git.oblomov.eu Git - git/blob - sha1_name.c

   1 #include "cache.h"
   2 #include "config.h"
   3 #include "tag.h"
   4 #include "commit.h"
   5 #include "tree.h"
   6 #include "blob.h"
   7 #include "tree-walk.h"
   8 #include "refs.h"
   9 #include "remote.h"
  10 #include "dir.h"
  11 #include "sha1-array.h"
  12
  13 static int get_sha1_oneline(const char *, unsigned char *, struct commit_list *);
  14
  15 typedef int (*disambiguate_hint_fn)(const struct object_id *, void *);
  16
  17 struct disambiguate_state {
  18         int len; /* length of prefix in hex chars */
  19         char hex_pfx[GIT_MAX_HEXSZ + 1];
  20         struct object_id bin_pfx;
  21
  22         disambiguate_hint_fn fn;
  23         void *cb_data;
  24         struct object_id candidate;
  25         unsigned candidate_exists:1;
  26         unsigned candidate_checked:1;
  27         unsigned candidate_ok:1;
  28         unsigned disambiguate_fn_used:1;
  29         unsigned ambiguous:1;
  30         unsigned always_call_fn:1;
  31 };
  32
  33 static void update_candidates(struct disambiguate_state *ds, const struct object_id *current)
  34 {
  35         if (ds->always_call_fn) {
  36                 ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
  37                 return;
  38         }
  39         if (!ds->candidate_exists) {
  40                 /* this is the first candidate */
  41                 oidcpy(&ds->candidate, current);
  42                 ds->candidate_exists = 1;
  43                 return;
  44         } else if (!oidcmp(&ds->candidate, current)) {
  45                 /* the same as what we already have seen */
  46                 return;
  47         }
  48
  49         if (!ds->fn) {
  50                 /* cannot disambiguate between ds->candidate and current */
  51                 ds->ambiguous = 1;
  52                 return;
  53         }
  54
  55         if (!ds->candidate_checked) {
  56                 ds->candidate_ok = ds->fn(&ds->candidate, ds->cb_data);
  57                 ds->disambiguate_fn_used = 1;
  58                 ds->candidate_checked = 1;
  59         }
  60
  61         if (!ds->candidate_ok) {
  62                 /* discard the candidate; we know it does not satisfy fn */
  63                 oidcpy(&ds->candidate, current);
  64                 ds->candidate_checked = 0;
  65                 return;
  66         }
  67
  68         /* if we reach this point, we know ds->candidate satisfies fn */
  69         if (ds->fn(current, ds->cb_data)) {
  70                 /*
  71                  * if both current and candidate satisfy fn, we cannot
  72                  * disambiguate.
  73                  */
  74                 ds->candidate_ok = 0;
  75                 ds->ambiguous = 1;
  76         }
  77
  78         /* otherwise, current can be discarded and candidate is still good */
  79 }
  80
  81 static int append_loose_object(const struct object_id *oid, const char *path,
  82                                void *data)
  83 {
  84         oid_array_append(data, oid);
  85         return 0;
  86 }
  87
  88 static int match_sha(unsigned, const unsigned char *, const unsigned char *);
  89
  90 static void find_short_object_filename(struct disambiguate_state *ds)
  91 {
  92         int subdir_nr = ds->bin_pfx.hash[0];
  93         struct alternate_object_database *alt;
  94         static struct alternate_object_database *fakeent;
  95
  96         if (!fakeent) {
  97                 /*
  98                  * Create a "fake" alternate object database that
  99                  * points to our own object database, to make it
 100                  * easier to get a temporary working space in
 101                  * alt->name/alt->base while iterating over the
 102                  * object databases including our own.
 103                  */
 104                 fakeent = alloc_alt_odb(get_object_directory());
 105         }
 106         fakeent->next = alt_odb_list;
 107
 108         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 109                 int pos;
 110
 111                 if (!alt->loose_objects_subdir_seen[subdir_nr]) {
 112                         struct strbuf *buf = alt_scratch_buf(alt);
 113                         for_each_file_in_obj_subdir(subdir_nr, buf,
 114                                                     append_loose_object,
 115                                                     NULL, NULL,
 116                                                     &alt->loose_objects_cache);
 117                         alt->loose_objects_subdir_seen[subdir_nr] = 1;
 118                 }
 119
 120                 pos = oid_array_lookup(&alt->loose_objects_cache, &ds->bin_pfx);
 121                 if (pos < 0)
 122                         pos = -1 - pos;
 123                 while (!ds->ambiguous && pos < alt->loose_objects_cache.nr) {
 124                         const struct object_id *oid;
 125                         oid = alt->loose_objects_cache.oid + pos;
 126                         if (!match_sha(ds->len, ds->bin_pfx.hash, oid->hash))
 127                                 break;
 128                         update_candidates(ds, oid);
 129                         pos++;
 130                 }
 131         }
 132 }
 133
 134 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 135 {
 136         do {
 137                 if (*a != *b)
 138                         return 0;
 139                 a++;
 140                 b++;
 141                 len -= 2;
 142         } while (len > 1);
 143         if (len)
 144                 if ((*a ^ *b) & 0xf0)
 145                         return 0;
 146         return 1;
 147 }
 148
 149 static void unique_in_pack(struct packed_git *p,
 150                            struct disambiguate_state *ds)
 151 {
 152         uint32_t num, last, i, first = 0;
 153         const struct object_id *current = NULL;
 154
 155         open_pack_index(p);
 156         num = p->num_objects;
 157         last = num;
 158         while (first < last) {
 159                 uint32_t mid = (first + last) / 2;
 160                 const unsigned char *current;
 161                 int cmp;
 162
 163                 current = nth_packed_object_sha1(p, mid);
 164                 cmp = hashcmp(ds->bin_pfx.hash, current);
 165                 if (!cmp) {
 166                         first = mid;
 167                         break;
 168                 }
 169                 if (cmp > 0) {
 170                         first = mid+1;
 171                         continue;
 172                 }
 173                 last = mid;
 174         }
 175
 176         /*
 177          * At this point, "first" is the location of the lowest object
 178          * with an object name that could match "bin_pfx".  See if we have
 179          * 0, 1 or more objects that actually match(es).
