Pileus Git - ~andy/git/blob - sha1_name.c

   1 #include "cache.h"
   2 #include "tag.h"
   3 #include "commit.h"
   4 #include "tree.h"
   5 #include "blob.h"
   6 #include "tree-walk.h"
   7 #include "refs.h"
   8 #include "remote.h"
   9
  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_ambiguous_refs && warn_on_object_refname_ambiguity) {
 455                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 456                         if (refs_found > 0) {
 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 (starts_with(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 (parse_commit(commit))
 585                 return -1;
 586         if (!idx) {
 587                 hashcpy(result, commit->object.sha1);
 588                 return 0;
 589         }
 590         p = commit->parents;
 591         while (p) {
 592                 if (!--idx) {
 593                         hashcpy(result, p->item->object.sha1);
 594                         return 0;
 595                 }
 596                 p = p->next;
 597         }
 598         return -1;
 599 }
 600
 601 static int get_nth_ancestor(const char *name, int len,
 602                             unsigned char *result, int generation)
 603 {
 604         unsigned char sha1[20];
 605         struct commit *commit;
 606         int ret;
 607
 608         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 609         if (ret)
 610                 return ret;
 611         commit = lookup_commit_reference(sha1);
 612         if (!commit)
 613                 return -1;
 614
 615         while (generation--) {
 616                 if (parse_commit(commit) || !commit->parents)
 617                         return -1;
 618                 commit = commit->parents->item;
 619         }
 620         hashcpy(result, commit->object.sha1);
 621         return 0;
 622 }
 623
 624 struct object *peel_to_type(const char *name, int namelen,
 625                             struct object *o, enum object_type expected_type)
 626 {
 627         if (name && !namelen)
 628                 namelen = strlen(name);
 629         while (1) {
 630                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 631                         return NULL;
 632                 if (expected_type == OBJ_ANY || o->type == expected_type)
 633                         return o;
 634                 if (o->type == OBJ_TAG)
 635                         o = ((struct tag*) o)->tagged;
 636                 else if (o->type == OBJ_COMMIT)
 637                         o = &(((struct commit *) o)->tree->object);
 638                 else {
 639                         if (name)
 640                                 error("%.*s: expected %s type, but the object "
 641                                       "dereferences to %s type",
 642                                       namelen, name, typename(expected_type),
 643                                       typename(o->type));
 644                         return NULL;
 645                 }
 646         }
 647 }
 648
 649 static int peel_onion(const char *name, int len, unsigned char *sha1)
 650 {
 651         unsigned char outer[20];
 652         const char *sp;
 653         unsigned int expected_type = 0;
 654         unsigned lookup_flags = 0;
 655         struct object *o;
 656
 657         /*
 658          * "ref^{type}" dereferences ref repeatedly until you cannot
 659          * dereference anymore, or you get an object of given type,
 660          * whichever comes first.  "ref^{}" means just dereference
 661          * tags until you get a non-tag.  "ref^0" is a shorthand for
 662          * "ref^{commit}".  "commit^{tree}" could be used to find the
 663          * top-level tree of the given commit.
 664          */
 665         if (len < 4 || name[len-1] != '}')
 666                 return -1;
 667
 668         for (sp = name + len - 1; name <= sp; sp--) {
 669                 int ch = *sp;
 670                 if (ch == '{' && name < sp && sp[-1] == '^')
 671                         break;
 672         }
 673         if (sp <= name)
 674                 return -1;
 675
 676         sp++; /* beginning of type name, or closing brace for empty */
 677         if (starts_with(sp, "commit}"))
 678                 expected_type = OBJ_COMMIT;
 679         else if (starts_with(sp, "tag}"))
 680                 expected_type = OBJ_TAG;
 681         else if (starts_with(sp, "tree}"))
 682                 expected_type = OBJ_TREE;
 683         else if (starts_with(sp, "blob}"))
 684                 expected_type = OBJ_BLOB;
 685         else if (starts_with(sp, "object}"))
 686                 expected_type = OBJ_ANY;
 687         else if (sp[0] == '}')
 688                 expected_type = OBJ_NONE;
 689         else if (sp[0] == '/')
 690                 expected_type = OBJ_COMMIT;
 691         else
 692                 return -1;
 693
 694         if (expected_type == OBJ_COMMIT)
 695                 lookup_flags = GET_SHA1_COMMITTISH;
 696         else if (expected_type == OBJ_TREE)
 697                 lookup_flags = GET_SHA1_TREEISH;
 698
 699         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 700                 return -1;
 701
 702         o = parse_object(outer);
 703         if (!o)
 704                 return -1;
 705         if (!expected_type) {
 706                 o = deref_tag(o, name, sp - name - 2);
 707                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 708                         return -1;
 709                 hashcpy(sha1, o->sha1);
 710                 return 0;
 711         }
 712
 713         /*
 714          * At this point, the syntax look correct, so
 715          * if we do not get the needed object, we should
 716          * barf.
