Andrew's git - gitweb.git/blob

   1#include "cache.h"
   2#include "tag.h"
   3#include "commit.h"
   4#include "tree.h"
   5#include "blob.h"
   6
   7static int find_short_object_filename(int len, const char *name, unsigned char *sha1)
   8{
   9        struct alternate_object_database *alt;
  10        char hex[40];
  11        int found = 0;
  12        static struct alternate_object_database *fakeent;
  13
  14        if (!fakeent) {
  15                const char *objdir = get_object_directory();
  16                int objdir_len = strlen(objdir);
  17                int entlen = objdir_len + 43;
  18                fakeent = xmalloc(sizeof(*fakeent) + entlen);
  19                memcpy(fakeent->base, objdir, objdir_len);
  20                fakeent->name = fakeent->base + objdir_len + 1;
  21                fakeent->name[-1] = '/';
  22        }
  23        fakeent->next = alt_odb_list;
  24
  25        sprintf(hex, "%.2s", name);
  26        for (alt = fakeent; alt && found < 2; alt = alt->next) {
  27                struct dirent *de;
  28                DIR *dir;
  29                sprintf(alt->name, "%.2s/", name);
  30                dir = opendir(alt->base);
  31                if (!dir)
  32                        continue;
  33                while ((de = readdir(dir)) != NULL) {
  34                        if (strlen(de->d_name) != 38)
  35                                continue;
  36                        if (memcmp(de->d_name, name + 2, len - 2))
  37                                continue;
  38                        if (!found) {
  39                                memcpy(hex + 2, de->d_name, 38);
  40                                found++;
  41                        }
  42                        else if (memcmp(hex + 2, de->d_name, 38)) {
  43                                found = 2;
  44                                break;
  45                        }
  46                }
  47                closedir(dir);
  48        }
  49        if (found == 1)
  50                return get_sha1_hex(hex, sha1) == 0;
  51        return found;
  52}
  53
  54static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
  55{
  56        do {
  57                if (*a != *b)
  58                        return 0;
  59                a++;
  60                b++;
  61                len -= 2;
  62        } while (len > 1);
  63        if (len)
  64                if ((*a ^ *b) & 0xf0)
  65                        return 0;
  66        return 1;
  67}
  68
  69static int find_short_packed_object(int len, const unsigned char *match, unsigned char *sha1)
  70{
  71        struct packed_git *p;
  72        unsigned char found_sha1[20];
  73        int found = 0;
  74
  75        prepare_packed_git();
  76        for (p = packed_git; p && found < 2; p = p->next) {
  77                unsigned num = num_packed_objects(p);
  78                unsigned first = 0, last = num;
  79                while (first < last) {
  80                        unsigned mid = (first + last) / 2;
  81                        unsigned char now[20];
  82                        int cmp;
  83
  84                        nth_packed_object_sha1(p, mid, now);
  85                        cmp = memcmp(match, now, 20);
  86                        if (!cmp) {
  87                                first = mid;
  88                                break;
  89                        }
  90                        if (cmp > 0) {
  91                                first = mid+1;
  92                                continue;
  93                        }
  94                        last = mid;
  95                }
  96                if (first < num) {
  97                        unsigned char now[20], next[20];
  98                        nth_packed_object_sha1(p, first, now);
  99                        if (match_sha(len, match, now)) {
 100                                if (nth_packed_object_sha1(p, first+1, next) ||
 101                                    !match_sha(len, match, next)) {
 102                                        /* unique within this pack */
 103                                        if (!found) {
 104                                                memcpy(found_sha1, now, 20);
 105                                                found++;
 106                                        }
 107                                        else if (memcmp(found_sha1, now, 20)) {
 108                                                found = 2;
 109                                                break;
 110                                        }
 111                                }
 112                                else {
 113                                        /* not even unique within this pack */
 114                                        found = 2;
 115                                        break;
 116                                }
 117                        }
 118                }
 119        }
 120        if (found == 1)
 121                memcpy(sha1, found_sha1, 20);
 122        return found;
 123}
 124
 125#define SHORT_NAME_NOT_FOUND (-1)
 126#define SHORT_NAME_AMBIGUOUS (-2)
 127
 128static int find_unique_short_object(int len, char *canonical,
 129                                    unsigned char *res, unsigned char *sha1)
 130{
 131        int has_unpacked, has_packed;
 132        unsigned char unpacked_sha1[20], packed_sha1[20];
 133
 134        has_unpacked = find_short_object_filename(len, canonical, unpacked_sha1);
 135        has_packed = find_short_packed_object(len, res, packed_sha1);
 136        if (!has_unpacked && !has_packed)
 137                return SHORT_NAME_NOT_FOUND;
 138        if (1 < has_unpacked || 1 < has_packed)
 139                return SHORT_NAME_AMBIGUOUS;
 140        if (has_unpacked != has_packed) {
 141                memcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1), 20);
 142                return 0;
 143        }
 144        /* Both have unique ones -- do they match? */
 145        if (memcmp(packed_sha1, unpacked_sha1, 20))
 146                return -2;
 147        memcpy(sha1, packed_sha1, 20);
 148        return 0;
 149}
 150
 151static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 152                          int quietly)
 153{
 154        int i, status;
 155        char canonical[40];
 156        unsigned char res[20];
 157
 158        if (len < 4)
 159                return -1;
 160        memset(res, 0, 20);
 161        memset(canonical, 'x', 40);
 162        for (i = 0; i < len ;i++) {
 163                unsigned char c = name[i];
