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                 size_t objdir_len = strlen(objdir);
  91                 fakeent = xmalloc(st_add3(sizeof(*fakeent), objdir_len, 43));
  92                 memcpy(fakeent->base, objdir, objdir_len);
  93                 fakeent->name = fakeent->base + objdir_len + 1;
  94                 fakeent->name[-1] = '/';
  95         }
  96         fakeent->next = alt_odb_list;
  97
  98         xsnprintf(hex, sizeof(hex), "%.2s", hex_pfx);
  99         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 100                 struct dirent *de;
 101                 DIR *dir;
 102                 /*
 103                  * every alt_odb struct has 42 extra bytes after the base
 104                  * for exactly this purpose
 105                  */
 106                 xsnprintf(alt->name, 42, "%.2s/", hex_pfx);
 107                 dir = opendir(alt->base);
 108                 if (!dir)
 109                         continue;
 110
 111                 while (!ds->ambiguous && (de = readdir(dir)) != NULL) {
 112                         unsigned char sha1[20];
 113
 114                         if (strlen(de->d_name) != 38)
 115                                 continue;
 116                         if (memcmp(de->d_name, hex_pfx + 2, len - 2))
 117                                 continue;
 118                         memcpy(hex + 2, de->d_name, 38);
 119                         if (!get_sha1_hex(hex, sha1))
 120                                 update_candidates(ds, sha1);
 121                 }
 122                 closedir(dir);
 123         }
 124 }
 125
 126 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 127 {
 128         do {
 129                 if (*a != *b)
 130                         return 0;
 131                 a++;
 132                 b++;
 133                 len -= 2;
 134         } while (len > 1);
 135         if (len)
 136                 if ((*a ^ *b) & 0xf0)
 137                         return 0;
 138         return 1;
 139 }
 140
 141 static void unique_in_pack(int len,
 142                           const unsigned char *bin_pfx,
 143                            struct packed_git *p,
 144                            struct disambiguate_state *ds)
 145 {
 146         uint32_t num, last, i, first = 0;
 147         const unsigned char *current = NULL;
 148
 149         open_pack_index(p);
 150         num = p->num_objects;
 151         last = num;
 152         while (first < last) {
 153                 uint32_t mid = (first + last) / 2;
 154                 const unsigned char *current;
 155                 int cmp;
 156
 157                 current = nth_packed_object_sha1(p, mid);
 158                 cmp = hashcmp(bin_pfx, current);
 159                 if (!cmp) {
 160                         first = mid;
 161                         break;
 162                 }
 163                 if (cmp > 0) {
 164                         first = mid+1;
 165                         continue;
 166                 }
 167                 last = mid;
 168         }
 169
 170         /*
 171          * At this point, "first" is the location of the lowest object
 172          * with an object name that could match "bin_pfx".  See if we have
 173          * 0, 1 or more objects that actually match(es).
 174          */
 175         for (i = first; i < num && !ds->ambiguous; i++) {
 176                 current = nth_packed_object_sha1(p, i);
 177                 if (!match_sha(len, bin_pfx, current))
 178                         break;
 179                 update_candidates(ds, current);
 180         }
 181 }
 182
 183 static void find_short_packed_object(int len, const unsigned char *bin_pfx,
 184                                      struct disambiguate_state *ds)
 185 {
 186         struct packed_git *p;
 187
 188         prepare_packed_git();
 189         for (p = packed_git; p && !ds->ambiguous; p = p->next)
 190                 unique_in_pack(len, bin_pfx, p, ds);
 191 }
 192
 193 #define SHORT_NAME_NOT_FOUND (-1)
 194 #define SHORT_NAME_AMBIGUOUS (-2)
 195
 196 static int finish_object_disambiguation(struct disambiguate_state *ds,
 197                                         unsigned char *sha1)
 198 {
 199         if (ds->ambiguous)
 200                 return SHORT_NAME_AMBIGUOUS;
 201
 202         if (!ds->candidate_exists)
 203                 return SHORT_NAME_NOT_FOUND;
 204
 205         if (!ds->candidate_checked)
 206                 /*
 207                  * If this is the only candidate, there is no point
 208                  * calling the disambiguation hint callback.
 209                  *
 210                  * On the other hand, if the current candidate
 211                  * replaced an earlier candidate that did _not_ pass
 212                  * the disambiguation hint callback, then we do have
 213                  * more than one objects that match the short name
 214                  * given, so we should make sure this one matches;
 215                  * otherwise, if we discovered this one and the one
 216                  * that we previously discarded in the reverse order,
 217                  * we would end up showing different results in the
 218                  * same repository!
