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
  10 static int get_sha1_oneline(const char *, unsigned char *, struct commit_list *);
  11
  12 typedef int (*disambiguate_hint_fn)(const unsigned char *, void *);
  13
  14 struct disambiguate_state {
  15         disambiguate_hint_fn fn;
  16         void *cb_data;
  17         unsigned char candidate[20];
  18         unsigned candidate_exists:1;
  19         unsigned candidate_checked:1;
  20         unsigned candidate_ok:1;
  21         unsigned disambiguate_fn_used:1;
  22         unsigned ambiguous:1;
  23         unsigned always_call_fn:1;
  24 };
  25
  26 static void update_candidates(struct disambiguate_state *ds, const unsigned char *current)
  27 {
  28         if (ds->always_call_fn) {
  29                 ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
  30                 return;
  31         }
  32         if (!ds->candidate_exists) {
  33                 /* this is the first candidate */
  34                 hashcpy(ds->candidate, current);
  35                 ds->candidate_exists = 1;
  36                 return;
  37         } else if (!hashcmp(ds->candidate, current)) {
  38                 /* the same as what we already have seen */
  39                 return;
  40         }
  41
  42         if (!ds->fn) {
  43                 /* cannot disambiguate between ds->candidate and current */
  44                 ds->ambiguous = 1;
  45                 return;
  46         }
  47
  48         if (!ds->candidate_checked) {
  49                 ds->candidate_ok = ds->fn(ds->candidate, ds->cb_data);
  50                 ds->disambiguate_fn_used = 1;
  51                 ds->candidate_checked = 1;
  52         }
  53
  54         if (!ds->candidate_ok) {
  55                 /* discard the candidate; we know it does not satisfy fn */
  56                 hashcpy(ds->candidate, current);
  57                 ds->candidate_checked = 0;
  58                 return;
  59         }
  60
  61         /* if we reach this point, we know ds->candidate satisfies fn */
  62         if (ds->fn(current, ds->cb_data)) {
  63                 /*
  64                  * if both current and candidate satisfy fn, we cannot
  65                  * disambiguate.
  66                  */
  67                 ds->candidate_ok = 0;
  68                 ds->ambiguous = 1;
  69         }
  70
  71         /* otherwise, current can be discarded and candidate is still good */
  72 }
  73
  74 static void find_short_object_filename(int len, const char *hex_pfx, struct disambiguate_state *ds)
  75 {
  76         struct alternate_object_database *alt;
  77         char hex[40];
  78         static struct alternate_object_database *fakeent;
  79
  80         if (!fakeent) {
  81                 /*
  82                  * Create a "fake" alternate object database that
  83                  * points to our own object database, to make it
  84                  * easier to get a temporary working space in
  85                  * alt->name/alt->base while iterating over the
  86                  * object databases including our own.
  87                  */
  88                 const char *objdir = get_object_directory();
  89                 int objdir_len = strlen(objdir);
  90                 int entlen = objdir_len + 43;
  91                 fakeent = xmalloc(sizeof(*fakeent) + entlen);
  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         sprintf(hex, "%.2s", hex_pfx);
  99         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 100                 struct dirent *de;
 101                 DIR *dir;
 102                 sprintf(alt->name, "%.2s/", hex_pfx);
 103                 dir = opendir(alt->base);
 104                 if (!dir)
 105                         continue;
 106
 107                 while (!ds->ambiguous && (de = readdir(dir)) != NULL) {
 108                         unsigned char sha1[20];
 109
 110                         if (strlen(de->d_name) != 38)
 111                                 continue;
 112                         if (memcmp(de->d_name, hex_pfx + 2, len - 2))
 113                                 continue;
 114                         memcpy(hex + 2, de->d_name, 38);
 115                         if (!get_sha1_hex(hex, sha1))
 116                                 update_candidates(ds, sha1);
 117                 }
 118                 closedir(dir);
 119         }
 120 }
 121
 122 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 123 {
 124         do {
 125                 if (*a != *b)
 126                         return 0;
 127                 a++;
 128                 b++;
 129                 len -= 2;
 130         } while (len > 1);
 131         if (len)
 132                 if ((*a ^ *b) & 0xf0)
 133                         return 0;
 134         return 1;
 135 }
 136
 137 static void unique_in_pack(int len,
 138                           const unsigned char *bin_pfx,
 139                            struct packed_git *p,
 140                            struct disambiguate_state *ds)
 141 {
 142         uint32_t num, last, i, first = 0;
 143         const unsigned char *current = NULL;
 144
 145         open_pack_index(p);
 146         num = p->num_objects;
 147         last = num;
 148         while (first < last) {
 149                 uint32_t mid = (first + last) / 2;
 150                 const unsigned char *current;
 151                 int cmp;
 152
 153                 current = nth_packed_object_sha1(p, mid);
 154                 cmp = hashcmp(bin_pfx, current);
 155                 if (!cmp) {
 156                         first = mid;
 157                         break;
 158                 }
 159                 if (cmp > 0) {
 160                         first = mid+1;
 161                         continue;
 162                 }
 163                 last = mid;
 164         }
 165
 166         /*
 167          * At this point, "first" is the location of the lowest object
 168          * with an object name that could match "bin_pfx".  See if we have
 169          * 0, 1 or more objects that actually match(es).
