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         sprintf(hex, "%.2s", hex_pfx);
 100         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 101                 struct dirent *de;
 102                 DIR *dir;
 103                 sprintf(alt->name, "%.2s/", hex_pfx);
 104                 dir = opendir(alt->base);
 105                 if (!dir)
 106                         continue;
 107
 108                 while (!ds->ambiguous && (de = readdir(dir)) != NULL) {
 109                         unsigned char sha1[20];
 110
 111                         if (strlen(de->d_name) != 38)
 112                                 continue;
 113                         if (memcmp(de->d_name, hex_pfx + 2, len - 2))
 114                                 continue;
 115                         memcpy(hex + 2, de->d_name, 38);
 116                         if (!get_sha1_hex(hex, sha1))
 117                                 update_candidates(ds, sha1);
 118                 }
 119                 closedir(dir);
 120         }
 121 }
 122
 123 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 124 {
 125         do {
 126                 if (*a != *b)
 127                         return 0;
 128                 a++;
 129                 b++;
 130                 len -= 2;
 131         } while (len > 1);
 132         if (len)
 133                 if ((*a ^ *b) & 0xf0)
 134                         return 0;
 135         return 1;
 136 }
 137
 138 static void unique_in_pack(int len,
 139                           const unsigned char *bin_pfx,
 140                            struct packed_git *p,
 141                            struct disambiguate_state *ds)
 142 {
 143         uint32_t num, last, i, first = 0;
 144         const unsigned char *current = NULL;
 145
 146         open_pack_index(p);
 147         num = p->num_objects;
 148         last = num;
 149         while (first < last) {
 150                 uint32_t mid = (first + last) / 2;
 151                 const unsigned char *current;
 152                 int cmp;
 153
 154                 current = nth_packed_object_sha1(p, mid);
 155                 cmp = hashcmp(bin_pfx, current);
 156                 if (!cmp) {
 157                         first = mid;
 158                         break;
 159                 }
 160                 if (cmp > 0) {
 161                         first = mid+1;
 162                         continue;
 163                 }
 164                 last = mid;
 165         }
 166
 167         /*
 168          * At this point, "first" is the location of the lowest object
 169          * with an object name that could match "bin_pfx".  See if we have
 170          * 0, 1 or more objects that actually match(es).
 171          */
 172         for (i = first; i < num && !ds->ambiguous; i++) {
 173                 current = nth_packed_object_sha1(p, i);
 174                 if (!match_sha(len, bin_pfx, current))
 175                         break;
 176                 update_candidates(ds, current);
 177         }
 178 }
 179
 180 static void find_short_packed_object(int len, const unsigned char *bin_pfx,
 181                                      struct disambiguate_state *ds)
 182 {
 183         struct packed_git *p;
 184
 185         prepare_packed_git();
 186         for (p = packed_git; p && !ds->ambiguous; p = p->next)
 187                 unique_in_pack(len, bin_pfx, p, ds);
 188 }
 189
 190 #define SHORT_NAME_NOT_FOUND (-1)
 191 #define SHORT_NAME_AMBIGUOUS (-2)
 192
 193 static int finish_object_disambiguation(struct disambiguate_state *ds,
 194                                         unsigned char *sha1)
 195 {
 196         if (ds->ambiguous)
 197                 return SHORT_NAME_AMBIGUOUS;
 198
 199         if (!ds->candidate_exists)
 200                 return SHORT_NAME_NOT_FOUND;
 201
 202         if (!ds->candidate_checked)
 203                 /*
 204                  * If this is the only candidate, there is no point
 205                  * calling the disambiguation hint callback.
 206                  *
 207                  * On the other hand, if the current candidate
 208                  * replaced an earlier candidate that did _not_ pass
 209                  * the disambiguation hint callback, then we do have
 210                  * more than one objects that match the short name
 211                  * given, so we should make sure this one matches;
 212                  * otherwise, if we discovered this one and the one
 213                  * that we previously discarded in the reverse order,
 214                  * we would end up showing different results in the
 215                  * same repository!