 180          */
 181         for (i = first; i < num && !ds->ambiguous; i++) {
 182                 struct object_id oid;
 183                 current = nth_packed_object_oid(&oid, p, i);
 184                 if (!match_sha(ds->len, ds->bin_pfx.hash, current->hash))
 185                         break;
 186                 update_candidates(ds, current);
 187         }
 188 }
 189
 190 static void find_short_packed_object(struct disambiguate_state *ds)
 191 {
 192         struct packed_git *p;
 193
 194         prepare_packed_git();
 195         for (p = packed_git; p && !ds->ambiguous; p = p->next)
 196                 unique_in_pack(p, ds);
 197 }
 198
 199 #define SHORT_NAME_NOT_FOUND (-1)
 200 #define SHORT_NAME_AMBIGUOUS (-2)
 201
 202 static int finish_object_disambiguation(struct disambiguate_state *ds,
 203                                         unsigned char *sha1)
 204 {
 205         if (ds->ambiguous)
 206                 return SHORT_NAME_AMBIGUOUS;
 207
 208         if (!ds->candidate_exists)
 209                 return SHORT_NAME_NOT_FOUND;
 210
 211         if (!ds->candidate_checked)
 212                 /*
 213                  * If this is the only candidate, there is no point
 214                  * calling the disambiguation hint callback.
 215                  *
 216                  * On the other hand, if the current candidate
 217                  * replaced an earlier candidate that did _not_ pass
 218                  * the disambiguation hint callback, then we do have
 219                  * more than one objects that match the short name
 220                  * given, so we should make sure this one matches;
 221                  * otherwise, if we discovered this one and the one
 222                  * that we previously discarded in the reverse order,
 223                  * we would end up showing different results in the
 224                  * same repository!
 225                  */
 226                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 227                                     ds->fn(&ds->candidate, ds->cb_data));
 228
 229         if (!ds->candidate_ok)
 230                 return SHORT_NAME_AMBIGUOUS;
 231
 232         hashcpy(sha1, ds->candidate.hash);
 233         return 0;
 234 }
 235
 236 static int disambiguate_commit_only(const struct object_id *oid, void *cb_data_unused)
 237 {
 238         int kind = sha1_object_info(oid->hash, NULL);
 239         return kind == OBJ_COMMIT;
 240 }
 241
 242 static int disambiguate_committish_only(const struct object_id *oid, void *cb_data_unused)
 243 {
 244         struct object *obj;
 245         int kind;
 246
 247         kind = sha1_object_info(oid->hash, NULL);
 248         if (kind == OBJ_COMMIT)
 249                 return 1;
 250         if (kind != OBJ_TAG)
 251                 return 0;
 252
 253         /* We need to do this the hard way... */
 254         obj = deref_tag(parse_object(oid), NULL, 0);
 255         if (obj && obj->type == OBJ_COMMIT)
 256                 return 1;
 257         return 0;
 258 }
 259
 260 static int disambiguate_tree_only(const struct object_id *oid, void *cb_data_unused)
 261 {
 262         int kind = sha1_object_info(oid->hash, NULL);
 263         return kind == OBJ_TREE;
 264 }
 265
 266 static int disambiguate_treeish_only(const struct object_id *oid, void *cb_data_unused)
 267 {
 268         struct object *obj;
 269         int kind;
 270
 271         kind = sha1_object_info(oid->hash, NULL);
 272         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 273                 return 1;
 274         if (kind != OBJ_TAG)
 275                 return 0;
 276
 277         /* We need to do this the hard way... */
 278         obj = deref_tag(parse_object(oid), NULL, 0);
 279         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 280                 return 1;
 281         return 0;
 282 }
 283
 284 static int disambiguate_blob_only(const struct object_id *oid, void *cb_data_unused)
 285 {
 286         int kind = sha1_object_info(oid->hash, NULL);
 287         return kind == OBJ_BLOB;
 288 }
 289
 290 static disambiguate_hint_fn default_disambiguate_hint;
 291
 292 int set_disambiguate_hint_config(const char *var, const char *value)
 293 {
 294         static const struct {
 295                 const char *name;
 296                 disambiguate_hint_fn fn;
 297         } hints[] = {
 298                 { "none", NULL },
 299                 { "commit", disambiguate_commit_only },
 300                 { "committish", disambiguate_committish_only },
 301                 { "tree", disambiguate_tree_only },
 302                 { "treeish", disambiguate_treeish_only },
 303                 { "blob", disambiguate_blob_only }
 304         };
 305         int i;
 306
 307         if (!value)
 308                 return config_error_nonbool(var);
 309
 310         for (i = 0; i < ARRAY_SIZE(hints); i++) {
 311                 if (!strcasecmp(value, hints[i].name)) {
 312                         default_disambiguate_hint = hints[i].fn;
 313                         return 0;
 314                 }
 315         }
 316
 317         return error("unknown hint type for '%s': %s", var, value);
 318 }
 319
 320 static int init_object_disambiguation(const char *name, int len,
 321                                       struct disambiguate_state *ds)