 170          */
 171         for (i = first; i < num && !ds->ambiguous; i++) {
 172                 current = nth_packed_object_sha1(p, i);
 173                 if (!match_sha(len, bin_pfx, current))
 174                         break;
 175                 update_candidates(ds, current);
 176         }
 177 }
 178
 179 static void find_short_packed_object(int len, const unsigned char *bin_pfx,
 180                                      struct disambiguate_state *ds)
 181 {
 182         struct packed_git *p;
 183
 184         prepare_packed_git();
 185         for (p = packed_git; p && !ds->ambiguous; p = p->next)
 186                 unique_in_pack(len, bin_pfx, p, ds);
 187 }
 188
 189 #define SHORT_NAME_NOT_FOUND (-1)
 190 #define SHORT_NAME_AMBIGUOUS (-2)
 191
 192 static int finish_object_disambiguation(struct disambiguate_state *ds,
 193                                         unsigned char *sha1)
 194 {
 195         if (ds->ambiguous)
 196                 return SHORT_NAME_AMBIGUOUS;
 197
 198         if (!ds->candidate_exists)
 199                 return SHORT_NAME_NOT_FOUND;
 200
 201         if (!ds->candidate_checked)
 202                 /*
 203                  * If this is the only candidate, there is no point
 204                  * calling the disambiguation hint callback.
 205                  *
 206                  * On the other hand, if the current candidate
 207                  * replaced an earlier candidate that did _not_ pass
 208                  * the disambiguation hint callback, then we do have
 209                  * more than one objects that match the short name
 210                  * given, so we should make sure this one matches;
 211                  * otherwise, if we discovered this one and the one
 212                  * that we previously discarded in the reverse order,
 213                  * we would end up showing different results in the
 214                  * same repository!
 215                  */
 216                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 217                                     ds->fn(ds->candidate, ds->cb_data));
 218
 219         if (!ds->candidate_ok)
 220                 return SHORT_NAME_AMBIGUOUS;
 221
 222         hashcpy(sha1, ds->candidate);
 223         return 0;
 224 }
 225
 226 static int disambiguate_commit_only(const unsigned char *sha1, void *cb_data_unused)
 227 {
 228         int kind = sha1_object_info(sha1, NULL);
 229         return kind == OBJ_COMMIT;
 230 }
 231
 232 static int disambiguate_committish_only(const unsigned char *sha1, void *cb_data_unused)
 233 {
 234         struct object *obj;
 235         int kind;
 236
 237         kind = sha1_object_info(sha1, NULL);
 238         if (kind == OBJ_COMMIT)
 239                 return 1;
 240         if (kind != OBJ_TAG)
 241                 return 0;
 242
 243         /* We need to do this the hard way... */
 244         obj = deref_tag(parse_object(sha1), NULL, 0);
 245         if (obj && obj->type == OBJ_COMMIT)
 246                 return 1;
 247         return 0;
 248 }
 249
 250 static int disambiguate_tree_only(const unsigned char *sha1, void *cb_data_unused)
 251 {
 252         int kind = sha1_object_info(sha1, NULL);
 253         return kind == OBJ_TREE;
 254 }
 255
 256 static int disambiguate_treeish_only(const unsigned char *sha1, void *cb_data_unused)
 257 {
 258         struct object *obj;
 259         int kind;
 260
 261         kind = sha1_object_info(sha1, NULL);
 262         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 263                 return 1;
 264         if (kind != OBJ_TAG)
 265                 return 0;
 266
 267         /* We need to do this the hard way... */
 268         obj = deref_tag(lookup_object(sha1), NULL, 0);
 269         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 270                 return 1;
 271         return 0;
 272 }
 273
 274 static int disambiguate_blob_only(const unsigned char *sha1, void *cb_data_unused)
 275 {
 276         int kind = sha1_object_info(sha1, NULL);
 277         return kind == OBJ_BLOB;
 278 }
 279
 280 static int prepare_prefixes(const char *name, int len,
 281                             unsigned char *bin_pfx,
 282                             char *hex_pfx)
 283 {
 284         int i;
 285
 286         hashclr(bin_pfx);
 287         memset(hex_pfx, 'x', 40);
 288         for (i = 0; i < len ;i++) {
 289                 unsigned char c = name[i];
 290                 unsigned char val;
 291                 if (c >= '0' && c <= '9')
 292                         val = c - '0';
 293                 else if (c >= 'a' && c <= 'f')
 294                         val = c - 'a' + 10;
 295                 else if (c >= 'A' && c <='F') {
 296                         val = c - 'A' + 10;
 297                         c -= 'A' - 'a';
 298                 }
 299                 else
 300                         return -1;
 301                 hex_pfx[i] = c;
 302                 if (!(i & 1))
 303                         val <<= 4;
 304                 bin_pfx[i >> 1] |= val;
 305         }
 306         return 0;
 307 }
 308
 309 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 310                           unsigned flags)
 311 {
 312         int status;
 313         char hex_pfx[40];
 314         unsigned char bin_pfx[20];
 315         struct disambiguate_state ds;
 316         int quietly = !!(flags & GET_SHA1_QUIETLY);
 317
 318         if (len < MINIMUM_ABBREV || len > 40)
 319                 return -1;
 320         if (prepare_prefixes(name, len, bin_pfx, hex_pfx) < 0)
 321                 return -1;
 322
 323         prepare_alt_odb();
 324
 325         memset(&ds, 0, sizeof(ds));
 326         if (flags & GET_SHA1_COMMIT)
 327                 ds.fn = disambiguate_commit_only;
 328         else if (flags & GET_SHA1_COMMITTISH)
 329                 ds.fn = disambiguate_committish_only;
 330         else if (flags & GET_SHA1_TREE)
 331                 ds.fn = disambiguate_tree_only;
 332         else if (flags & GET_SHA1_TREEISH)
 333                 ds.fn = disambiguate_treeish_only;
 334         else if (flags & GET_SHA1_BLOB)
 335                 ds.fn = disambiguate_blob_only;
 336
 337         find_short_object_filename(len, hex_pfx, &ds);
 338         find_short_packed_object(len, bin_pfx, &ds);
 339         status = finish_object_disambiguation(&ds, sha1);
 340
 341         if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
