Andrew's git / gitweb.git / sha1_name.c
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sha1_name.con commit Fix random segfaults in pack-objects. (f5b1b5a)
   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
   9static int find_short_object_filename(int len, const char *name, unsigned char *sha1)
  10{
  11        struct alternate_object_database *alt;
  12        char hex[40];
  13        int found = 0;
  14        static struct alternate_object_database *fakeent;
  15
  16        if (!fakeent) {
  17                const char *objdir = get_object_directory();
  18                int objdir_len = strlen(objdir);
  19                int entlen = objdir_len + 43;
  20                fakeent = xmalloc(sizeof(*fakeent) + entlen);
  21                memcpy(fakeent->base, objdir, objdir_len);
  22                fakeent->name = fakeent->base + objdir_len + 1;
  23                fakeent->name[-1] = '/';
  24        }
  25        fakeent->next = alt_odb_list;
  26
  27        sprintf(hex, "%.2s", name);
  28        for (alt = fakeent; alt && found < 2; alt = alt->next) {
  29                struct dirent *de;
  30                DIR *dir;
  31                sprintf(alt->name, "%.2s/", name);
  32                dir = opendir(alt->base);
  33                if (!dir)
  34                        continue;
  35                while ((de = readdir(dir)) != NULL) {
  36                        if (strlen(de->d_name) != 38)
  37                                continue;
  38                        if (memcmp(de->d_name, name + 2, len - 2))
  39                                continue;
  40                        if (!found) {
  41                                memcpy(hex + 2, de->d_name, 38);
  42                                found++;
  43                        }
  44                        else if (memcmp(hex + 2, de->d_name, 38)) {
  45                                found = 2;
  46                                break;
  47                        }
  48                }
  49                closedir(dir);
  50        }
  51        if (found == 1)
  52                return get_sha1_hex(hex, sha1) == 0;
  53        return found;
  54}
  55
  56static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
  57{
  58        do {
  59                if (*a != *b)
  60                        return 0;
  61                a++;
  62                b++;
  63                len -= 2;
  64        } while (len > 1);
  65        if (len)
  66                if ((*a ^ *b) & 0xf0)
  67                        return 0;
  68        return 1;
  69}
  70
  71static int find_short_packed_object(int len, const unsigned char *match, unsigned char *sha1)
  72{
  73        struct packed_git *p;
  74        unsigned char found_sha1[20];
  75        int found = 0;
  76
  77        prepare_packed_git();
  78        for (p = packed_git; p && found < 2; p = p->next) {
  79                unsigned num = num_packed_objects(p);
  80                unsigned first = 0, last = num;
  81                while (first < last) {
  82                        unsigned mid = (first + last) / 2;
  83                        unsigned char now[20];
  84                        int cmp;
  85
  86                        nth_packed_object_sha1(p, mid, now);
  87                        cmp = hashcmp(match, now);
  88                        if (!cmp) {
  89                                first = mid;
  90                                break;
  91                        }
  92                        if (cmp > 0) {
  93                                first = mid+1;
  94                                continue;
  95                        }
  96                        last = mid;
  97                }
  98                if (first < num) {
  99                        unsigned char now[20], next[20];
 100                        nth_packed_object_sha1(p, first, now);
 101                        if (match_sha(len, match, now)) {
 102                                if (nth_packed_object_sha1(p, first+1, next) ||
 103                                    !match_sha(len, match, next)) {
 104                                        /* unique within this pack */
 105                                        if (!found) {
 106                                                hashcpy(found_sha1, now);
 107                                                found++;
 108                                        }
 109                                        else if (hashcmp(found_sha1, now)) {
 110                                                found = 2;
 111                                                break;
 112                                        }
 113                                }
 114                                else {
 115                                        /* not even unique within this pack */
 116                                        found = 2;
 117                                        break;
 118                                }
 119                        }
 120                }
 121        }
 122        if (found == 1)
 123                hashcpy(sha1, found_sha1);
 124        return found;
 125}
 126
 127#define SHORT_NAME_NOT_FOUND (-1)
 128#define SHORT_NAME_AMBIGUOUS (-2)
 129
 130static int find_unique_short_object(int len, char *canonical,
 131                                    unsigned char *res, unsigned char *sha1)
 132{
 133        int has_unpacked, has_packed;
 134        unsigned char unpacked_sha1[20], packed_sha1[20];
 135
 136        has_unpacked = find_short_object_filename(len, canonical, unpacked_sha1);
 137        has_packed = find_short_packed_object(len, res, packed_sha1);
 138        if (!has_unpacked && !has_packed)
 139                return SHORT_NAME_NOT_FOUND;
 140        if (1 < has_unpacked || 1 < has_packed)