 164                unsigned char val;
 165                if (c >= '0' && c <= '9')
 166                        val = c - '0';
 167                else if (c >= 'a' && c <= 'f')
 168                        val = c - 'a' + 10;
 169                else if (c >= 'A' && c <='F') {
 170                        val = c - 'A' + 10;
 171                        c -= 'A' - 'a';
 172                }
 173                else
 174                        return -1;
 175                canonical[i] = c;
 176                if (!(i & 1))
 177                        val <<= 4;
 178                res[i >> 1] |= val;
 179        }
 180
 181        status = find_unique_short_object(i, canonical, res, sha1);
 182        if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
 183                return error("short SHA1 %.*s is ambiguous.", len, canonical);
 184        return status;
 185}
 186
 187const char *find_unique_abbrev(const unsigned char *sha1, int len)
 188{
 189        int status;
 190        static char hex[41];
 191        memcpy(hex, sha1_to_hex(sha1), 40);
 192        while (len < 40) {
 193                unsigned char sha1_ret[20];
 194                status = get_short_sha1(hex, len, sha1_ret, 1);
 195                if (!status) {
 196                        hex[len] = 0;
 197                        return hex;
 198                }
 199                if (status != SHORT_NAME_AMBIGUOUS)
 200                        return NULL;
 201                len++;
 202        }
 203        return NULL;
 204}
 205
 206static int ambiguous_path(const char *path, int len)
 207{
 208        int slash = 1;
 209        int cnt;
 210
 211        for (cnt = 0; cnt < len; cnt++) {
 212                switch (*path++) {
 213                case '\0':
 214                        break;
 215                case '/':
 216                        if (slash)
 217                                break;
 218                        slash = 1;
 219                        continue;
 220                case '.':
 221                        continue;
 222                default:
 223                        slash = 0;
 224                        continue;
 225                }
 226                return slash;
 227        }
 228        return slash;
 229}
 230
 231static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 232{
 233        static const char *prefix[] = {
 234                "",
 235                "refs",
 236                "refs/tags",
 237                "refs/heads",
 238                NULL
 239        };
 240        const char **p;
 241        int found = 0;
 242
 243        if (len == 40 && !get_sha1_hex(str, sha1))
 244                return 0;
 245
 246        /* Accept only unambiguous ref paths. */
 247        if (ambiguous_path(str, len))
 248                return -1;
 249
 250        for (p = prefix; *p; p++) {
 251                char *pathname = git_path("%s/%.*s", *p, len, str);
 252
 253                if (!read_ref(pathname, sha1)) {
 254                        /* Must be unique; i.e. when heads/foo and
 255                         * tags/foo are both present, reject "foo".
 256                         */
 257                        if (1 < found++)
 258                                return -1;
 259                }
 260
 261                /* We want to allow .git/description file and
 262                 * "description" branch to exist at the same time.
 263                 * "git-rev-parse description" should silently skip
 264                 * .git/description file as a candidate for
 265                 * get_sha1().  However, having garbage file anywhere
 266                 * under refs/ is not OK, and we would not have caught
 267                 * ambiguous heads and tags with the above test.
 268                 */
 269                else if (**p && !access(pathname, F_OK)) {
 270                        /* Garbage exists under .git/refs */
 271                        return error("garbage ref found '%s'", pathname);
 272                }
 273        }
 274        switch (found) {
 275        case 0:
 276                return -1;
 277        case 1:
 278                return 0;
 279        default:
 280                return error("ambiguous refname '%.*s'", len, str);
 281        }
 282}
 283
 284static int get_sha1_1(const char *name, int len, unsigned char *sha1);
 285
 286static int get_parent(const char *name, int len,
 287                      unsigned char *result, int idx)
 288{
 289        unsigned char sha1[20];
 290        int ret = get_sha1_1(name, len, sha1);
 291        struct commit *commit;
 292        struct commit_list *p;
 293
 294        if (ret)
 295                return ret;
 296        commit = lookup_commit_reference(sha1);
 297        if (!commit)
 298                return -1;
 299        if (parse_commit(commit))
 300                return -1;
 301        if (!idx) {
 302                memcpy(result, commit->object.sha1, 20);
 303                return 0;
 304        }
 305        p = commit->parents;
 306        while (p) {
 307                if (!--idx) {
 308                        memcpy(result, p->item->object.sha1, 20);
 309                        return 0;
 310                }
 311                p = p->next;
 312        }
 313        return -1;
 314}
 315
 316static int get_nth_ancestor(const char *name, int len,
 317                            unsigned char *result, int generation)
 318{
 319        unsigned char sha1[20];
 320        int ret = get_sha1_1(name, len, sha1);
 321        if (ret)
 322                return ret;
 323
 324        while (generation--) {
 325                struct commit *commit = lookup_commit_reference(sha1);
 326
 327                if (!commit || parse_commit(commit) || !commit->parents)
 328                        return -1;
 329                memcpy(sha1, commit->parents->item->object.sha1, 20);
 330        }
 331        memcpy(result, sha1, 20);
 332        return 0;
 333}
 334
 335static int peel_onion(const char *name, int len, unsigned char *sha1)
 336{
 337        unsigned char outer[20];
 338        const char *sp;
 339        const char *type_string = NULL;
 340        struct object *o;
 341
 342        /*
 343         * "ref^{type}" dereferences ref repeatedly until you cannot
 344         * dereference anymore, or you get an object of given type,
 345         * whichever comes first.  "ref^{}" means just dereference
 346         * tags until you get a non-tag.  "ref^0" is a shorthand for
 347         * "ref^{commit}".  "commit^{tree}" could be used to find the
 348         * top-level tree of the given commit.
