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         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 upstream_mark(const char *string, int len)
 420 {
 421         const char *suffix[] = { "@{upstream}", "@{u}" };
 422         int i;
 423
 424         for (i = 0; i < ARRAY_SIZE(suffix); 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 int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 434 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 435
 436 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 437                           unsigned int flags)
 438 {
 439         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 440         static const char *object_name_msg = N_(
 441         "Git normally never creates a ref that ends with 40 hex characters\n"
 442         "because it will be ignored when you just specify 40-hex. These refs\n"
 443         "may be created by mistake. For example,\n"
 444         "\n"
 445         "  git checkout -b $br $(git rev-parse ...)\n"
 446         "\n"
 447         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 448         "examine these refs and maybe delete them. Turn this message off by\n"
 449         "running \"git config advice.objectNameWarning false\"");
 450         unsigned char tmp_sha1[20];
 451         char *real_ref = NULL;
 452         int refs_found = 0;
 453         int at, reflog_len, nth_prior = 0;
 454
 455         if (len == 40 && !get_sha1_hex(str, sha1)) {
 456                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 457                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 458                         if (refs_found > 0) {
 459                                 warning(warn_msg, len, str);
 460                                 if (advice_object_name_warning)
 461                                         fprintf(stderr, "%s\n", _(object_name_msg));
 462                         }
 463                         free(real_ref);
 464                 }
 465                 return 0;
 466         }
 467
 468         /* basic@{time or number or -number} format to query ref-log */
 469         reflog_len = at = 0;
 470         if (len && str[len-1] == '}') {
 471                 for (at = len-4; at >= 0; at--) {
 472                         if (str[at] == '@' && str[at+1] == '{') {
 473                                 if (str[at+2] == '-') {
 474                                         if (at != 0)
 475                                                 /* @{-N} not at start */
 476                                                 return -1;
 477                                         nth_prior = 1;
 478                                         continue;
 479                                 }
 480                                 if (!upstream_mark(str + at, len - at)) {
 481                                         reflog_len = (len-1) - (at+2);
 482                                         len = at;
 483                                 }
 484                                 break;
 485                         }
 486                 }
 487         }
 488
 489         /* Accept only unambiguous ref paths. */
 490         if (len && ambiguous_path(str, len))
 491                 return -1;
 492
 493         if (nth_prior) {
 494                 struct strbuf buf = STRBUF_INIT;
 495                 int detached;
 496
 497                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 498                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 499                         strbuf_release(&buf);
 500                         if (detached)
 501                                 return 0;
 502                 }
 503         }
 504
 505         if (!len && reflog_len)
 506                 /* allow "@{...}" to mean the current branch reflog */
 507                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 508         else if (reflog_len)
 509                 refs_found = dwim_log(str, len, sha1, &real_ref);
 510         else
 511                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 512
 513         if (!refs_found)
 514                 return -1;
 515
 516         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 517             (refs_found > 1 ||
 518              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 519                 warning(warn_msg, len, str);
 520
 521         if (reflog_len) {
 522                 int nth, i;
 523                 unsigned long at_time;
 524                 unsigned long co_time;
 525                 int co_tz, co_cnt;
 526
 527                 /* Is it asking for N-th entry, or approxidate? */
 528                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 529                         char ch = str[at+2+i];
 530                         if ('0' <= ch && ch <= '9')
 531                                 nth = nth * 10 + ch - '0';
 532                         else
 533                                 nth = -1;
 534                 }
 535                 if (100000000 <= nth) {
 536                         at_time = nth;
 537                         nth = -1;
 538                 } else if (0 <= nth)
 539                         at_time = 0;
 540                 else {
 541                         int errors = 0;
 542                         char *tmp = xstrndup(str + at + 2, reflog_len);
 543                         at_time = approxidate_careful(tmp, &errors);