 141                return SHORT_NAME_AMBIGUOUS;
 142        if (has_unpacked != has_packed) {
 143                hashcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1));
 144                return 0;
 145        }
 146        /* Both have unique ones -- do they match? */
 147        if (hashcmp(packed_sha1, unpacked_sha1))
 148                return SHORT_NAME_AMBIGUOUS;
 149        hashcpy(sha1, packed_sha1);
 150        return 0;
 151}
 152
 153static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 154                          int quietly)
 155{
 156        int i, status;
 157        char canonical[40];
 158        unsigned char res[20];
 159
 160        if (len < MINIMUM_ABBREV || len > 40)
 161                return -1;
 162        hashclr(res);
 163        memset(canonical, 'x', 40);
 164        for (i = 0; i < len ;i++) {
 165                unsigned char c = name[i];
 166                unsigned char val;
 167                if (c >= '0' && c <= '9')
 168                        val = c - '0';
 169                else if (c >= 'a' && c <= 'f')
 170                        val = c - 'a' + 10;
 171                else if (c >= 'A' && c <='F') {
 172                        val = c - 'A' + 10;
 173                        c -= 'A' - 'a';
 174                }
 175                else
 176                        return -1;
 177                canonical[i] = c;
 178                if (!(i & 1))
 179                        val <<= 4;
 180                res[i >> 1] |= val;
 181        }
 182
 183        status = find_unique_short_object(i, canonical, res, sha1);
 184        if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
 185                return error("short SHA1 %.*s is ambiguous.", len, canonical);
 186        return status;
 187}
 188
 189const char *find_unique_abbrev(const unsigned char *sha1, int len)
 190{
 191        int status, is_null;
 192        static char hex[41];
 193
 194        is_null = is_null_sha1(sha1);
 195        memcpy(hex, sha1_to_hex(sha1), 40);
 196        if (len == 40 || !len)
 197                return hex;
 198        while (len < 40) {
 199                unsigned char sha1_ret[20];
 200                status = get_short_sha1(hex, len, sha1_ret, 1);
 201                if (!status ||
 202                    (is_null && status != SHORT_NAME_AMBIGUOUS)) {
 203                        hex[len] = 0;
 204                        return hex;
 205                }
 206                if (status != SHORT_NAME_AMBIGUOUS)
 207                        return NULL;
 208                len++;
 209        }
 210        return NULL;
 211}
 212
 213static int ambiguous_path(const char *path, int len)
 214{
 215        int slash = 1;
 216        int cnt;
 217
 218        for (cnt = 0; cnt < len; cnt++) {
 219                switch (*path++) {
 220                case '\0':
 221                        break;
 222                case '/':
 223                        if (slash)
 224                                break;
 225                        slash = 1;
 226                        continue;
 227                case '.':
 228                        continue;
 229                default:
 230                        slash = 0;
 231                        continue;
 232                }
 233                break;
 234        }
 235        return slash;
 236}
 237
 238static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 239{
 240        static const char *fmt[] = {
 241                "%.*s",
 242                "refs/%.*s",
 243                "refs/tags/%.*s",
 244                "refs/heads/%.*s",
 245                "refs/remotes/%.*s",
 246                "refs/remotes/%.*s/HEAD",
 247                NULL
 248        };
 249        static const char *warning = "warning: refname '%.*s' is ambiguous.\n";
 250        const char **p, *ref;
 251        char *real_ref = NULL;
 252        int refs_found = 0;
 253        int at, reflog_len;
 254        unsigned char *this_result;
 255        unsigned char sha1_from_ref[20];
 256
 257        if (len == 40 && !get_sha1_hex(str, sha1))
 258                return 0;
 259
 260        /* basic@{time or number} format to query ref-log */
 261        reflog_len = at = 0;
 262        if (str[len-1] == '}') {
 263                for (at = 1; at < len - 1; at++) {
 264                        if (str[at] == '@' && str[at+1] == '{') {
 265                                reflog_len = (len-1) - (at+2);
 266                                len = at;
 267                                break;
 268                        }
 269                }
 270        }
 271
 272        /* Accept only unambiguous ref paths. */
 273        if (ambiguous_path(str, len))
 274                return -1;
 275
 276        for (p = fmt; *p; p++) {
 277                this_result = refs_found ? sha1_from_ref : sha1;
 278                ref = resolve_ref(mkpath(*p, len, str), this_result, 1, NULL);
 279                if (ref) {
 280                        if (!refs_found++)
 281                                real_ref = xstrdup(ref);
 282                        if (!warn_ambiguous_refs)
 283                                break;
 284                }
 285        }
 286
 287        if (!refs_found)
 288                return -1;
 289
 290        if (warn_ambiguous_refs && refs_found > 1)
 291                fprintf(stderr, warning, len, str);
 292
 293        if (reflog_len) {
 294                /* Is it asking for N-th entry, or approxidate? */
 295                int nth, i;
 296                unsigned long at_time;
 297                for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 298                        char ch = str[at+2+i];
 299                        if ('0' <= ch && ch <= '9')
 300                                nth = nth * 10 + ch - '0';