 219                  */
 220                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 221                                     ds->fn(ds->candidate, ds->cb_data));
 222
 223         if (!ds->candidate_ok)
 224                 return SHORT_NAME_AMBIGUOUS;
 225
 226         hashcpy(sha1, ds->candidate);
 227         return 0;
 228 }
 229
 230 static int disambiguate_commit_only(const unsigned char *sha1, void *cb_data_unused)
 231 {
 232         int kind = sha1_object_info(sha1, NULL);
 233         return kind == OBJ_COMMIT;
 234 }
 235
 236 static int disambiguate_committish_only(const unsigned char *sha1, void *cb_data_unused)
 237 {
 238         struct object *obj;
 239         int kind;
 240
 241         kind = sha1_object_info(sha1, NULL);
 242         if (kind == OBJ_COMMIT)
 243                 return 1;
 244         if (kind != OBJ_TAG)
 245                 return 0;
 246
 247         /* We need to do this the hard way... */
 248         obj = deref_tag(parse_object(sha1), NULL, 0);
 249         if (obj && obj->type == OBJ_COMMIT)
 250                 return 1;
 251         return 0;
 252 }
 253
 254 static int disambiguate_tree_only(const unsigned char *sha1, void *cb_data_unused)
 255 {
 256         int kind = sha1_object_info(sha1, NULL);
 257         return kind == OBJ_TREE;
 258 }
 259
 260 static int disambiguate_treeish_only(const unsigned char *sha1, void *cb_data_unused)
 261 {
 262         struct object *obj;
 263         int kind;
 264
 265         kind = sha1_object_info(sha1, NULL);
 266         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 267                 return 1;
 268         if (kind != OBJ_TAG)
 269                 return 0;
 270
 271         /* We need to do this the hard way... */
 272         obj = deref_tag(parse_object(sha1), NULL, 0);
 273         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 274                 return 1;
 275         return 0;
 276 }
 277
 278 static int disambiguate_blob_only(const unsigned char *sha1, void *cb_data_unused)
 279 {
 280         int kind = sha1_object_info(sha1, NULL);
 281         return kind == OBJ_BLOB;
 282 }
 283
 284 static int prepare_prefixes(const char *name, int len,
 285                             unsigned char *bin_pfx,
 286                             char *hex_pfx)
 287 {
 288         int i;
 289
 290         hashclr(bin_pfx);
 291         memset(hex_pfx, 'x', 40);
 292         for (i = 0; i < len ;i++) {
 293                 unsigned char c = name[i];
 294                 unsigned char val;
 295                 if (c >= '0' && c <= '9')
 296                         val = c - '0';
 297                 else if (c >= 'a' && c <= 'f')
 298                         val = c - 'a' + 10;
 299                 else if (c >= 'A' && c <='F') {
 300                         val = c - 'A' + 10;
 301                         c -= 'A' - 'a';
 302                 }
 303                 else
 304                         return -1;
 305                 hex_pfx[i] = c;
 306                 if (!(i & 1))
 307                         val <<= 4;
 308                 bin_pfx[i >> 1] |= val;
 309         }
 310         return 0;
 311 }
 312
 313 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 314                           unsigned flags)
 315 {
 316         int status;
 317         char hex_pfx[40];
 318         unsigned char bin_pfx[20];
 319         struct disambiguate_state ds;
 320         int quietly = !!(flags & GET_SHA1_QUIETLY);
 321
 322         if (len < MINIMUM_ABBREV || len > 40)
 323                 return -1;
 324         if (prepare_prefixes(name, len, bin_pfx, hex_pfx) < 0)
 325                 return -1;
 326
 327         prepare_alt_odb();
 328
 329         memset(&ds, 0, sizeof(ds));
 330
 331         if (HAS_MULTI_BITS(flags & GET_SHA1_DISAMBIGUATORS))
 332                 die("BUG: multiple get_short_sha1 disambiguator flags");
 333
 334         if (flags & GET_SHA1_COMMIT)
 335                 ds.fn = disambiguate_commit_only;
 336         else if (flags & GET_SHA1_COMMITTISH)
 337                 ds.fn = disambiguate_committish_only;
 338         else if (flags & GET_SHA1_TREE)
 339                 ds.fn = disambiguate_tree_only;
 340         else if (flags & GET_SHA1_TREEISH)
 341                 ds.fn = disambiguate_treeish_only;
 342         else if (flags & GET_SHA1_BLOB)
 343                 ds.fn = disambiguate_blob_only;
 344
 345         find_short_object_filename(len, hex_pfx, &ds);
 346         find_short_packed_object(len, bin_pfx, &ds);
 347         status = finish_object_disambiguation(&ds, sha1);
 348
 349         if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
 350                 return error("short SHA1 %.*s is ambiguous.", len, hex_pfx);
 351         return status;
 352 }
 353
 354 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 355 {
 356         char hex_pfx[40];
 357         unsigned char bin_pfx[20];
 358         struct disambiguate_state ds;
 359         int len = strlen(prefix);
 360
 361         if (len < MINIMUM_ABBREV || len > 40)
 362                 return -1;
 363         if (prepare_prefixes(prefix, len, bin_pfx, hex_pfx) < 0)
 364                 return -1;
 365
 366         prepare_alt_odb();
 367
 368         memset(&ds, 0, sizeof(ds));
 369         ds.always_call_fn = 1;
 370         ds.cb_data = cb_data;
 371         ds.fn = fn;
 372
 373         find_short_object_filename(len, hex_pfx, &ds);
 374         find_short_packed_object(len, bin_pfx, &ds);
 375         return ds.ambiguous;
 376 }
 377
 378 int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 379 {
 380         int status, exists;
 381
 382         sha1_to_hex_r(hex, sha1);
 383         if (len == 40 || !len)
 384                 return 40;
 385         exists = has_sha1_file(sha1);
 386         while (len < 40) {
 387                 unsigned char sha1_ret[20];
 388                 status = get_short_sha1(hex, len, sha1_ret, GET_SHA1_QUIETLY);
 389                 if (exists
 390                     ? !status
 391                     : status == SHORT_NAME_NOT_FOUND) {
 392                         hex[len] = 0;
 393                         return len;
 394                 }
 395                 len++;
 396         }
 397         return len;
 398 }
 399
 400 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 401 {
 402         static char hex[GIT_SHA1_HEXSZ + 1];
 403         find_unique_abbrev_r(hex, sha1, len);
 404         return hex;
 405 }
 406
 407 static int ambiguous_path(const char *path, int len)
 408 {
 409         int slash = 1;
 410         int cnt;
 411
 412         for (cnt = 0; cnt < len; cnt++) {
 413                 switch (*path++) {
 414                 case '\0':
 415                         break;
 416                 case '/':
 417                         if (slash)
 418                                 break;
 419                         slash = 1;
 420                         continue;
 421                 case '.':
 422                         continue;
 423                 default:
 424                         slash = 0;
 425                         continue;
 426                 }
 427                 break;
 428         }
 429         return slash;
 430 }
 431
 432 static inline int at_mark(const char *string, int len,
 433                           const char **suffix, int nr)
 434 {
 435         int i;