 322 {
 323         int i;
 324
 325         if (len < MINIMUM_ABBREV || len > GIT_SHA1_HEXSZ)
 326                 return -1;
 327
 328         memset(ds, 0, sizeof(*ds));
 329
 330         for (i = 0; i < len ;i++) {
 331                 unsigned char c = name[i];
 332                 unsigned char val;
 333                 if (c >= '0' && c <= '9')
 334                         val = c - '0';
 335                 else if (c >= 'a' && c <= 'f')
 336                         val = c - 'a' + 10;
 337                 else if (c >= 'A' && c <='F') {
 338                         val = c - 'A' + 10;
 339                         c -= 'A' - 'a';
 340                 }
 341                 else
 342                         return -1;
 343                 ds->hex_pfx[i] = c;
 344                 if (!(i & 1))
 345                         val <<= 4;
 346                 ds->bin_pfx.hash[i >> 1] |= val;
 347         }
 348
 349         ds->len = len;
 350         ds->hex_pfx[len] = '\0';
 351         prepare_alt_odb();
 352         return 0;
 353 }
 354
 355 static int show_ambiguous_object(const struct object_id *oid, void *data)
 356 {
 357         const struct disambiguate_state *ds = data;
 358         struct strbuf desc = STRBUF_INIT;
 359         int type;
 360
 361
 362         if (ds->fn && !ds->fn(oid, ds->cb_data))
 363                 return 0;
 364
 365         type = sha1_object_info(oid->hash, NULL);
 366         if (type == OBJ_COMMIT) {
 367                 struct commit *commit = lookup_commit(oid);
 368                 if (commit) {
 369                         struct pretty_print_context pp = {0};
 370                         pp.date_mode.type = DATE_SHORT;
 371                         format_commit_message(commit, " %ad - %s", &desc, &pp);
 372                 }
 373         } else if (type == OBJ_TAG) {
 374                 struct tag *tag = lookup_tag(oid);
 375                 if (!parse_tag(tag) && tag->tag)
 376                         strbuf_addf(&desc, " %s", tag->tag);
 377         }
 378
 379         advise("  %s %s%s",
 380                find_unique_abbrev(oid->hash, DEFAULT_ABBREV),
 381                typename(type) ? typename(type) : "unknown type",
 382                desc.buf);
 383
 384         strbuf_release(&desc);
 385         return 0;
 386 }
 387
 388 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 389                           unsigned flags)
 390 {
 391         int status;
 392         struct disambiguate_state ds;
 393         int quietly = !!(flags & GET_SHA1_QUIETLY);
 394
 395         if (init_object_disambiguation(name, len, &ds) < 0)
 396                 return -1;
 397
 398         if (HAS_MULTI_BITS(flags & GET_SHA1_DISAMBIGUATORS))
 399                 die("BUG: multiple get_short_sha1 disambiguator flags");
 400
 401         if (flags & GET_SHA1_COMMIT)
 402                 ds.fn = disambiguate_commit_only;
 403         else if (flags & GET_SHA1_COMMITTISH)
 404                 ds.fn = disambiguate_committish_only;
 405         else if (flags & GET_SHA1_TREE)
 406                 ds.fn = disambiguate_tree_only;
 407         else if (flags & GET_SHA1_TREEISH)
 408                 ds.fn = disambiguate_treeish_only;
 409         else if (flags & GET_SHA1_BLOB)
 410                 ds.fn = disambiguate_blob_only;
 411         else
 412                 ds.fn = default_disambiguate_hint;
 413
 414         find_short_object_filename(&ds);
 415         find_short_packed_object(&ds);
 416         status = finish_object_disambiguation(&ds, sha1);
 417
 418         if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
 419                 error(_("short SHA1 %s is ambiguous"), ds.hex_pfx);
 420
 421                 /*
 422                  * We may still have ambiguity if we simply saw a series of
 423                  * candidates that did not satisfy our hint function. In
 424                  * that case, we still want to show them, so disable the hint
 425                  * function entirely.
 426                  */
 427                 if (!ds.ambiguous)
 428                         ds.fn = NULL;
 429
 430                 advise(_("The candidates are:"));
 431                 for_each_abbrev(ds.hex_pfx, show_ambiguous_object, &ds);
 432         }
 433
 434         return status;
 435 }
 436
 437 static int collect_ambiguous(const struct object_id *oid, void *data)
 438 {
 439         oid_array_append(data, oid);
 440         return 0;
 441 }
 442
 443 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 444 {
 445         struct oid_array collect = OID_ARRAY_INIT;
 446         struct disambiguate_state ds;
 447         int ret;
 448
 449         if (init_object_disambiguation(prefix, strlen(prefix), &ds) < 0)
 450                 return -1;
 451
 452         ds.always_call_fn = 1;
 453         ds.fn = collect_ambiguous;
 454         ds.cb_data = &collect;
 455         find_short_object_filename(&ds);
 456         find_short_packed_object(&ds);
 457
 458         ret = oid_array_for_each_unique(&collect, fn, cb_data);
 459         oid_array_clear(&collect);
 460         return ret;
 461 }
 462
 463 /*
 464  * Return the slot of the most-significant bit set in "val". There are various
 465  * ways to do this quickly with fls() or __builtin_clzl(), but speed is
 466  * probably not a big deal here.
