git.oblomov.eu Git - git/blob - sha1_name.c

   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 #include "dir.h"
  10
  11 static int get_sha1_oneline(const char *, unsigned char *, struct commit_list *);
  12
  13 typedef int (*disambiguate_hint_fn)(const unsigned char *, void *);
  14
  15 struct disambiguate_state {
  16         disambiguate_hint_fn fn;
  17         void *cb_data;
  18         unsigned char candidate[20];
  19         unsigned candidate_exists:1;
  20         unsigned candidate_checked:1;
  21         unsigned candidate_ok:1;
  22         unsigned disambiguate_fn_used:1;
  23         unsigned ambiguous:1;
  24         unsigned always_call_fn:1;
  25 };
  26
  27 static void update_candidates(struct disambiguate_state *ds, const unsigned char *current)
  28 {
  29         if (ds->always_call_fn) {
  30                 ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
  31                 return;
  32         }
  33         if (!ds->candidate_exists) {
  34                 /* this is the first candidate */
  35                 hashcpy(ds->candidate, current);
  36                 ds->candidate_exists = 1;
  37                 return;
  38         } else if (!hashcmp(ds->candidate, current)) {
  39                 /* the same as what we already have seen */
  40                 return;
  41         }
  42
  43         if (!ds->fn) {
  44                 /* cannot disambiguate between ds->candidate and current */
  45                 ds->ambiguous = 1;
  46                 return;
  47         }
  48
  49         if (!ds->candidate_checked) {
  50                 ds->candidate_ok = ds->fn(ds->candidate, ds->cb_data);
  51                 ds->disambiguate_fn_used = 1;
  52                 ds->candidate_checked = 1;
  53         }
  54
  55         if (!ds->candidate_ok) {
  56                 /* discard the candidate; we know it does not satisfy fn */
  57                 hashcpy(ds->candidate, current);
  58                 ds->candidate_checked = 0;
  59                 return;
  60         }
  61
  62         /* if we reach this point, we know ds->candidate satisfies fn */
  63         if (ds->fn(current, ds->cb_data)) {
  64                 /*
  65                  * if both current and candidate satisfy fn, we cannot
  66                  * disambiguate.
  67                  */
  68                 ds->candidate_ok = 0;
  69                 ds->ambiguous = 1;
  70         }
  71
  72         /* otherwise, current can be discarded and candidate is still good */
  73 }
  74
  75 static void find_short_object_filename(int len, const char *hex_pfx, struct disambiguate_state *ds)
  76 {
  77         struct alternate_object_database *alt;
  78         char hex[40];
  79         static struct alternate_object_database *fakeent;
  80
  81         if (!fakeent) {
  82                 /*
  83                  * Create a "fake" alternate object database that
  84                  * points to our own object database, to make it
  85                  * easier to get a temporary working space in
  86                  * alt->name/alt->base while iterating over the
  87                  * object databases including our own.
  88                  */
  89                 const char *objdir = get_object_directory();
  90                 int objdir_len = strlen(objdir);
  91                 int entlen = objdir_len + 43;
  92                 fakeent = xmalloc(sizeof(*fakeent) + entlen);
  93                 memcpy(fakeent->base, objdir, objdir_len);
  94                 fakeent->name = fakeent->base + objdir_len + 1;
  95                 fakeent->name[-1] = '/';
  96         }
  97         fakeent->next = alt_odb_list;
  98
  99         xsnprintf(hex, sizeof(hex), "%.2s", hex_pfx);
 100         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 101                 struct dirent *de;
 102                 DIR *dir;
 103                 /*
 104                  * every alt_odb struct has 42 extra bytes after the base
 105                  * for exactly this purpose
 106                  */
 107                 xsnprintf(alt->name, 42, "%.2s/", hex_pfx);
 108                 dir = opendir(alt->base);
 109                 if (!dir)
 110                         continue;
 111
 112                 while (!ds->ambiguous && (de = readdir(dir)) != NULL) {
 113                         unsigned char sha1[20];
 114
 115                         if (strlen(de->d_name) != 38)
 116                                 continue;
 117                         if (memcmp(de->d_name, hex_pfx + 2, len - 2))
 118                                 continue;
 119                         memcpy(hex + 2, de->d_name, 38);
 120                         if (!get_sha1_hex(hex, sha1))
 121                                 update_candidates(ds, sha1);
 122                 }
 123                 closedir(dir);
 124         }
 125 }
 126
 127 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 128 {
 129         do {
 130                 if (*a != *b)
 131                         return 0;
 132                 a++;
 133                 b++;
 134                 len -= 2;
 135         } while (len > 1);
 136         if (len)
 137                 if ((*a ^ *b) & 0xf0)
 138                         return 0;
 139         return 1;
 140 }
 141
 142 static void unique_in_pack(int len,
 143                           const unsigned char *bin_pfx,
 144                            struct packed_git *p,
 145                            struct disambiguate_state *ds)
 146 {
 147         uint32_t num, last, i, first = 0;
 148         const unsigned char *current = NULL;
 149
 150         open_pack_index(p);
 151         num = p->num_objects;
 152         last = num;
 153         while (first < last) {
 154                 uint32_t mid = (first + last) / 2;
 155                 const unsigned char *current;
 156                 int cmp;
 157
 158                 current = nth_packed_object_sha1(p, mid);
 159                 cmp = hashcmp(bin_pfx, current);
 160                 if (!cmp) {
 161                         first = mid;
 162                         break;
 163                 }
 164                 if (cmp > 0) {
 165                         first = mid+1;
 166                         continue;
 167                 }
 168                 last = mid;
 169         }
 170
 171         /*
 172          * At this point, "first" is the location of the lowest object
 173          * with an object name that could match "bin_pfx".  See if we have
 174          * 0, 1 or more objects that actually match(es).
