (has_suffix == '^')
 640                        return get_parent(name, len1, sha1, num);
 641                /* else if (has_suffix == '~') -- goes without saying */
 642                return get_nth_ancestor(name, len1, sha1, num);
 643        }
 644
 645        ret = peel_onion(name, len, sha1);
 646        if (!ret)
 647                return 0;
 648
 649        ret = get_sha1_basic(name, len, sha1);
 650        if (!ret)
 651                return 0;
 652
 653        /* It could be describe output that is "SOMETHING-gXXXX" */
 654        ret = get_describe_name(name, len, sha1);
 655        if (!ret)
 656                return 0;
 657
 658        return get_short_sha1(name, len, sha1, 0);
 659}
 660
 661/*
 662 * This interprets names like ':/Initial revision of "git"' by searching
 663 * through history and returning the first commit whose message starts
 664 * the given regular expression.
 665 *
 666 * For future extension, ':/!' is reserved. If you want to match a message
 667 * beginning with a '!', you have to repeat the exclamation mark.
 668 */
 669#define ONELINE_SEEN (1u<<20)
 670
 671static int handle_one_ref(const char *path,
 672                const unsigned char *sha1, int flag, void *cb_data)
 673{
 674        struct commit_list **list = cb_data;
 675        struct object *object = parse_object(sha1);
 676        if (!object)
 677                return 0;
 678        if (object->type == OBJ_TAG) {
 679                object = deref_tag(object, path, strlen(path));
 680                if (!object)
 681                        return 0;
 682        }
 683        if (object->type != OBJ_COMMIT)
 684                return 0;
 685        commit_list_insert_by_date((struct commit *)object, list);
 686        return 0;
 687}
 688
 689static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 690                            struct commit_list *list)
 691{
 692        struct commit_list *backup = NULL, *l;
 693        int found = 0;
 694        regex_t regex;
 695
 696        if (prefix[0] == '!') {
 697                if (prefix[1] != '!')
 698                        die ("Invalid search pattern: %s", prefix);
 699                prefix++;
 700        }
 701
 702        if (regcomp(&regex, prefix, REG_EXTENDED))
 703                die("Invalid search pattern: %s", prefix);
 704
 705        for (l = list; l; l = l->next) {
 706                l->item->object.flags |= ONELINE_SEEN;
 707                commit_list_insert(l->item, &backup);
 708        }
 709        while (list) {
 710                char *p, *to_free = NULL;
 711                struct commit *commit;
 712                enum object_type type;
 713                unsigned long size;
 714                int matches;
 715
 716                commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 717                if (!parse_object(commit->object.sha1))
 718                        continue;
 719                if (commit->buffer)
 720                        p = commit->buffer;
 721                else {
 722                        p = read_sha1_file(commit->object.sha1, &type, &size);
 723                        if (!p)
 724                                continue;
 725                        to_free = p;
 726                }
 727
 728                p = strstr(p, "\n\n");
 729                matches = p && !regexec(&regex, p + 2, 0, NULL, 0);
 730                free(to_free);
 731
 732                if (matches) {
 733                        hashcpy(sha1, commit->object.sha1);
 734                        found = 1;
 735                        break;
 736                }
 737        }
 738        regfree(&regex);
 739        free_commit_list(list);
 740        for (l = backup; l; l = l->next)
 741                clear_commit_marks(l->item, ONELINE_SEEN);
 742        free_commit_list(backup);
 743        return found ? 0 : -1;
 744}
 745
 746struct grab_nth_branch_switch_cbdata {
 747        long cnt, alloc;
 748        struct strbuf *buf;
 749};
 750
 751static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 752                                  const char *email, unsigned long timestamp, int tz,
 753                                  const char *message, void *cb_data)
 754{
 755        struct grab_nth_branch_switch_cbdata *cb = cb_data;
 756        const char *match = NULL, *target = NULL;
 757        size_t len;
 758        int nth;
 759
 760        if (!prefixcmp(message, "checkout: moving from ")) {
 761                match = message + strlen("checkout: moving from ");
 762                target = strstr(match, " to ");
 763        }
 764
 765        if (!match || !target)
 766                return 0;
 767
 768        len = target - match;
 769        nth = cb->cnt++ % cb->alloc;
 770        strbuf_reset(&cb->buf[nth]);
 771        strbuf_add(&cb->buf[nth], match, len);
 772        return 0;
 773}
 774
 775/*
 776 * Parse @{-N} syntax, return the number of characters parsed
 777 * if successful; otherwise signal an error with negative value.