 467  */
 468 static unsigned msb(unsigned long val)
 469 {
 470         unsigned r = 0;
 471         while (val >>= 1)
 472                 r++;
 473         return r;
 474 }
 475
 476 int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 477 {
 478         int status, exists;
 479
 480         if (len < 0) {
 481                 unsigned long count = approximate_object_count();
 482                 /*
 483                  * Add one because the MSB only tells us the highest bit set,
 484                  * not including the value of all the _other_ bits (so "15"
 485                  * is only one off of 2^4, but the MSB is the 3rd bit.
 486                  */
 487                 len = msb(count) + 1;
 488                 /*
 489                  * We now know we have on the order of 2^len objects, which
 490                  * expects a collision at 2^(len/2). But we also care about hex
 491                  * chars, not bits, and there are 4 bits per hex. So all
 492                  * together we need to divide by 2 and round up.
 493                  */
 494                 len = DIV_ROUND_UP(len, 2);
 495                 /*
 496                  * For very small repos, we stick with our regular fallback.
 497                  */
 498                 if (len < FALLBACK_DEFAULT_ABBREV)
 499                         len = FALLBACK_DEFAULT_ABBREV;
 500         }
 501
 502         sha1_to_hex_r(hex, sha1);
 503         if (len == 40 || !len)
 504                 return 40;
 505         exists = has_sha1_file(sha1);
 506         while (len < 40) {
 507                 unsigned char sha1_ret[20];
 508                 status = get_short_sha1(hex, len, sha1_ret, GET_SHA1_QUIETLY);
 509                 if (exists
 510                     ? !status
 511                     : status == SHORT_NAME_NOT_FOUND) {
 512                         hex[len] = 0;
 513                         return len;
 514                 }
 515                 len++;
 516         }
 517         return len;
 518 }
 519
 520 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 521 {
 522         static int bufno;
 523         static char hexbuffer[4][GIT_MAX_HEXSZ + 1];
 524         char *hex = hexbuffer[bufno];
 525         bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
 526         find_unique_abbrev_r(hex, sha1, len);
 527         return hex;
 528 }
 529
 530 static int ambiguous_path(const char *path, int len)
 531 {
 532         int slash = 1;
 533         int cnt;
 534
 535         for (cnt = 0; cnt < len; cnt++) {
 536                 switch (*path++) {
 537                 case '\0':
 538                         break;
 539                 case '/':
 540                         if (slash)
 541                                 break;
 542                         slash = 1;
 543                         continue;
 544                 case '.':
 545                         continue;
 546                 default:
 547                         slash = 0;
 548                         continue;
 549                 }
 550                 break;
 551         }
 552         return slash;
 553 }
 554
 555 static inline int at_mark(const char *string, int len,
 556                           const char **suffix, int nr)
 557 {
 558         int i;
 559
 560         for (i = 0; i < nr; i++) {
 561                 int suffix_len = strlen(suffix[i]);
 562                 if (suffix_len <= len
 563                     && !strncasecmp(string, suffix[i], suffix_len))
 564                         return suffix_len;
 565         }
 566         return 0;
 567 }
 568
 569 static inline int upstream_mark(const char *string, int len)
 570 {
 571         const char *suffix[] = { "@{upstream}", "@{u}" };
 572         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 573 }
 574
 575 static inline int push_mark(const char *string, int len)
 576 {
 577         const char *suffix[] = { "@{push}" };
 578         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 579 }
 580
 581 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 582 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 583
 584 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 585                           unsigned int flags)
 586 {
 587         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 588         static const char *object_name_msg = N_(
 589         "Git normally never creates a ref that ends with 40 hex characters\n"
 590         "because it will be ignored when you just specify 40-hex. These refs\n"
 591         "may be created by mistake. For example,\n"
 592         "\n"
 593         "  git checkout -b $br $(git rev-parse ...)\n"
 594         "\n"
 595         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 596         "examine these refs and maybe delete them. Turn this message off by\n"
 597         "running \"git config advice.objectNameWarning false\"");
 598         unsigned char tmp_sha1[20];
 599         char *real_ref = NULL;
 600         int refs_found = 0;
 601         int at, reflog_len, nth_prior = 0;
 602
 603         if (len == 40 && !get_sha1_hex(str, sha1)) {
 604                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 605                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 606                         if (refs_found > 0) {
 607                                 warning(warn_msg, len, str);
 608                                 if (advice_object_name_warning)
 609                                         fprintf(stderr, "%s\n", _(object_name_msg));
 610                         }
 611                         free(real_ref);
 612                 }
 613                 return 0;
 614         }
 615
 616         /* basic@{time or number or -number} format to query ref-log */
 617         reflog_len = at = 0;
 618         if (len && str[len-1] == '}') {
 619                 for (at = len-4; at >= 0; at--) {
 620                         if (str[at] == '@' && str[at+1] == '{') {
 621                                 if (str[at+2] == '-') {
 622                                         if (at != 0)
 623                                                 /* @{-N} not at start */
 624                                                 return -1;
 625                                         nth_prior = 1;
 626                                         continue;
 627                                 }
 628                                 if (!upstream_mark(str + at, len - at) &&
 629                                     !push_mark(str + at, len - at)) {
 630                                         reflog_len = (len-1) - (at+2);
 631                                         len = at;
 632                                 }
 633                                 break;
 634                         }
 635                 }
 636         }
 637
 638         /* Accept only unambiguous ref paths. */
 639         if (len && ambiguous_path(str, len))
 640                 return -1;
 641
 642         if (nth_prior) {
 643                 struct strbuf buf = STRBUF_INIT;
 644                 int detached;
 645
 646                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 647                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 648                         strbuf_release(&buf);