 544                         free(tmp);
 545                         if (errors) {
 546                                 free(real_ref);
 547                                 return -1;
 548                         }
 549                 }
 550                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 551                                 &co_time, &co_tz, &co_cnt)) {
 552                         if (!len) {
 553                                 if (starts_with(real_ref, "refs/heads/")) {
 554                                         str = real_ref + 11;
 555                                         len = strlen(real_ref + 11);
 556                                 } else {
 557                                         /* detached HEAD */
 558                                         str = "HEAD";
 559                                         len = 4;
 560                                 }
 561                         }
 562                         if (at_time) {
 563                                 if (!(flags & GET_SHA1_QUIETLY)) {
 564                                         warning("Log for '%.*s' only goes "
 565                                                 "back to %s.", len, str,
 566                                                 show_date(co_time, co_tz, DATE_RFC2822));
 567                                 }
 568                         } else {
 569                                 if (flags & GET_SHA1_QUIETLY) {
 570                                         exit(128);
 571                                 }
 572                                 die("Log for '%.*s' only has %d entries.",
 573                                     len, str, co_cnt);
 574                         }
 575                 }
 576         }
 577
 578         free(real_ref);
 579         return 0;
 580 }
 581
 582 static int get_parent(const char *name, int len,
 583                       unsigned char *result, int idx)
 584 {
 585         unsigned char sha1[20];
 586         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 587         struct commit *commit;
 588         struct commit_list *p;
 589
 590         if (ret)
 591                 return ret;
 592         commit = lookup_commit_reference(sha1);
 593         if (parse_commit(commit))
 594                 return -1;
 595         if (!idx) {
 596                 hashcpy(result, commit->object.sha1);
 597                 return 0;
 598         }
 599         p = commit->parents;
 600         while (p) {
 601                 if (!--idx) {
 602                         hashcpy(result, p->item->object.sha1);
 603                         return 0;
 604                 }
 605                 p = p->next;
 606         }
 607         return -1;
 608 }
 609
 610 static int get_nth_ancestor(const char *name, int len,
 611                             unsigned char *result, int generation)
 612 {
 613         unsigned char sha1[20];
 614         struct commit *commit;
 615         int ret;
 616
 617         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 618         if (ret)
 619                 return ret;
 620         commit = lookup_commit_reference(sha1);
 621         if (!commit)
 622                 return -1;
 623
 624         while (generation--) {
 625                 if (parse_commit(commit) || !commit->parents)
 626                         return -1;
 627                 commit = commit->parents->item;
 628         }
 629         hashcpy(result, commit->object.sha1);
 630         return 0;
 631 }
 632
 633 struct object *peel_to_type(const char *name, int namelen,
 634                             struct object *o, enum object_type expected_type)
 635 {
 636         if (name && !namelen)
 637                 namelen = strlen(name);
 638         while (1) {
 639                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 640                         return NULL;
 641                 if (expected_type == OBJ_ANY || o->type == expected_type)
 642                         return o;
 643                 if (o->type == OBJ_TAG)
 644                         o = ((struct tag*) o)->tagged;
 645                 else if (o->type == OBJ_COMMIT)
 646                         o = &(((struct commit *) o)->tree->object);
 647                 else {
 648                         if (name)
 649                                 error("%.*s: expected %s type, but the object "
 650                                       "dereferences to %s type",
 651                                       namelen, name, typename(expected_type),
 652                                       typename(o->type));
 653                         return NULL;
 654                 }
 655         }
 656 }
 657
 658 static int peel_onion(const char *name, int len, unsigned char *sha1)
 659 {
 660         unsigned char outer[20];
 661         const char *sp;
 662         unsigned int expected_type = 0;
 663         unsigned lookup_flags = 0;
 664         struct object *o;
 665
 666         /*
 667          * "ref^{type}" dereferences ref repeatedly until you cannot
 668          * dereference anymore, or you get an object of given type,
 669          * whichever comes first.  "ref^{}" means just dereference
 670          * tags until you get a non-tag.  "ref^0" is a shorthand for
 671          * "ref^{commit}".  "commit^{tree}" could be used to find the
 672          * top-level tree of the given commit.