 778 */
 779static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf)
 780{
 781        long nth;
 782        int i, retval;
 783        struct grab_nth_branch_switch_cbdata cb;
 784        const char *brace;
 785        char *num_end;
 786
 787        if (name[0] != '@' || name[1] != '{' || name[2] != '-')
 788                return -1;
 789        brace = strchr(name, '}');
 790        if (!brace)
 791                return -1;
 792        nth = strtol(name+3, &num_end, 10);
 793        if (num_end != brace)
 794                return -1;
 795        if (nth <= 0)
 796                return -1;
 797        cb.alloc = nth;
 798        cb.buf = xmalloc(nth * sizeof(struct strbuf));
 799        for (i = 0; i < nth; i++)
 800                strbuf_init(&cb.buf[i], 20);
 801        cb.cnt = 0;
 802        retval = 0;
 803        for_each_recent_reflog_ent("HEAD", grab_nth_branch_switch, 40960, &cb);
 804        if (cb.cnt < nth) {
 805                cb.cnt = 0;
 806                for_each_reflog_ent("HEAD", grab_nth_branch_switch, &cb);
 807        }
 808        if (cb.cnt < nth)
 809                goto release_return;
 810        i = cb.cnt % nth;
 811        strbuf_reset(buf);
 812        strbuf_add(buf, cb.buf[i].buf, cb.buf[i].len);
 813        retval = brace-name+1;
 814
 815release_return:
 816        for (i = 0; i < nth; i++)
 817                strbuf_release(&cb.buf[i]);
 818        free(cb.buf);
 819
 820        return retval;
 821}
 822
 823int get_sha1_mb(const char *name, unsigned char *sha1)
 824{
 825        struct commit *one, *two;
 826        struct commit_list *mbs;
 827        unsigned char sha1_tmp[20];
 828        const char *dots;
 829        int st;
 830
 831        dots = strstr(name, "...");
 832        if (!dots)
 833                return get_sha1(name, sha1);
 834        if (dots == name)
 835                st = get_sha1("HEAD", sha1_tmp);
 836        else {
 837                struct strbuf sb;
 838                strbuf_init(&sb, dots - name);
 839                strbuf_add(&sb, name, dots - name);
 840                st = get_sha1(sb.buf, sha1_tmp);
 841                strbuf_release(&sb);
 842        }
 843        if (st)
 844                return st;
 845        one = lookup_commit_reference_gently(sha1_tmp, 0);
 846        if (!one)
 847                return -1;
 848
 849        if (get_sha1(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
 850                return -1;
 851        two = lookup_commit_reference_gently(sha1_tmp, 0);
 852        if (!two)
 853                return -1;
 854        mbs = get_merge_bases(one, two, 1);
 855        if (!mbs || mbs->next)
 856                st = -1;
 857        else {
 858                st = 0;
 859                hashcpy(sha1, mbs->item->object.sha1);
 860        }
 861        free_commit_list(mbs);
 862        return st;
 863}
 864
 865/*
 866 * This reads short-hand syntax that not only evaluates to a commit
 867 * object name, but also can act as if the end user spelled the name
 868 * of the branch from the command line.
 869 *
 870 * - "@{-N}" finds the name of the Nth previous branch we were on, and
 871 *   places the name of the branch in the given buf and returns the
 872 *   number of characters parsed if successful.
 873 *
 874 * - "<branch>@{upstream}" finds the name of the other ref that
 875 *   <branch> is configured to merge with (missing <branch> defaults
 876 *   to the current branch), and places the name of the branch in the
 877 *   given buf and returns the number of characters parsed if
 878 *   successful.