 717          */
 718         o = peel_to_type(name, len, o, expected_type);
 719         if (!o)
 720                 return -1;
 721
 722         hashcpy(sha1, o->sha1);
 723         if (sp[0] == '/') {
 724                 /* "$commit^{/foo}" */
 725                 char *prefix;
 726                 int ret;
 727                 struct commit_list *list = NULL;
 728
 729                 /*
 730                  * $commit^{/}. Some regex implementation may reject.
 731                  * We don't need regex anyway. '' pattern always matches.
 732                  */
 733                 if (sp[1] == '}')
 734                         return 0;
 735
 736                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 737                 commit_list_insert((struct commit *)o, &list);
 738                 ret = get_sha1_oneline(prefix, sha1, list);
 739                 free(prefix);
 740                 return ret;
 741         }
 742         return 0;
 743 }
 744
 745 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 746 {
 747         const char *cp;
 748         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 749
 750         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 751                 char ch = *cp;
 752                 if (hexval(ch) & ~0377) {
 753                         /* We must be looking at g in "SOMETHING-g"
 754                          * for it to be describe output.
 755                          */
 756                         if (ch == 'g' && cp[-1] == '-') {
 757                                 cp++;
 758                                 len -= cp - name;
 759                                 return get_short_sha1(cp, len, sha1, flags);
 760                         }
 761                 }
 762         }
 763         return -1;
 764 }
 765
 766 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 767 {
 768         int ret, has_suffix;
 769         const char *cp;
 770
 771         /*
 772          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 773          */
 774         has_suffix = 0;
 775         for (cp = name + len - 1; name <= cp; cp--) {
 776                 int ch = *cp;
 777                 if ('0' <= ch && ch <= '9')
 778                         continue;
 779                 if (ch == '~' || ch == '^')
 780                         has_suffix = ch;
 781                 break;
 782         }
 783
 784         if (has_suffix) {
 785                 int num = 0;
 786                 int len1 = cp - name;
 787                 cp++;
 788                 while (cp < name + len)
 789                         num = num * 10 + *cp++ - '0';
 790                 if (!num && len1 == len - 1)
 791                         num = 1;
 792                 if (has_suffix == '^')
 793                         return get_parent(name, len1, sha1, num);
 794                 /* else if (has_suffix == '~') -- goes without saying */
 795                 return get_nth_ancestor(name, len1, sha1, num);
 796         }
 797
 798         ret = peel_onion(name, len, sha1);
 799         if (!ret)
 800                 return 0;
 801
 802         ret = get_sha1_basic(name, len, sha1);
 803         if (!ret)
 804                 return 0;
 805
 806         /* It could be describe output that is "SOMETHING-gXXXX" */
 807         ret = get_describe_name(name, len, sha1);
 808         if (!ret)
 809                 return 0;
 810
 811         return get_short_sha1(name, len, sha1, lookup_flags);
 812 }
 813
 814 /*
 815  * This interprets names like ':/Initial revision of "git"' by searching
 816  * through history and returning the first commit whose message starts
 817  * the given regular expression.
 818  *
 819  * For future extension, ':/!' is reserved. If you want to match a message
 820  * beginning with a '!', you have to repeat the exclamation mark.