 436
 437         for (i = 0; i < nr; i++) {
 438                 int suffix_len = strlen(suffix[i]);
 439                 if (suffix_len <= len
 440                     && !memcmp(string, suffix[i], suffix_len))
 441                         return suffix_len;
 442         }
 443         return 0;
 444 }
 445
 446 static inline int upstream_mark(const char *string, int len)
 447 {
 448         const char *suffix[] = { "@{upstream}", "@{u}" };
 449         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 450 }
 451
 452 static inline int push_mark(const char *string, int len)
 453 {
 454         const char *suffix[] = { "@{push}" };
 455         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 456 }
 457
 458 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 459 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 460
 461 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 462                           unsigned int flags)
 463 {
 464         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 465         static const char *object_name_msg = N_(
 466         "Git normally never creates a ref that ends with 40 hex characters\n"
 467         "because it will be ignored when you just specify 40-hex. These refs\n"
 468         "may be created by mistake. For example,\n"
 469         "\n"
 470         "  git checkout -b $br $(git rev-parse ...)\n"
 471         "\n"
 472         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 473         "examine these refs and maybe delete them. Turn this message off by\n"
 474         "running \"git config advice.objectNameWarning false\"");
 475         unsigned char tmp_sha1[20];
 476         char *real_ref = NULL;
 477         int refs_found = 0;
 478         int at, reflog_len, nth_prior = 0;
 479
 480         if (len == 40 && !get_sha1_hex(str, sha1)) {
 481                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 482                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 483                         if (refs_found > 0) {
 484                                 warning(warn_msg, len, str);
 485                                 if (advice_object_name_warning)
 486                                         fprintf(stderr, "%s\n", _(object_name_msg));
 487                         }
 488                         free(real_ref);
 489                 }
 490                 return 0;
 491         }
 492
 493         /* basic@{time or number or -number} format to query ref-log */
 494         reflog_len = at = 0;
 495         if (len && str[len-1] == '}') {
 496                 for (at = len-4; at >= 0; at--) {
 497                         if (str[at] == '@' && str[at+1] == '{') {
 498                                 if (str[at+2] == '-') {
 499                                         if (at != 0)
 500                                                 /* @{-N} not at start */
 501                                                 return -1;
 502                                         nth_prior = 1;
 503                                         continue;
 504                                 }
 505                                 if (!upstream_mark(str + at, len - at) &&
 506                                     !push_mark(str + at, len - at)) {
 507                                         reflog_len = (len-1) - (at+2);
 508                                         len = at;
 509                                 }
 510                                 break;
 511                         }
 512                 }
 513         }
 514
 515         /* Accept only unambiguous ref paths. */
 516         if (len && ambiguous_path(str, len))
 517                 return -1;
 518
 519         if (nth_prior) {
 520                 struct strbuf buf = STRBUF_INIT;
 521                 int detached;
 522
 523                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 524                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 525                         strbuf_release(&buf);
 526                         if (detached)
 527                                 return 0;
 528                 }
 529         }
 530
 531         if (!len && reflog_len)
 532                 /* allow "@{...}" to mean the current branch reflog */
 533                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 534         else if (reflog_len)
 535                 refs_found = dwim_log(str, len, sha1, &real_ref);
 536         else
 537                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 538
 539         if (!refs_found)
 540                 return -1;
 541
 542         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 543             (refs_found > 1 ||
 544              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 545                 warning(warn_msg, len, str);
 546
 547         if (reflog_len) {
 548                 int nth, i;
 549                 unsigned long at_time;
 550                 unsigned long co_time;
 551                 int co_tz, co_cnt;
 552
 553                 /* Is it asking for N-th entry, or approxidate? */
 554                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 555                         char ch = str[at+2+i];
 556                         if ('0' <= ch && ch <= '9')
 557                                 nth = nth * 10 + ch - '0';
 558                         else
 559                                 nth = -1;
 560                 }
 561                 if (100000000 <= nth) {
 562                         at_time = nth;
 563                         nth = -1;
 564                 } else if (0 <= nth)
 565                         at_time = 0;
 566                 else {
 567                         int errors = 0;
 568                         char *tmp = xstrndup(str + at + 2, reflog_len);
 569                         at_time = approxidate_careful(tmp, &errors);
 570                         free(tmp);
 571                         if (errors) {
 572                                 free(real_ref);
 573                                 return -1;
 574                         }
 575                 }
 576                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 577                                 &co_time, &co_tz, &co_cnt)) {
 578                         if (!len) {
 579                                 if (starts_with(real_ref, "refs/heads/")) {
 580                                         str = real_ref + 11;
 581                                         len = strlen(real_ref + 11);
 582                                 } else {
 583                                         /* detached HEAD */
 584                                         str = "HEAD";
 585                                         len = 4;
 586                                 }
 587                         }
 588                         if (at_time) {
 589                                 if (!(flags & GET_SHA1_QUIETLY)) {
 590                                         warning("Log for '%.*s' only goes "
 591                                                 "back to %s.", len, str,
 592                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 593                                 }
 594                         } else {
 595                                 if (flags & GET_SHA1_QUIETLY) {
 596                                         exit(128);
 597                                 }