 301                        else
 302                                nth = -1;
 303                }
 304                if (0 <= nth)
 305                        at_time = 0;
 306                else
 307                        at_time = approxidate(str + at + 2);
 308                read_ref_at(real_ref, at_time, nth, sha1);
 309        }
 310
 311        free(real_ref);
 312        return 0;
 313}
 314
 315static int get_sha1_1(const char *name, int len, unsigned char *sha1);
 316
 317static int get_parent(const char *name, int len,
 318                      unsigned char *result, int idx)
 319{
 320        unsigned char sha1[20];
 321        int ret = get_sha1_1(name, len, sha1);
 322        struct commit *commit;
 323        struct commit_list *p;
 324
 325        if (ret)
 326                return ret;
 327        commit = lookup_commit_reference(sha1);
 328        if (!commit)
 329                return -1;
 330        if (parse_commit(commit))
 331                return -1;
 332        if (!idx) {
 333                hashcpy(result, commit->object.sha1);
 334                return 0;
 335        }
 336        p = commit->parents;
 337        while (p) {
 338                if (!--idx) {
 339                        hashcpy(result, p->item->object.sha1);
 340                        return 0;
 341                }
 342                p = p->next;
 343        }
 344        return -1;
 345}
 346
 347static int get_nth_ancestor(const char *name, int len,
 348                            unsigned char *result, int generation)
 349{
 350        unsigned char sha1[20];
 351        int ret = get_sha1_1(name, len, sha1);
 352        if (ret)
 353                return ret;
 354
 355        while (generation--) {
 356                struct commit *commit = lookup_commit_reference(sha1);
 357
 358                if (!commit || parse_commit(commit) || !commit->parents)
 359                        return -1;
 360                hashcpy(sha1, commit->parents->item->object.sha1);
 361        }
 362        hashcpy(result, sha1);
 363        return 0;
 364}
 365
 366static int peel_onion(const char *name, int len, unsigned char *sha1)
 367{
 368        unsigned char outer[20];
 369        const char *sp;
 370        unsigned int expected_type = 0;
 371        struct object *o;
 372
 373        /*
 374         * "ref^{type}" dereferences ref repeatedly until you cannot
 375         * dereference anymore, or you get an object of given type,
 376         * whichever comes first.  "ref^{}" means just dereference
 377         * tags until you get a non-tag.  "ref^0" is a shorthand for
 378         * "ref^{commit}".  "commit^{tree}" could be used to find the
 379         * top-level tree of the given commit.
 380         */
 381        if (len < 4 || name[len-1] != '}')
 382                return -1;
 383
 384        for (sp = name + len - 1; name <= sp; sp--) {
 385                int ch = *sp;
 386                if (ch == '{' && name < sp && sp[-1] == '^')
 387                        break;
 388        }
 389        if (sp <= name)
 390                return -1;
 391
 392        sp++; /* beginning of type name, or closing brace for empty */
 393        if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
 394                expected_type = OBJ_COMMIT;
 395        else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
 396                expected_type = OBJ_TREE;
 397        else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
 398                expected_type = OBJ_BLOB;
 399        else if (sp[0] == '}')
 400                expected_type = OBJ_NONE;
 401        else
 402                return -1;
 403
 404        if (get_sha1_1(name, sp - name - 2, outer))
 405                return -1;
 406
 407        o = parse_object(outer);
 408        if (!o)
 409                return -1;
 410        if (!expected_type) {
 411                o = deref_tag(o, name, sp - name - 2);
 412                if (!o || (!o->parsed && !parse_object(o->sha1)))
 413                        return -1;
 414                hashcpy(sha1, o->sha1);
 415        }
 416        else {
 417                /* At this point, the syntax look correct, so
 418                 * if we do not get the needed object, we should
 419                 * barf.
 420                 */
 421
 422                while (1) {
 423                        if (!o || (!o->parsed && !parse_object(o->sha1)))
 424                                return -1;
 425                        if (o->type == expected_type) {
 426                                hashcpy(sha1, o->sha1);
 427                                return 0;
 428                        }
 429                        if (o->type == OBJ_TAG)
 430                                o = ((struct tag*) o)->tagged;
 431                        else if (o->type == OBJ_COMMIT)
 432                                o = &(((struct commit *) o)->tree->object);
 433                        else
 434                                return error("%.*s: expected %s type, but the object dereferences to %s type",
 435                                             len, name, typename(expected_type),
 436                                             typename(o->type));
 437                        if (!o->parsed)
 438                                parse_object(o->sha1);
 439                }
 440        }
 441        return 0;
 442}
 443
 444static int get_describe_name(const char *name, int len, unsigned char *sha1)
 445{
 446        const char *cp;
 447
 448        for (cp = name + len - 1; name + 2 <= cp; cp--) {
 449                char ch = *cp;
 450                if (hexval(ch) & ~0377) {
 451                        /* We must be looking at g in "SOMETHING-g"
 452                         * for it to be describe output.