 821  */
 822 #define ONELINE_SEEN (1u<<20)
 823
 824 static int handle_one_ref(const char *path,
 825                 const unsigned char *sha1, int flag, void *cb_data)
 826 {
 827         struct commit_list **list = cb_data;
 828         struct object *object = parse_object(sha1);
 829         if (!object)
 830                 return 0;
 831         if (object->type == OBJ_TAG) {
 832                 object = deref_tag(object, path, strlen(path));
 833                 if (!object)
 834                         return 0;
 835         }
 836         if (object->type != OBJ_COMMIT)
 837                 return 0;
 838         commit_list_insert_by_date((struct commit *)object, list);
 839         return 0;
 840 }
 841
 842 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 843                             struct commit_list *list)
 844 {
 845         struct commit_list *backup = NULL, *l;
 846         int found = 0;
 847         regex_t regex;
 848
 849         if (prefix[0] == '!') {
 850                 if (prefix[1] != '!')
 851                         die ("Invalid search pattern: %s", prefix);
 852                 prefix++;
 853         }
 854
 855         if (regcomp(&regex, prefix, REG_EXTENDED))
 856                 die("Invalid search pattern: %s", prefix);
 857
 858         for (l = list; l; l = l->next) {
 859                 l->item->object.flags |= ONELINE_SEEN;
 860                 commit_list_insert(l->item, &backup);
 861         }
 862         while (list) {
 863                 char *p, *to_free = NULL;
 864                 struct commit *commit;
 865                 enum object_type type;
 866                 unsigned long size;
 867                 int matches;
 868
 869                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 870                 if (!parse_object(commit->object.sha1))
 871                         continue;
 872                 if (commit->buffer)
 873                         p = commit->buffer;
 874                 else {
 875                         p = read_sha1_file(commit->object.sha1, &type, &size);
 876                         if (!p)
 877                                 continue;
 878                         to_free = p;
 879                 }
 880
 881                 p = strstr(p, "\n\n");
 882                 matches = p && !regexec(&regex, p + 2, 0, NULL, 0);
 883                 free(to_free);
 884
 885                 if (matches) {
 886                         hashcpy(sha1, commit->object.sha1);
 887                         found = 1;
 888                         break;
 889                 }
 890         }
 891         regfree(&regex);
 892         free_commit_list(list);
 893         for (l = backup; l; l = l->next)
 894                 clear_commit_marks(l->item, ONELINE_SEEN);
 895         free_commit_list(backup);
 896         return found ? 0 : -1;
 897 }
 898
 899 struct grab_nth_branch_switch_cbdata {
 900         int remaining;
 901         struct strbuf buf;
 902 };
 903
 904 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 905                                   const char *email, unsigned long timestamp, int tz,
 906                                   const char *message, void *cb_data)
 907 {
 908         struct grab_nth_branch_switch_cbdata *cb = cb_data;
 909         const char *match = NULL, *target = NULL;
 910         size_t len;
 911
 912         if (starts_with(message, "checkout: moving from ")) {
 913                 match = message + strlen("checkout: moving from ");
 914                 target = strstr(match, " to ");
 915         }
 916
 917         if (!match || !target)
 918                 return 0;
 919         if (--(cb->remaining) == 0) {
 920                 len = target - match;
 921                 strbuf_reset(&cb->buf);
 922                 strbuf_add(&cb->buf, match, len);
 923                 return 1; /* we are done */
 924         }
 925         return 0;
 926 }
 927
 928 /*
 929  * Parse @{-N} syntax, return the number of characters parsed
 930  * if successful; otherwise signal an error with negative value.