 175          */
 176         for (i = first; i < num && !ds->ambiguous; i++) {
 177                 current = nth_packed_object_sha1(p, i);
 178                 if (!match_sha(len, bin_pfx, current))
 179                         break;
 180                 update_candidates(ds, current);
 181         }
 182 }
 183
 184 static void find_short_packed_object(int len, const unsigned char *bin_pfx,
 185                                      struct disambiguate_state *ds)
 186 {
 187         struct packed_git *p;
 188
 189         prepare_packed_git();
 190         for (p = packed_git; p && !ds->ambiguous; p = p->next)
 191                 unique_in_pack(len, bin_pfx, p, ds);
 192 }
 193
 194 #define SHORT_NAME_NOT_FOUND (-1)
 195 #define SHORT_NAME_AMBIGUOUS (-2)
 196
 197 static int finish_object_disambiguation(struct disambiguate_state *ds,
 198                                         unsigned char *sha1)
 199 {
 200         if (ds->ambiguous)
 201                 return SHORT_NAME_AMBIGUOUS;
 202
 203         if (!ds->candidate_exists)
 204                 return SHORT_NAME_NOT_FOUND;
 205
 206         if (!ds->candidate_checked)
 207                 /*
 208                  * If this is the only candidate, there is no point
 209                  * calling the disambiguation hint callback.
 210                  *
 211                  * On the other hand, if the current candidate
 212                  * replaced an earlier candidate that did _not_ pass
 213                  * the disambiguation hint callback, then we do have
 214                  * more than one objects that match the short name
 215                  * given, so we should make sure this one matches;
 216                  * otherwise, if we discovered this one and the one
 217                  * that we previously discarded in the reverse order,
 218                  * we would end up showing different results in the
 219                  * same repository!
 220                  */
 221                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 222                                     ds->fn(ds->candidate, ds->cb_data));
 223
 224         if (!ds->candidate_ok)
 225                 return SHORT_NAME_AMBIGUOUS;
 226
 227         hashcpy(sha1, ds->candidate);
 228         return 0;
 229 }
 230
 231 static int disambiguate_commit_only(const unsigned char *sha1, void *cb_data_unused)
 232 {
 233         int kind = sha1_object_info(sha1, NULL);
 234         return kind == OBJ_COMMIT;
 235 }
 236
 237 static int disambiguate_committish_only(const unsigned char *sha1, void *cb_data_unused)
 238 {
 239         struct object *obj;
 240         int kind;
 241
 242         kind = sha1_object_info(sha1, NULL);
 243         if (kind == OBJ_COMMIT)
 244                 return 1;
 245         if (kind != OBJ_TAG)
 246                 return 0;
 247
 248         /* We need to do this the hard way... */
 249         obj = deref_tag(parse_object(sha1), NULL, 0);
 250         if (obj && obj->type == OBJ_COMMIT)
 251                 return 1;
 252         return 0;
 253 }
 254
 255 static int disambiguate_tree_only(const unsigned char *sha1, void *cb_data_unused)
 256 {
 257         int kind = sha1_object_info(sha1, NULL);
 258         return kind == OBJ_TREE;
 259 }
 260
 261 static int disambiguate_treeish_only(const unsigned char *sha1, void *cb_data_unused)
 262 {
 263         struct object *obj;
 264         int kind;
 265
 266         kind = sha1_object_info(sha1, NULL);
 267         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 268                 return 1;
 269         if (kind != OBJ_TAG)
 270                 return 0;
 271
 272         /* We need to do this the hard way... */
 273         obj = deref_tag(lookup_object(sha1), NULL, 0);
 274         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 275                 return 1;
 276         return 0;
 277 }
 278
 279 static int disambiguate_blob_only(const unsigned char *sha1, void *cb_data_unused)
 280 {
 281         int kind = sha1_object_info(sha1, NULL);
 282         return kind == OBJ_BLOB;
 283 }
 284
 285 static int prepare_prefixes(const char *name, int len,
 286                             unsigned char *bin_pfx,
 287                             char *hex_pfx)
 288 {
 289         int i;
 290
 291         hashclr(bin_pfx);
 292         memset(hex_pfx, 'x', 40);
 293         for (i = 0; i < len ;i++) {
 294                 unsigned char c = name[i];
 295                 unsigned char val;
 296                 if (c >= '0' && c <= '9')
 297                         val = c - '0';
 298                 else if (c >= 'a' && c <= 'f')
 299                         val = c - 'a' + 10;
 300                 else if (c >= 'A' && c <='F') {
 301                         val = c - 'A' + 10;
 302                         c -= 'A' - 'a';
 303                 }
 304                 else
 305                         return -1;
 306                 hex_pfx[i] = c;
 307                 if (!(i & 1))
 308                         val <<= 4;
 309                 bin_pfx[i >> 1] |= val;
 310         }
 311         return 0;
 312 }
 313
 314 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 315                           unsigned flags)
 316 {
 317         int status;
 318         char hex_pfx[40];
 319         unsigned char bin_pfx[20];
 320         struct disambiguate_state ds;
 321         int quietly = !!(flags & GET_SHA1_QUIETLY);
 322
 323         if (len < MINIMUM_ABBREV || len > 40)
 324                 return -1;
 325         if (prepare_prefixes(name, len, bin_pfx, hex_pfx) < 0)
 326                 return -1;
 327
 328         prepare_alt_odb();
 329
 330         memset(&ds, 0, sizeof(ds));
 331         if (flags & GET_SHA1_COMMIT)
 332                 ds.fn = disambiguate_commit_only;
 333         else if (flags & GET_SHA1_COMMITTISH)
 334                 ds.fn = disambiguate_committish_only;
 335         else if (flags & GET_SHA1_TREE)
 336                 ds.fn = disambiguate_tree_only;
 337         else if (flags & GET_SHA1_TREEISH)
 338                 ds.fn = disambiguate_treeish_only;
 339         else if (flags & GET_SHA1_BLOB)
 340                 ds.fn = disambiguate_blob_only;
 341
 342         find_short_object_filename(len, hex_pfx, &ds);
 343         find_short_packed_object(len, bin_pfx, &ds);
 344         status = finish_object_disambiguation(&ds, sha1);
 345
 346         if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
 347                 return error("short SHA1 %.*s is ambiguous.", len, hex_pfx);
 348         return status;
 349 }
 350
 351 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 352 {
 353         char hex_pfx[40];
 354         unsigned char bin_pfx[20];
 355         struct disambiguate_state ds;
 356         int len = strlen(prefix);
 357
 358         if (len < MINIMUM_ABBREV || len > 40)
 359                 return -1;
 360         if (prepare_prefixes(prefix, len, bin_pfx, hex_pfx) < 0)
 361                 return -1;
 362
 363         prepare_alt_odb();
 364
 365         memset(&ds, 0, sizeof(ds));
 366         ds.always_call_fn = 1;
 367         ds.cb_data = cb_data;
 368         ds.fn = fn;
 369
 370         find_short_object_filename(len, hex_pfx, &ds);
 371         find_short_packed_object(len, bin_pfx, &ds);
 372         return ds.ambiguous;
 373 }
 374
 375 int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 376 {
 377         int status, exists;
 378
 379         sha1_to_hex_r(hex, sha1);
 380         if (len == 40 || !len)
 381                 return 40;
 382         exists = has_sha1_file(sha1);