 342                 return error("short SHA1 %.*s is ambiguous.", len, hex_pfx);
 343         return status;
 344 }
 345
 346 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 347 {
 348         char hex_pfx[40];
 349         unsigned char bin_pfx[20];
 350         struct disambiguate_state ds;
 351         int len = strlen(prefix);
 352
 353         if (len < MINIMUM_ABBREV || len > 40)
 354                 return -1;
 355         if (prepare_prefixes(prefix, len, bin_pfx, hex_pfx) < 0)
 356                 return -1;
 357
 358         prepare_alt_odb();
 359
 360         memset(&ds, 0, sizeof(ds));
 361         ds.always_call_fn = 1;
 362         ds.cb_data = cb_data;
 363         ds.fn = fn;
 364
 365         find_short_object_filename(len, hex_pfx, &ds);
 366         find_short_packed_object(len, bin_pfx, &ds);
 367         return ds.ambiguous;
 368 }
 369
 370 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 371 {
 372         int status, exists;
 373         static char hex[41];
 374
 375         exists = has_sha1_file(sha1);
 376         memcpy(hex, sha1_to_hex(sha1), 40);
 377         if (len == 40 || !len)
 378                 return hex;
 379         while (len < 40) {
 380                 unsigned char sha1_ret[20];
 381                 status = get_short_sha1(hex, len, sha1_ret, GET_SHA1_QUIETLY);
 382                 if (exists
 383                     ? !status
 384                     : status == SHORT_NAME_NOT_FOUND) {
 385                         hex[len] = 0;
 386                         return hex;
 387                 }
 388                 len++;
 389         }
 390         return hex;
 391 }
 392
 393 static int ambiguous_path(const char *path, int len)
 394 {
 395         int slash = 1;
 396         int cnt;
 397
 398         for (cnt = 0; cnt < len; cnt++) {
 399                 switch (*path++) {
 400                 case '\0':
 401                         break;
 402                 case '/':
 403                         if (slash)
 404                                 break;
 405                         slash = 1;
 406                         continue;
 407                 case '.':
 408                         continue;
 409                 default:
 410                         slash = 0;
 411                         continue;
 412                 }
 413                 break;
 414         }
 415         return slash;
 416 }
 417
 418 static inline int upstream_mark(const char *string, int len)
 419 {
 420         const char *suffix[] = { "@{upstream}", "@{u}" };
 421         int i;
 422
 423         for (i = 0; i < ARRAY_SIZE(suffix); i++) {
 424                 int suffix_len = strlen(suffix[i]);
 425                 if (suffix_len <= len
 426                     && !memcmp(string, suffix[i], suffix_len))
 427                         return suffix_len;
 428         }
 429         return 0;
 430 }
 431
 432 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 433 static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf);
 434
 435 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 436 {
 437         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 438         static const char *object_name_msg = N_(
 439         "Git normally never creates a ref that ends with 40 hex characters\n"
 440         "because it will be ignored when you just specify 40-hex. These refs\n"
 441         "may be created by mistake. For example,\n"
 442         "\n"
 443         "  git checkout -b $br $(git rev-parse ...)\n"
 444         "\n"
 445         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 446         "examine these refs and maybe delete them. Turn this message off by\n"
 447         "running \"git config advice.objectNameWarning false\"");
 448         unsigned char tmp_sha1[20];
 449         char *real_ref = NULL;
 450         int refs_found = 0;
 451         int at, reflog_len, nth_prior = 0;
 452
 453         if (len == 40 && !get_sha1_hex(str, sha1)) {
 454                 if (warn_on_object_refname_ambiguity) {
 455                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 456                         if (refs_found > 0 && warn_ambiguous_refs) {
 457                                 warning(warn_msg, len, str);
 458                                 if (advice_object_name_warning)
 459                                         fprintf(stderr, "%s\n", _(object_name_msg));
 460                         }
 461                         free(real_ref);
 462                 }
 463                 return 0;
 464         }
 465
 466         /* basic@{time or number or -number} format to query ref-log */
 467         reflog_len = at = 0;
 468         if (len && str[len-1] == '}') {
 469                 for (at = len-4; at >= 0; at--) {
 470                         if (str[at] == '@' && str[at+1] == '{') {
 471                                 if (str[at+2] == '-') {
 472                                         if (at != 0)
 473                                                 /* @{-N} not at start */
 474                                                 return -1;
 475                                         nth_prior = 1;
 476                                         continue;
 477                                 }
 478                                 if (!upstream_mark(str + at, len - at)) {
 479                                         reflog_len = (len-1) - (at+2);
 480                                         len = at;
 481                                 }
 482                                 break;
 483                         }
 484                 }
 485         }
 486
 487         /* Accept only unambiguous ref paths. */
 488         if (len && ambiguous_path(str, len))
 489                 return -1;
 490
 491         if (nth_prior) {
 492                 struct strbuf buf = STRBUF_INIT;
 493                 int detached;
 494
 495                 if (interpret_nth_prior_checkout(str, &buf) > 0) {
 496                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 497                         strbuf_release(&buf);
 498                         if (detached)
 499                                 return 0;
 500                 }
 501         }
 502
 503         if (!len && reflog_len)
 504                 /* allow "@{...}" to mean the current branch reflog */
 505                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 506         else if (reflog_len)
 507                 refs_found = dwim_log(str, len, sha1, &real_ref);