 931  */
 932 static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf)
 933 {
 934         long nth;
 935         int retval;
 936         struct grab_nth_branch_switch_cbdata cb;
 937         const char *brace;
 938         char *num_end;
 939
 940         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
 941                 return -1;
 942         brace = strchr(name, '}');
 943         if (!brace)
 944                 return -1;
 945         nth = strtol(name + 3, &num_end, 10);
 946         if (num_end != brace)
 947                 return -1;
 948         if (nth <= 0)
 949                 return -1;
 950         cb.remaining = nth;
 951         strbuf_init(&cb.buf, 20);
 952
 953         retval = 0;
 954         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
 955                 strbuf_reset(buf);
 956                 strbuf_add(buf, cb.buf.buf, cb.buf.len);
 957                 retval = brace - name + 1;
 958         }
 959
 960         strbuf_release(&cb.buf);
 961         return retval;
 962 }
 963
 964 int get_sha1_mb(const char *name, unsigned char *sha1)
 965 {
 966         struct commit *one, *two;
 967         struct commit_list *mbs;
 968         unsigned char sha1_tmp[20];
 969         const char *dots;
 970         int st;
 971
 972         dots = strstr(name, "...");
 973         if (!dots)
 974                 return get_sha1(name, sha1);
 975         if (dots == name)
 976                 st = get_sha1("HEAD", sha1_tmp);
 977         else {
 978                 struct strbuf sb;
 979                 strbuf_init(&sb, dots - name);
 980                 strbuf_add(&sb, name, dots - name);
 981                 st = get_sha1_committish(sb.buf, sha1_tmp);
 982                 strbuf_release(&sb);
 983         }
 984         if (st)
 985                 return st;
 986         one = lookup_commit_reference_gently(sha1_tmp, 0);
 987         if (!one)
 988                 return -1;
 989
 990         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
 991                 return -1;
 992         two = lookup_commit_reference_gently(sha1_tmp, 0);
 993         if (!two)
 994                 return -1;
 995         mbs = get_merge_bases(one, two, 1);
 996         if (!mbs || mbs->next)
 997                 st = -1;
 998         else {
 999                 st = 0;
1000                 hashcpy(sha1, mbs->item->object.sha1);
1001         }
1002         free_commit_list(mbs);
1003         return st;
1004 }
1005
1006 /* parse @something syntax, when 'something' is not {.*} */
1007 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1008 {
1009         const char *next;
1010
1011         if (len || name[1] == '{')
1012                 return -1;
1013
1014         /* make sure it's a single @, or @@{.*}, not @foo */
1015         next = strchr(name + len + 1, '@');
1016         if (next && next[1] != '{')
1017                 return -1;
1018         if (!next)
1019                 next = name + namelen;
1020         if (next != name + 1)
1021                 return -1;
1022
1023         strbuf_reset(buf);
1024         strbuf_add(buf, "HEAD", 4);
1025         return 1;
1026 }
1027
1028 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1029 {
1030         /* we have extra data, which might need further processing */
1031         struct strbuf tmp = STRBUF_INIT;
1032         int used = buf->len;
1033         int ret;
1034
1035         strbuf_add(buf, name + len, namelen - len);
1036         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1037         /* that data was not interpreted, remove our cruft */
1038         if (ret < 0) {
1039                 strbuf_setlen(buf, used);
1040                 return len;
1041         }
1042         strbuf_reset(buf);
1043         strbuf_addbuf(buf, &tmp);
1044         strbuf_release(&tmp);
1045         /* tweak for size of {-N} versus expanded ref name */
1046         return ret - used + len;
1047 }
1048
1049 /*
1050  * This reads short-hand syntax that not only evaluates to a commit
1051  * object name, but also can act as if the end user spelled the name
1052  * of the branch from the command line.
1053  *
1054  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1055  *   places the name of the branch in the given buf and returns the
1056  *   number of characters parsed if successful.
1057  *
1058  * - "<branch>@{upstream}" finds the name of the other ref that
1059  *   <branch> is configured to merge with (missing <branch> defaults
1060  *   to the current branch), and places the name of the branch in the
1061  *   given buf and returns the number of characters parsed if
1062  *   successful.
1063  *
1064  * If the input is not of the accepted format, it returns a negative
1065  * number to signal an error.
1066  *
1067  * If the input was ok but there are not N branch switches in the
1068  * reflog, it returns 0.