 383         while (len < 40) {
 384                 unsigned char sha1_ret[20];
 385                 status = get_short_sha1(hex, len, sha1_ret, GET_SHA1_QUIETLY);
 386                 if (exists
 387                     ? !status
 388                     : status == SHORT_NAME_NOT_FOUND) {
 389                         hex[len] = 0;
 390                         return len;
 391                 }
 392                 len++;
 393         }
 394         return len;
 395 }
 396
 397 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 398 {
 399         static char hex[GIT_SHA1_HEXSZ + 1];
 400         find_unique_abbrev_r(hex, sha1, len);
 401         return hex;
 402 }
 403
 404 static int ambiguous_path(const char *path, int len)
 405 {
 406         int slash = 1;
 407         int cnt;
 408
 409         for (cnt = 0; cnt < len; cnt++) {
 410                 switch (*path++) {
 411                 case '\0':
 412                         break;
 413                 case '/':
 414                         if (slash)
 415                                 break;
 416                         slash = 1;
 417                         continue;
 418                 case '.':
 419                         continue;
 420                 default:
 421                         slash = 0;
 422                         continue;
 423                 }
 424                 break;
 425         }
 426         return slash;
 427 }
 428
 429 static inline int at_mark(const char *string, int len,
 430                           const char **suffix, int nr)
 431 {
 432         int i;
 433
 434         for (i = 0; i < nr; i++) {
 435                 int suffix_len = strlen(suffix[i]);
 436                 if (suffix_len <= len
 437                     && !memcmp(string, suffix[i], suffix_len))
 438                         return suffix_len;
 439         }
 440         return 0;
 441 }
 442
 443 static inline int upstream_mark(const char *string, int len)
 444 {
 445         const char *suffix[] = { "upstream", "u" };
 446         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 447 }
 448
 449 static inline int push_mark(const char *string, int len)
 450 {
 451         const char *suffix[] = { "push" };
 452         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 453 }
 454
 455 static inline int publish_mark(const char *string, int len)
 456 {
 457         const char *suffix[] = { "publish", "p" };
 458         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 459 }
 460
 461 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 462 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 463
 464 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 465                           unsigned int flags)
 466 {
 467         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 468         static const char *object_name_msg = N_(
 469         "Git normally never creates a ref that ends with 40 hex characters\n"
 470         "because it will be ignored when you just specify 40-hex. These refs\n"
 471         "may be created by mistake. For example,\n"
 472         "\n"
 473         "  git checkout -b $br $(git rev-parse ...)\n"
 474         "\n"
 475         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 476         "examine these refs and maybe delete them. Turn this message off by\n"
 477         "running \"git config advice.objectNameWarning false\"");
 478         unsigned char tmp_sha1[20];
 479         char *real_ref = NULL;
 480         int refs_found = 0;
 481         int at, reflog_len, nth_prior = 0;
 482
 483         if (len == 40 && !get_sha1_hex(str, sha1)) {
 484                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 485                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 486                         if (refs_found > 0) {
 487                                 warning(warn_msg, len, str);
 488                                 if (advice_object_name_warning)
 489                                         fprintf(stderr, "%s\n", _(object_name_msg));
 490                         }
 491                         free(real_ref);
 492                 }
 493                 return 0;
 494         }
 495
 496         /* basic@{time or number or -number} format to query ref-log */
 497         reflog_len = at = 0;
 498         if (len && str[len-1] == '}') {
 499                 for (at = len-4; at >= 0; at--) {
 500                         if (str[at] == '@' && str[at+1] == '{') {
 501                                 if (str[at+2] == '-') {
 502                                         if (at != 0)
 503                                                 /* @{-N} not at start */
 504                                                 return -1;
 505                                         nth_prior = 1;
 506                                         continue;
 507                                 }
 508                                 if (!upstream_mark(str + at + 2, len - at - 3) &&
 509                                     !push_mark(str + at + 2, len - at - 3) &&
 510                                     !publish_mark(str + at + 2, len - at - 3)) {
 511                                         reflog_len = (len-1) - (at+2);
 512                                         len = at;
 513                                 }
 514                                 break;
 515                         }
 516                 }
 517         }
 518
 519         /* Accept only unambiguous ref paths. */
 520         if (len && ambiguous_path(str, len))
 521                 return -1;
 522
 523         if (nth_prior) {
 524                 struct strbuf buf = STRBUF_INIT;
 525                 int detached;
 526
 527                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 528                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 529                         strbuf_release(&buf);
 530                         if (detached)
 531                                 return 0;
 532                 }
 533         }
 534
 535         if (!len && reflog_len)
 536                 /* allow "@{...}" to mean the current branch reflog */
 537                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 538         else if (reflog_len)
 539                 refs_found = dwim_log(str, len, sha1, &real_ref);
 540         else
 541                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 542
 543         if (!refs_found)
 544                 return -1;
 545
 546         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 547             (refs_found > 1 ||
 548              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 549                 warning(warn_msg, len, str);
 550
 551         if (reflog_len) {
 552                 int nth, i;
 553                 unsigned long at_time;
 554                 unsigned long co_time;
 555                 int co_tz, co_cnt;
 556
 557                 /* Is it asking for N-th entry, or approxidate? */
 558                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 559                         char ch = str[at+2+i];
 560                         if ('0' <= ch && ch <= '9')
 561                                 nth = nth * 10 + ch - '0';
 562                         else
 563                                 nth = -1;
 564                 }
 565                 if (100000000 <= nth) {
 566                         at_time = nth;
 567                         nth = -1;
 568                 } else if (0 <= nth)
 569                         at_time = 0;
 570                 else {