 508         else
 509                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 510
 511         if (!refs_found)
 512                 return -1;
 513
 514         if (warn_ambiguous_refs &&
 515             (refs_found > 1 ||
 516              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 517                 warning(warn_msg, len, str);
 518
 519         if (reflog_len) {
 520                 int nth, i;
 521                 unsigned long at_time;
 522                 unsigned long co_time;
 523                 int co_tz, co_cnt;
 524
 525                 /* Is it asking for N-th entry, or approxidate? */
 526                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 527                         char ch = str[at+2+i];
 528                         if ('0' <= ch && ch <= '9')
 529                                 nth = nth * 10 + ch - '0';
 530                         else
 531                                 nth = -1;
 532                 }
 533                 if (100000000 <= nth) {
 534                         at_time = nth;
 535                         nth = -1;
 536                 } else if (0 <= nth)
 537                         at_time = 0;
 538                 else {
 539                         int errors = 0;
 540                         char *tmp = xstrndup(str + at + 2, reflog_len);
 541                         at_time = approxidate_careful(tmp, &errors);
 542                         free(tmp);
 543                         if (errors)
 544                                 return -1;
 545                 }
 546                 if (read_ref_at(real_ref, at_time, nth, sha1, NULL,
 547                                 &co_time, &co_tz, &co_cnt)) {
 548                         if (!len) {
 549                                 if (!prefixcmp(real_ref, "refs/heads/")) {
 550                                         str = real_ref + 11;
 551                                         len = strlen(real_ref + 11);
 552                                 } else {
 553                                         /* detached HEAD */
 554                                         str = "HEAD";
 555                                         len = 4;
 556                                 }
 557                         }
 558                         if (at_time)
 559                                 warning("Log for '%.*s' only goes "
 560                                         "back to %s.", len, str,
 561                                         show_date(co_time, co_tz, DATE_RFC2822));
 562                         else {
 563                                 die("Log for '%.*s' only has %d entries.",
 564                                     len, str, co_cnt);
 565                         }
 566                 }
 567         }
 568
 569         free(real_ref);
 570         return 0;
 571 }
 572
 573 static int get_parent(const char *name, int len,
 574                       unsigned char *result, int idx)
 575 {
 576         unsigned char sha1[20];
 577         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 578         struct commit *commit;
 579         struct commit_list *p;
 580
 581         if (ret)
 582                 return ret;
 583         commit = lookup_commit_reference(sha1);
 584         if (!commit)
 585                 return -1;
 586         if (parse_commit(commit))
 587                 return -1;
 588         if (!idx) {
 589                 hashcpy(result, commit->object.sha1);
 590                 return 0;
 591         }
 592         p = commit->parents;
 593         while (p) {
 594                 if (!--idx) {
 595                         hashcpy(result, p->item->object.sha1);
 596                         return 0;
 597                 }
 598                 p = p->next;
 599         }
 600         return -1;
 601 }
 602
 603 static int get_nth_ancestor(const char *name, int len,
 604                             unsigned char *result, int generation)
 605 {
 606         unsigned char sha1[20];
 607         struct commit *commit;
 608         int ret;
 609
 610         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 611         if (ret)
 612                 return ret;
 613         commit = lookup_commit_reference(sha1);
 614         if (!commit)
 615                 return -1;
 616
 617         while (generation--) {
 618                 if (parse_commit(commit) || !commit->parents)
 619                         return -1;
 620                 commit = commit->parents->item;
 621         }
 622         hashcpy(result, commit->object.sha1);
 623         return 0;
 624 }
 625
 626 struct object *peel_to_type(const char *name, int namelen,
 627                             struct object *o, enum object_type expected_type)
 628 {
 629         if (name && !namelen)
 630                 namelen = strlen(name);
 631         while (1) {
 632                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 633                         return NULL;
 634                 if (expected_type == OBJ_ANY || o->type == expected_type)
 635                         return o;
 636                 if (o->type == OBJ_TAG)
 637                         o = ((struct tag*) o)->tagged;
 638                 else if (o->type == OBJ_COMMIT)
 639                         o = &(((struct commit *) o)->tree->object);
 640                 else {
 641                         if (name)
 642                                 error("%.*s: expected %s type, but the object "
 643                                       "dereferences to %s type",
 644                                       namelen, name, typename(expected_type),
 645                                       typename(o->type));
 646                         return NULL;
 647                 }
 648         }
 649 }
 650
 651 static int peel_onion(const char *name, int len, unsigned char *sha1)
 652 {
 653         unsigned char outer[20];
 654         const char *sp;
 655         unsigned int expected_type = 0;
 656         unsigned lookup_flags = 0;
 657         struct object *o;
 658
 659         /*
 660          * "ref^{type}" dereferences ref repeatedly until you cannot
 661          * dereference anymore, or you get an object of given type,
 662          * whichever comes first.  "ref^{}" means just dereference
 663          * tags until you get a non-tag.  "ref^0" is a shorthand for
 664          * "ref^{commit}".  "commit^{tree}" could be used to find the
 665          * top-level tree of the given commit.