 673          */
 674         if (len < 4 || name[len-1] != '}')
 675                 return -1;
 676
 677         for (sp = name + len - 1; name <= sp; sp--) {
 678                 int ch = *sp;
 679                 if (ch == '{' && name < sp && sp[-1] == '^')
 680                         break;
 681         }
 682         if (sp <= name)
 683                 return -1;
 684
 685         sp++; /* beginning of type name, or closing brace for empty */
 686         if (starts_with(sp, "commit}"))
 687                 expected_type = OBJ_COMMIT;
 688         else if (starts_with(sp, "tag}"))
 689                 expected_type = OBJ_TAG;
 690         else if (starts_with(sp, "tree}"))
 691                 expected_type = OBJ_TREE;
 692         else if (starts_with(sp, "blob}"))
 693                 expected_type = OBJ_BLOB;
 694         else if (starts_with(sp, "object}"))
 695                 expected_type = OBJ_ANY;
 696         else if (sp[0] == '}')
 697                 expected_type = OBJ_NONE;
 698         else if (sp[0] == '/')
 699                 expected_type = OBJ_COMMIT;
 700         else
 701                 return -1;
 702
 703         if (expected_type == OBJ_COMMIT)
 704                 lookup_flags = GET_SHA1_COMMITTISH;
 705         else if (expected_type == OBJ_TREE)
 706                 lookup_flags = GET_SHA1_TREEISH;
 707
 708         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 709                 return -1;
 710
 711         o = parse_object(outer);
 712         if (!o)
 713                 return -1;
 714         if (!expected_type) {
 715                 o = deref_tag(o, name, sp - name - 2);
 716                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 717                         return -1;
 718                 hashcpy(sha1, o->sha1);
 719                 return 0;
 720         }
 721
 722         /*
 723          * At this point, the syntax look correct, so
 724          * if we do not get the needed object, we should
 725          * barf.
 726          */
 727         o = peel_to_type(name, len, o, expected_type);
 728         if (!o)
 729                 return -1;
 730
 731         hashcpy(sha1, o->sha1);
 732         if (sp[0] == '/') {
 733                 /* "$commit^{/foo}" */
 734                 char *prefix;
 735                 int ret;
 736                 struct commit_list *list = NULL;
 737
 738                 /*
 739                  * $commit^{/}. Some regex implementation may reject.
 740                  * We don't need regex anyway. '' pattern always matches.
 741                  */
 742                 if (sp[1] == '}')
 743                         return 0;
 744
 745                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 746                 commit_list_insert((struct commit *)o, &list);
 747                 ret = get_sha1_oneline(prefix, sha1, list);
 748                 free(prefix);
 749                 return ret;
 750         }
 751         return 0;
 752 }
 753
 754 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 755 {
 756         const char *cp;
 757         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 758
 759         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 760                 char ch = *cp;
 761                 if (!isxdigit(ch)) {
 762                         /* We must be looking at g in "SOMETHING-g"
 763                          * for it to be describe output.
 764                          */
 765                         if (ch == 'g' && cp[-1] == '-') {
 766                                 cp++;
 767                                 len -= cp - name;
 768                                 return get_short_sha1(cp, len, sha1, flags);
 769                         }
 770                 }
 771         }
 772         return -1;
 773 }
 774
 775 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 776 {
 777         int ret, has_suffix;
 778         const char *cp;
 779
 780         /*
 781          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 782          */
 783         has_suffix = 0;
 784         for (cp = name + len - 1; name <= cp; cp--) {
 785                 int ch = *cp;
 786                 if ('0' <= ch && ch <= '9')
 787                         continue;
 788                 if (ch == '~' || ch == '^')
 789                         has_suffix = ch;
 790                 break;
 791         }
 792
 793         if (has_suffix) {
 794                 int num = 0;
 795                 int len1 = cp - name;
 796                 cp++;
 797                 while (cp < name + len)
 798                         num = num * 10 + *cp++ - '0';
 799                 if (!num && len1 == len - 1)
 800                         num = 1;
 801                 if (has_suffix == '^')
 802                         return get_parent(name, len1, sha1, num);
 803                 /* else if (has_suffix == '~') -- goes without saying */
 804                 return get_nth_ancestor(name, len1, sha1, num);
 805         }
 806
 807         ret = peel_onion(name, len, sha1);
 808         if (!ret)
 809                 return 0;
 810
 811         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 812         if (!ret)
 813                 return 0;
 814
 815         /* It could be describe output that is "SOMETHING-gXXXX" */
 816         ret = get_describe_name(name, len, sha1);
 817         if (!ret)
 818                 return 0;
 819
 820         return get_short_sha1(name, len, sha1, lookup_flags);
 821 }
 822
 823 /*
 824  * This interprets names like ':/Initial revision of "git"' by searching
 825  * through history and returning the first commit whose message starts
 826  * the given regular expression.
 827  *
 828  * For future extension, ':/!' is reserved. If you want to match a message
 829  * beginning with a '!', you have to repeat the exclamation mark.