 571                         int errors = 0;
 572                         char *tmp = xstrndup(str + at + 2, reflog_len);
 573                         at_time = approxidate_careful(tmp, &errors);
 574                         free(tmp);
 575                         if (errors) {
 576                                 free(real_ref);
 577                                 return -1;
 578                         }
 579                 }
 580                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 581                                 &co_time, &co_tz, &co_cnt)) {
 582                         if (!len) {
 583                                 if (starts_with(real_ref, "refs/heads/")) {
 584                                         str = real_ref + 11;
 585                                         len = strlen(real_ref + 11);
 586                                 } else {
 587                                         /* detached HEAD */
 588                                         str = "HEAD";
 589                                         len = 4;
 590                                 }
 591                         }
 592                         if (at_time) {
 593                                 if (!(flags & GET_SHA1_QUIETLY)) {
 594                                         warning("Log for '%.*s' only goes "
 595                                                 "back to %s.", len, str,
 596                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 597                                 }
 598                         } else {
 599                                 if (flags & GET_SHA1_QUIETLY) {
 600                                         exit(128);
 601                                 }
 602                                 die("Log for '%.*s' only has %d entries.",
 603                                     len, str, co_cnt);
 604                         }
 605                 }
 606         }
 607
 608         free(real_ref);
 609         return 0;
 610 }
 611
 612 static int get_parent(const char *name, int len,
 613                       unsigned char *result, int idx)
 614 {
 615         unsigned char sha1[20];
 616         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 617         struct commit *commit;
 618         struct commit_list *p;
 619
 620         if (ret)
 621                 return ret;
 622         commit = lookup_commit_reference(sha1);
 623         if (parse_commit(commit))
 624                 return -1;
 625         if (!idx) {
 626                 hashcpy(result, commit->object.oid.hash);
 627                 return 0;
 628         }
 629         p = commit->parents;
 630         while (p) {
 631                 if (!--idx) {
 632                         hashcpy(result, p->item->object.oid.hash);
 633                         return 0;
 634                 }
 635                 p = p->next;
 636         }
 637         return -1;
 638 }
 639
 640 static int get_nth_ancestor(const char *name, int len,
 641                             unsigned char *result, int generation)
 642 {
 643         unsigned char sha1[20];
 644         struct commit *commit;
 645         int ret;
 646
 647         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 648         if (ret)
 649                 return ret;
 650         commit = lookup_commit_reference(sha1);
 651         if (!commit)
 652                 return -1;
 653
 654         while (generation--) {
 655                 if (parse_commit(commit) || !commit->parents)
 656                         return -1;
 657                 commit = commit->parents->item;
 658         }
 659         hashcpy(result, commit->object.oid.hash);
 660         return 0;
 661 }
 662
 663 struct object *peel_to_type(const char *name, int namelen,
 664                             struct object *o, enum object_type expected_type)
 665 {
 666         if (name && !namelen)
 667                 namelen = strlen(name);
 668         while (1) {
 669                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 670                         return NULL;
 671                 if (expected_type == OBJ_ANY || o->type == expected_type)
 672                         return o;
 673                 if (o->type == OBJ_TAG)
 674                         o = ((struct tag*) o)->tagged;
 675                 else if (o->type == OBJ_COMMIT)
 676                         o = &(((struct commit *) o)->tree->object);
 677                 else {
 678                         if (name)
 679                                 error("%.*s: expected %s type, but the object "
 680                                       "dereferences to %s type",
 681                                       namelen, name, typename(expected_type),
 682                                       typename(o->type));
 683                         return NULL;
 684                 }
 685         }
 686 }
 687
 688 static int peel_onion(const char *name, int len, unsigned char *sha1)
 689 {
 690         unsigned char outer[20];
 691         const char *sp;
 692         unsigned int expected_type = 0;
 693         unsigned lookup_flags = 0;
 694         struct object *o;
 695
 696         /*
 697          * "ref^{type}" dereferences ref repeatedly until you cannot
 698          * dereference anymore, or you get an object of given type,
 699          * whichever comes first.  "ref^{}" means just dereference
 700          * tags until you get a non-tag.  "ref^0" is a shorthand for
 701          * "ref^{commit}".  "commit^{tree}" could be used to find the
 702          * top-level tree of the given commit.
 703          */
 704         if (len < 4 || name[len-1] != '}')
 705                 return -1;
 706
 707         for (sp = name + len - 1; name <= sp; sp--) {
 708                 int ch = *sp;
 709                 if (ch == '{' && name < sp && sp[-1] == '^')
 710                         break;
 711         }
 712         if (sp <= name)
 713                 return -1;
 714
 715         sp++; /* beginning of type name, or closing brace for empty */
 716         if (starts_with(sp, "commit}"))
 717                 expected_type = OBJ_COMMIT;
 718         else if (starts_with(sp, "tag}"))
 719                 expected_type = OBJ_TAG;
 720         else if (starts_with(sp, "tree}"))
 721                 expected_type = OBJ_TREE;
 722         else if (starts_with(sp, "blob}"))
 723                 expected_type = OBJ_BLOB;
 724         else if (starts_with(sp, "object}"))
 725                 expected_type = OBJ_ANY;
 726         else if (sp[0] == '}')
 727                 expected_type = OBJ_NONE;
 728         else if (sp[0] == '/')
 729                 expected_type = OBJ_COMMIT;
 730         else
 731                 return -1;
 732
 733         if (expected_type == OBJ_COMMIT)
 734                 lookup_flags = GET_SHA1_COMMITTISH;
 735         else if (expected_type == OBJ_TREE)
 736                 lookup_flags = GET_SHA1_TREEISH;
 737
 738         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 739                 return -1;
 740
 741         o = parse_object(outer);
 742         if (!o)
 743                 return -1;
 744         if (!expected_type) {
 745                 o = deref_tag(o, name, sp - name - 2);
 746                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 747                         return -1;
 748                 hashcpy(sha1, o->oid.hash);
 749                 return 0;
 750         }
 751
 752         /*
 753          * At this point, the syntax look correct, so
 754          * if we do not get the needed object, we should
 755          * barf.