 649                         if (detached)
 650                                 return 0;
 651                 }
 652         }
 653
 654         if (!len && reflog_len)
 655                 /* allow "@{...}" to mean the current branch reflog */
 656                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 657         else if (reflog_len)
 658                 refs_found = dwim_log(str, len, sha1, &real_ref);
 659         else
 660                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 661
 662         if (!refs_found)
 663                 return -1;
 664
 665         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 666             (refs_found > 1 ||
 667              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 668                 warning(warn_msg, len, str);
 669
 670         if (reflog_len) {
 671                 int nth, i;
 672                 timestamp_t at_time;
 673                 timestamp_t co_time;
 674                 int co_tz, co_cnt;
 675
 676                 /* Is it asking for N-th entry, or approxidate? */
 677                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 678                         char ch = str[at+2+i];
 679                         if ('0' <= ch && ch <= '9')
 680                                 nth = nth * 10 + ch - '0';
 681                         else
 682                                 nth = -1;
 683                 }
 684                 if (100000000 <= nth) {
 685                         at_time = nth;
 686                         nth = -1;
 687                 } else if (0 <= nth)
 688                         at_time = 0;
 689                 else {
 690                         int errors = 0;
 691                         char *tmp = xstrndup(str + at + 2, reflog_len);
 692                         at_time = approxidate_careful(tmp, &errors);
 693                         free(tmp);
 694                         if (errors) {
 695                                 free(real_ref);
 696                                 return -1;
 697                         }
 698                 }
 699                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 700                                 &co_time, &co_tz, &co_cnt)) {
 701                         if (!len) {
 702                                 if (starts_with(real_ref, "refs/heads/")) {
 703                                         str = real_ref + 11;
 704                                         len = strlen(real_ref + 11);
 705                                 } else {
 706                                         /* detached HEAD */
 707                                         str = "HEAD";
 708                                         len = 4;
 709                                 }
 710                         }
 711                         if (at_time) {
 712                                 if (!(flags & GET_SHA1_QUIETLY)) {
 713                                         warning("Log for '%.*s' only goes "
 714                                                 "back to %s.", len, str,
 715                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 716                                 }
 717                         } else {
 718                                 if (flags & GET_SHA1_QUIETLY) {
 719                                         exit(128);
 720                                 }
 721                                 die("Log for '%.*s' only has %d entries.",
 722                                     len, str, co_cnt);
 723                         }
 724                 }
 725         }
 726
 727         free(real_ref);
 728         return 0;
 729 }
 730
 731 static int get_parent(const char *name, int len,
 732                       unsigned char *result, int idx)
 733 {
 734         struct object_id oid;
 735         int ret = get_sha1_1(name, len, oid.hash, GET_SHA1_COMMITTISH);
 736         struct commit *commit;
 737         struct commit_list *p;
 738
 739         if (ret)
 740                 return ret;
 741         commit = lookup_commit_reference(&oid);
 742         if (parse_commit(commit))
 743                 return -1;
 744         if (!idx) {
 745                 hashcpy(result, commit->object.oid.hash);
 746                 return 0;
 747         }
 748         p = commit->parents;
 749         while (p) {
 750                 if (!--idx) {
 751                         hashcpy(result, p->item->object.oid.hash);
 752                         return 0;
 753                 }
 754                 p = p->next;
 755         }
 756         return -1;
 757 }
 758
 759 static int get_nth_ancestor(const char *name, int len,
 760                             unsigned char *result, int generation)
 761 {
 762         struct object_id oid;
 763         struct commit *commit;
 764         int ret;
 765
 766         ret = get_sha1_1(name, len, oid.hash, GET_SHA1_COMMITTISH);
 767         if (ret)
 768                 return ret;
 769         commit = lookup_commit_reference(&oid);
 770         if (!commit)
 771                 return -1;
 772
 773         while (generation--) {
 774                 if (parse_commit(commit) || !commit->parents)
 775                         return -1;
 776                 commit = commit->parents->item;
 777         }
 778         hashcpy(result, commit->object.oid.hash);
 779         return 0;
 780 }
 781
 782 struct object *peel_to_type(const char *name, int namelen,
 783                             struct object *o, enum object_type expected_type)
 784 {
 785         if (name && !namelen)
 786                 namelen = strlen(name);
 787         while (1) {
 788                 if (!o || (!o->parsed && !parse_object(&o->oid)))
 789                         return NULL;
 790                 if (expected_type == OBJ_ANY || o->type == expected_type)
 791                         return o;
 792                 if (o->type == OBJ_TAG)
 793                         o = ((struct tag*) o)->tagged;
 794                 else if (o->type == OBJ_COMMIT)
 795                         o = &(((struct commit *) o)->tree->object);
 796                 else {
 797                         if (name)
 798                                 error("%.*s: expected %s type, but the object "
 799                                       "dereferences to %s type",
 800                                       namelen, name, typename(expected_type),
 801                                       typename(o->type));
 802                         return NULL;
 803                 }
 804         }
 805 }
 806
 807 static int peel_onion(const char *name, int len, unsigned char *sha1,
 808                       unsigned lookup_flags)
 809 {
 810         struct object_id outer;
 811         const char *sp;
 812         unsigned int expected_type = 0;
 813         struct object *o;
 814
 815         /*
 816          * "ref^{type}" dereferences ref repeatedly until you cannot
 817          * dereference anymore, or you get an object of given type,
 818          * whichever comes first.  "ref^{}" means just dereference
 819          * tags until you get a non-tag.  "ref^0" is a shorthand for
 820          * "ref^{commit}".  "commit^{tree}" could be used to find the
 821          * top-level tree of the given commit.