 598                                 die("Log for '%.*s' only has %d entries.",
 599                                     len, str, co_cnt);
 600                         }
 601                 }
 602         }
 603
 604         free(real_ref);
 605         return 0;
 606 }
 607
 608 static int get_parent(const char *name, int len,
 609                       unsigned char *result, int idx)
 610 {
 611         unsigned char sha1[20];
 612         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 613         struct commit *commit;
 614         struct commit_list *p;
 615
 616         if (ret)
 617                 return ret;
 618         commit = lookup_commit_reference(sha1);
 619         if (parse_commit(commit))
 620                 return -1;
 621         if (!idx) {
 622                 hashcpy(result, commit->object.oid.hash);
 623                 return 0;
 624         }
 625         p = commit->parents;
 626         while (p) {
 627                 if (!--idx) {
 628                         hashcpy(result, p->item->object.oid.hash);
 629                         return 0;
 630                 }
 631                 p = p->next;
 632         }
 633         return -1;
 634 }
 635
 636 static int get_nth_ancestor(const char *name, int len,
 637                             unsigned char *result, int generation)
 638 {
 639         unsigned char sha1[20];
 640         struct commit *commit;
 641         int ret;
 642
 643         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 644         if (ret)
 645                 return ret;
 646         commit = lookup_commit_reference(sha1);
 647         if (!commit)
 648                 return -1;
 649
 650         while (generation--) {
 651                 if (parse_commit(commit) || !commit->parents)
 652                         return -1;
 653                 commit = commit->parents->item;
 654         }
 655         hashcpy(result, commit->object.oid.hash);
 656         return 0;
 657 }
 658
 659 struct object *peel_to_type(const char *name, int namelen,
 660                             struct object *o, enum object_type expected_type)
 661 {
 662         if (name && !namelen)
 663                 namelen = strlen(name);
 664         while (1) {
 665                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 666                         return NULL;
 667                 if (expected_type == OBJ_ANY || o->type == expected_type)
 668                         return o;
 669                 if (o->type == OBJ_TAG)
 670                         o = ((struct tag*) o)->tagged;
 671                 else if (o->type == OBJ_COMMIT)
 672                         o = &(((struct commit *) o)->tree->object);
 673                 else {
 674                         if (name)
 675                                 error("%.*s: expected %s type, but the object "
 676                                       "dereferences to %s type",
 677                                       namelen, name, typename(expected_type),
 678                                       typename(o->type));
 679                         return NULL;
 680                 }
 681         }
 682 }
 683
 684 static int peel_onion(const char *name, int len, unsigned char *sha1,
 685                       unsigned lookup_flags)
 686 {
 687         unsigned char outer[20];
 688         const char *sp;
 689         unsigned int expected_type = 0;
 690         struct object *o;
 691
 692         /*
 693          * "ref^{type}" dereferences ref repeatedly until you cannot
 694          * dereference anymore, or you get an object of given type,
 695          * whichever comes first.  "ref^{}" means just dereference
 696          * tags until you get a non-tag.  "ref^0" is a shorthand for
 697          * "ref^{commit}".  "commit^{tree}" could be used to find the
 698          * top-level tree of the given commit.
 699          */
 700         if (len < 4 || name[len-1] != '}')
 701                 return -1;
 702
 703         for (sp = name + len - 1; name <= sp; sp--) {
 704                 int ch = *sp;
 705                 if (ch == '{' && name < sp && sp[-1] == '^')
 706                         break;
 707         }
 708         if (sp <= name)
 709                 return -1;
 710
 711         sp++; /* beginning of type name, or closing brace for empty */
 712         if (starts_with(sp, "commit}"))
 713                 expected_type = OBJ_COMMIT;
 714         else if (starts_with(sp, "tag}"))
 715                 expected_type = OBJ_TAG;
 716         else if (starts_with(sp, "tree}"))
 717                 expected_type = OBJ_TREE;
 718         else if (starts_with(sp, "blob}"))
 719                 expected_type = OBJ_BLOB;
 720         else if (starts_with(sp, "object}"))
 721                 expected_type = OBJ_ANY;
 722         else if (sp[0] == '}')
 723                 expected_type = OBJ_NONE;
 724         else if (sp[0] == '/')
 725                 expected_type = OBJ_COMMIT;
 726         else
 727                 return -1;
 728
 729         lookup_flags &= ~GET_SHA1_DISAMBIGUATORS;
 730         if (expected_type == OBJ_COMMIT)
 731                 lookup_flags |= GET_SHA1_COMMITTISH;
 732         else if (expected_type == OBJ_TREE)
 733                 lookup_flags |= GET_SHA1_TREEISH;
 734
 735         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 736                 return -1;
 737
 738         o = parse_object(outer);
 739         if (!o)
 740                 return -1;
 741         if (!expected_type) {
 742                 o = deref_tag(o, name, sp - name - 2);
 743                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 744                         return -1;
 745                 hashcpy(sha1, o->oid.hash);
 746                 return 0;
 747         }
 748
 749         /*
 750          * At this point, the syntax look correct, so
 751          * if we do not get the needed object, we should
 752          * barf.
 753          */
 754         o = peel_to_type(name, len, o, expected_type);
 755         if (!o)
 756                 return -1;
 757
 758         hashcpy(sha1, o->oid.hash);
 759         if (sp[0] == '/') {
 760                 /* "$commit^{/foo}" */
 761                 char *prefix;
 762                 int ret;
 763                 struct commit_list *list = NULL;
 764
 765                 /*
 766                  * $commit^{/}. Some regex implementation may reject.
 767                  * We don't need regex anyway. '' pattern always matches.
 768                  */
 769                 if (sp[1] == '}')
 770                         return 0;
 771
 772                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 773                 commit_list_insert((struct commit *)o, &list);
 774                 ret = get_sha1_oneline(prefix, sha1, list);
 775                 free(prefix);
 776                 return ret;
 777         }
 778         return 0;
 779 }
 780
 781 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 782 {
 783         const char *cp;
 784         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 785
 786         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 787                 char ch = *cp;
 788                 if (!isxdigit(ch)) {
 789                         /* We must be looking at g in "SOMETHING-g"
 790                          * for it to be describe output.