 756          */
 757         o = peel_to_type(name, len, o, expected_type);
 758         if (!o)
 759                 return -1;
 760
 761         hashcpy(sha1, o->oid.hash);
 762         if (sp[0] == '/') {
 763                 /* "$commit^{/foo}" */
 764                 char *prefix;
 765                 int ret;
 766                 struct commit_list *list = NULL;
 767
 768                 /*
 769                  * $commit^{/}. Some regex implementation may reject.
 770                  * We don't need regex anyway. '' pattern always matches.
 771                  */
 772                 if (sp[1] == '}')
 773                         return 0;
 774
 775                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 776                 commit_list_insert((struct commit *)o, &list);
 777                 ret = get_sha1_oneline(prefix, sha1, list);
 778                 free(prefix);
 779                 return ret;
 780         }
 781         return 0;
 782 }
 783
 784 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 785 {
 786         const char *cp;
 787         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 788
 789         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 790                 char ch = *cp;
 791                 if (!isxdigit(ch)) {
 792                         /* We must be looking at g in "SOMETHING-g"
 793                          * for it to be describe output.
 794                          */
 795                         if (ch == 'g' && cp[-1] == '-') {
 796                                 cp++;
 797                                 len -= cp - name;
 798                                 return get_short_sha1(cp, len, sha1, flags);
 799                         }
 800                 }
 801         }
 802         return -1;
 803 }
 804
 805 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 806 {
 807         int ret, has_suffix;
 808         const char *cp;
 809
 810         /*
 811          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 812          */
 813         has_suffix = 0;
 814         for (cp = name + len - 1; name <= cp; cp--) {
 815                 int ch = *cp;
 816                 if ('0' <= ch && ch <= '9')
 817                         continue;
 818                 if (ch == '~' || ch == '^')
 819                         has_suffix = ch;
 820                 break;
 821         }
 822
 823         if (has_suffix) {
 824                 int num = 0;
 825                 int len1 = cp - name;
 826                 cp++;
 827                 while (cp < name + len)
 828                         num = num * 10 + *cp++ - '0';
 829                 if (!num && len1 == len - 1)
 830                         num = 1;
 831                 if (has_suffix == '^')
 832                         return get_parent(name, len1, sha1, num);
 833                 /* else if (has_suffix == '~') -- goes without saying */
 834                 return get_nth_ancestor(name, len1, sha1, num);
 835         }
 836
 837         ret = peel_onion(name, len, sha1);
 838         if (!ret)
 839                 return 0;
 840
 841         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 842         if (!ret)
 843                 return 0;
 844
 845         /* It could be describe output that is "SOMETHING-gXXXX" */
 846         ret = get_describe_name(name, len, sha1);
 847         if (!ret)
 848                 return 0;
 849
 850         return get_short_sha1(name, len, sha1, lookup_flags);
 851 }
 852
 853 /*
 854  * This interprets names like ':/Initial revision of "git"' by searching
 855  * through history and returning the first commit whose message starts
 856  * the given regular expression.
 857  *
 858  * For future extension, ':/!' is reserved. If you want to match a message
 859  * beginning with a '!', you have to repeat the exclamation mark.
 860  */
 861
 862 /* Remember to update object flag allocation in object.h */
 863 #define ONELINE_SEEN (1u<<20)
 864
 865 static int handle_one_ref(const char *path, const struct object_id *oid,
 866                           int flag, void *cb_data)
 867 {
 868         struct commit_list **list = cb_data;
 869         struct object *object = parse_object(oid->hash);
 870         if (!object)
 871                 return 0;
 872         if (object->type == OBJ_TAG) {
 873                 object = deref_tag(object, path, strlen(path));
 874                 if (!object)
 875                         return 0;
 876         }
 877         if (object->type != OBJ_COMMIT)
 878                 return 0;
 879         commit_list_insert((struct commit *)object, list);
 880         return 0;
 881 }
 882
 883 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 884                             struct commit_list *list)
 885 {
 886         struct commit_list *backup = NULL, *l;
 887         int found = 0;
 888         regex_t regex;
 889
 890         if (prefix[0] == '!') {
 891                 if (prefix[1] != '!')
 892                         die ("Invalid search pattern: %s", prefix);
 893                 prefix++;
 894         }
 895
 896         if (regcomp(&regex, prefix, REG_EXTENDED))
 897                 die("Invalid search pattern: %s", prefix);
 898
 899         for (l = list; l; l = l->next) {
 900                 l->item->object.flags |= ONELINE_SEEN;
 901                 commit_list_insert(l->item, &backup);
 902         }
 903         while (list) {
 904                 const char *p, *buf;
 905                 struct commit *commit;
 906                 int matches;
 907
 908                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 909                 if (!parse_object(commit->object.oid.hash))
 910                         continue;
 911                 buf = get_commit_buffer(commit, NULL);
 912                 p = strstr(buf, "\n\n");
 913                 matches = p && !regexec(&regex, p + 2, 0, NULL, 0);
 914                 unuse_commit_buffer(commit, buf);
 915
 916                 if (matches) {
 917                         hashcpy(sha1, commit->object.oid.hash);
 918                         found = 1;
 919                         break;
 920                 }
 921         }
 922         regfree(&regex);
 923         free_commit_list(list);
 924         for (l = backup; l; l = l->next)
 925                 clear_commit_marks(l->item, ONELINE_SEEN);
 926         free_commit_list(backup);
 927         return found ? 0 : -1;
 928 }
 929
 930 struct grab_nth_branch_switch_cbdata {
 931         int remaining;
 932         struct strbuf buf;
 933 };
 934
 935 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 936                                   const char *email, unsigned long timestamp, int tz,
 937                                   const char *message, void *cb_data)
 938 {
 939         struct grab_nth_branch_switch_cbdata *cb = cb_data;
 940         const char *match = NULL, *target = NULL;
 941         size_t len;
 942
 943         if (skip_prefix(message, "checkout: moving from ", &match))
 944                 target = strstr(match, " to ");
 945
 946         if (!match || !target)
 947                 return 0;
 948         if (--(cb->remaining) == 0) {
 949                 len = target - match;
 950                 strbuf_reset(&cb->buf);
 951                 strbuf_add(&cb->buf, match, len);
 952                 return 1; /* we are done */
 953         }
 954         return 0;
 955 }
 956
 957 /*
 958  * Parse @{-N} syntax, return the number of characters parsed
 959  * if successful; otherwise signal an error with negative value.