 453                         */
 454                        if (ch == 'g' && cp[-1] == '-') {
 455                                cp++;
 456                                len -= cp - name;
 457                                return get_short_sha1(cp, len, sha1, 1);
 458                        }
 459                }
 460        }
 461        return -1;
 462}
 463
 464static int get_sha1_1(const char *name, int len, unsigned char *sha1)
 465{
 466        int ret, has_suffix;
 467        const char *cp;
 468
 469        /* "name~3" is "name^^^",
 470         * "name~" and "name~0" are name -- not "name^0"!
 471         * "name^" is not "name^0"; it is "name^1".
 472         */
 473        has_suffix = 0;
 474        for (cp = name + len - 1; name <= cp; cp--) {
 475                int ch = *cp;
 476                if ('0' <= ch && ch <= '9')
 477                        continue;
 478                if (ch == '~' || ch == '^')
 479                        has_suffix = ch;
 480                break;
 481        }
 482
 483        if (has_suffix) {
 484                int num = 0;
 485                int len1 = cp - name;
 486                cp++;
 487                while (cp < name + len)
 488                        num = num * 10 + *cp++ - '0';
 489                if (has_suffix == '^') {
 490                        if (!num && len1 == len - 1)
 491                                num = 1;
 492                        return get_parent(name, len1, sha1, num);
 493                }
 494                /* else if (has_suffix == '~') -- goes without saying */
 495                return get_nth_ancestor(name, len1, sha1, num);
 496        }
 497
 498        ret = peel_onion(name, len, sha1);
 499        if (!ret)
 500                return 0;
 501
 502        ret = get_sha1_basic(name, len, sha1);
 503        if (!ret)
 504                return 0;
 505
 506        /* It could be describe output that is "SOMETHING-gXXXX" */
 507        ret = get_describe_name(name, len, sha1);
 508        if (!ret)
 509                return 0;
 510
 511        return get_short_sha1(name, len, sha1, 0);
 512}
 513
 514/*
 515 * This is like "get_sha1_basic()", except it allows "sha1 expressions",
 516 * notably "xyz^" for "parent of xyz"
 517 */
 518int get_sha1(const char *name, unsigned char *sha1)
 519{
 520        int ret, bracket_depth;
 521        unsigned unused;
 522        int namelen = strlen(name);
 523        const char *cp;
 524
 525        prepare_alt_odb();
 526        ret = get_sha1_1(name, namelen, sha1);
 527        if (!ret)
 528                return ret;
 529        /* sha1:path --> object name of path in ent sha1
 530         * :path -> object name of path in index
 531         * :[0-3]:path -> object name of path in index at stage
 532         */
 533        if (name[0] == ':') {
 534                int stage = 0;
 535                struct cache_entry *ce;
 536                int pos;
 537                if (namelen < 3 ||
 538                    name[2] != ':' ||
 539                    name[1] < '0' || '3' < name[1])
 540                        cp = name + 1;
 541                else {
 542                        stage = name[1] - '0';
 543                        cp = name + 3;
 544                }
 545                namelen = namelen - (cp - name);
 546                if (!active_cache)
 547                        read_cache();
 548                if (active_nr < 0)
 549                        return -1;
 550                pos = cache_name_pos(cp, namelen);
 551                if (pos < 0)
 552                        pos = -pos - 1;
 553                while (pos < active_nr) {
 554                        ce = active_cache[pos];
 555                        if (ce_namelen(ce) != namelen ||
 556                            memcmp(ce->name, cp, namelen))
 557                                break;
 558                        if (ce_stage(ce) == stage) {
 559                                hashcpy(sha1, ce->sha1);
 560                                return 0;
 561                        }
 562                        pos++;
 563                }
 564                return -1;
 565        }
 566        for (cp = name, bracket_depth = 0; *cp; cp++) {
 567                if (*cp == '{')
 568                        bracket_depth++;
 569                else if (bracket_depth && *cp == '}')
 570                        bracket_depth--;
 571                else if (!bracket_depth && *cp == ':')
 572                        break;
 573        }
 574        if (*cp == ':') {
 575                unsigned char tree_sha1[20];
 576                if (!get_sha1_1(name, cp-name, tree_sha1))
 577                        return get_tree_entry(tree_sha1, cp+1, sha1,
 578                                              &unused);
 579        }
 580        return ret;
 581}