 791                          */
 792                         if (ch == 'g' && cp[-1] == '-') {
 793                                 cp++;
 794                                 len -= cp - name;
 795                                 return get_short_sha1(cp, len, sha1, flags);
 796                         }
 797                 }
 798         }
 799         return -1;
 800 }
 801
 802 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 803 {
 804         int ret, has_suffix;
 805         const char *cp;
 806
 807         /*
 808          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 809          */
 810         has_suffix = 0;
 811         for (cp = name + len - 1; name <= cp; cp--) {
 812                 int ch = *cp;
 813                 if ('0' <= ch && ch <= '9')
 814                         continue;
 815                 if (ch == '~' || ch == '^')
 816                         has_suffix = ch;
 817                 break;
 818         }
 819
 820         if (has_suffix) {
 821                 int num = 0;
 822                 int len1 = cp - name;
 823                 cp++;
 824                 while (cp < name + len)
 825                         num = num * 10 + *cp++ - '0';
 826                 if (!num && len1 == len - 1)
 827                         num = 1;
 828                 if (has_suffix == '^')
 829                         return get_parent(name, len1, sha1, num);
 830                 /* else if (has_suffix == '~') -- goes without saying */
 831                 return get_nth_ancestor(name, len1, sha1, num);
 832         }
 833
 834         ret = peel_onion(name, len, sha1, lookup_flags);
 835         if (!ret)
 836                 return 0;
 837
 838         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 839         if (!ret)
 840                 return 0;
 841
 842         /* It could be describe output that is "SOMETHING-gXXXX" */
 843         ret = get_describe_name(name, len, sha1);
 844         if (!ret)
 845                 return 0;
 846
 847         return get_short_sha1(name, len, sha1, lookup_flags);
 848 }
 849
 850 /*
 851  * This interprets names like ':/Initial revision of "git"' by searching
 852  * through history and returning the first commit whose message starts
 853  * the given regular expression.
 854  *
 855  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
 856  *
 857  * For a literal '!' character at the beginning of a pattern, you have to repeat
 858  * that, like: ':/!!foo'
 859  *
 860  * For future extension, all other sequences beginning with ':/!' are reserved.
 861  */
 862
 863 /* Remember to update object flag allocation in object.h */
 864 #define ONELINE_SEEN (1u<<20)
 865
 866 static int handle_one_ref(const char *path, const struct object_id *oid,
 867                           int flag, void *cb_data)
 868 {
 869         struct commit_list **list = cb_data;
 870         struct object *object = parse_object(oid->hash);
 871         if (!object)
 872                 return 0;
 873         if (object->type == OBJ_TAG) {
 874                 object = deref_tag(object, path, strlen(path));
 875                 if (!object)
 876                         return 0;
 877         }
 878         if (object->type != OBJ_COMMIT)
 879                 return 0;
 880         commit_list_insert((struct commit *)object, list);
 881         return 0;
 882 }
 883
 884 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 885                             struct commit_list *list)
 886 {
 887         struct commit_list *backup = NULL, *l;
 888         int found = 0;
 889         int negative = 0;
 890         regex_t regex;
 891
 892         if (prefix[0] == '!') {
 893                 prefix++;
 894
 895                 if (prefix[0] == '-') {
 896                         prefix++;
 897                         negative = 1;
 898                 } else if (prefix[0] != '!') {
 899                         return -1;
 900                 }
 901         }
 902
 903         if (regcomp(&regex, prefix, REG_EXTENDED))
 904                 return -1;
 905
 906         for (l = list; l; l = l->next) {
 907                 l->item->object.flags |= ONELINE_SEEN;
 908                 commit_list_insert(l->item, &backup);
 909         }
 910         while (list) {
 911                 const char *p, *buf;
 912                 struct commit *commit;
 913                 int matches;
 914
 915                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 916                 if (!parse_object(commit->object.oid.hash))
 917                         continue;
 918                 buf = get_commit_buffer(commit, NULL);
 919                 p = strstr(buf, "\n\n");
 920                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
 921                 unuse_commit_buffer(commit, buf);
 922
 923                 if (matches) {
 924                         hashcpy(sha1, commit->object.oid.hash);
 925                         found = 1;
 926                         break;
 927                 }
 928         }
 929         regfree(&regex);
 930         free_commit_list(list);
 931         for (l = backup; l; l = l->next)
 932                 clear_commit_marks(l->item, ONELINE_SEEN);
 933         free_commit_list(backup);
 934         return found ? 0 : -1;
 935 }
 936
 937 struct grab_nth_branch_switch_cbdata {
 938         int remaining;
 939         struct strbuf buf;
 940 };
 941
 942 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 943                                   const char *email, unsigned long timestamp, int tz,
 944                                   const char *message, void *cb_data)
 945 {
 946         struct grab_nth_branch_switch_cbdata *cb = cb_data;
 947         const char *match = NULL, *target = NULL;
 948         size_t len;
 949
 950         if (skip_prefix(message, "checkout: moving from ", &match))
 951                 target = strstr(match, " to ");
 952
 953         if (!match || !target)
 954                 return 0;
 955         if (--(cb->remaining) == 0) {
 956                 len = target - match;
 957                 strbuf_reset(&cb->buf);
 958                 strbuf_add(&cb->buf, match, len);
 959                 return 1; /* we are done */
 960         }
 961         return 0;
 962 }
 963
 964 /*
 965  * Parse @{-N} syntax, return the number of characters parsed
 966  * if successful; otherwise signal an error with negative value.