 960  */
 961 static int interpret_nth_prior_checkout(const char *name, int namelen,
 962                                         struct strbuf *buf)
 963 {
 964         long nth;
 965         int retval;
 966         struct grab_nth_branch_switch_cbdata cb;
 967         const char *brace;
 968         char *num_end;
 969
 970         if (namelen < 4)
 971                 return -1;
 972         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
 973                 return -1;
 974         brace = memchr(name, '}', namelen);
 975         if (!brace)
 976                 return -1;
 977         nth = strtol(name + 3, &num_end, 10);
 978         if (num_end != brace)
 979                 return -1;
 980         if (nth <= 0)
 981                 return -1;
 982         cb.remaining = nth;
 983         strbuf_init(&cb.buf, 20);
 984
 985         retval = 0;
 986         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
 987                 strbuf_reset(buf);
 988                 strbuf_addbuf(buf, &cb.buf);
 989                 retval = brace - name + 1;
 990         }
 991
 992         strbuf_release(&cb.buf);
 993         return retval;
 994 }
 995
 996 int get_sha1_mb(const char *name, unsigned char *sha1)
 997 {
 998         struct commit *one, *two;
 999         struct commit_list *mbs;
1000         unsigned char sha1_tmp[20];
1001         const char *dots;
1002         int st;
1003
1004         dots = strstr(name, "...");
1005         if (!dots)
1006                 return get_sha1(name, sha1);
1007         if (dots == name)
1008                 st = get_sha1("HEAD", sha1_tmp);
1009         else {
1010                 struct strbuf sb;
1011                 strbuf_init(&sb, dots - name);
1012                 strbuf_add(&sb, name, dots - name);
1013                 st = get_sha1_committish(sb.buf, sha1_tmp);
1014                 strbuf_release(&sb);
1015         }
1016         if (st)
1017                 return st;
1018         one = lookup_commit_reference_gently(sha1_tmp, 0);
1019         if (!one)
1020                 return -1;
1021
1022         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
1023                 return -1;
1024         two = lookup_commit_reference_gently(sha1_tmp, 0);
1025         if (!two)
1026                 return -1;
1027         mbs = get_merge_bases(one, two);
1028         if (!mbs || mbs->next)
1029                 st = -1;
1030         else {
1031                 st = 0;
1032                 hashcpy(sha1, mbs->item->object.oid.hash);
1033         }
1034         free_commit_list(mbs);
1035         return st;
1036 }
1037
1038 /* parse @something syntax, when 'something' is not {.*} */
1039 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1040 {
1041         const char *next;
1042
1043         if (len || name[1] == '{')
1044                 return -1;
1045
1046         /* make sure it's a single @, or @@{.*}, not @foo */
1047         next = memchr(name + len + 1, '@', namelen - len - 1);
1048         if (next && next[1] != '{')
1049                 return -1;
1050         if (!next)
1051                 next = name + namelen;
1052         if (next != name + 1)
1053                 return -1;
1054
1055         strbuf_reset(buf);
1056         strbuf_add(buf, "HEAD", 4);
1057         return 1;
1058 }
1059
1060 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1061 {
1062         /* we have extra data, which might need further processing */
1063         struct strbuf tmp = STRBUF_INIT;
1064         int used = buf->len;
1065         int ret;
1066
1067         strbuf_add(buf, name + len, namelen - len);
1068         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1069         /* that data was not interpreted, remove our cruft */
1070         if (ret < 0) {
1071                 strbuf_setlen(buf, used);
1072                 return len;
1073         }
1074         strbuf_reset(buf);
1075         strbuf_addbuf(buf, &tmp);
1076         strbuf_release(&tmp);
1077         /* tweak for size of {-N} versus expanded ref name */
1078         return ret - used + len;
1079 }
1080
1081 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1082 {
1083         char *s = shorten_unambiguous_ref(ref, 0);
1084         strbuf_reset(buf);
1085         strbuf_addstr(buf, s);
1086         free(s);
1087 }
1088
1089 static int interpret_branch_mark(const char *name, int namelen,
1090                                  int at, struct strbuf *buf,
1091                                  int (*get_mark)(const char *, int),
1092                                  const char *(*get_data)(struct branch *,
1093                                                          struct strbuf *))
1094 {
1095         int len;
1096         struct branch *branch;
1097         struct strbuf err = STRBUF_INIT;
1098         const char *value;
1099
1100         if (name[at + 1] != '{' || name[namelen - 1] != '}')
1101                 return -1;
1102
1103         len = get_mark(name + at + 2, namelen - at - 3);
1104         if (!len)
1105                 return -1;
1106
1107         if (memchr(name, ':', at))
1108                 return -1;
1109
1110         if (at) {
1111                 char *name_str = xmemdupz(name, at);
1112                 branch = branch_get(name_str);
1113                 free(name_str);
1114         } else
1115                 branch = branch_get(NULL);
1116
1117         value = get_data(branch, &err);
1118         if (!value)
1119                 die("%s", err.buf);
1120
1121         set_shortened_ref(buf, value);
1122         return len + at + 3;
1123 }
1124
1125 /*
1126  * This reads short-hand syntax that not only evaluates to a commit
1127  * object name, but also can act as if the end user spelled the name
1128  * of the branch from the command line.
1129  *
1130  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1131  *   places the name of the branch in the given buf and returns the
1132  *   number of characters parsed if successful.
1133  *
1134  * - "<branch>@{upstream}" finds the name of the other ref that
1135  *   <branch> is configured to merge with (missing <branch> defaults
1136  *   to the current branch), and places the name of the branch in the
1137  *   given buf and returns the number of characters parsed if
1138  *   successful.
1139  *
1140  * If the input is not of the accepted format, it returns a negative
1141  * number to signal an error.