 216                  */
 217                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 218                                     ds->fn(ds->candidate, ds->cb_data));
 219
 220         if (!ds->candidate_ok)
 221                 return SHORT_NAME_AMBIGUOUS;
 222
 223         hashcpy(sha1, ds->candidate);
 224         return 0;
 225 }
 226
 227 static int disambiguate_commit_only(const unsigned char *sha1, void *cb_data_unused)
 228 {
 229         int kind = sha1_object_info(sha1, NULL);
 230         return kind == OBJ_COMMIT;
 231 }
 232
 233 static int disambiguate_committish_only(const unsigned char *sha1, void *cb_data_unused)
 234 {
 235         struct object *obj;
 236         int kind;
 237
 238         kind = sha1_object_info(sha1, NULL);
 239         if (kind == OBJ_COMMIT)
 240                 return 1;
 241         if (kind != OBJ_TAG)
 242                 return 0;
 243
 244         /* We need to do this the hard way... */
 245         obj = deref_tag(parse_object(sha1), NULL, 0);
 246         if (obj && obj->type == OBJ_COMMIT)
 247                 return 1;
 248         return 0;
 249 }
 250
 251 static int disambiguate_tree_only(const unsigned char *sha1, void *cb_data_unused)
 252 {
 253         int kind = sha1_object_info(sha1, NULL);
 254         return kind == OBJ_TREE;
 255 }
 256
 257 static int disambiguate_treeish_only(const unsigned char *sha1, void *cb_data_unused)
 258 {
 259         struct object *obj;
 260         int kind;
 261
 262         kind = sha1_object_info(sha1, NULL);
 263         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 264                 return 1;
 265         if (kind != OBJ_TAG)
 266                 return 0;
 267
 268         /* We need to do this the hard way... */
 269         obj = deref_tag(lookup_object(sha1), NULL, 0);
 270         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 271                 return 1;
 272         return 0;
 273 }
 274
 275 static int disambiguate_blob_only(const unsigned char *sha1, void *cb_data_unused)
 276 {
 277         int kind = sha1_object_info(sha1, NULL);
 278         return kind == OBJ_BLOB;
 279 }
 280
 281 static int prepare_prefixes(const char *name, int len,
 282                             unsigned char *bin_pfx,
 283                             char *hex_pfx)
 284 {
 285         int i;
 286
 287         hashclr(bin_pfx);
 288         memset(hex_pfx, 'x', 40);
 289         for (i = 0; i < len ;i++) {
 290                 unsigned char c = name[i];
 291                 unsigned char val;
 292                 if (c >= '0' && c <= '9')
 293                         val = c - '0';
 294                 else if (c >= 'a' && c <= 'f')
 295                         val = c - 'a' + 10;
 296                 else if (c >= 'A' && c <='F') {
 297                         val = c - 'A' + 10;
 298                         c -= 'A' - 'a';
 299                 }
 300                 else
 301                         return -1;
 302                 hex_pfx[i] = c;
 303                 if (!(i & 1))
 304                         val <<= 4;
 305                 bin_pfx[i >> 1] |= val;
 306         }
 307         return 0;
 308 }
 309
 310 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 311                           unsigned flags)
 312 {
 313         int status;
 314         char hex_pfx[40];
 315         unsigned char bin_pfx[20];
 316         struct disambiguate_state ds;
 317         int quietly = !!(flags & GET_SHA1_QUIETLY);
 318
 319         if (len < MINIMUM_ABBREV || len > 40)
 320                 return -1;
 321         if (prepare_prefixes(name, len, bin_pfx, hex_pfx) < 0)
 322                 return -1;
 323
 324         prepare_alt_odb();
 325
 326         memset(&ds, 0, sizeof(ds));
 327         if (flags & GET_SHA1_COMMIT)
 328                 ds.fn = disambiguate_commit_only;
 329         else if (flags & GET_SHA1_COMMITTISH)
 330                 ds.fn = disambiguate_committish_only;
 331         else if (flags & GET_SHA1_TREE)
 332                 ds.fn = disambiguate_tree_only;
 333         else if (flags & GET_SHA1_TREEISH)
 334                 ds.fn = disambiguate_treeish_only;
 335         else if (flags & GET_SHA1_BLOB)
 336                 ds.fn = disambiguate_blob_only;
 337
 338         find_short_object_filename(len, hex_pfx, &ds);
 339         find_short_packed_object(len, bin_pfx, &ds);
 340         status = finish_object_disambiguation(&ds, sha1);
 341
 342         if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
 343                 return error("short SHA1 %.*s is ambiguous.", len, hex_pfx);
 344         return status;
 345 }
 346
 347 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 348 {
 349         char hex_pfx[40];
 350         unsigned char bin_pfx[20];
 351         struct disambiguate_state ds;
 352         int len = strlen(prefix);
 353
 354         if (len < MINIMUM_ABBREV || len > 40)
 355                 return -1;
 356         if (prepare_prefixes(prefix, len, bin_pfx, hex_pfx) < 0)
 357                 return -1;
 358
 359         prepare_alt_odb();
 360
 361         memset(&ds, 0, sizeof(ds));
 362         ds.always_call_fn = 1;
 363         ds.cb_data = cb_data;
 364         ds.fn = fn;
 365
 366         find_short_object_filename(len, hex_pfx, &ds);
 367         find_short_packed_object(len, bin_pfx, &ds);
 368         return ds.ambiguous;
 369 }
 370
 371 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 372 {
 373         int status, exists;
 374         static char hex[41];
 375
 376         memcpy(hex, sha1_to_hex(sha1), 40);
 377         if (len == 40 || !len)
 378                 return hex;
 379         exists = has_sha1_file(sha1);
 380         while (len < 40) {
 381                 unsigned char sha1_ret[20];
 382                 status = get_short_sha1(hex, len, sha1_ret, GET_SHA1_QUIETLY);
 383                 if (exists
 384                     ? !status
 385                     : status == SHORT_NAME_NOT_FOUND) {
 386                         hex[len] = 0;
 387                         return hex;
 388                 }
 389                 len++;
 390         }
 391         return hex;
 392 }
 393
 394 static int ambiguous_path(const char *path, int len)
 395 {
 396         int slash = 1;
 397         int cnt;
 398
 399         for (cnt = 0; cnt < len; cnt++) {
 400                 switch (*path++) {
 401                 case '\0':
 402                         break;
 403                 case '/':
 404                         if (slash)
 405                                 break;
 406                         slash = 1;
 407                         continue;
 408                 case '.':
 409                         continue;
 410                 default:
 411                         slash = 0;
 412                         continue;
 413                 }
 414                 break;
 415         }
 416         return slash;
 417 }
 418
 419 static inline int at_mark(const char *string, int len,
 420                           const char **suffix, int nr)
 421 {
 422         int i;
 423
 424         for (i = 0; i < nr; i++) {
 425                 int suffix_len = strlen(suffix[i]);
 426                 if (suffix_len <= len
 427                     && !memcmp(string, suffix[i], suffix_len))