 967  */
 968 static int interpret_nth_prior_checkout(const char *name, int namelen,
 969                                         struct strbuf *buf)
 970 {
 971         long nth;
 972         int retval;
 973         struct grab_nth_branch_switch_cbdata cb;
 974         const char *brace;
 975         char *num_end;
 976
 977         if (namelen < 4)
 978                 return -1;
 979         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
 980                 return -1;
 981         brace = memchr(name, '}', namelen);
 982         if (!brace)
 983                 return -1;
 984         nth = strtol(name + 3, &num_end, 10);
 985         if (num_end != brace)
 986                 return -1;
 987         if (nth <= 0)
 988                 return -1;
 989         cb.remaining = nth;
 990         strbuf_init(&cb.buf, 20);
 991
 992         retval = 0;
 993         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
 994                 strbuf_reset(buf);
 995                 strbuf_addbuf(buf, &cb.buf);
 996                 retval = brace - name + 1;
 997         }
 998
 999         strbuf_release(&cb.buf);
1000         return retval;
1001 }
1002
1003 int get_oid_mb(const char *name, struct object_id *oid)
1004 {
1005         struct commit *one, *two;
1006         struct commit_list *mbs;
1007         struct object_id oid_tmp;
1008         const char *dots;
1009         int st;
1010
1011         dots = strstr(name, "...");
1012         if (!dots)
1013                 return get_oid(name, oid);
1014         if (dots == name)
1015                 st = get_oid("HEAD", &oid_tmp);
1016         else {
1017                 struct strbuf sb;
1018                 strbuf_init(&sb, dots - name);
1019                 strbuf_add(&sb, name, dots - name);
1020                 st = get_sha1_committish(sb.buf, oid_tmp.hash);
1021                 strbuf_release(&sb);
1022         }
1023         if (st)
1024                 return st;
1025         one = lookup_commit_reference_gently(oid_tmp.hash, 0);
1026         if (!one)
1027                 return -1;
1028
1029         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", oid_tmp.hash))
1030                 return -1;
1031         two = lookup_commit_reference_gently(oid_tmp.hash, 0);
1032         if (!two)
1033                 return -1;
1034         mbs = get_merge_bases(one, two);
1035         if (!mbs || mbs->next)
1036                 st = -1;
1037         else {
1038                 st = 0;
1039                 oidcpy(oid, &mbs->item->object.oid);
1040         }
1041         free_commit_list(mbs);
1042         return st;
1043 }
1044
1045 /* parse @something syntax, when 'something' is not {.*} */
1046 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1047 {
1048         const char *next;
1049
1050         if (len || name[1] == '{')
1051                 return -1;
1052
1053         /* make sure it's a single @, or @@{.*}, not @foo */
1054         next = memchr(name + len + 1, '@', namelen - len - 1);
1055         if (next && next[1] != '{')
1056                 return -1;
1057         if (!next)
1058                 next = name + namelen;
1059         if (next != name + 1)
1060                 return -1;
1061
1062         strbuf_reset(buf);
1063         strbuf_add(buf, "HEAD", 4);
1064         return 1;
1065 }
1066
1067 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1068 {
1069         /* we have extra data, which might need further processing */
1070         struct strbuf tmp = STRBUF_INIT;
1071         int used = buf->len;
1072         int ret;
1073
1074         strbuf_add(buf, name + len, namelen - len);
1075         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1076         /* that data was not interpreted, remove our cruft */
1077         if (ret < 0) {
1078                 strbuf_setlen(buf, used);
1079                 return len;
1080         }
1081         strbuf_reset(buf);
1082         strbuf_addbuf(buf, &tmp);
1083         strbuf_release(&tmp);
1084         /* tweak for size of {-N} versus expanded ref name */
1085         return ret - used + len;
1086 }
1087
1088 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1089 {
1090         char *s = shorten_unambiguous_ref(ref, 0);
1091         strbuf_reset(buf);
1092         strbuf_addstr(buf, s);
1093         free(s);
1094 }
1095
1096 static int interpret_branch_mark(const char *name, int namelen,
1097                                  int at, struct strbuf *buf,
1098                                  int (*get_mark)(const char *, int),
1099                                  const char *(*get_data)(struct branch *,
1100                                                          struct strbuf *))
1101 {
1102         int len;
1103         struct branch *branch;
1104         struct strbuf err = STRBUF_INIT;
1105         const char *value;
1106
1107         len = get_mark(name + at, namelen - at);
1108         if (!len)
1109                 return -1;
1110
1111         if (memchr(name, ':', at))
1112                 return -1;
1113
1114         if (at) {
1115                 char *name_str = xmemdupz(name, at);
1116                 branch = branch_get(name_str);
1117                 free(name_str);
1118         } else
1119                 branch = branch_get(NULL);
1120
1121         value = get_data(branch, &err);
1122         if (!value)
1123                 die("%s", err.buf);
1124
1125         set_shortened_ref(buf, value);
1126         return len + at;
1127 }
1128
1129 /*
1130  * This reads short-hand syntax that not only evaluates to a commit
1131  * object name, but also can act as if the end user spelled the name
1132  * of the branch from the command line.
1133  *
1134  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1135  *   places the name of the branch in the given buf and returns the
1136  *   number of characters parsed if successful.
1137  *
1138  * - "<branch>@{upstream}" finds the name of the other ref that
1139  *   <branch> is configured to merge with (missing <branch> defaults
1140  *   to the current branch), and places the name of the branch in the
1141  *   given buf and returns the number of characters parsed if
1142  *   successful.
1143  *
1144  * If the input is not of the accepted format, it returns a negative
1145  * number to signal an error.
1146  *
1147  * If the input was ok but there are not N branch switches in the
1148  * reflog, it returns 0.