 830  */
 831
 832 /* Remember to update object flag allocation in object.h */
 833 #define ONELINE_SEEN (1u<<20)
 834
 835 static int handle_one_ref(const char *path,
 836                 const unsigned char *sha1, int flag, void *cb_data)
 837 {
 838         struct commit_list **list = cb_data;
 839         struct object *object = parse_object(sha1);
 840         if (!object)
 841                 return 0;
 842         if (object->type == OBJ_TAG) {
 843                 object = deref_tag(object, path, strlen(path));
 844                 if (!object)
 845                         return 0;
 846         }
 847         if (object->type != OBJ_COMMIT)
 848                 return 0;
 849         commit_list_insert((struct commit *)object, list);
 850         return 0;
 851 }
 852
 853 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 854                             struct commit_list *list)
 855 {
 856         struct commit_list *backup = NULL, *l;
 857         int found = 0;
 858         regex_t regex;
 859
 860         if (prefix[0] == '!') {
 861                 if (prefix[1] != '!')
 862                         die ("Invalid search pattern: %s", prefix);
 863                 prefix++;
 864         }
 865
 866         if (regcomp(&regex, prefix, REG_EXTENDED))
 867                 die("Invalid search pattern: %s", prefix);
 868
 869         for (l = list; l; l = l->next) {
 870                 l->item->object.flags |= ONELINE_SEEN;
 871                 commit_list_insert(l->item, &backup);
 872         }
 873         while (list) {
 874                 const char *p, *buf;
 875                 struct commit *commit;
 876                 int matches;
 877
 878                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 879                 if (!parse_object(commit->object.sha1))
 880                         continue;
 881                 buf = get_commit_buffer(commit, NULL);
 882                 p = strstr(buf, "\n\n");
 883                 matches = p && !regexec(&regex, p + 2, 0, NULL, 0);
 884                 unuse_commit_buffer(commit, buf);
 885
 886                 if (matches) {
 887                         hashcpy(sha1, commit->object.sha1);
 888                         found = 1;
 889                         break;
 890                 }
 891         }
 892         regfree(&regex);
 893         free_commit_list(list);
 894         for (l = backup; l; l = l->next)
 895                 clear_commit_marks(l->item, ONELINE_SEEN);
 896         free_commit_list(backup);
 897         return found ? 0 : -1;
 898 }
 899
 900 struct grab_nth_branch_switch_cbdata {
 901         int remaining;
 902         struct strbuf buf;
 903 };
 904
 905 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 906                                   const char *email, unsigned long timestamp, int tz,
 907                                   const char *message, void *cb_data)
 908 {
 909         struct grab_nth_branch_switch_cbdata *cb = cb_data;
 910         const char *match = NULL, *target = NULL;
 911         size_t len;
 912
 913         if (skip_prefix(message, "checkout: moving from ", &match))
 914                 target = strstr(match, " to ");
 915
 916         if (!match || !target)
 917                 return 0;
 918         if (--(cb->remaining) == 0) {
 919                 len = target - match;
 920                 strbuf_reset(&cb->buf);
 921                 strbuf_add(&cb->buf, match, len);
 922                 return 1; /* we are done */
 923         }
 924         return 0;
 925 }
 926
 927 /*
 928  * Parse @{-N} syntax, return the number of characters parsed
 929  * if successful; otherwise signal an error with negative value.