 428                         return suffix_len;
 429         }
 430         return 0;
 431 }
 432
 433 static inline int upstream_mark(const char *string, int len)
 434 {
 435         const char *suffix[] = { "@{upstream}", "@{u}" };
 436         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 437 }
 438
 439 static inline int push_mark(const char *string, int len)
 440 {
 441         const char *suffix[] = { "@{push}" };
 442         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 443 }
 444
 445 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 446 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 447
 448 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 449                           unsigned int flags)
 450 {
 451         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 452         static const char *object_name_msg = N_(
 453         "Git normally never creates a ref that ends with 40 hex characters\n"
 454         "because it will be ignored when you just specify 40-hex. These refs\n"
 455         "may be created by mistake. For example,\n"
 456         "\n"
 457         "  git checkout -b $br $(git rev-parse ...)\n"
 458         "\n"
 459         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 460         "examine these refs and maybe delete them. Turn this message off by\n"
 461         "running \"git config advice.objectNameWarning false\"");
 462         unsigned char tmp_sha1[20];
 463         char *real_ref = NULL;
 464         int refs_found = 0;
 465         int at, reflog_len, nth_prior = 0;
 466
 467         if (len == 40 && !get_sha1_hex(str, sha1)) {
 468                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 469                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 470                         if (refs_found > 0) {
 471                                 warning(warn_msg, len, str);
 472                                 if (advice_object_name_warning)
 473                                         fprintf(stderr, "%s\n", _(object_name_msg));
 474                         }
 475                         free(real_ref);
 476                 }
 477                 return 0;
 478         }
 479
 480         /* basic@{time or number or -number} format to query ref-log */
 481         reflog_len = at = 0;
 482         if (len && str[len-1] == '}') {
 483                 for (at = len-4; at >= 0; at--) {
 484                         if (str[at] == '@' && str[at+1] == '{') {
 485                                 if (str[at+2] == '-') {
 486                                         if (at != 0)
 487                                                 /* @{-N} not at start */
 488                                                 return -1;
 489                                         nth_prior = 1;
 490                                         continue;
 491                                 }
 492                                 if (!upstream_mark(str + at, len - at) &&
 493                                     !push_mark(str + at, len - at)) {
 494                                         reflog_len = (len-1) - (at+2);
 495                                         len = at;
 496                                 }
 497                                 break;
 498                         }
 499                 }
 500         }
 501
 502         /* Accept only unambiguous ref paths. */
 503         if (len && ambiguous_path(str, len))
 504                 return -1;
 505
 506         if (nth_prior) {
 507                 struct strbuf buf = STRBUF_INIT;
 508                 int detached;
 509
 510                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 511                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 512                         strbuf_release(&buf);
 513                         if (detached)
 514                                 return 0;
 515                 }
 516         }
 517
 518         if (!len && reflog_len)
 519                 /* allow "@{...}" to mean the current branch reflog */
 520                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 521         else if (reflog_len)
 522                 refs_found = dwim_log(str, len, sha1, &real_ref);
 523         else
 524                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 525
 526         if (!refs_found)
 527                 return -1;
 528
 529         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 530             (refs_found > 1 ||
 531              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 532                 warning(warn_msg, len, str);
 533
 534         if (reflog_len) {
 535                 int nth, i;
 536                 unsigned long at_time;
 537                 unsigned long co_time;
 538                 int co_tz, co_cnt;
 539
 540                 /* Is it asking for N-th entry, or approxidate? */
 541                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 542                         char ch = str[at+2+i];
 543                         if ('0' <= ch && ch <= '9')
 544                                 nth = nth * 10 + ch - '0';
 545                         else
 546                                 nth = -1;
 547                 }
 548                 if (100000000 <= nth) {
 549                         at_time = nth;
 550                         nth = -1;
 551                 } else if (0 <= nth)
 552                         at_time = 0;
 553                 else {
 554                         int errors = 0;
 555                         char *tmp = xstrndup(str + at + 2, reflog_len);
 556                         at_time = approxidate_careful(tmp, &errors);
 557                         free(tmp);
 558                         if (errors) {
 559                                 free(real_ref);
 560                                 return -1;
 561                         }
 562                 }
 563                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 564                                 &co_time, &co_tz, &co_cnt)) {
 565                         if (!len) {
 566                                 if (starts_with(real_ref, "refs/heads/")) {
 567                                         str = real_ref + 11;
 568                                         len = strlen(real_ref + 11);
 569                                 } else {
 570                                         /* detached HEAD */
 571                                         str = "HEAD";
 572                                         len = 4;
 573                                 }
 574                         }
 575                         if (at_time) {
 576                                 if (!(flags & GET_SHA1_QUIETLY)) {
 577                                         warning("Log for '%.*s' only goes "
 578                                                 "back to %s.", len, str,
 579                                                 show_date(co_time, co_tz, DATE_RFC2822));
 580                                 }
 581                         } else {
 582                                 if (flags & GET_SHA1_QUIETLY) {
 583                                         exit(128);
 584                                 }