1149  */
1150 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1151 {
1152         char *at;
1153         const char *start;
1154         int len = interpret_nth_prior_checkout(name, namelen, buf);
1155
1156         if (!namelen)
1157                 namelen = strlen(name);
1158
1159         if (!len) {
1160                 return len; /* syntax Ok, not enough switches */
1161         } else if (len > 0) {
1162                 if (len == namelen)
1163                         return len; /* consumed all */
1164                 else
1165                         return reinterpret(name, namelen, len, buf);
1166         }
1167
1168         for (start = name;
1169              (at = memchr(start, '@', namelen - (start - name)));
1170              start = at + 1) {
1171
1172                 len = interpret_empty_at(name, namelen, at - name, buf);
1173                 if (len > 0)
1174                         return reinterpret(name, namelen, len, buf);
1175
1176                 len = interpret_branch_mark(name, namelen, at - name, buf,
1177                                             upstream_mark, branch_get_upstream);
1178                 if (len > 0)
1179                         return len;
1180
1181                 len = interpret_branch_mark(name, namelen, at - name, buf,
1182                                             push_mark, branch_get_push);
1183                 if (len > 0)
1184                         return len;
1185         }
1186
1187         return -1;
1188 }
1189
1190 int strbuf_branchname(struct strbuf *sb, const char *name)
1191 {
1192         int len = strlen(name);
1193         int used = interpret_branch_name(name, len, sb);
1194
1195         if (used == len)
1196                 return 0;
1197         if (used < 0)
1198                 used = 0;
1199         strbuf_add(sb, name + used, len - used);
1200         return len;
1201 }
1202
1203 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1204 {
1205         strbuf_branchname(sb, name);
1206         if (name[0] == '-')
1207                 return -1;
1208         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1209         return check_refname_format(sb->buf, 0);
1210 }
1211
1212 /*
1213  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1214  * notably "xyz^" for "parent of xyz"
1215  */
1216 int get_sha1(const char *name, unsigned char *sha1)
1217 {
1218         struct object_context unused;
1219         return get_sha1_with_context(name, 0, sha1, &unused);
1220 }
1221
1222 /*
1223  * This is like "get_sha1()", but for struct object_id.
1224  */
1225 int get_oid(const char *name, struct object_id *oid)
1226 {
1227         return get_sha1(name, oid->hash);
1228 }
1229
1230
1231 /*
1232  * Many callers know that the user meant to name a commit-ish by
1233  * syntactical positions where the object name appears.  Calling this
1234  * function allows the machinery to disambiguate shorter-than-unique
1235  * abbreviated object names between commit-ish and others.
1236  *
1237  * Note that this does NOT error out when the named object is not a
1238  * commit-ish. It is merely to give a hint to the disambiguation
1239  * machinery.
1240  */
1241 int get_sha1_committish(const char *name, unsigned char *sha1)
1242 {
1243         struct object_context unused;
1244         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1245                                      sha1, &unused);
1246 }
1247
1248 int get_sha1_treeish(const char *name, unsigned char *sha1)
1249 {
1250         struct object_context unused;
1251         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1252                                      sha1, &unused);
1253 }
1254
1255 int get_sha1_commit(const char *name, unsigned char *sha1)
1256 {
1257         struct object_context unused;
1258         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1259                                      sha1, &unused);
1260 }
1261
1262 int get_sha1_tree(const char *name, unsigned char *sha1)
1263 {
1264         struct object_context unused;
1265         return get_sha1_with_context(name, GET_SHA1_TREE,
1266                                      sha1, &unused);
1267 }
1268
1269 int get_sha1_blob(const char *name, unsigned char *sha1)
1270 {
1271         struct object_context unused;
1272         return get_sha1_with_context(name, GET_SHA1_BLOB,
1273                                      sha1, &unused);
1274 }
1275
1276 /* Must be called only when object_name:filename doesn't exist. */
1277 static void diagnose_invalid_sha1_path(const char *prefix,
1278                                        const char *filename,
1279                                        const unsigned char *tree_sha1,
1280                                        const char *object_name,
1281                                        int object_name_len)
1282 {
1283         unsigned char sha1[20];
1284         unsigned mode;
1285
1286         if (!prefix)
1287                 prefix = "";
1288
1289         if (file_exists(filename))
1290                 die("Path '%s' exists on disk, but not in '%.*s'.",
1291                     filename, object_name_len, object_name);
1292         if (errno == ENOENT || errno == ENOTDIR) {
1293                 char *fullname = xstrfmt("%s%s", prefix, filename);
1294
1295                 if (!get_tree_entry(tree_sha1, fullname,
1296                                     sha1, &mode)) {
1297                         die("Path '%s' exists, but not '%s'.\n"
1298                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1299                             fullname,
1300                             filename,
1301                             object_name_len, object_name,
1302                             fullname,
1303                             object_name_len, object_name,
1304                             filename);
1305                 }
1306                 die("Path '%s' does not exist in '%.*s'",
1307                     filename, object_name_len, object_name);
1308         }
1309 }
1310
1311 /* Must be called only when :stage:filename doesn't exist. */
1312 static void diagnose_invalid_index_path(int stage,
1313                                         const char *prefix,
1314                                         const char *filename)
1315 {
1316         const struct cache_entry *ce;
1317         int pos;
1318         unsigned namelen = strlen(filename);
1319         struct strbuf fullname = STRBUF_INIT;
1320
1321         if (!prefix)
1322                 prefix = "";
1323
1324         /* Wrong stage number? */
1325         pos = cache_name_pos(filename, namelen);
1326         if (pos < 0)
1327                 pos = -pos - 1;
1328         if (pos < active_nr) {
1329                 ce = active_cache[pos];
1330                 if (ce_namelen(ce) == namelen &&
1331                     !memcmp(ce->name, filename, namelen))
1332                         die("Path '%s' is in the index, but not at stage %d.\n"
1333                             "Did you mean ':%d:%s'?",
1334                             filename, stage,
1335                             ce_stage(ce), filename);
1336         }
1337
1338         /* Confusion between relative and absolute filenames? */
1339         strbuf_addstr(&fullname, prefix);
1340         strbuf_addstr(&fullname, filename);
1341         pos = cache_name_pos(fullname.buf, fullname.len);
1342         if (pos < 0)
1343                 pos = -pos - 1;
1344         if (pos < active_nr) {
1345                 ce = active_cache[pos];
1346                 if (ce_namelen(ce) == fullname.len &&
1347                     !memcmp(ce->name, fullname.buf, fullname.len))
1348                         die("Path '%s' is in the index, but not '%s'.\n"
1349                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1350                             fullname.buf, filename,