 822          */
 823         if (len < 4 || name[len-1] != '}')
 824                 return -1;
 825
 826         for (sp = name + len - 1; name <= sp; sp--) {
 827                 int ch = *sp;
 828                 if (ch == '{' && name < sp && sp[-1] == '^')
 829                         break;
 830         }
 831         if (sp <= name)
 832                 return -1;
 833
 834         sp++; /* beginning of type name, or closing brace for empty */
 835         if (starts_with(sp, "commit}"))
 836                 expected_type = OBJ_COMMIT;
 837         else if (starts_with(sp, "tag}"))
 838                 expected_type = OBJ_TAG;
 839         else if (starts_with(sp, "tree}"))
 840                 expected_type = OBJ_TREE;
 841         else if (starts_with(sp, "blob}"))
 842                 expected_type = OBJ_BLOB;
 843         else if (starts_with(sp, "object}"))
 844                 expected_type = OBJ_ANY;
 845         else if (sp[0] == '}')
 846                 expected_type = OBJ_NONE;
 847         else if (sp[0] == '/')
 848                 expected_type = OBJ_COMMIT;
 849         else
 850                 return -1;
 851
 852         lookup_flags &= ~GET_SHA1_DISAMBIGUATORS;
 853         if (expected_type == OBJ_COMMIT)
 854                 lookup_flags |= GET_SHA1_COMMITTISH;
 855         else if (expected_type == OBJ_TREE)
 856                 lookup_flags |= GET_SHA1_TREEISH;
 857
 858         if (get_sha1_1(name, sp - name - 2, outer.hash, lookup_flags))
 859                 return -1;
 860
 861         o = parse_object(&outer);
 862         if (!o)
 863                 return -1;
 864         if (!expected_type) {
 865                 o = deref_tag(o, name, sp - name - 2);
 866                 if (!o || (!o->parsed && !parse_object(&o->oid)))
 867                         return -1;
 868                 hashcpy(sha1, o->oid.hash);
 869                 return 0;
 870         }
 871
 872         /*
 873          * At this point, the syntax look correct, so
 874          * if we do not get the needed object, we should
 875          * barf.
 876          */
 877         o = peel_to_type(name, len, o, expected_type);
 878         if (!o)
 879                 return -1;
 880
 881         hashcpy(sha1, o->oid.hash);
 882         if (sp[0] == '/') {
 883                 /* "$commit^{/foo}" */
 884                 char *prefix;
 885                 int ret;
 886                 struct commit_list *list = NULL;
 887
 888                 /*
 889                  * $commit^{/}. Some regex implementation may reject.
 890                  * We don't need regex anyway. '' pattern always matches.
 891                  */
 892                 if (sp[1] == '}')
 893                         return 0;
 894
 895                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 896                 commit_list_insert((struct commit *)o, &list);
 897                 ret = get_sha1_oneline(prefix, sha1, list);
 898                 free(prefix);
 899                 return ret;
 900         }
 901         return 0;
 902 }
 903
 904 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 905 {
 906         const char *cp;
 907         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 908
 909         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 910                 char ch = *cp;
 911                 if (!isxdigit(ch)) {
 912                         /* We must be looking at g in "SOMETHING-g"
 913                          * for it to be describe output.
 914                          */
 915                         if (ch == 'g' && cp[-1] == '-') {
 916                                 cp++;
 917                                 len -= cp - name;
 918                                 return get_short_sha1(cp, len, sha1, flags);
 919                         }
 920                 }
 921         }
 922         return -1;
 923 }
 924
 925 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 926 {
 927         int ret, has_suffix;
 928         const char *cp;
 929
 930         /*
 931          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 932          */
 933         has_suffix = 0;
 934         for (cp = name + len - 1; name <= cp; cp--) {
 935                 int ch = *cp;
 936                 if ('0' <= ch && ch <= '9')
 937                         continue;
 938                 if (ch == '~' || ch == '^')
 939                         has_suffix = ch;
 940                 break;
 941         }
 942
 943         if (has_suffix) {
 944                 int num = 0;
 945                 int len1 = cp - name;
 946                 cp++;
 947                 while (cp < name + len)
 948                         num = num * 10 + *cp++ - '0';
 949                 if (!num && len1 == len - 1)
 950                         num = 1;
 951                 if (has_suffix == '^')
 952                         return get_parent(name, len1, sha1, num);
 953                 /* else if (has_suffix == '~') -- goes without saying */
 954                 return get_nth_ancestor(name, len1, sha1, num);
 955         }
 956
 957         ret = peel_onion(name, len, sha1, lookup_flags);
 958         if (!ret)
 959                 return 0;
 960
 961         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 962         if (!ret)
 963                 return 0;
 964
 965         /* It could be describe output that is "SOMETHING-gXXXX" */
 966         ret = get_describe_name(name, len, sha1);
 967         if (!ret)
 968                 return 0;
 969
 970         return get_short_sha1(name, len, sha1, lookup_flags);
 971 }
 972
 973 /*
 974  * This interprets names like ':/Initial revision of "git"' by searching
 975  * through history and returning the first commit whose message starts
 976  * the given regular expression.
 977  *
 978  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
 979  *
 980  * For a literal '!' character at the beginning of a pattern, you have to repeat
 981  * that, like: ':/!!foo'
 982  *
 983  * For future extension, all other sequences beginning with ':/!' are reserved.