 666          */
 667         if (len < 4 || name[len-1] != '}')
 668                 return -1;
 669
 670         for (sp = name + len - 1; name <= sp; sp--) {
 671                 int ch = *sp;
 672                 if (ch == '{' && name < sp && sp[-1] == '^')
 673                         break;
 674         }
 675         if (sp <= name)
 676                 return -1;
 677
 678         sp++; /* beginning of type name, or closing brace for empty */
 679         if (!prefixcmp(sp, "commit}"))
 680                 expected_type = OBJ_COMMIT;
 681         else if (!prefixcmp(sp, "tag}"))
 682                 expected_type = OBJ_TAG;
 683         else if (!prefixcmp(sp, "tree}"))
 684                 expected_type = OBJ_TREE;
 685         else if (!prefixcmp(sp, "blob}"))
 686                 expected_type = OBJ_BLOB;
 687         else if (!prefixcmp(sp, "object}"))
 688                 expected_type = OBJ_ANY;
 689         else if (sp[0] == '}')
 690                 expected_type = OBJ_NONE;
 691         else if (sp[0] == '/')
 692                 expected_type = OBJ_COMMIT;
 693         else
 694                 return -1;
 695
 696         if (expected_type == OBJ_COMMIT)
 697                 lookup_flags = GET_SHA1_COMMITTISH;
 698         else if (expected_type == OBJ_TREE)
 699                 lookup_flags = GET_SHA1_TREEISH;
 700
 701         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 702                 return -1;
 703
 704         o = parse_object(outer);
 705         if (!o)
 706                 return -1;
 707         if (!expected_type) {
 708                 o = deref_tag(o, name, sp - name - 2);
 709                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 710                         return -1;
 711                 hashcpy(sha1, o->sha1);
 712                 return 0;
 713         }
 714
 715         /*
 716          * At this point, the syntax look correct, so
 717          * if we do not get the needed object, we should
 718          * barf.
 719          */
 720         o = peel_to_type(name, len, o, expected_type);
 721         if (!o)
 722                 return -1;
 723
 724         hashcpy(sha1, o->sha1);
 725         if (sp[0] == '/') {
 726                 /* "$commit^{/foo}" */
 727                 char *prefix;
 728                 int ret;
 729                 struct commit_list *list = NULL;
 730
 731                 /*
 732                  * $commit^{/}. Some regex implementation may reject.
 733                  * We don't need regex anyway. '' pattern always matches.
 734                  */
 735                 if (sp[1] == '}')
 736                         return 0;
 737
 738                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 739                 commit_list_insert((struct commit *)o, &list);
 740                 ret = get_sha1_oneline(prefix, sha1, list);
 741                 free(prefix);
 742                 return ret;
 743         }
 744         return 0;
 745 }
 746
 747 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 748 {
 749         const char *cp;
 750         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 751
 752         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 753                 char ch = *cp;
 754                 if (hexval(ch) & ~0377) {
 755                         /* We must be looking at g in "SOMETHING-g"
 756                          * for it to be describe output.
 757                          */
 758                         if (ch == 'g' && cp[-1] == '-') {
 759                                 cp++;
 760                                 len -= cp - name;
 761                                 return get_short_sha1(cp, len, sha1, flags);
 762                         }
 763                 }
 764         }
 765         return -1;
 766 }
 767
 768 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 769 {
 770         int ret, has_suffix;
 771         const char *cp;
 772
 773         /*
 774          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 775          */
 776         has_suffix = 0;
 777         for (cp = name + len - 1; name <= cp; cp--) {
 778                 int ch = *cp;
 779                 if ('0' <= ch && ch <= '9')
 780                         continue;
 781                 if (ch == '~' || ch == '^')
 782                         has_suffix = ch;
 783                 break;
 784         }
 785
 786         if (has_suffix) {
 787                 int num = 0;
 788                 int len1 = cp - name;
 789                 cp++;
 790                 while (cp < name + len)
 791                         num = num * 10 + *cp++ - '0';
 792                 if (!num && len1 == len - 1)
 793                         num = 1;
 794                 if (has_suffix == '^')
 795                         return get_parent(name, len1, sha1, num);
 796                 /* else if (has_suffix == '~') -- goes without saying */
 797                 return get_nth_ancestor(name, len1, sha1, num);
 798         }
 799
 800         ret = peel_onion(name, len, sha1);
 801         if (!ret)
 802                 return 0;
 803
 804         ret = get_sha1_basic(name, len, sha1);
 805         if (!ret)
 806                 return 0;
 807
 808         /* It could be describe output that is "SOMETHING-gXXXX" */
 809         ret = get_describe_name(name, len, sha1);
 810         if (!ret)
 811                 return 0;
 812
 813         return get_short_sha1(name, len, sha1, lookup_flags);
 814 }
 815
 816 /*
 817  * This interprets names like ':/Initial revision of "git"' by searching
 818  * through history and returning the first commit whose message starts
 819  * the given regular expression.
 820  *
 821  * For future extension, ':/!' is reserved. If you want to match a message
 822  * beginning with a '!', you have to repeat the exclamation mark.
 823  */
 824 #define ONELINE_SEEN (1u<<20)
 825
 826 static int handle_one_ref(const char *path,
 827                 const unsigned char *sha1, int flag, void *cb_data)
 828 {
 829         struct commit_list **list = cb_data;
 830         struct object *object = parse_object(sha1);
 831         if (!object)
 832                 return 0;
 833         if (object->type == OBJ_TAG) {
 834                 object = deref_tag(object, path, strlen(path));
 835                 if (!object)
 836                         return 0;
 837         }
 838         if (object->type != OBJ_COMMIT)
 839                 return 0;
 840         commit_list_insert_by_date((struct commit *)object, list);
 841         return 0;
 842 }
 843
 844 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 845                             struct commit_list *list)
 846 {
 847         struct commit_list *backup = NULL, *l;
 848         int found = 0;
 849         regex_t regex;
 850
 851         if (prefix[0] == '!') {
 852                 if (prefix[1] != '!')