1069  */
1070 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1071 {
1072         char *cp;
1073         struct branch *upstream;
1074         int len = interpret_nth_prior_checkout(name, buf);
1075         int tmp_len;
1076
1077         if (!namelen)
1078                 namelen = strlen(name);
1079
1080         if (!len) {
1081                 return len; /* syntax Ok, not enough switches */
1082         } else if (len > 0) {
1083                 if (len == namelen)
1084                         return len; /* consumed all */
1085                 else
1086                         return reinterpret(name, namelen, len, buf);
1087         }
1088
1089         cp = strchr(name, '@');
1090         if (!cp)
1091                 return -1;
1092
1093         len = interpret_empty_at(name, namelen, cp - name, buf);
1094         if (len > 0)
1095                 return reinterpret(name, namelen, len, buf);
1096
1097         tmp_len = upstream_mark(cp, namelen - (cp - name));
1098         if (!tmp_len)
1099                 return -1;
1100
1101         len = cp + tmp_len - name;
1102         cp = xstrndup(name, cp - name);
1103         upstream = branch_get(*cp ? cp : NULL);
1104         /*
1105          * Upstream can be NULL only if cp refers to HEAD and HEAD
1106          * points to something different than a branch.
1107          */
1108         if (!upstream)
1109                 die(_("HEAD does not point to a branch"));
1110         if (!upstream->merge || !upstream->merge[0]->dst) {
1111                 if (!ref_exists(upstream->refname))
1112                         die(_("No such branch: '%s'"), cp);
1113                 if (!upstream->merge) {
1114                         die(_("No upstream configured for branch '%s'"),
1115                                 upstream->name);
1116                 }
1117                 die(
1118                         _("Upstream branch '%s' not stored as a remote-tracking branch"),
1119                         upstream->merge[0]->src);
1120         }
1121         free(cp);
1122         cp = shorten_unambiguous_ref(upstream->merge[0]->dst, 0);
1123         strbuf_reset(buf);
1124         strbuf_addstr(buf, cp);
1125         free(cp);
1126         return len;
1127 }
1128
1129 int strbuf_branchname(struct strbuf *sb, const char *name)
1130 {
1131         int len = strlen(name);
1132         int used = interpret_branch_name(name, len, sb);
1133
1134         if (used == len)
1135                 return 0;
1136         if (used < 0)
1137                 used = 0;
1138         strbuf_add(sb, name + used, len - used);
1139         return len;
1140 }
1141
1142 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1143 {
1144         strbuf_branchname(sb, name);
1145         if (name[0] == '-')
1146                 return -1;
1147         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1148         return check_refname_format(sb->buf, 0);
1149 }
1150
1151 /*
1152  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1153  * notably "xyz^" for "parent of xyz"
1154  */
1155 int get_sha1(const char *name, unsigned char *sha1)
1156 {
1157         struct object_context unused;
1158         return get_sha1_with_context(name, 0, sha1, &unused);
1159 }
1160
1161 /*
1162  * Many callers know that the user meant to name a commit-ish by
1163  * syntactical positions where the object name appears.  Calling this
1164  * function allows the machinery to disambiguate shorter-than-unique
1165  * abbreviated object names between commit-ish and others.
1166  *
1167  * Note that this does NOT error out when the named object is not a
1168  * commit-ish. It is merely to give a hint to the disambiguation
1169  * machinery.
1170  */
1171 int get_sha1_committish(const char *name, unsigned char *sha1)
1172 {
1173         struct object_context unused;
1174         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1175                                      sha1, &unused);
1176 }
1177
1178 int get_sha1_treeish(const char *name, unsigned char *sha1)
1179 {
1180         struct object_context unused;
1181         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1182                                      sha1, &unused);
1183 }
1184
1185 int get_sha1_commit(const char *name, unsigned char *sha1)
1186 {
1187         struct object_context unused;
1188         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1189                                      sha1, &unused);
1190 }
1191
1192 int get_sha1_tree(const char *name, unsigned char *sha1)
1193 {
1194         struct object_context unused;
1195         return get_sha1_with_context(name, GET_SHA1_TREE,
1196                                      sha1, &unused);
1197 }
1198
1199 int get_sha1_blob(const char *name, unsigned char *sha1)
1200 {
1201         struct object_context unused;
1202         return get_sha1_with_context(name, GET_SHA1_BLOB,
1203                                      sha1, &unused);
1204 }
1205
1206 /* Must be called only when object_name:filename doesn't exist. */
1207 static void diagnose_invalid_sha1_path(const char *prefix,
1208                                        const char *filename,
1209                                        const unsigned char *tree_sha1,
1210                                        const char *object_name,