 930  */
 931 static int interpret_nth_prior_checkout(const char *name, int namelen,
 932                                         struct strbuf *buf)
 933 {
 934         long nth;
 935         int retval;
 936         struct grab_nth_branch_switch_cbdata cb;
 937         const char *brace;
 938         char *num_end;
 939
 940         if (namelen < 4)
 941                 return -1;
 942         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
 943                 return -1;
 944         brace = memchr(name, '}', namelen);
 945         if (!brace)
 946                 return -1;
 947         nth = strtol(name + 3, &num_end, 10);
 948         if (num_end != brace)
 949                 return -1;
 950         if (nth <= 0)
 951                 return -1;
 952         cb.remaining = nth;
 953         strbuf_init(&cb.buf, 20);
 954
 955         retval = 0;
 956         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
 957                 strbuf_reset(buf);
 958                 strbuf_addbuf(buf, &cb.buf);
 959                 retval = brace - name + 1;
 960         }
 961
 962         strbuf_release(&cb.buf);
 963         return retval;
 964 }
 965
 966 int get_sha1_mb(const char *name, unsigned char *sha1)
 967 {
 968         struct commit *one, *two;
 969         struct commit_list *mbs;
 970         unsigned char sha1_tmp[20];
 971         const char *dots;
 972         int st;
 973
 974         dots = strstr(name, "...");
 975         if (!dots)
 976                 return get_sha1(name, sha1);
 977         if (dots == name)
 978                 st = get_sha1("HEAD", sha1_tmp);
 979         else {
 980                 struct strbuf sb;
 981                 strbuf_init(&sb, dots - name);
 982                 strbuf_add(&sb, name, dots - name);
 983                 st = get_sha1_committish(sb.buf, sha1_tmp);
 984                 strbuf_release(&sb);
 985         }
 986         if (st)
 987                 return st;
 988         one = lookup_commit_reference_gently(sha1_tmp, 0);
 989         if (!one)
 990                 return -1;
 991
 992         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
 993                 return -1;
 994         two = lookup_commit_reference_gently(sha1_tmp, 0);
 995         if (!two)
 996                 return -1;
 997         mbs = get_merge_bases(one, two);
 998         if (!mbs || mbs->next)
 999                 st = -1;
1000         else {
1001                 st = 0;
1002                 hashcpy(sha1, mbs->item->object.sha1);
1003         }
1004         free_commit_list(mbs);
1005         return st;
1006 }
1007
1008 /* parse @something syntax, when 'something' is not {.*} */
1009 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1010 {
1011         const char *next;
1012
1013         if (len || name[1] == '{')
1014                 return -1;
1015
1016         /* make sure it's a single @, or @@{.*}, not @foo */
1017         next = memchr(name + len + 1, '@', namelen - len - 1);
1018         if (next && next[1] != '{')
1019                 return -1;
1020         if (!next)
1021                 next = name + namelen;
1022         if (next != name + 1)
1023                 return -1;
1024
1025         strbuf_reset(buf);
1026         strbuf_add(buf, "HEAD", 4);
1027         return 1;
1028 }
1029
1030 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1031 {
1032         /* we have extra data, which might need further processing */
1033         struct strbuf tmp = STRBUF_INIT;
1034         int used = buf->len;
1035         int ret;
1036
1037         strbuf_add(buf, name + len, namelen - len);
1038         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1039         /* that data was not interpreted, remove our cruft */
1040         if (ret < 0) {
1041                 strbuf_setlen(buf, used);
1042                 return len;
1043         }
1044         strbuf_reset(buf);
1045         strbuf_addbuf(buf, &tmp);
1046         strbuf_release(&tmp);
1047         /* tweak for size of {-N} versus expanded ref name */
1048         return ret - used + len;
1049 }
1050
1051 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1052 {
1053         char *s = shorten_unambiguous_ref(ref, 0);
1054         strbuf_reset(buf);
1055         strbuf_addstr(buf, s);
1056         free(s);
1057 }
1058
1059 static const char *get_upstream_branch(const char *branch_buf, int len)
1060 {
1061         char *branch = xstrndup(branch_buf, len);
1062         struct branch *upstream = branch_get(*branch ? branch : NULL);
1063
1064         /*
1065          * Upstream can be NULL only if branch refers to HEAD and HEAD
1066          * points to something different than a branch.
1067          */
1068         if (!upstream)
1069                 die(_("HEAD does not point to a branch"));
1070         if (!upstream->merge || !upstream->merge[0]->dst) {
1071                 if (!ref_exists(upstream->refname))
1072                         die(_("No such branch: '%s'"), branch);
1073                 if (!upstream->merge) {
1074                         die(_("No upstream configured for branch '%s'"),
1075                                 upstream->name);
1076                 }
1077                 die(
1078                         _("Upstream branch '%s' not stored as a remote-tracking branch"),
1079                         upstream->merge[0]->src);
1080         }
1081         free(branch);
1082
1083         return upstream->merge[0]->dst;
1084 }
1085
1086 static int interpret_upstream_mark(const char *name, int namelen,
1087                                    int at, struct strbuf *buf)
1088 {
1089         int len;
1090
1091         len = upstream_mark(name + at, namelen - at);
1092         if (!len)
1093                 return -1;
1094
1095         if (memchr(name, ':', at))
1096                 return -1;
1097
1098         set_shortened_ref(buf, get_upstream_branch(name, at));
1099         return len + at;
1100 }
1101
1102 /*
1103  * This reads short-hand syntax that not only evaluates to a commit
1104  * object name, but also can act as if the end user spelled the name
1105  * of the branch from the command line.