 984  */
 985
 986 /* Remember to update object flag allocation in object.h */
 987 #define ONELINE_SEEN (1u<<20)
 988
 989 static int handle_one_ref(const char *path, const struct object_id *oid,
 990                           int flag, void *cb_data)
 991 {
 992         struct commit_list **list = cb_data;
 993         struct object *object = parse_object(oid);
 994         if (!object)
 995                 return 0;
 996         if (object->type == OBJ_TAG) {
 997                 object = deref_tag(object, path, strlen(path));
 998                 if (!object)
 999                         return 0;
1000         }
1001         if (object->type != OBJ_COMMIT)
1002                 return 0;
1003         commit_list_insert((struct commit *)object, list);
1004         return 0;
1005 }
1006
1007 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
1008                             struct commit_list *list)
1009 {
1010         struct commit_list *backup = NULL, *l;
1011         int found = 0;
1012         int negative = 0;
1013         regex_t regex;
1014
1015         if (prefix[0] == '!') {
1016                 prefix++;
1017
1018                 if (prefix[0] == '-') {
1019                         prefix++;
1020                         negative = 1;
1021                 } else if (prefix[0] != '!') {
1022                         return -1;
1023                 }
1024         }
1025
1026         if (regcomp(&regex, prefix, REG_EXTENDED))
1027                 return -1;
1028
1029         for (l = list; l; l = l->next) {
1030                 l->item->object.flags |= ONELINE_SEEN;
1031                 commit_list_insert(l->item, &backup);
1032         }
1033         while (list) {
1034                 const char *p, *buf;
1035                 struct commit *commit;
1036                 int matches;
1037
1038                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
1039                 if (!parse_object(&commit->object.oid))
1040                         continue;
1041                 buf = get_commit_buffer(commit, NULL);
1042                 p = strstr(buf, "\n\n");
1043                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
1044                 unuse_commit_buffer(commit, buf);
1045
1046                 if (matches) {
1047                         hashcpy(sha1, commit->object.oid.hash);
1048                         found = 1;
1049                         break;
1050                 }
1051         }
1052         regfree(&regex);
1053         free_commit_list(list);
1054         for (l = backup; l; l = l->next)
1055                 clear_commit_marks(l->item, ONELINE_SEEN);
1056         free_commit_list(backup);
1057         return found ? 0 : -1;
1058 }
1059
1060 struct grab_nth_branch_switch_cbdata {
1061         int remaining;
1062         struct strbuf buf;
1063 };
1064
1065 static int grab_nth_branch_switch(struct object_id *ooid, struct object_id *noid,
1066                                   const char *email, timestamp_t timestamp, int tz,
1067                                   const char *message, void *cb_data)
1068 {
1069         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1070         const char *match = NULL, *target = NULL;
1071         size_t len;
1072
1073         if (skip_prefix(message, "checkout: moving from ", &match))
1074                 target = strstr(match, " to ");
1075
1076         if (!match || !target)
1077                 return 0;
1078         if (--(cb->remaining) == 0) {
1079                 len = target - match;
1080                 strbuf_reset(&cb->buf);
1081                 strbuf_add(&cb->buf, match, len);
1082                 return 1; /* we are done */
1083         }
1084         return 0;
1085 }
1086
1087 /*
1088  * Parse @{-N} syntax, return the number of characters parsed
1089  * if successful; otherwise signal an error with negative value.
1090  */
1091 static int interpret_nth_prior_checkout(const char *name, int namelen,
1092                                         struct strbuf *buf)
1093 {
1094         long nth;
1095         int retval;
1096         struct grab_nth_branch_switch_cbdata cb;
1097         const char *brace;
1098         char *num_end;
1099
1100         if (namelen < 4)
1101                 return -1;
1102         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1103                 return -1;
1104         brace = memchr(name, '}', namelen);
1105         if (!brace)
1106                 return -1;
1107         nth = strtol(name + 3, &num_end, 10);
1108         if (num_end != brace)
1109                 return -1;
1110         if (nth <= 0)
1111                 return -1;
1112         cb.remaining = nth;
1113         strbuf_init(&cb.buf, 20);
1114
1115         retval = 0;
1116         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1117                 strbuf_reset(buf);
1118                 strbuf_addbuf(buf, &cb.buf);
1119                 retval = brace - name + 1;
1120         }
1121
1122         strbuf_release(&cb.buf);
1123         return retval;
1124 }
1125
1126 int get_oid_mb(const char *name, struct object_id *oid)
1127 {
1128         struct commit *one, *two;
1129         struct commit_list *mbs;
1130         struct object_id oid_tmp;
1131         const char *dots;
1132         int st;
1133
1134         dots = strstr(name, "...");
1135         if (!dots)
1136                 return get_oid(name, oid);
1137         if (dots == name)
1138                 st = get_oid("HEAD", &oid_tmp);
1139         else {
1140                 struct strbuf sb;
1141                 strbuf_init(&sb, dots - name);
1142                 strbuf_add(&sb, name, dots - name);
1143                 st = get_sha1_committish(sb.buf, oid_tmp.hash);
1144                 strbuf_release(&sb);
1145         }
1146         if (st)
1147                 return st;
1148         one = lookup_commit_reference_gently(&oid_tmp, 0);
1149         if (!one)
1150                 return -1;
1151
1152         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", oid_tmp.hash))
1153                 return -1;
1154         two = lookup_commit_reference_gently(&oid_tmp, 0);
1155         if (!two)
1156                 return -1;