1211                                        int object_name_len)
1212 {
1213         struct stat st;
1214         unsigned char sha1[20];
1215         unsigned mode;
1216
1217         if (!prefix)
1218                 prefix = "";
1219
1220         if (!lstat(filename, &st))
1221                 die("Path '%s' exists on disk, but not in '%.*s'.",
1222                     filename, object_name_len, object_name);
1223         if (errno == ENOENT || errno == ENOTDIR) {
1224                 char *fullname = xmalloc(strlen(filename)
1225                                              + strlen(prefix) + 1);
1226                 strcpy(fullname, prefix);
1227                 strcat(fullname, filename);
1228
1229                 if (!get_tree_entry(tree_sha1, fullname,
1230                                     sha1, &mode)) {
1231                         die("Path '%s' exists, but not '%s'.\n"
1232                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1233                             fullname,
1234                             filename,
1235                             object_name_len, object_name,
1236                             fullname,
1237                             object_name_len, object_name,
1238                             filename);
1239                 }
1240                 die("Path '%s' does not exist in '%.*s'",
1241                     filename, object_name_len, object_name);
1242         }
1243 }
1244
1245 /* Must be called only when :stage:filename doesn't exist. */
1246 static void diagnose_invalid_index_path(int stage,
1247                                         const char *prefix,
1248                                         const char *filename)
1249 {
1250         struct stat st;
1251         const struct cache_entry *ce;
1252         int pos;
1253         unsigned namelen = strlen(filename);
1254         unsigned fullnamelen;
1255         char *fullname;
1256
1257         if (!prefix)
1258                 prefix = "";
1259
1260         /* Wrong stage number? */
1261         pos = cache_name_pos(filename, namelen);
1262         if (pos < 0)
1263                 pos = -pos - 1;
1264         if (pos < active_nr) {
1265                 ce = active_cache[pos];
1266                 if (ce_namelen(ce) == namelen &&
1267                     !memcmp(ce->name, filename, namelen))
1268                         die("Path '%s' is in the index, but not at stage %d.\n"
1269                             "Did you mean ':%d:%s'?",
1270                             filename, stage,
1271                             ce_stage(ce), filename);
1272         }
1273
1274         /* Confusion between relative and absolute filenames? */
1275         fullnamelen = namelen + strlen(prefix);
1276         fullname = xmalloc(fullnamelen + 1);
1277         strcpy(fullname, prefix);
1278         strcat(fullname, filename);
1279         pos = cache_name_pos(fullname, fullnamelen);
1280         if (pos < 0)
1281                 pos = -pos - 1;
1282         if (pos < active_nr) {
1283                 ce = active_cache[pos];
1284                 if (ce_namelen(ce) == fullnamelen &&
1285                     !memcmp(ce->name, fullname, fullnamelen))
1286                         die("Path '%s' is in the index, but not '%s'.\n"
1287                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1288                             fullname, filename,
1289                             ce_stage(ce), fullname,
1290                             ce_stage(ce), filename);
1291         }
1292
1293         if (!lstat(filename, &st))
1294                 die("Path '%s' exists on disk, but not in the index.", filename);
1295         if (errno == ENOENT || errno == ENOTDIR)
1296                 die("Path '%s' does not exist (neither on disk nor in the index).",
1297                     filename);
1298
1299         free(fullname);
1300 }
1301
1302
1303 static char *resolve_relative_path(const char *rel)
1304 {
1305         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1306                 return NULL;
1307
1308         if (!startup_info)
1309                 die("BUG: startup_info struct is not initialized.");
1310
1311         if (!is_inside_work_tree())
1312                 die("relative path syntax can't be used outside working tree.");
1313
1314         /* die() inside prefix_path() if resolved path is outside worktree */
1315         return prefix_path(startup_info->prefix,
1316                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1317                            rel);
1318 }
1319
1320 static int get_sha1_with_context_1(const char *name,
1321                                    unsigned flags,
1322                                    const char *prefix,
1323                                    unsigned char *sha1,
1324                                    struct object_context *oc)
1325 {
1326         int ret, bracket_depth;
1327         int namelen = strlen(name);
1328         const char *cp;
1329         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1330
1331         memset(oc, 0, sizeof(*oc));
1332         oc->mode = S_IFINVALID;
1333         ret = get_sha1_1(name, namelen, sha1, flags);
1334         if (!ret)
1335                 return ret;