 585                                 die("Log for '%.*s' only has %d entries.",
 586                                     len, str, co_cnt);
 587                         }
 588                 }
 589         }
 590
 591         free(real_ref);
 592         return 0;
 593 }
 594
 595 static int get_parent(const char *name, int len,
 596                       unsigned char *result, int idx)
 597 {
 598         unsigned char sha1[20];
 599         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 600         struct commit *commit;
 601         struct commit_list *p;
 602
 603         if (ret)
 604                 return ret;
 605         commit = lookup_commit_reference(sha1);
 606         if (parse_commit(commit))
 607                 return -1;
 608         if (!idx) {
 609                 hashcpy(result, commit->object.sha1);
 610                 return 0;
 611         }
 612         p = commit->parents;
 613         while (p) {
 614                 if (!--idx) {
 615                         hashcpy(result, p->item->object.sha1);
 616                         return 0;
 617                 }
 618                 p = p->next;
 619         }
 620         return -1;
 621 }
 622
 623 static int get_nth_ancestor(const char *name, int len,
 624                             unsigned char *result, int generation)
 625 {
 626         unsigned char sha1[20];
 627         struct commit *commit;
 628         int ret;
 629
 630         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 631         if (ret)
 632                 return ret;
 633         commit = lookup_commit_reference(sha1);
 634         if (!commit)
 635                 return -1;
 636
 637         while (generation--) {
 638                 if (parse_commit(commit) || !commit->parents)
 639                         return -1;
 640                 commit = commit->parents->item;
 641         }
 642         hashcpy(result, commit->object.sha1);
 643         return 0;
 644 }
 645
 646 struct object *peel_to_type(const char *name, int namelen,
 647                             struct object *o, enum object_type expected_type)
 648 {
 649         if (name && !namelen)
 650                 namelen = strlen(name);
 651         while (1) {
 652                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 653                         return NULL;
 654                 if (expected_type == OBJ_ANY || o->type == expected_type)
 655                         return o;
 656                 if (o->type == OBJ_TAG)
 657                         o = ((struct tag*) o)->tagged;
 658                 else if (o->type == OBJ_COMMIT)
 659                         o = &(((struct commit *) o)->tree->object);
 660                 else {
 661                         if (name)
 662                                 error("%.*s: expected %s type, but the object "
 663                                       "dereferences to %s type",
 664                                       namelen, name, typename(expected_type),
 665                                       typename(o->type));
 666                         return NULL;
 667                 }
 668         }
 669 }
 670
 671 static int peel_onion(const char *name, int len, unsigned char *sha1)
 672 {
 673         unsigned char outer[20];
 674         const char *sp;
 675         unsigned int expected_type = 0;
 676         unsigned lookup_flags = 0;
 677         struct object *o;
 678
 679         /*
 680          * "ref^{type}" dereferences ref repeatedly until you cannot
 681          * dereference anymore, or you get an object of given type,
 682          * whichever comes first.  "ref^{}" means just dereference
 683          * tags until you get a non-tag.  "ref^0" is a shorthand for
 684          * "ref^{commit}".  "commit^{tree}" could be used to find the
 685          * top-level tree of the given commit.
 686          */
 687         if (len < 4 || name[len-1] != '}')
 688                 return -1;
 689
 690         for (sp = name + len - 1; name <= sp; sp--) {
 691                 int ch = *sp;
 692                 if (ch == '{' && name < sp && sp[-1] == '^')
 693                         break;
 694         }
 695         if (sp <= name)
 696                 return -1;
 697
 698         sp++; /* beginning of type name, or closing brace for empty */
 699         if (starts_with(sp, "commit}"))
 700                 expected_type = OBJ_COMMIT;
 701         else if (starts_with(sp, "tag}"))
 702                 expected_type = OBJ_TAG;
 703         else if (starts_with(sp, "tree}"))
 704                 expected_type = OBJ_TREE;
 705         else if (starts_with(sp, "blob}"))
 706                 expected_type = OBJ_BLOB;
 707         else if (starts_with(sp, "object}"))
 708                 expected_type = OBJ_ANY;
 709         else if (sp[0] == '}')
 710                 expected_type = OBJ_NONE;
 711         else if (sp[0] == '/')
 712                 expected_type = OBJ_COMMIT;
 713         else
 714                 return -1;
 715
 716         if (expected_type == OBJ_COMMIT)
 717                 lookup_flags = GET_SHA1_COMMITTISH;
 718         else if (expected_type == OBJ_TREE)
 719                 lookup_flags = GET_SHA1_TREEISH;
 720
 721         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 722                 return -1;
 723
 724         o = parse_object(outer);
 725         if (!o)
 726                 return -1;
 727         if (!expected_type) {
 728                 o = deref_tag(o, name, sp - name - 2);
 729                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 730                         return -1;
 731                 hashcpy(sha1, o->sha1);
 732                 return 0;
 733         }
 734
 735         /*
 736          * At this point, the syntax look correct, so
 737          * if we do not get the needed object, we should
 738          * barf.
 739          */
 740         o = peel_to_type(name, len, o, expected_type);
 741         if (!o)
 742                 return -1;
 743
 744         hashcpy(sha1, o->sha1);
 745         if (sp[0] == '/') {
 746                 /* "$commit^{/foo}" */
 747                 char *prefix;
 748                 int ret;
 749                 struct commit_list *list = NULL;
 750
 751                 /*
 752                  * $commit^{/}. Some regex implementation may reject.
 753                  * We don't need regex anyway. '' pattern always matches.
 754                  */
 755                 if (sp[1] == '}')
 756                         return 0;
 757
 758                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 759                 commit_list_insert((struct commit *)o, &list);
 760                 ret = get_sha1_oneline(prefix, sha1, list);
 761                 free(prefix);
 762                 return ret;
 763         }
 764         return 0;
 765 }
 766
 767 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 768 {
 769         const char *cp;
 770         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 771
 772         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 773                 char ch = *cp;
 774                 if (!isxdigit(ch)) {
 775                         /* We must be looking at g in "SOMETHING-g"
 776                          * for it to be describe output.