 879 *
 880 * If the input is not of the accepted format, it returns a negative
 881 * number to signal an error.
 882 *
 883 * If the input was ok but there are not N branch switches in the
 884 * reflog, it returns 0.
 885 */
 886int interpret_branch_name(const char *name, struct strbuf *buf)
 887{
 888        char *cp;
 889        struct branch *upstream;
 890        int namelen = strlen(name);
 891        int len = interpret_nth_prior_checkout(name, buf);
 892        int tmp_len;
 893
 894        if (!len)
 895                return len; /* syntax Ok, not enough switches */
 896        if (0 < len && len == namelen)
 897                return len; /* consumed all */
 898        else if (0 < len) {
 899                /* we have extra data, which might need further processing */
 900                struct strbuf tmp = STRBUF_INIT;
 901                int used = buf->len;
 902                int ret;
 903
 904                strbuf_add(buf, name + len, namelen - len);
 905                ret = interpret_branch_name(buf->buf, &tmp);
 906                /* that data was not interpreted, remove our cruft */
 907                if (ret < 0) {
 908                        strbuf_setlen(buf, used);
 909                        return len;
 910                }
 911                strbuf_reset(buf);
 912                strbuf_addbuf(buf, &tmp);
 913                strbuf_release(&tmp);
 914                /* tweak for size of {-N} versus expanded ref name */
 915                return ret - used + len;
 916        }
 917
 918        cp = strchr(name, '@');
 919        if (!cp)
 920                return -1;
 921        tmp_len = upstream_mark(cp, namelen - (cp - name));
 922        if (!tmp_len)
 923                return -1;
 924        len = cp + tmp_len - name;
 925        cp = xstrndup(name, cp - name);
 926        upstream = branch_get(*cp ? cp : NULL);
 927        if (!upstream
 928            || !upstream->merge
 929            || !upstream->merge[0]->dst)
 930                return error("No upstream branch found for '%s'", cp);
 931        free(cp);
 932        cp = shorten_unambiguous_ref(upstream->merge[0]->dst, 0);
 933        strbuf_reset(buf);
 934        strbuf_addstr(buf, cp);
 935        free(cp);
 936        return len;
 937}
 938
 939int strbuf_branchname(struct strbuf *sb, const char *name)
 940{
 941        int len = strlen(name);
 942        if (interpret_branch_name(name, sb) == len)
 943                return 0;
 944        strbuf_add(sb, name, len);
 945        return len;
 946}
 947
 948int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
 949{
 950        strbuf_branchname(sb, name);
 951        if (name[0] == '-')
 952                return -1;
 953        strbuf_splice(sb, 0, 0, "refs/heads/", 11);
 954        return check_refname_format(sb->buf, 0);
 955}
 956
 957/*
 958 * This is like "get_sha1_basic()", except it allows "sha1 expressions",
 959 * notably "xyz^" for "parent of xyz"
 960 */
 961int get_sha1(const char *name, unsigned char *sha1)
 962{
 963        struct object_context unused;
 964        return get_sha1_with_context(name, sha1, &unused);
 965}
 966
 967/* Must be called only when object_name:filename doesn't exist. */
 968static void diagnose_invalid_sha1_path(const char *prefix,
 969                                       const char *filename,
 970                                       const unsigned char *tree_sha1,
 971                                       const char *object_name)
 972{
 973        struct stat st;
 974        unsigned char sha1[20];
 975        unsigned mode;
 976
 977        if (!prefix)
 978                prefix = "";
 979
 980        if (!lstat(filename, &st))
 981                die("Path '%s' exists on disk, but not in '%s'.",
 982                    filename, object_name);
 983        if (errno == ENOENT || errno == ENOTDIR) {
 984                char *fullname = xmalloc(strlen(filename)
 985                                             + strlen(prefix) + 1);
 986                strcpy(fullname, prefix);
 987                strcat(fullname, filename);
 988
 989                if (!get_tree_entry(tree_sha1, fullname,
 990                                    sha1, &mode)) {
 991                        die("Path '%s' exists, but not '%s'.\n"
 992                            "Did you mean '%s:%s' aka '%s:./%s'?",
 993                            fullname,
 994                            filename,
 995                            object_name,
 996                            fullname,
 997                            object_name,