1106  *
1107  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1108  *   places the name of the branch in the given buf and returns the
1109  *   number of characters parsed if successful.
1110  *
1111  * - "<branch>@{upstream}" finds the name of the other ref that
1112  *   <branch> is configured to merge with (missing <branch> defaults
1113  *   to the current branch), and places the name of the branch in the
1114  *   given buf and returns the number of characters parsed if
1115  *   successful.
1116  *
1117  * If the input is not of the accepted format, it returns a negative
1118  * number to signal an error.
1119  *
1120  * If the input was ok but there are not N branch switches in the
1121  * reflog, it returns 0.
1122  */
1123 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1124 {
1125         char *at;
1126         const char *start;
1127         int len = interpret_nth_prior_checkout(name, namelen, buf);
1128
1129         if (!namelen)
1130                 namelen = strlen(name);
1131
1132         if (!len) {
1133                 return len; /* syntax Ok, not enough switches */
1134         } else if (len > 0) {
1135                 if (len == namelen)
1136                         return len; /* consumed all */
1137                 else
1138                         return reinterpret(name, namelen, len, buf);
1139         }
1140
1141         for (start = name;
1142              (at = memchr(start, '@', namelen - (start - name)));
1143              start = at + 1) {
1144
1145                 len = interpret_empty_at(name, namelen, at - name, buf);
1146                 if (len > 0)
1147                         return reinterpret(name, namelen, len, buf);
1148
1149                 len = interpret_upstream_mark(name, namelen, at - name, buf);
1150                 if (len > 0)
1151                         return len;
1152         }
1153
1154         return -1;
1155 }
1156
1157 int strbuf_branchname(struct strbuf *sb, const char *name)
1158 {
1159         int len = strlen(name);
1160         int used = interpret_branch_name(name, len, sb);
1161
1162         if (used == len)
1163                 return 0;
1164         if (used < 0)
1165                 used = 0;
1166         strbuf_add(sb, name + used, len - used);
1167         return len;
1168 }
1169
1170 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1171 {
1172         strbuf_branchname(sb, name);
1173         if (name[0] == '-')
1174                 return -1;
1175         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1176         return check_refname_format(sb->buf, 0);
1177 }
1178
1179 /*
1180  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1181  * notably "xyz^" for "parent of xyz"
1182  */
1183 int get_sha1(const char *name, unsigned char *sha1)
1184 {
1185         struct object_context unused;
1186         return get_sha1_with_context(name, 0, sha1, &unused);
1187 }
1188
1189 /*
1190  * Many callers know that the user meant to name a commit-ish by
1191  * syntactical positions where the object name appears.  Calling this
1192  * function allows the machinery to disambiguate shorter-than-unique
1193  * abbreviated object names between commit-ish and others.
1194  *
1195  * Note that this does NOT error out when the named object is not a
1196  * commit-ish. It is merely to give a hint to the disambiguation
1197  * machinery.