 777                          */
 778                         if (ch == 'g' && cp[-1] == '-') {
 779                                 cp++;
 780                                 len -= cp - name;
 781                                 return get_short_sha1(cp, len, sha1, flags);
 782                         }
 783                 }
 784         }
 785         return -1;
 786 }
 787
 788 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 789 {
 790         int ret, has_suffix;
 791         const char *cp;
 792
 793         /*
 794          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 795          */
 796         has_suffix = 0;
 797         for (cp = name + len - 1; name <= cp; cp--) {
 798                 int ch = *cp;
 799                 if ('0' <= ch && ch <= '9')
 800                         continue;
 801                 if (ch == '~' || ch == '^')
 802                         has_suffix = ch;
 803                 break;
 804         }
 805
 806         if (has_suffix) {
 807                 int num = 0;
 808                 int len1 = cp - name;
 809                 cp++;
 810                 while (cp < name + len)
 811                         num = num * 10 + *cp++ - '0';
 812                 if (!num && len1 == len - 1)
 813                         num = 1;
 814                 if (has_suffix == '^')
 815                         return get_parent(name, len1, sha1, num);
 816                 /* else if (has_suffix == '~') -- goes without saying */
 817                 return get_nth_ancestor(name, len1, sha1, num);
 818         }
 819
 820         ret = peel_onion(name, len, sha1);
 821         if (!ret)
 822                 return 0;
 823
 824         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 825         if (!ret)
 826                 return 0;
 827
 828         /* It could be describe output that is "SOMETHING-gXXXX" */
 829         ret = get_describe_name(name, len, sha1);
 830         if (!ret)
 831                 return 0;
 832
 833         return get_short_sha1(name, len, sha1, lookup_flags);
 834 }
 835
 836 /*
 837  * This interprets names like ':/Initial revision of "git"' by searching
 838  * through history and returning the first commit whose message starts
 839  * the given regular expression.
 840  *
 841  * For future extension, ':/!' is reserved. If you want to match a message
 842  * beginning with a '!', you have to repeat the exclamation mark.
 843  */
 844
 845 /* Remember to update object flag allocation in object.h */
 846 #define ONELINE_SEEN (1u<<20)
 847
 848 static int handle_one_ref(const char *path, const struct object_id *oid,
 849                           int flag, void *cb_data)
 850 {
 851         struct commit_list **list = cb_data;
 852         struct object *object = parse_object(oid->hash);
 853         if (!object)
 854                 return 0;
 855         if (object->type == OBJ_TAG) {
 856                 object = deref_tag(object, path, strlen(path));
 857                 if (!object)
 858                         return 0;
 859         }
 860         if (object->type != OBJ_COMMIT)
 861                 return 0;
 862         commit_list_insert((struct commit *)object, list);
 863         return 0;
 864 }
 865
 866 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 867                             struct commit_list *list)
 868 {
 869         struct commit_list *backup = NULL, *l;
 870         int found = 0;
 871         regex_t regex;
 872
 873         if (prefix[0] == '!') {
 874                 if (prefix[1] != '!')
 875                         die ("Invalid search pattern: %s", prefix);
 876                 prefix++;
 877         }
 878
 879         if (regcomp(&regex, prefix, REG_EXTENDED))
 880                 die("Invalid search pattern: %s", prefix);
 881
 882         for (l = list; l; l = l->next) {
 883                 l->item->object.flags |= ONELINE_SEEN;
 884                 commit_list_insert(l->item, &backup);
 885         }
 886         while (list) {
 887                 const char *p, *buf;
 888                 struct commit *commit;
 889                 int matches;
 890
 891                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 892                 if (!parse_object(commit->object.sha1))
 893                         continue;
 894                 buf = get_commit_buffer(commit, NULL);
 895                 p = strstr(buf, "\n\n");
 896                 matches = p && !regexec(&regex, p + 2, 0, NULL, 0);
 897                 unuse_commit_buffer(commit, buf);
 898
 899                 if (matches) {
 900                         hashcpy(sha1, commit->object.sha1);
 901                         found = 1;
 902                         break;
 903                 }
 904         }
 905         regfree(&regex);
 906         free_commit_list(list);
 907         for (l = backup; l; l = l->next)
 908                 clear_commit_marks(l->item, ONELINE_SEEN);
 909         free_commit_list(backup);
 910         return found ? 0 : -1;
 911 }
 912
 913 struct grab_nth_branch_switch_cbdata {
 914         int remaining;
 915         struct strbuf buf;
 916 };
 917
 918 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 919                                   const char *email, unsigned long timestamp, int tz,
 920                                   const char *message, void *cb_data)
 921 {
 922         struct grab_nth_branch_switch_cbdata *cb = cb_data;
 923         const char *match = NULL, *target = NULL;
 924         size_t len;
 925
 926         if (skip_prefix(message, "checkout: moving from ", &match))
 927                 target = strstr(match, " to ");
 928
 929         if (!match || !target)
 930                 return 0;
 931         if (--(cb->remaining) == 0) {
 932                 len = target - match;
 933                 strbuf_reset(&cb->buf);
 934                 strbuf_add(&cb->buf, match, len);
 935                 return 1; /* we are done */
 936         }
 937         return 0;
 938 }
 939
 940 /*
 941  * Parse @{-N} syntax, return the number of characters parsed
 942  * if successful; otherwise signal an error with negative value.