 349         */
 350        if (len < 4 || name[len-1] != '}')
 351                return -1;
 352
 353        for (sp = name + len - 1; name <= sp; sp--) {
 354                int ch = *sp;
 355                if (ch == '{' && name < sp && sp[-1] == '^')
 356                        break;
 357        }
 358        if (sp <= name)
 359                return -1;
 360
 361        sp++; /* beginning of type name, or closing brace for empty */
 362        if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
 363                type_string = commit_type;
 364        else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
 365                type_string = tree_type;
 366        else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
 367                type_string = blob_type;
 368        else if (sp[0] == '}')
 369                type_string = NULL;
 370        else
 371                return -1;
 372
 373        if (get_sha1_1(name, sp - name - 2, outer))
 374                return -1;
 375
 376        o = parse_object(outer);
 377        if (!o)
 378                return -1;
 379        if (!type_string) {
 380                o = deref_tag(o, name, sp - name - 2);
 381                if (!o || (!o->parsed && !parse_object(o->sha1)))
 382                        return -1;
 383                memcpy(sha1, o->sha1, 20);
 384        }
 385        else {
 386                /* At this point, the syntax look correct, so
 387                 * if we do not get the needed object, we should
 388                 * barf.
 389                 */
 390
 391                while (1) {
 392                        if (!o || (!o->parsed && !parse_object(o->sha1)))
 393                                return -1;
 394                        if (o->type == type_string) {
 395                                memcpy(sha1, o->sha1, 20);
 396                                return 0;
 397                        }
 398                        if (o->type == tag_type)
 399                                o = ((struct tag*) o)->tagged;
 400                        else if (o->type == commit_type)
 401                                o = &(((struct commit *) o)->tree->object);
 402                        else
 403                                return error("%.*s: expected %s type, but the object dereferences to %s type",
 404                                             len, name, type_string,
 405                                             o->type);
 406                        if (!o->parsed)
 407                                parse_object(o->sha1);
 408                }
 409        }
 410        return 0;
 411}
 412
 413static int get_sha1_1(const char *name, int len, unsigned char *sha1)
 414{
 415        int parent, ret;
 416        const char *cp;
 417
 418        /* foo^[0-9] or foo^ (== foo^1); we do not do more than 9 parents. */
 419        if (len > 2 && name[len-2] == '^' &&
 420            name[len-1] >= '0' && name[len-1] <= '9') {
 421                parent = name[len-1] - '0';
 422                len -= 2;
 423        }
 424        else if (len > 1 && name[len-1] == '^') {
 425                parent = 1;
 426                len--;
 427        } else
 428                parent = -1;
 429
 430        if (parent >= 0)
 431                return get_parent(name, len, sha1, parent);
 432
 433        /* "name~3" is "name^^^",
 434         * "name~12" is "name^^^^^^^^^^^^", and
 435         * "name~" and "name~0" are name -- not "name^0"!
 436         */
 437        parent = 0;
 438        for (cp = name + len - 1; name <= cp; cp--) {
 439                int ch = *cp;
 440                if ('0' <= ch && ch <= '9')
 441                        continue;
 442                if (ch != '~')
 443                        parent = -1;
 444                break;
 445        }
 446        if (!parent && *cp == '~') {
 447                int len1 = cp - name;
 448                cp++;
 449                while (cp < name + len)
 450                        parent = parent * 10 + *cp++ - '0';
 451                return get_nth_ancestor(name, len1, sha1, parent);
 452        }
 453
 454        ret = peel_onion(name, len, sha1);
 455        if (!ret)
 456                return 0;
 457
 458        ret = get_sha1_basic(name, len, sha1);
 459        if (!ret)
 460                return 0;
 461        return get_short_sha1(name, len, sha1, 0);
 462}
 463
 464/*
 465 * This is like "get_sha1_basic()", except it allows "sha1 expressions",
 466 * notably "xyz^" for "parent of xyz"
 467 */
 468int get_sha1(const char *name, unsigned char *sha1)
 469{
 470        prepare_alt_odb();
 471        return get_sha1_1(name, strlen(name), sha1);
 472}