 998                            filename);
 999                }
1000                die("Path '%s' does not exist in '%s'",
1001                    filename, object_name);
1002        }
1003}
1004
1005/* Must be called only when :stage:filename doesn't exist. */
1006static void diagnose_invalid_index_path(int stage,
1007                                        const char *prefix,
1008                                        const char *filename)
1009{
1010        struct stat st;
1011        struct cache_entry *ce;
1012        int pos;
1013        unsigned namelen = strlen(filename);
1014        unsigned fullnamelen;
1015        char *fullname;
1016
1017        if (!prefix)
1018                prefix = "";
1019
1020        /* Wrong stage number? */
1021        pos = cache_name_pos(filename, namelen);
1022        if (pos < 0)
1023                pos = -pos - 1;
1024        if (pos < active_nr) {
1025                ce = active_cache[pos];
1026                if (ce_namelen(ce) == namelen &&
1027                    !memcmp(ce->name, filename, namelen))
1028                        die("Path '%s' is in the index, but not at stage %d.\n"
1029                            "Did you mean ':%d:%s'?",
1030                            filename, stage,
1031                            ce_stage(ce), filename);
1032        }
1033
1034        /* Confusion between relative and absolute filenames? */
1035        fullnamelen = namelen + strlen(prefix);
1036        fullname = xmalloc(fullnamelen + 1);
1037        strcpy(fullname, prefix);
1038        strcat(fullname, filename);
1039        pos = cache_name_pos(fullname, fullnamelen);
1040        if (pos < 0)
1041                pos = -pos - 1;
1042        if (pos < active_nr) {
1043                ce = active_cache[pos];
1044                if (ce_namelen(ce) == fullnamelen &&
1045                    !memcmp(ce->name, fullname, fullnamelen))
1046                        die("Path '%s' is in the index, but not '%s'.\n"
1047                            "Did you mean ':%d:%s' aka ':%d:./%s'?",
1048                            fullname, filename,
1049                            ce_stage(ce), fullname,
1050                            ce_stage(ce), filename);
1051        }
1052
1053        if (!lstat(filename, &st))
1054                die("Path '%s' exists on disk, but not in the index.", filename);
1055        if (errno == ENOENT || errno == ENOTDIR)
1056                die("Path '%s' does not exist (neither on disk nor in the index).",
1057                    filename);
1058
1059        free(fullname);
1060}
1061
1062
1063static char *resolve_relative_path(const char *rel)
1064{
1065        if (prefixcmp(rel, "./") && prefixcmp(rel, "../"))
1066                return NULL;
1067
1068        if (!startup_info)
1069                die("BUG: startup_info struct is not initialized.");
1070
1071        if (!is_inside_work_tree())
1072                die("relative path syntax can't be used outside working tree.");
1073
1074        /* die() inside prefix_path() if resolved path is outside worktree */
1075        return prefix_path(startup_info->prefix,
1076                           startup_info->prefix ? strlen(startup_info->prefix) : 0,
1077                           rel);
1078}
1079
1080static int get_sha1_with_context_1(const char *name, unsigned char *sha1,
1081                                   struct object_context *oc,
1082                                   int only_to_die, const char *prefix)
1083{
1084        int ret, bracket_depth;
1085        int namelen = strlen(name);
1086        const char *cp;
1087
1088        memset(oc, 0, sizeof(*oc));
1089        oc->mode = S_IFINVALID;
1090        ret = get_sha1_1(name, namelen, sha1);
1091        if (!ret)
1092                return ret;
1093        /* sha1:path --> object name of path in ent sha1
1094         * :path -> object name of absolute path in index
1095         * :./path -> object name of path relative to cwd in index
1096         * :[0-3]:path -> object name of path in index at stage
1097         * :/foo -> recent commit matching foo
1098         */
1099        if (name[0] == ':') {
1100                int stage = 0;
1101                struct cache_entry *ce;
1102                char *new_path = NULL;
1103                int pos;
1104                if (!only_to_die && namelen > 2 && name[1] == '/') {
1105                        struct commit_list *list = NULL;
1106                        for_each_ref(handle_one_ref, &list);
1107                        return get_sha1_oneline(name + 2, sha1, list);
1108                }