 943  */
 944 static int interpret_nth_prior_checkout(const char *name, int namelen,
 945                                         struct strbuf *buf)
 946 {
 947         long nth;
 948         int retval;
 949         struct grab_nth_branch_switch_cbdata cb;
 950         const char *brace;
 951         char *num_end;
 952
 953         if (namelen < 4)
 954                 return -1;
 955         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
 956                 return -1;
 957         brace = memchr(name, '}', namelen);
 958         if (!brace)
 959                 return -1;
 960         nth = strtol(name + 3, &num_end, 10);
 961         if (num_end != brace)
 962                 return -1;
 963         if (nth <= 0)
 964                 return -1;
 965         cb.remaining = nth;
 966         strbuf_init(&cb.buf, 20);
 967
 968         retval = 0;
 969         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
 970                 strbuf_reset(buf);
 971                 strbuf_addbuf(buf, &cb.buf);
 972                 retval = brace - name + 1;
 973         }
 974
 975         strbuf_release(&cb.buf);
 976         return retval;
 977 }
 978
 979 int get_sha1_mb(const char *name, unsigned char *sha1)
 980 {
 981         struct commit *one, *two;
 982         struct commit_list *mbs;
 983         unsigned char sha1_tmp[20];
 984         const char *dots;
 985         int st;
 986
 987         dots = strstr(name, "...");
 988         if (!dots)
 989                 return get_sha1(name, sha1);
 990         if (dots == name)
 991                 st = get_sha1("HEAD", sha1_tmp);
 992         else {
 993                 struct strbuf sb;
 994                 strbuf_init(&sb, dots - name);
 995                 strbuf_add(&sb, name, dots - name);
 996                 st = get_sha1_committish(sb.buf, sha1_tmp);
 997                 strbuf_release(&sb);
 998         }
 999         if (st)
1000                 return st;
1001         one = lookup_commit_reference_gently(sha1_tmp, 0);
1002         if (!one)
1003                 return -1;
1004
1005         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
1006                 return -1;
1007         two = lookup_commit_reference_gently(sha1_tmp, 0);
1008         if (!two)
1009                 return -1;
1010         mbs = get_merge_bases(one, two);
1011         if (!mbs || mbs->next)
1012                 st = -1;
1013         else {
1014                 st = 0;
1015                 hashcpy(sha1, mbs->item->object.sha1);
1016         }
1017         free_commit_list(mbs);
1018         return st;
1019 }
1020
1021 /* parse @something syntax, when 'something' is not {.*} */
1022 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1023 {
1024         const char *next;
1025
1026         if (len || name[1] == '{')
1027                 return -1;
1028
1029         /* make sure it's a single @, or @@{.*}, not @foo */
1030         next = memchr(name + len + 1, '@', namelen - len - 1);
1031         if (next && next[1] != '{')
1032                 return -1;
1033         if (!next)
1034                 next = name + namelen;
1035         if (next != name + 1)
1036                 return -1;
1037
1038         strbuf_reset(buf);
1039         strbuf_add(buf, "HEAD", 4);
1040         return 1;
1041 }
1042
1043 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1044 {
1045         /* we have extra data, which might need further processing */
1046         struct strbuf tmp = STRBUF_INIT;
1047         int used = buf->len;
1048         int ret;
1049
1050         strbuf_add(buf, name + len, namelen - len);
1051         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1052         /* that data was not interpreted, remove our cruft */
1053         if (ret < 0) {
1054                 strbuf_setlen(buf, used);
1055                 return len;
1056         }
1057         strbuf_reset(buf);
1058         strbuf_addbuf(buf, &tmp);
1059         strbuf_release(&tmp);
1060         /* tweak for size of {-N} versus expanded ref name */
1061         return ret - used + len;
1062 }
1063
1064 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1065 {
1066         char *s = shorten_unambiguous_ref(ref, 0);
1067         strbuf_reset(buf);
1068         strbuf_addstr(buf, s);
1069         free(s);
1070 }
1071
1072 static int interpret_branch_mark(const char *name, int namelen,
1073                                  int at, struct strbuf *buf,
1074                                  int (*get_mark)(const char *, int),
1075                                  const char *(*get_data)(struct branch *,
1076                                                          struct strbuf *))
1077 {
1078         int len;
1079         struct branch *branch;
1080         struct strbuf err = STRBUF_INIT;
1081         const char *value;
1082
1083         len = get_mark(name + at, namelen - at);
1084         if (!len)
1085                 return -1;
1086
1087         if (memchr(name, ':', at))
1088                 return -1;
1089
1090         if (at) {
1091                 char *name_str = xmemdupz(name, at);
1092                 branch = branch_get(name_str);
1093                 free(name_str);
1094         } else
1095                 branch = branch_get(NULL);
1096
1097         value = get_data(branch, &err);
1098         if (!value)
1099                 die("%s", err.buf);
1100
1101         set_shortened_ref(buf, value);
1102         return len + at;
1103 }
1104
1105 /*
1106  * This reads short-hand syntax that not only evaluates to a commit
1107  * object name, but also can act as if the end user spelled the name
1108  * of the branch from the command line.
1109  *
1110  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1111  *   places the name of the branch in the given buf and returns the
1112  *   number of characters parsed if successful.
1113  *
1114  * - "<branch>@{upstream}" finds the name of the other ref that
1115  *   <branch> is configured to merge with (missing <branch> defaults
1116  *   to the current branch), and places the name of the branch in the
1117  *   given buf and returns the number of characters parsed if
1118  *   successful.
1119  *
1120  * If the input is not of the accepted format, it returns a negative
1121  * number to signal an error.
1122  *
1123  * If the input was ok but there are not N branch switches in the
1124  * reflog, it returns 0.