1351                             ce_stage(ce), fullname.buf,
1352                             ce_stage(ce), filename);
1353         }
1354
1355         if (file_exists(filename))
1356                 die("Path '%s' exists on disk, but not in the index.", filename);
1357         if (errno == ENOENT || errno == ENOTDIR)
1358                 die("Path '%s' does not exist (neither on disk nor in the index).",
1359                     filename);
1360
1361         strbuf_release(&fullname);
1362 }
1363
1364
1365 static char *resolve_relative_path(const char *rel)
1366 {
1367         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1368                 return NULL;
1369
1370         if (!is_inside_work_tree())
1371                 die("relative path syntax can't be used outside working tree.");
1372
1373         /* die() inside prefix_path() if resolved path is outside worktree */
1374         return prefix_path(startup_info->prefix,
1375                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1376                            rel);
1377 }
1378
1379 static int get_sha1_with_context_1(const char *name,
1380                                    unsigned flags,
1381                                    const char *prefix,
1382                                    unsigned char *sha1,
1383                                    struct object_context *oc)
1384 {
1385         int ret, bracket_depth;
1386         int namelen = strlen(name);
1387         const char *cp;
1388         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1389
1390         if (only_to_die)
1391                 flags |= GET_SHA1_QUIETLY;
1392
1393         memset(oc, 0, sizeof(*oc));
1394         oc->mode = S_IFINVALID;
1395         ret = get_sha1_1(name, namelen, sha1, flags);
1396         if (!ret)
1397                 return ret;
1398         /*
1399          * sha1:path --> object name of path in ent sha1
1400          * :path -> object name of absolute path in index
1401          * :./path -> object name of path relative to cwd in index
1402          * :[0-3]:path -> object name of path in index at stage
1403          * :/foo -> recent commit matching foo
1404          */
1405         if (name[0] == ':') {
1406                 int stage = 0;
1407                 const struct cache_entry *ce;
1408                 char *new_path = NULL;
1409                 int pos;
1410                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1411                         struct commit_list *list = NULL;
1412
1413                         for_each_ref(handle_one_ref, &list);
1414                         commit_list_sort_by_date(&list);
1415                         return get_sha1_oneline(name + 2, sha1, list);
1416                 }
1417                 if (namelen < 3 ||
1418                     name[2] != ':' ||
1419                     name[1] < '0' || '3' < name[1])
1420                         cp = name + 1;
1421                 else {
1422                         stage = name[1] - '0';
1423                         cp = name + 3;
1424                 }
1425                 new_path = resolve_relative_path(cp);
1426                 if (!new_path) {
1427                         namelen = namelen - (cp - name);
1428                 } else {
1429                         cp = new_path;
1430                         namelen = strlen(cp);
1431                 }
1432
1433                 strlcpy(oc->path, cp, sizeof(oc->path));
1434
1435                 if (!active_cache)
1436                         read_cache();
1437                 pos = cache_name_pos(cp, namelen);
1438                 if (pos < 0)
1439                         pos = -pos - 1;
1440                 while (pos < active_nr) {
1441                         ce = active_cache[pos];
1442                         if (ce_namelen(ce) != namelen ||
1443                             memcmp(ce->name, cp, namelen))
1444                                 break;
1445                         if (ce_stage(ce) == stage) {
1446                                 hashcpy(sha1, ce->oid.hash);
1447                                 oc->mode = ce->ce_mode;
1448                                 free(new_path);
1449                                 return 0;
1450                         }
1451                         pos++;
1452                 }
1453                 if (only_to_die && name[1] && name[1] != '/')
1454                         diagnose_invalid_index_path(stage, prefix, cp);
1455                 free(new_path);
1456                 return -1;
1457         }
1458         for (cp = name, bracket_depth = 0; *cp; cp++) {
1459                 if (*cp == '{')
1460                         bracket_depth++;
1461                 else if (bracket_depth && *cp == '}')
1462                         bracket_depth--;
1463                 else if (!bracket_depth && *cp == ':')
1464                         break;
1465         }
1466         if (*cp == ':') {
1467                 unsigned char tree_sha1[20];
1468                 int len = cp - name;
1469                 unsigned sub_flags = flags;
1470
1471                 sub_flags &= ~GET_SHA1_DISAMBIGUATORS;
1472                 sub_flags |= GET_SHA1_TREEISH;
1473
1474                 if (!get_sha1_1(name, len, tree_sha1, sub_flags)) {
1475                         const char *filename = cp+1;
1476                         char *new_filename = NULL;
1477
1478                         new_filename = resolve_relative_path(filename);
1479                         if (new_filename)
1480                                 filename = new_filename;
1481                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1482                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1483                                         filename, sha1, &oc->symlink_path,
1484                                         &oc->mode);
1485                         } else {
1486                                 ret = get_tree_entry(tree_sha1, filename,
1487                                                      sha1, &oc->mode);
1488                                 if (ret && only_to_die) {
1489                                         diagnose_invalid_sha1_path(prefix,
1490                                                                    filename,
1491                                                                    tree_sha1,
1492                                                                    name, len);
1493                                 }
1494                         }
1495                         hashcpy(oc->tree, tree_sha1);
1496                         strlcpy(oc->path, filename, sizeof(oc->path));
1497
1498                         free(new_filename);
1499                         return ret;
1500                 } else {
1501                         if (only_to_die)
1502                                 die("Invalid object name '%.*s'.", len, name);
1503                 }
1504         }
1505         return ret;
1506 }
1507
1508 /*
1509  * Call this function when you know "name" given by the end user must
1510  * name an object but it doesn't; the function _may_ die with a better
1511  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1512  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1513  * you have a chance to diagnose the error further.
1514  */
1515 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1516 {
1517         struct object_context oc;
1518         unsigned char sha1[20];
1519         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1520 }
1521
1522 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1523 {
1524         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1525                 die("BUG: incompatible flags for get_sha1_with_context");
1526         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1527 }