 853                         die ("Invalid search pattern: %s", prefix);
 854                 prefix++;
 855         }
 856
 857         if (regcomp(&regex, prefix, REG_EXTENDED))
 858                 die("Invalid search pattern: %s", prefix);
 859
 860         for (l = list; l; l = l->next) {
 861                 l->item->object.flags |= ONELINE_SEEN;
 862                 commit_list_insert(l->item, &backup);
 863         }
 864         while (list) {
 865                 char *p, *to_free = NULL;
 866                 struct commit *commit;
 867                 enum object_type type;
 868                 unsigned long size;
 869                 int matches;
 870
 871                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 872                 if (!parse_object(commit->object.sha1))
 873                         continue;
 874                 if (commit->buffer)
 875                         p = commit->buffer;
 876                 else {
 877                         p = read_sha1_file(commit->object.sha1, &type, &size);
 878                         if (!p)
 879                                 continue;
 880                         to_free = p;
 881                 }
 882
 883                 p = strstr(p, "\n\n");
 884                 matches = p && !regexec(&regex, p + 2, 0, NULL, 0);
 885                 free(to_free);
 886
 887                 if (matches) {
 888                         hashcpy(sha1, commit->object.sha1);
 889                         found = 1;
 890                         break;
 891                 }
 892         }
 893         regfree(&regex);
 894         free_commit_list(list);
 895         for (l = backup; l; l = l->next)
 896                 clear_commit_marks(l->item, ONELINE_SEEN);
 897         free_commit_list(backup);
 898         return found ? 0 : -1;
 899 }
 900
 901 struct grab_nth_branch_switch_cbdata {
 902         int remaining;
 903         struct strbuf buf;
 904 };
 905
 906 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 907                                   const char *email, unsigned long timestamp, int tz,
 908                                   const char *message, void *cb_data)
 909 {
 910         struct grab_nth_branch_switch_cbdata *cb = cb_data;
 911         const char *match = NULL, *target = NULL;
 912         size_t len;
 913
 914         if (!prefixcmp(message, "checkout: moving from ")) {
 915                 match = message + strlen("checkout: moving from ");
 916                 target = strstr(match, " to ");
 917         }
 918
 919         if (!match || !target)
 920                 return 0;
 921         if (--(cb->remaining) == 0) {
 922                 len = target - match;
 923                 strbuf_reset(&cb->buf);
 924                 strbuf_add(&cb->buf, match, len);
 925                 return 1; /* we are done */
 926         }
 927         return 0;
 928 }
 929
 930 /*
 931  * Parse @{-N} syntax, return the number of characters parsed
 932  * if successful; otherwise signal an error with negative value.
 933  */
 934 static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf)
 935 {
 936         long nth;
 937         int retval;
 938         struct grab_nth_branch_switch_cbdata cb;
 939         const char *brace;
 940         char *num_end;
 941
 942         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
 943                 return -1;
 944         brace = strchr(name, '}');
 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_add(buf, cb.buf.buf, cb.buf.len);
 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, 1);
 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 = strchr(name + 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 /*
1052  * This reads short-hand syntax that not only evaluates to a commit
1053  * object name, but also can act as if the end user spelled the name
1054  * of the branch from the command line.
1055  *
1056  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1057  *   places the name of the branch in the given buf and returns the
1058  *   number of characters parsed if successful.
1059  *
1060  * - "<branch>@{upstream}" finds the name of the other ref that
1061  *   <branch> is configured to merge with (missing <branch> defaults
1062  *   to the current branch), and places the name of the branch in the
1063  *   given buf and returns the number of characters parsed if
1064  *   successful.
1065  *
1066  * If the input is not of the accepted format, it returns a negative
1067  * number to signal an error.
1068  *
1069  * If the input was ok but there are not N branch switches in the
1070  * reflog, it returns 0.
1071  */
1072 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1073 {
1074         char *cp;
1075         struct branch *upstream;
1076         int len = interpret_nth_prior_checkout(name, buf);
1077         int tmp_len;
1078
1079         if (!namelen)
1080                 namelen = strlen(name);
1081
1082         if (!len) {
1083                 return len; /* syntax Ok, not enough switches */
1084         } else if (len > 0) {
1085                 if (len == namelen)
1086                         return len; /* consumed all */
1087                 else
1088                         return reinterpret(name, namelen, len, buf);
1089         }
1090
1091         cp = strchr(name, '@');
1092         if (!cp)
1093                 return -1;
1094
1095         len = interpret_empty_at(name, namelen, cp - name, buf);
1096         if (len > 0)
1097                 return reinterpret(name, namelen, len, buf);
1098
1099         tmp_len = upstream_mark(cp, namelen - (cp - name));
1100         if (!tmp_len)
1101                 return -1;
1102
1103         len = cp + tmp_len - name;
1104         cp = xstrndup(name, cp - name);
1105         upstream = branch_get(*cp ? cp : NULL);
1106         /*
1107          * Upstream can be NULL only if cp refers to HEAD and HEAD
1108          * points to something different than a branch.