1109                if (namelen < 3 ||
1110                    name[2] != ':' ||
1111                    name[1] < '0' || '3' < name[1])
1112                        cp = name + 1;
1113                else {
1114                        stage = name[1] - '0';
1115                        cp = name + 3;
1116                }
1117                new_path = resolve_relative_path(cp);
1118                if (!new_path) {
1119                        namelen = namelen - (cp - name);
1120                } else {
1121                        cp = new_path;
1122                        namelen = strlen(cp);
1123                }
1124
1125                strncpy(oc->path, cp,
1126                        sizeof(oc->path));
1127                oc->path[sizeof(oc->path)-1] = '\0';
1128
1129                if (!active_cache)
1130                        read_cache();
1131                pos = cache_name_pos(cp, namelen);
1132                if (pos < 0)
1133                        pos = -pos - 1;
1134                while (pos < active_nr) {
1135                        ce = active_cache[pos];
1136                        if (ce_namelen(ce) != namelen ||
1137                            memcmp(ce->name, cp, namelen))
1138                                break;
1139                        if (ce_stage(ce) == stage) {
1140                                hashcpy(sha1, ce->sha1);
1141                                oc->mode = ce->ce_mode;
1142                                free(new_path);
1143                                return 0;
1144                        }
1145                        pos++;
1146                }
1147                if (only_to_die && name[1] && name[1] != '/')
1148                        diagnose_invalid_index_path(stage, prefix, cp);
1149                free(new_path);
1150                return -1;
1151        }
1152        for (cp = name, bracket_depth = 0; *cp; cp++) {
1153                if (*cp == '{')
1154                        bracket_depth++;
1155                else if (bracket_depth && *cp == '}')
1156                        bracket_depth--;
1157                else if (!bracket_depth && *cp == ':')
1158                        break;
1159        }
1160        if (*cp == ':') {
1161                unsigned char tree_sha1[20];
1162                char *object_name = NULL;
1163                if (only_to_die) {
1164                        object_name = xmalloc(cp-name+1);
1165                        strncpy(object_name, name, cp-name);
1166                        object_name[cp-name] = '\0';
1167                }
1168                if (!get_sha1_1(name, cp-name, tree_sha1)) {
1169                        const char *filename = cp+1;
1170                        char *new_filename = NULL;
1171
1172                        new_filename = resolve_relative_path(filename);
1173                        if (new_filename)
1174                                filename = new_filename;
1175                        ret = get_tree_entry(tree_sha1, filename, sha1, &oc->mode);
1176                        if (only_to_die) {
1177                                diagnose_invalid_sha1_path(prefix, filename,
1178                                                           tree_sha1, object_name);
1179                                free(object_name);
1180                        }
1181                        hashcpy(oc->tree, tree_sha1);
1182                        strncpy(oc->path, filename,
1183                                sizeof(oc->path));
1184                        oc->path[sizeof(oc->path)-1] = '\0';
1185
1186                        free(new_filename);
1187                        return ret;
1188                } else {
1189                        if (only_to_die)
1190                                die("Invalid object name '%s'.", object_name);
1191                }
1192        }
1193        return ret;
1194}
1195
1196/*
1197 * Call this function when you know "name" given by the end user must
1198 * name an object but it doesn't; the function _may_ die with a better
1199 * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1200 * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1201 * you have a chance to diagnose the error further.
1202 */
1203void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1204{
1205        struct object_context oc;
1206        unsigned char sha1[20];
1207        get_sha1_with_context_1(name, sha1, &oc, 1, prefix);
1208}
1209
1210int get_sha1_with_context(const char *str, unsigned char *sha1, struct object_context *orc)
1211{
1212        return get_sha1_with_context_1(str, sha1, orc, 0, NULL);
1213}