1198  */
1199 int get_sha1_committish(const char *name, unsigned char *sha1)
1200 {
1201         struct object_context unused;
1202         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1203                                      sha1, &unused);
1204 }
1205
1206 int get_sha1_treeish(const char *name, unsigned char *sha1)
1207 {
1208         struct object_context unused;
1209         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1210                                      sha1, &unused);
1211 }
1212
1213 int get_sha1_commit(const char *name, unsigned char *sha1)
1214 {
1215         struct object_context unused;
1216         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1217                                      sha1, &unused);
1218 }
1219
1220 int get_sha1_tree(const char *name, unsigned char *sha1)
1221 {
1222         struct object_context unused;
1223         return get_sha1_with_context(name, GET_SHA1_TREE,
1224                                      sha1, &unused);
1225 }
1226
1227 int get_sha1_blob(const char *name, unsigned char *sha1)
1228 {
1229         struct object_context unused;
1230         return get_sha1_with_context(name, GET_SHA1_BLOB,
1231                                      sha1, &unused);
1232 }
1233
1234 /* Must be called only when object_name:filename doesn't exist. */
1235 static void diagnose_invalid_sha1_path(const char *prefix,
1236                                        const char *filename,
1237                                        const unsigned char *tree_sha1,
1238                                        const char *object_name,
1239                                        int object_name_len)
1240 {
1241         unsigned char sha1[20];
1242         unsigned mode;
1243
1244         if (!prefix)
1245                 prefix = "";
1246
1247         if (file_exists(filename))
1248                 die("Path '%s' exists on disk, but not in '%.*s'.",
1249                     filename, object_name_len, object_name);
1250         if (errno == ENOENT || errno == ENOTDIR) {
1251                 char *fullname = xstrfmt("%s%s", prefix, filename);
1252
1253                 if (!get_tree_entry(tree_sha1, fullname,
1254                                     sha1, &mode)) {
1255                         die("Path '%s' exists, but not '%s'.\n"
1256                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1257                             fullname,
1258                             filename,
1259                             object_name_len, object_name,
1260                             fullname,
1261                             object_name_len, object_name,
1262                             filename);
1263                 }
1264                 die("Path '%s' does not exist in '%.*s'",
1265                     filename, object_name_len, object_name);
1266         }
1267 }
1268
1269 /* Must be called only when :stage:filename doesn't exist. */
1270 static void diagnose_invalid_index_path(int stage,
1271                                         const char *prefix,
1272                                         const char *filename)
1273 {
1274         const struct cache_entry *ce;
1275         int pos;
1276         unsigned namelen = strlen(filename);
1277         unsigned fullnamelen;
1278         char *fullname;
1279
1280         if (!prefix)
1281                 prefix = "";
1282
1283         /* Wrong stage number? */
1284         pos = cache_name_pos(filename, namelen);
1285         if (pos < 0)
1286                 pos = -pos - 1;
1287         if (pos < active_nr) {
1288                 ce = active_cache[pos];
1289                 if (ce_namelen(ce) == namelen &&
1290                     !memcmp(ce->name, filename, namelen))
1291                         die("Path '%s' is in the index, but not at stage %d.\n"
1292                             "Did you mean ':%d:%s'?",
1293                             filename, stage,
1294                             ce_stage(ce), filename);
1295         }
1296
1297         /* Confusion between relative and absolute filenames? */
1298         fullnamelen = namelen + strlen(prefix);
1299         fullname = xmalloc(fullnamelen + 1);
1300         strcpy(fullname, prefix);
1301         strcat(fullname, filename);
1302         pos = cache_name_pos(fullname, fullnamelen);
1303         if (pos < 0)
1304                 pos = -pos - 1;
1305         if (pos < active_nr) {
1306                 ce = active_cache[pos];
1307                 if (ce_namelen(ce) == fullnamelen &&
1308                     !memcmp(ce->name, fullname, fullnamelen))
1309                         die("Path '%s' is in the index, but not '%s'.\n"
1310                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1311                             fullname, filename,
1312                             ce_stage(ce), fullname,
1313                             ce_stage(ce), filename);
1314         }
1315
1316         if (file_exists(filename))
1317                 die("Path '%s' exists on disk, but not in the index.", filename);
1318         if (errno == ENOENT || errno == ENOTDIR)
1319                 die("Path '%s' does not exist (neither on disk nor in the index).",
1320                     filename);
1321
1322         free(fullname);
1323 }
1324
1325
1326 static char *resolve_relative_path(const char *rel)
1327 {
1328         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1329                 return NULL;
1330
1331         if (!startup_info)
1332                 die("BUG: startup_info struct is not initialized.");
1333
1334         if (!is_inside_work_tree())
1335                 die("relative path syntax can't be used outside working tree.");
1336
1337         /* die() inside prefix_path() if resolved path is outside worktree */
1338         return prefix_path(startup_info->prefix,
1339                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1340                            rel);
1341 }
1342
1343 static int get_sha1_with_context_1(const char *name,
1344                                    unsigned flags,
1345                                    const char *prefix,
1346                                    unsigned char *sha1,
1347                                    struct object_context *oc)