1142  *
1143  * If the input was ok but there are not N branch switches in the
1144  * reflog, it returns 0.
1145  */
1146 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1147 {
1148         char *at;
1149         const char *start;
1150         int len = interpret_nth_prior_checkout(name, namelen, buf);
1151
1152         if (!namelen)
1153                 namelen = strlen(name);
1154
1155         if (!len) {
1156                 return len; /* syntax Ok, not enough switches */
1157         } else if (len > 0) {
1158                 if (len == namelen)
1159                         return len; /* consumed all */
1160                 else
1161                         return reinterpret(name, namelen, len, buf);
1162         }
1163
1164         for (start = name;
1165              (at = memchr(start, '@', namelen - (start - name)));
1166              start = at + 1) {
1167
1168                 len = interpret_empty_at(name, namelen, at - name, buf);
1169                 if (len > 0)
1170                         return reinterpret(name, namelen, len, buf);
1171
1172                 len = interpret_branch_mark(name, namelen, at - name, buf,
1173                                             upstream_mark, branch_get_upstream);
1174                 if (len > 0)
1175                         return len;
1176
1177                 len = interpret_branch_mark(name, namelen, at - name, buf,
1178                                             push_mark, branch_get_push);
1179                 if (len > 0)
1180                         return len;
1181
1182                 len = interpret_branch_mark(name, namelen, at - name, buf,
1183                                             publish_mark, branch_get_publish);
1184                 if (len > 0)
1185                         return len;
1186         }
1187
1188         return -1;
1189 }
1190
1191 int strbuf_branchname(struct strbuf *sb, const char *name)
1192 {
1193         int len = strlen(name);
1194         int used = interpret_branch_name(name, len, sb);
1195
1196         if (used == len)
1197                 return 0;
1198         if (used < 0)
1199                 used = 0;
1200         strbuf_add(sb, name + used, len - used);
1201         return len;
1202 }
1203
1204 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1205 {
1206         strbuf_branchname(sb, name);
1207         if (name[0] == '-')
1208                 return -1;
1209         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1210         return check_refname_format(sb->buf, 0);
1211 }
1212
1213 /*
1214  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1215  * notably "xyz^" for "parent of xyz"
1216  */
1217 int get_sha1(const char *name, unsigned char *sha1)
1218 {
1219         struct object_context unused;
1220         return get_sha1_with_context(name, 0, sha1, &unused);
1221 }
1222
1223 /*
1224  * Many callers know that the user meant to name a commit-ish by
1225  * syntactical positions where the object name appears.  Calling this
1226  * function allows the machinery to disambiguate shorter-than-unique
1227  * abbreviated object names between commit-ish and others.
1228  *
1229  * Note that this does NOT error out when the named object is not a
1230  * commit-ish. It is merely to give a hint to the disambiguation
1231  * machinery.
1232  */
1233 int get_sha1_committish(const char *name, unsigned char *sha1)
1234 {
1235         struct object_context unused;
1236         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1237                                      sha1, &unused);
1238 }
1239
1240 int get_sha1_treeish(const char *name, unsigned char *sha1)
1241 {
1242         struct object_context unused;
1243         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1244                                      sha1, &unused);
1245 }
1246
1247 int get_sha1_commit(const char *name, unsigned char *sha1)
1248 {
1249         struct object_context unused;
1250         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1251                                      sha1, &unused);
1252 }
1253
1254 int get_sha1_tree(const char *name, unsigned char *sha1)
1255 {
1256         struct object_context unused;
1257         return get_sha1_with_context(name, GET_SHA1_TREE,
1258                                      sha1, &unused);
1259 }
1260
1261 int get_sha1_blob(const char *name, unsigned char *sha1)
1262 {
1263         struct object_context unused;
1264         return get_sha1_with_context(name, GET_SHA1_BLOB,
1265                                      sha1, &unused);
1266 }
1267
1268 /* Must be called only when object_name:filename doesn't exist. */
1269 static void diagnose_invalid_sha1_path(const char *prefix,
1270                                        const char *filename,
1271                                        const unsigned char *tree_sha1,
1272                                        const char *object_name,
1273                                        int object_name_len)
1274 {
1275         unsigned char sha1[20];
1276         unsigned mode;
1277
1278         if (!prefix)
1279                 prefix = "";
1280
1281         if (file_exists(filename))
1282                 die("Path '%s' exists on disk, but not in '%.*s'.",
1283                     filename, object_name_len, object_name);
1284         if (errno == ENOENT || errno == ENOTDIR) {
1285                 char *fullname = xstrfmt("%s%s", prefix, filename);
1286
1287                 if (!get_tree_entry(tree_sha1, fullname,
1288                                     sha1, &mode)) {
1289                         die("Path '%s' exists, but not '%s'.\n"
1290                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1291                             fullname,
1292                             filename,
1293                             object_name_len, object_name,
1294                             fullname,
1295                             object_name_len, object_name,
1296                             filename);
1297                 }
1298                 die("Path '%s' does not exist in '%.*s'",
1299                     filename, object_name_len, object_name);
1300         }
1301 }
1302
1303 /* Must be called only when :stage:filename doesn't exist. */
1304 static void diagnose_invalid_index_path(int stage,
1305                                         const char *prefix,
1306                                         const char *filename)
1307 {
1308         const struct cache_entry *ce;
1309         int pos;
1310         unsigned namelen = strlen(filename);
1311         struct strbuf fullname = STRBUF_INIT;
1312
1313         if (!prefix)
1314                 prefix = "";
1315
1316         /* Wrong stage number? */
1317         pos = cache_name_pos(filename, namelen);
1318         if (pos < 0)
1319                 pos = -pos - 1;
1320         if (pos < active_nr) {
1321                 ce = active_cache[pos];
1322                 if (ce_namelen(ce) == namelen &&
1323                     !memcmp(ce->name, filename, namelen))
1324                         die("Path '%s' is in the index, but not at stage %d.\n"
1325                             "Did you mean ':%d:%s'?",
1326                             filename, stage,
1327                             ce_stage(ce), filename);
1328         }
1329
1330         /* Confusion between relative and absolute filenames? */
1331         strbuf_addstr(&fullname, prefix);
1332         strbuf_addstr(&fullname, filename);
1333         pos = cache_name_pos(fullname.buf, fullname.len);
1334         if (pos < 0)
1335                 pos = -pos - 1;
1336         if (pos < active_nr) {
1337                 ce = active_cache[pos];
1338                 if (ce_namelen(ce) == fullname.len &&
1339                     !memcmp(ce->name, fullname.buf, fullname.len))
1340                         die("Path '%s' is in the index, but not '%s'.\n"