1336         /*
1337          * sha1:path --> object name of path in ent sha1
1338          * :path -> object name of absolute path in index
1339          * :./path -> object name of path relative to cwd in index
1340          * :[0-3]:path -> object name of path in index at stage
1341          * :/foo -> recent commit matching foo
1342          */
1343         if (name[0] == ':') {
1344                 int stage = 0;
1345                 const struct cache_entry *ce;
1346                 char *new_path = NULL;
1347                 int pos;
1348                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1349                         struct commit_list *list = NULL;
1350                         for_each_ref(handle_one_ref, &list);
1351                         return get_sha1_oneline(name + 2, sha1, list);
1352                 }
1353                 if (namelen < 3 ||
1354                     name[2] != ':' ||
1355                     name[1] < '0' || '3' < name[1])
1356                         cp = name + 1;
1357                 else {
1358                         stage = name[1] - '0';
1359                         cp = name + 3;
1360                 }
1361                 new_path = resolve_relative_path(cp);
1362                 if (!new_path) {
1363                         namelen = namelen - (cp - name);
1364                 } else {
1365                         cp = new_path;
1366                         namelen = strlen(cp);
1367                 }
1368
1369                 strncpy(oc->path, cp,
1370                         sizeof(oc->path));
1371                 oc->path[sizeof(oc->path)-1] = '\0';
1372
1373                 if (!active_cache)
1374                         read_cache();
1375                 pos = cache_name_pos(cp, namelen);
1376                 if (pos < 0)
1377                         pos = -pos - 1;
1378                 while (pos < active_nr) {
1379                         ce = active_cache[pos];
1380                         if (ce_namelen(ce) != namelen ||
1381                             memcmp(ce->name, cp, namelen))
1382                                 break;
1383                         if (ce_stage(ce) == stage) {
1384                                 hashcpy(sha1, ce->sha1);
1385                                 oc->mode = ce->ce_mode;
1386                                 free(new_path);
1387                                 return 0;
1388                         }
1389                         pos++;
1390                 }
1391                 if (only_to_die && name[1] && name[1] != '/')
1392                         diagnose_invalid_index_path(stage, prefix, cp);
1393                 free(new_path);
1394                 return -1;
1395         }
1396         for (cp = name, bracket_depth = 0; *cp; cp++) {
1397                 if (*cp == '{')
1398                         bracket_depth++;
1399                 else if (bracket_depth && *cp == '}')
1400                         bracket_depth--;
1401                 else if (!bracket_depth && *cp == ':')
1402                         break;
1403         }
1404         if (*cp == ':') {
1405                 unsigned char tree_sha1[20];
1406                 int len = cp - name;
1407                 if (!get_sha1_1(name, len, tree_sha1, GET_SHA1_TREEISH)) {
1408                         const char *filename = cp+1;
1409                         char *new_filename = NULL;
1410
1411                         new_filename = resolve_relative_path(filename);
1412                         if (new_filename)
1413                                 filename = new_filename;
1414                         ret = get_tree_entry(tree_sha1, filename, sha1, &oc->mode);
1415                         if (ret && only_to_die) {
1416                                 diagnose_invalid_sha1_path(prefix, filename,
1417                                                            tree_sha1,
1418                                                            name, len);
1419                         }
1420                         hashcpy(oc->tree, tree_sha1);
1421                         strncpy(oc->path, filename,
1422                                 sizeof(oc->path));
1423                         oc->path[sizeof(oc->path)-1] = '\0';
1424
1425                         free(new_filename);
1426                         return ret;
1427                 } else {
1428                         if (only_to_die)
1429                                 die("Invalid object name '%.*s'.", len, name);
1430                 }
1431         }
1432         return ret;
1433 }
1434
1435 /*
1436  * Call this function when you know "name" given by the end user must
1437  * name an object but it doesn't; the function _may_ die with a better
1438  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1439  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1440  * you have a chance to diagnose the error further.
1441  */
1442 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1443 {
1444         struct object_context oc;
1445         unsigned char sha1[20];
1446         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1447 }
1448
1449 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1450 {
1451         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1452 }