1348 {
1349         int ret, bracket_depth;
1350         int namelen = strlen(name);
1351         const char *cp;
1352         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1353
1354         memset(oc, 0, sizeof(*oc));
1355         oc->mode = S_IFINVALID;
1356         ret = get_sha1_1(name, namelen, sha1, flags);
1357         if (!ret)
1358                 return ret;
1359         /*
1360          * sha1:path --> object name of path in ent sha1
1361          * :path -> object name of absolute path in index
1362          * :./path -> object name of path relative to cwd in index
1363          * :[0-3]:path -> object name of path in index at stage
1364          * :/foo -> recent commit matching foo
1365          */
1366         if (name[0] == ':') {
1367                 int stage = 0;
1368                 const struct cache_entry *ce;
1369                 char *new_path = NULL;
1370                 int pos;
1371                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1372                         struct commit_list *list = NULL;
1373                         for_each_ref(handle_one_ref, &list);
1374                         commit_list_sort_by_date(&list);
1375                         return get_sha1_oneline(name + 2, sha1, list);
1376                 }
1377                 if (namelen < 3 ||
1378                     name[2] != ':' ||
1379                     name[1] < '0' || '3' < name[1])
1380                         cp = name + 1;
1381                 else {
1382                         stage = name[1] - '0';
1383                         cp = name + 3;
1384                 }
1385                 new_path = resolve_relative_path(cp);
1386                 if (!new_path) {
1387                         namelen = namelen - (cp - name);
1388                 } else {
1389                         cp = new_path;
1390                         namelen = strlen(cp);
1391                 }
1392
1393                 strlcpy(oc->path, cp, sizeof(oc->path));
1394
1395                 if (!active_cache)
1396                         read_cache();
1397                 pos = cache_name_pos(cp, namelen);
1398                 if (pos < 0)
1399                         pos = -pos - 1;
1400                 while (pos < active_nr) {
1401                         ce = active_cache[pos];
1402                         if (ce_namelen(ce) != namelen ||
1403                             memcmp(ce->name, cp, namelen))
1404                                 break;
1405                         if (ce_stage(ce) == stage) {
1406                                 hashcpy(sha1, ce->sha1);
1407                                 oc->mode = ce->ce_mode;
1408                                 free(new_path);
1409                                 return 0;
1410                         }
1411                         pos++;
1412                 }
1413                 if (only_to_die && name[1] && name[1] != '/')
1414                         diagnose_invalid_index_path(stage, prefix, cp);
1415                 free(new_path);
1416                 return -1;
1417         }
1418         for (cp = name, bracket_depth = 0; *cp; cp++) {
1419                 if (*cp == '{')
1420                         bracket_depth++;
1421                 else if (bracket_depth && *cp == '}')
1422                         bracket_depth--;
1423                 else if (!bracket_depth && *cp == ':')
1424                         break;
1425         }
1426         if (*cp == ':') {
1427                 unsigned char tree_sha1[20];
1428                 int len = cp - name;
1429                 if (!get_sha1_1(name, len, tree_sha1, GET_SHA1_TREEISH)) {
1430                         const char *filename = cp+1;
1431                         char *new_filename = NULL;
1432
1433                         new_filename = resolve_relative_path(filename);
1434                         if (new_filename)
1435                                 filename = new_filename;
1436                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1437                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1438                                         filename, sha1, &oc->symlink_path,
1439                                         &oc->mode);
1440                         } else {
1441                                 ret = get_tree_entry(tree_sha1, filename,
1442                                                      sha1, &oc->mode);
1443                                 if (ret && only_to_die) {
1444                                         diagnose_invalid_sha1_path(prefix,
1445                                                                    filename,
1446                                                                    tree_sha1,
1447                                                                    name, len);
1448                                 }
1449                         }
1450                         hashcpy(oc->tree, tree_sha1);
1451                         strlcpy(oc->path, filename, sizeof(oc->path));
1452
1453                         free(new_filename);
1454                         return ret;
1455                 } else {
1456                         if (only_to_die)
1457                                 die("Invalid object name '%.*s'.", len, name);
1458                 }
1459         }
1460         return ret;
1461 }
1462
1463 /*
1464  * Call this function when you know "name" given by the end user must
1465  * name an object but it doesn't; the function _may_ die with a better
1466  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1467  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1468  * you have a chance to diagnose the error further.
1469  */
1470 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1471 {
1472         struct object_context oc;
1473         unsigned char sha1[20];
1474         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1475 }
1476
1477 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1478 {
1479         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1480                 die("BUG: incompatible flags for get_sha1_with_context");
1481         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1482 }