1125  */
1126 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1127 {
1128         char *at;
1129         const char *start;
1130         int len = interpret_nth_prior_checkout(name, namelen, buf);
1131
1132         if (!namelen)
1133                 namelen = strlen(name);
1134
1135         if (!len) {
1136                 return len; /* syntax Ok, not enough switches */
1137         } else if (len > 0) {
1138                 if (len == namelen)
1139                         return len; /* consumed all */
1140                 else
1141                         return reinterpret(name, namelen, len, buf);
1142         }
1143
1144         for (start = name;
1145              (at = memchr(start, '@', namelen - (start - name)));
1146              start = at + 1) {
1147
1148                 len = interpret_empty_at(name, namelen, at - name, buf);
1149                 if (len > 0)
1150                         return reinterpret(name, namelen, len, buf);
1151
1152                 len = interpret_branch_mark(name, namelen, at - name, buf,
1153                                             upstream_mark, branch_get_upstream);
1154                 if (len > 0)
1155                         return len;
1156
1157                 len = interpret_branch_mark(name, namelen, at - name, buf,
1158                                             push_mark, branch_get_push);
1159                 if (len > 0)
1160                         return len;
1161         }
1162
1163         return -1;
1164 }
1165
1166 int strbuf_branchname(struct strbuf *sb, const char *name)
1167 {
1168         int len = strlen(name);
1169         int used = interpret_branch_name(name, len, sb);
1170
1171         if (used == len)
1172                 return 0;
1173         if (used < 0)
1174                 used = 0;
1175         strbuf_add(sb, name + used, len - used);
1176         return len;
1177 }
1178
1179 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1180 {
1181         strbuf_branchname(sb, name);
1182         if (name[0] == '-')
1183                 return -1;
1184         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1185         return check_refname_format(sb->buf, 0);
1186 }
1187
1188 /*
1189  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1190  * notably "xyz^" for "parent of xyz"
1191  */
1192 int get_sha1(const char *name, unsigned char *sha1)
1193 {
1194         struct object_context unused;
1195         return get_sha1_with_context(name, 0, sha1, &unused);
1196 }
1197
1198 /*
1199  * Many callers know that the user meant to name a commit-ish by
1200  * syntactical positions where the object name appears.  Calling this
1201  * function allows the machinery to disambiguate shorter-than-unique
1202  * abbreviated object names between commit-ish and others.
1203  *
1204  * Note that this does NOT error out when the named object is not a
1205  * commit-ish. It is merely to give a hint to the disambiguation
1206  * machinery.
1207  */
1208 int get_sha1_committish(const char *name, unsigned char *sha1)
1209 {
1210         struct object_context unused;
1211         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1212                                      sha1, &unused);
1213 }
1214
1215 int get_sha1_treeish(const char *name, unsigned char *sha1)
1216 {
1217         struct object_context unused;
1218         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1219                                      sha1, &unused);
1220 }
1221
1222 int get_sha1_commit(const char *name, unsigned char *sha1)
1223 {
1224         struct object_context unused;
1225         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1226                                      sha1, &unused);
1227 }
1228
1229 int get_sha1_tree(const char *name, unsigned char *sha1)
1230 {
1231         struct object_context unused;
1232         return get_sha1_with_context(name, GET_SHA1_TREE,
1233                                      sha1, &unused);
1234 }
1235
1236 int get_sha1_blob(const char *name, unsigned char *sha1)
1237 {
1238         struct object_context unused;
1239         return get_sha1_with_context(name, GET_SHA1_BLOB,
1240                                      sha1, &unused);
1241 }
1242
1243 /* Must be called only when object_name:filename doesn't exist. */
1244 static void diagnose_invalid_sha1_path(const char *prefix,
1245                                        const char *filename,
1246                                        const unsigned char *tree_sha1,
1247                                        const char *object_name,
1248                                        int object_name_len)
1249 {
1250         unsigned char sha1[20];
1251         unsigned mode;
1252
1253         if (!prefix)
1254                 prefix = "";
1255
1256         if (file_exists(filename))
1257                 die("Path '%s' exists on disk, but not in '%.*s'.",
1258                     filename, object_name_len, object_name);
1259         if (errno == ENOENT || errno == ENOTDIR) {
1260                 char *fullname = xstrfmt("%s%s", prefix, filename);
1261
1262                 if (!get_tree_entry(tree_sha1, fullname,
1263                                     sha1, &mode)) {
1264                         die("Path '%s' exists, but not '%s'.\n"
1265                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1266                             fullname,
1267                             filename,
1268                             object_name_len, object_name,
1269                             fullname,
1270                             object_name_len, object_name,
1271                             filename);
1272                 }
1273                 die("Path '%s' does not exist in '%.*s'",
1274                     filename, object_name_len, object_name);
1275         }
1276 }
1277
1278 /* Must be called only when :stage:filename doesn't exist. */
1279 static void diagnose_invalid_index_path(int stage,
1280                                         const char *prefix,
1281                                         const char *filename)
1282 {
1283         const struct cache_entry *ce;
1284         int pos;
1285         unsigned namelen = strlen(filename);
1286         unsigned fullnamelen;
1287         char *fullname;
1288
1289         if (!prefix)
1290                 prefix = "";
1291
1292         /* Wrong stage number? */
1293         pos = cache_name_pos(filename, namelen);
1294         if (pos < 0)
1295                 pos = -pos - 1;
1296         if (pos < active_nr) {
1297                 ce = active_cache[pos];
1298                 if (ce_namelen(ce) == namelen &&
1299                     !memcmp(ce->name, filename, namelen))
1300                         die("Path '%s' is in the index, but not at stage %d.\n"
1301                             "Did you mean ':%d:%s'?",
1302                             filename, stage,
1303                             ce_stage(ce), filename);
1304         }
1305
1306         /* Confusion between relative and absolute filenames? */
1307         fullnamelen = namelen + strlen(prefix);
1308         fullname = xmalloc(fullnamelen + 1);
1309         strcpy(fullname, prefix);
1310         strcat(fullname, filename);
1311         pos = cache_name_pos(fullname, fullnamelen);
1312         if (pos < 0)
1313                 pos = -pos - 1;
1314         if (pos < active_nr) {
1315                 ce = active_cache[pos];
1316                 if (ce_namelen(ce) == fullnamelen &&
1317                     !memcmp(ce->name, fullname, fullnamelen))
1318                         die("Path '%s' is in the index, but not '%s'.\n"
1319                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1320                             fullname, filename,