1341                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1342                             fullname.buf, filename,
1343                             ce_stage(ce), fullname.buf,
1344                             ce_stage(ce), filename);
1345         }
1346
1347         if (file_exists(filename))
1348                 die("Path '%s' exists on disk, but not in the index.", filename);
1349         if (errno == ENOENT || errno == ENOTDIR)
1350                 die("Path '%s' does not exist (neither on disk nor in the index).",
1351                     filename);
1352
1353         strbuf_release(&fullname);
1354 }
1355
1356
1357 static char *resolve_relative_path(const char *rel)
1358 {
1359         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1360                 return NULL;
1361
1362         if (!startup_info)
1363                 die("BUG: startup_info struct is not initialized.");
1364
1365         if (!is_inside_work_tree())
1366                 die("relative path syntax can't be used outside working tree.");
1367
1368         /* die() inside prefix_path() if resolved path is outside worktree */
1369         return prefix_path(startup_info->prefix,
1370                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1371                            rel);
1372 }
1373
1374 static int get_sha1_with_context_1(const char *name,
1375                                    unsigned flags,
1376                                    const char *prefix,
1377                                    unsigned char *sha1,
1378                                    struct object_context *oc)
1379 {
1380         int ret, bracket_depth;
1381         int namelen = strlen(name);
1382         const char *cp;
1383         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1384
1385         memset(oc, 0, sizeof(*oc));
1386         oc->mode = S_IFINVALID;
1387         ret = get_sha1_1(name, namelen, sha1, flags);
1388         if (!ret)
1389                 return ret;
1390         /*
1391          * sha1:path --> object name of path in ent sha1
1392          * :path -> object name of absolute path in index
1393          * :./path -> object name of path relative to cwd in index
1394          * :[0-3]:path -> object name of path in index at stage
1395          * :/foo -> recent commit matching foo
1396          */
1397         if (name[0] == ':') {
1398                 int stage = 0;
1399                 const struct cache_entry *ce;
1400                 char *new_path = NULL;
1401                 int pos;
1402                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1403                         struct commit_list *list = NULL;
1404
1405                         for_each_ref(handle_one_ref, &list);
1406                         commit_list_sort_by_date(&list);
1407                         return get_sha1_oneline(name + 2, sha1, list);
1408                 }
1409                 if (namelen < 3 ||
1410                     name[2] != ':' ||
1411                     name[1] < '0' || '3' < name[1])
1412                         cp = name + 1;
1413                 else {
1414                         stage = name[1] - '0';
1415                         cp = name + 3;
1416                 }
1417                 new_path = resolve_relative_path(cp);
1418                 if (!new_path) {
1419                         namelen = namelen - (cp - name);
1420                 } else {
1421                         cp = new_path;
1422                         namelen = strlen(cp);
1423                 }
1424
1425                 strlcpy(oc->path, cp, sizeof(oc->path));
1426
1427                 if (!active_cache)
1428                         read_cache();
1429                 pos = cache_name_pos(cp, namelen);
1430                 if (pos < 0)
1431                         pos = -pos - 1;
1432                 while (pos < active_nr) {
1433                         ce = active_cache[pos];
1434                         if (ce_namelen(ce) != namelen ||
1435                             memcmp(ce->name, cp, namelen))
1436                                 break;
1437                         if (ce_stage(ce) == stage) {
1438                                 hashcpy(sha1, ce->sha1);
1439                                 oc->mode = ce->ce_mode;
1440                                 free(new_path);
1441                                 return 0;
1442                         }
1443                         pos++;
1444                 }
1445                 if (only_to_die && name[1] && name[1] != '/')
1446                         diagnose_invalid_index_path(stage, prefix, cp);
1447                 free(new_path);
1448                 return -1;
1449         }
1450         for (cp = name, bracket_depth = 0; *cp; cp++) {
1451                 if (*cp == '{')
1452                         bracket_depth++;
1453                 else if (bracket_depth && *cp == '}')
1454                         bracket_depth--;
1455                 else if (!bracket_depth && *cp == ':')
1456                         break;
1457         }
1458         if (*cp == ':') {
1459                 unsigned char tree_sha1[20];
1460                 int len = cp - name;
1461                 if (!get_sha1_1(name, len, tree_sha1, GET_SHA1_TREEISH)) {
1462                         const char *filename = cp+1;
1463                         char *new_filename = NULL;
1464
1465                         new_filename = resolve_relative_path(filename);
1466                         if (new_filename)
1467                                 filename = new_filename;
1468                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1469                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1470                                         filename, sha1, &oc->symlink_path,
1471                                         &oc->mode);
1472                         } else {
1473                                 ret = get_tree_entry(tree_sha1, filename,
1474                                                      sha1, &oc->mode);
1475                                 if (ret && only_to_die) {
1476                                         diagnose_invalid_sha1_path(prefix,
1477                                                                    filename,
1478                                                                    tree_sha1,
1479                                                                    name, len);
1480                                 }
1481                         }
1482                         hashcpy(oc->tree, tree_sha1);
1483                         strlcpy(oc->path, filename, sizeof(oc->path));
1484
1485                         free(new_filename);
1486                         return ret;
1487                 } else {
1488                         if (only_to_die)
1489                                 die("Invalid object name '%.*s'.", len, name);
1490                 }
1491         }
1492         return ret;
1493 }
1494
1495 /*
1496  * Call this function when you know "name" given by the end user must
1497  * name an object but it doesn't; the function _may_ die with a better
1498  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1499  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1500  * you have a chance to diagnose the error further.
1501  */
1502 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1503 {
1504         struct object_context oc;
1505         unsigned char sha1[20];
1506         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1507 }
1508
1509 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1510 {
1511         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1512                 die("BUG: incompatible flags for get_sha1_with_context");
1513         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1514 }