1109          */
1110         if (!upstream)
1111                 die(_("HEAD does not point to a branch"));
1112         if (!upstream->merge || !upstream->merge[0]->dst) {
1113                 if (!ref_exists(upstream->refname))
1114                         die(_("No such branch: '%s'"), cp);
1115                 if (!upstream->merge) {
1116                         die(_("No upstream configured for branch '%s'"),
1117                                 upstream->name);
1118                 }
1119                 die(
1120                         _("Upstream branch '%s' not stored as a remote-tracking branch"),
1121                         upstream->merge[0]->src);
1122         }
1123         free(cp);
1124         cp = shorten_unambiguous_ref(upstream->merge[0]->dst, 0);
1125         strbuf_reset(buf);
1126         strbuf_addstr(buf, cp);
1127         free(cp);
1128         return len;
1129 }
1130
1131 int strbuf_branchname(struct strbuf *sb, const char *name)
1132 {
1133         int len = strlen(name);
1134         int used = interpret_branch_name(name, len, sb);
1135
1136         if (used == len)
1137                 return 0;
1138         if (used < 0)
1139                 used = 0;
1140         strbuf_add(sb, name + used, len - used);
1141         return len;
1142 }
1143
1144 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1145 {
1146         strbuf_branchname(sb, name);
1147         if (name[0] == '-')
1148                 return -1;
1149         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1150         return check_refname_format(sb->buf, 0);
1151 }
1152
1153 /*
1154  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1155  * notably "xyz^" for "parent of xyz"
1156  */
1157 int get_sha1(const char *name, unsigned char *sha1)
1158 {
1159         struct object_context unused;
1160         return get_sha1_with_context(name, 0, sha1, &unused);
1161 }
1162
1163 /*
1164  * Many callers know that the user meant to name a commit-ish by
1165  * syntactical positions where the object name appears.  Calling this
1166  * function allows the machinery to disambiguate shorter-than-unique
1167  * abbreviated object names between commit-ish and others.
1168  *
1169  * Note that this does NOT error out when the named object is not a
1170  * commit-ish. It is merely to give a hint to the disambiguation
1171  * machinery.
1172  */
1173 int get_sha1_committish(const char *name, unsigned char *sha1)
1174 {
1175         struct object_context unused;
1176         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1177                                      sha1, &unused);
1178 }
1179
1180 int get_sha1_treeish(const char *name, unsigned char *sha1)
1181 {
1182         struct object_context unused;
1183         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1184                                      sha1, &unused);
1185 }
1186
1187 int get_sha1_commit(const char *name, unsigned char *sha1)
1188 {
1189         struct object_context unused;
1190         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1191                                      sha1, &unused);
1192 }
1193
1194 int get_sha1_tree(const char *name, unsigned char *sha1)
1195 {
1196         struct object_context unused;
1197         return get_sha1_with_context(name, GET_SHA1_TREE,
1198                                      sha1, &unused);
1199 }
1200
1201 int get_sha1_blob(const char *name, unsigned char *sha1)
1202 {
1203         struct object_context unused;
1204         return get_sha1_with_context(name, GET_SHA1_BLOB,
1205                                      sha1, &unused);
1206 }
1207
1208 /* Must be called only when object_name:filename doesn't exist. */
1209 static void diagnose_invalid_sha1_path(const char *prefix,
1210                                        const char *filename,
1211                                        const unsigned char *tree_sha1,
1212                                        const char *object_name,
1213                                        int object_name_len)
1214 {
1215         struct stat st;
1216         unsigned char sha1[20];
1217         unsigned mode;
1218
1219         if (!prefix)
1220                 prefix = "";
1221
1222         if (!lstat(filename, &st))
1223                 die("Path '%s' exists on disk, but not in '%.*s'.",
1224                     filename, object_name_len, object_name);
1225         if (errno == ENOENT || errno == ENOTDIR) {
1226                 char *fullname = xmalloc(strlen(filename)
1227                                              + strlen(prefix) + 1);
1228                 strcpy(fullname, prefix);
1229                 strcat(fullname, filename);
1230
1231                 if (!get_tree_entry(tree_sha1, fullname,
1232                                     sha1, &mode)) {
1233                         die("Path '%s' exists, but not '%s'.\n"
1234                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1235                             fullname,
1236                             filename,
1237                             object_name_len, object_name,
1238                             fullname,
1239                             object_name_len, object_name,
1240                             filename);
1241                 }
1242                 die("Path '%s' does not exist in '%.*s'",
1243                     filename, object_name_len, object_name);
1244         }
1245 }
1246
1247 /* Must be called only when :stage:filename doesn't exist. */
1248 static void diagnose_invalid_index_path(int stage,
1249                                         const char *prefix,
1250                                         const char *filename)
1251 {
1252         struct stat st;
1253         const struct cache_entry *ce;
1254         int pos;
1255         unsigned namelen = strlen(filename);
1256         unsigned fullnamelen;
1257         char *fullname;
1258
1259         if (!prefix)
1260                 prefix = "";
1261
1262         /* Wrong stage number? */
1263         pos = cache_name_pos(filename, namelen);
1264         if (pos < 0)
1265                 pos = -pos - 1;
1266         if (pos < active_nr) {
1267                 ce = active_cache[pos];
1268                 if (ce_namelen(ce) == namelen &&
1269                     !memcmp(ce->name, filename, namelen))
1270                         die("Path '%s' is in the index, but not at stage %d.\n"
1271                             "Did you mean ':%d:%s'?",
1272                             filename, stage,
1273                             ce_stage(ce), filename);
1274         }
1275
1276         /* Confusion between relative and absolute filenames? */
1277         fullnamelen = namelen + strlen(prefix);
1278         fullname = xmalloc(fullnamelen + 1);
1279         strcpy(fullname, prefix);
1280         strcat(fullname, filename);
1281         pos = cache_name_pos(fullname, fullnamelen);
1282         if (pos < 0)
1283                 pos = -pos - 1;
1284         if (pos < active_nr) {
1285                 ce = active_cache[pos];
1286                 if (ce_namelen(ce) == fullnamelen &&
1287                     !memcmp(ce->name, fullname, fullnamelen))
1288                         die("Path '%s' is in the index, but not '%s'.\n"