1321                             ce_stage(ce), fullname,
1322                             ce_stage(ce), filename);
1323         }
1324
1325         if (file_exists(filename))
1326                 die("Path '%s' exists on disk, but not in the index.", filename);
1327         if (errno == ENOENT || errno == ENOTDIR)
1328                 die("Path '%s' does not exist (neither on disk nor in the index).",
1329                     filename);
1330
1331         free(fullname);
1332 }
1333
1334
1335 static char *resolve_relative_path(const char *rel)
1336 {
1337         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1338                 return NULL;
1339
1340         if (!startup_info)
1341                 die("BUG: startup_info struct is not initialized.");
1342
1343         if (!is_inside_work_tree())
1344                 die("relative path syntax can't be used outside working tree.");
1345
1346         /* die() inside prefix_path() if resolved path is outside worktree */
1347         return prefix_path(startup_info->prefix,
1348                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1349                            rel);
1350 }
1351
1352 static int get_sha1_with_context_1(const char *name,
1353                                    unsigned flags,
1354                                    const char *prefix,
1355                                    unsigned char *sha1,
1356                                    struct object_context *oc)
1357 {
1358         int ret, bracket_depth;
1359         int namelen = strlen(name);
1360         const char *cp;
1361         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1362
1363         memset(oc, 0, sizeof(*oc));
1364         oc->mode = S_IFINVALID;
1365         ret = get_sha1_1(name, namelen, sha1, flags);
1366         if (!ret)
1367                 return ret;
1368         /*
1369          * sha1:path --> object name of path in ent sha1
1370          * :path -> object name of absolute path in index
1371          * :./path -> object name of path relative to cwd in index
1372          * :[0-3]:path -> object name of path in index at stage
1373          * :/foo -> recent commit matching foo
1374          */
1375         if (name[0] == ':') {
1376                 int stage = 0;
1377                 const struct cache_entry *ce;
1378                 char *new_path = NULL;
1379                 int pos;
1380                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1381                         struct commit_list *list = NULL;
1382
1383                         for_each_ref(handle_one_ref, &list);
1384                         commit_list_sort_by_date(&list);
1385                         return get_sha1_oneline(name + 2, sha1, list);
1386                 }
1387                 if (namelen < 3 ||
1388                     name[2] != ':' ||
1389                     name[1] < '0' || '3' < name[1])
1390                         cp = name + 1;
1391                 else {
1392                         stage = name[1] - '0';
1393                         cp = name + 3;
1394                 }
1395                 new_path = resolve_relative_path(cp);
1396                 if (!new_path) {
1397                         namelen = namelen - (cp - name);
1398                 } else {
1399                         cp = new_path;
1400                         namelen = strlen(cp);
1401                 }
1402
1403                 strlcpy(oc->path, cp, sizeof(oc->path));
1404
1405                 if (!active_cache)
1406                         read_cache();
1407                 pos = cache_name_pos(cp, namelen);
1408                 if (pos < 0)
1409                         pos = -pos - 1;
1410                 while (pos < active_nr) {
1411                         ce = active_cache[pos];
1412                         if (ce_namelen(ce) != namelen ||
1413                             memcmp(ce->name, cp, namelen))
1414                                 break;
1415                         if (ce_stage(ce) == stage) {
1416                                 hashcpy(sha1, ce->sha1);
1417                                 oc->mode = ce->ce_mode;
1418                                 free(new_path);
1419                                 return 0;
1420                         }
1421                         pos++;
1422                 }
1423                 if (only_to_die && name[1] && name[1] != '/')
1424                         diagnose_invalid_index_path(stage, prefix, cp);
1425                 free(new_path);
1426                 return -1;
1427         }
1428         for (cp = name, bracket_depth = 0; *cp; cp++) {
1429                 if (*cp == '{')
1430                         bracket_depth++;
1431                 else if (bracket_depth && *cp == '}')
1432                         bracket_depth--;
1433                 else if (!bracket_depth && *cp == ':')
1434                         break;
1435         }
1436         if (*cp == ':') {
1437                 unsigned char tree_sha1[20];
1438                 int len = cp - name;
1439                 if (!get_sha1_1(name, len, tree_sha1, GET_SHA1_TREEISH)) {
1440                         const char *filename = cp+1;
1441                         char *new_filename = NULL;
1442
1443                         new_filename = resolve_relative_path(filename);
1444                         if (new_filename)
1445                                 filename = new_filename;
1446                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1447                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1448                                         filename, sha1, &oc->symlink_path,
1449                                         &oc->mode);
1450                         } else {
1451                                 ret = get_tree_entry(tree_sha1, filename,
1452                                                      sha1, &oc->mode);
1453                                 if (ret && only_to_die) {
1454                                         diagnose_invalid_sha1_path(prefix,
1455                                                                    filename,
1456                                                                    tree_sha1,
1457                                                                    name, len);
1458                                 }
1459                         }
1460                         hashcpy(oc->tree, tree_sha1);
1461                         strlcpy(oc->path, filename, sizeof(oc->path));
1462
1463                         free(new_filename);
1464                         return ret;
1465                 } else {
1466                         if (only_to_die)
1467                                 die("Invalid object name '%.*s'.", len, name);
1468                 }
1469         }
1470         return ret;
1471 }
1472
1473 /*
1474  * Call this function when you know "name" given by the end user must
1475  * name an object but it doesn't; the function _may_ die with a better
1476  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1477  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1478  * you have a chance to diagnose the error further.
1479  */
1480 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1481 {
1482         struct object_context oc;
1483         unsigned char sha1[20];
1484         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1485 }
1486
1487 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1488 {
1489         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1490                 die("BUG: incompatible flags for get_sha1_with_context");
1491         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1492 }