1289                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1290                             fullname, filename,
1291                             ce_stage(ce), fullname,
1292                             ce_stage(ce), filename);
1293         }
1294
1295         if (!lstat(filename, &st))
1296                 die("Path '%s' exists on disk, but not in the index.", filename);
1297         if (errno == ENOENT || errno == ENOTDIR)
1298                 die("Path '%s' does not exist (neither on disk nor in the index).",
1299                     filename);
1300
1301         free(fullname);
1302 }
1303
1304
1305 static char *resolve_relative_path(const char *rel)
1306 {
1307         if (prefixcmp(rel, "./") && prefixcmp(rel, "../"))
1308                 return NULL;
1309
1310         if (!startup_info)
1311                 die("BUG: startup_info struct is not initialized.");
1312
1313         if (!is_inside_work_tree())
1314                 die("relative path syntax can't be used outside working tree.");
1315
1316         /* die() inside prefix_path() if resolved path is outside worktree */
1317         return prefix_path(startup_info->prefix,
1318                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1319                            rel);
1320 }
1321
1322 static int get_sha1_with_context_1(const char *name,
1323                                    unsigned flags,
1324                                    const char *prefix,
1325                                    unsigned char *sha1,
1326                                    struct object_context *oc)
1327 {
1328         int ret, bracket_depth;
1329         int namelen = strlen(name);
1330         const char *cp;
1331         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1332
1333         memset(oc, 0, sizeof(*oc));
1334         oc->mode = S_IFINVALID;
1335         ret = get_sha1_1(name, namelen, sha1, flags);
1336         if (!ret)
1337                 return ret;
1338         /*
1339          * sha1:path --> object name of path in ent sha1
1340          * :path -> object name of absolute path in index
1341          * :./path -> object name of path relative to cwd in index
1342          * :[0-3]:path -> object name of path in index at stage
1343          * :/foo -> recent commit matching foo
1344          */
1345         if (name[0] == ':') {
1346                 int stage = 0;
1347                 const struct cache_entry *ce;
1348                 char *new_path = NULL;
1349                 int pos;
1350                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1351                         struct commit_list *list = NULL;
1352                         for_each_ref(handle_one_ref, &list);
1353                         return get_sha1_oneline(name + 2, sha1, list);
1354                 }
1355                 if (namelen < 3 ||
1356                     name[2] != ':' ||
1357                     name[1] < '0' || '3' < name[1])
1358                         cp = name + 1;
1359                 else {
1360                         stage = name[1] - '0';
1361                         cp = name + 3;
1362                 }
1363                 new_path = resolve_relative_path(cp);
1364                 if (!new_path) {
1365                         namelen = namelen - (cp - name);
1366                 } else {
1367                         cp = new_path;
1368                         namelen = strlen(cp);
1369                 }
1370
1371                 strncpy(oc->path, cp,
1372                         sizeof(oc->path));
1373                 oc->path[sizeof(oc->path)-1] = '\0';
1374
1375                 if (!active_cache)
1376                         read_cache();
1377                 pos = cache_name_pos(cp, namelen);
1378                 if (pos < 0)
1379                         pos = -pos - 1;
1380                 while (pos < active_nr) {
1381                         ce = active_cache[pos];
1382                         if (ce_namelen(ce) != namelen ||
1383                             memcmp(ce->name, cp, namelen))
1384                                 break;
1385                         if (ce_stage(ce) == stage) {
1386                                 hashcpy(sha1, ce->sha1);
1387                                 oc->mode = ce->ce_mode;
1388                                 free(new_path);
1389                                 return 0;
1390                         }
1391                         pos++;
1392                 }
1393                 if (only_to_die && name[1] && name[1] != '/')
1394                         diagnose_invalid_index_path(stage, prefix, cp);
1395                 free(new_path);
1396                 return -1;
1397         }
1398         for (cp = name, bracket_depth = 0; *cp; cp++) {
1399                 if (*cp == '{')
1400                         bracket_depth++;
1401                 else if (bracket_depth && *cp == '}')
1402                         bracket_depth--;
1403                 else if (!bracket_depth && *cp == ':')
1404                         break;
1405         }
1406         if (*cp == ':') {
1407                 unsigned char tree_sha1[20];
1408                 int len = cp - name;
1409                 if (!get_sha1_1(name, len, tree_sha1, GET_SHA1_TREEISH)) {
1410                         const char *filename = cp+1;
1411                         char *new_filename = NULL;
1412
1413                         new_filename = resolve_relative_path(filename);
1414                         if (new_filename)
1415                                 filename = new_filename;
1416                         ret = get_tree_entry(tree_sha1, filename, sha1, &oc->mode);
1417                         if (ret && only_to_die) {
1418                                 diagnose_invalid_sha1_path(prefix, filename,
1419                                                            tree_sha1,
1420                                                            name, len);
1421                         }
1422                         hashcpy(oc->tree, tree_sha1);
1423                         strncpy(oc->path, filename,
1424                                 sizeof(oc->path));
1425                         oc->path[sizeof(oc->path)-1] = '\0';
1426
1427                         free(new_filename);
1428                         return ret;
1429                 } else {
1430                         if (only_to_die)
1431                                 die("Invalid object name '%.*s'.", len, name);
1432                 }
1433         }
1434         return ret;
1435 }
1436
1437 /*
1438  * Call this function when you know "name" given by the end user must
1439  * name an object but it doesn't; the function _may_ die with a better
1440  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1441  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1442  * you have a chance to diagnose the error further.
1443  */
1444 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1445 {
1446         struct object_context oc;
1447         unsigned char sha1[20];
1448         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1449 }
1450
1451 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1452 {
1453         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1454 }