1157         mbs = get_merge_bases(one, two);
1158         if (!mbs || mbs->next)
1159                 st = -1;
1160         else {
1161                 st = 0;
1162                 oidcpy(oid, &mbs->item->object.oid);
1163         }
1164         free_commit_list(mbs);
1165         return st;
1166 }
1167
1168 /* parse @something syntax, when 'something' is not {.*} */
1169 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1170 {
1171         const char *next;
1172
1173         if (len || name[1] == '{')
1174                 return -1;
1175
1176         /* make sure it's a single @, or @@{.*}, not @foo */
1177         next = memchr(name + len + 1, '@', namelen - len - 1);
1178         if (next && next[1] != '{')
1179                 return -1;
1180         if (!next)
1181                 next = name + namelen;
1182         if (next != name + 1)
1183                 return -1;
1184
1185         strbuf_reset(buf);
1186         strbuf_add(buf, "HEAD", 4);
1187         return 1;
1188 }
1189
1190 static int reinterpret(const char *name, int namelen, int len,
1191                        struct strbuf *buf, unsigned allowed)
1192 {
1193         /* we have extra data, which might need further processing */
1194         struct strbuf tmp = STRBUF_INIT;
1195         int used = buf->len;
1196         int ret;
1197
1198         strbuf_add(buf, name + len, namelen - len);
1199         ret = interpret_branch_name(buf->buf, buf->len, &tmp, allowed);
1200         /* that data was not interpreted, remove our cruft */
1201         if (ret < 0) {
1202                 strbuf_setlen(buf, used);
1203                 return len;
1204         }
1205         strbuf_reset(buf);
1206         strbuf_addbuf(buf, &tmp);
1207         strbuf_release(&tmp);
1208         /* tweak for size of {-N} versus expanded ref name */
1209         return ret - used + len;
1210 }
1211
1212 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1213 {
1214         char *s = shorten_unambiguous_ref(ref, 0);
1215         strbuf_reset(buf);
1216         strbuf_addstr(buf, s);
1217         free(s);
1218 }
1219
1220 static int branch_interpret_allowed(const char *refname, unsigned allowed)
1221 {
1222         if (!allowed)
1223                 return 1;
1224
1225         if ((allowed & INTERPRET_BRANCH_LOCAL) &&
1226             starts_with(refname, "refs/heads/"))
1227                 return 1;
1228         if ((allowed & INTERPRET_BRANCH_REMOTE) &&
1229             starts_with(refname, "refs/remotes/"))
1230                 return 1;
1231
1232         return 0;
1233 }
1234
1235 static int interpret_branch_mark(const char *name, int namelen,
1236                                  int at, struct strbuf *buf,
1237                                  int (*get_mark)(const char *, int),
1238                                  const char *(*get_data)(struct branch *,
1239                                                          struct strbuf *),
1240                                  unsigned allowed)
1241 {
1242         int len;
1243         struct branch *branch;
1244         struct strbuf err = STRBUF_INIT;
1245         const char *value;
1246
1247         len = get_mark(name + at, namelen - at);
1248         if (!len)
1249                 return -1;
1250
1251         if (memchr(name, ':', at))
1252                 return -1;
1253
1254         if (at) {
1255                 char *name_str = xmemdupz(name, at);
1256                 branch = branch_get(name_str);
1257                 free(name_str);
1258         } else
1259                 branch = branch_get(NULL);
1260
1261         value = get_data(branch, &err);
1262         if (!value)
1263                 die("%s", err.buf);
1264
1265         if (!branch_interpret_allowed(value, allowed))
1266                 return -1;
1267
1268         set_shortened_ref(buf, value);
1269         return len + at;
1270 }
1271
1272 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf,
1273                           unsigned allowed)
1274 {
1275         char *at;
1276         const char *start;
1277         int len;
1278
1279         if (!namelen)
1280                 namelen = strlen(name);
1281
1282         if (!allowed || (allowed & INTERPRET_BRANCH_LOCAL)) {
1283                 len = interpret_nth_prior_checkout(name, namelen, buf);
1284                 if (!len) {
1285                         return len; /* syntax Ok, not enough switches */
1286                 } else if (len > 0) {
1287                         if (len == namelen)
1288                                 return len; /* consumed all */
1289                         else
1290                                 return reinterpret(name, namelen, len, buf, allowed);
1291                 }
1292         }
1293
1294         for (start = name;
1295              (at = memchr(start, '@', namelen - (start - name)));
1296              start = at + 1) {
1297
1298                 if (!allowed || (allowed & INTERPRET_BRANCH_HEAD)) {
1299                         len = interpret_empty_at(name, namelen, at - name, buf);
1300                         if (len > 0)
1301                                 return reinterpret(name, namelen, len, buf,
1302                                                    allowed);
1303                 }
1304
1305                 len = interpret_branch_mark(name, namelen, at - name, buf,
1306                                             upstream_mark, branch_get_upstream,
1307                                             allowed);
1308                 if (len > 0)
1309                         return len;
1310
1311                 len = interpret_branch_mark(name, namelen, at - name, buf,
1312                                             push_mark, branch_get_push,
1313                                             allowed);
1314                 if (len > 0)
1315                         return len;
1316         }
1317
1318         return -1;
1319 }
1320
1321 void strbuf_branchname(struct strbuf *sb, const char *name, unsigned allowed)
1322 {
1323         int len = strlen(name);
1324         int used = interpret_branch_name(name, len, sb, allowed);
1325
1326         if (used < 0)
1327                 used = 0;
1328         strbuf_add(sb, name + used, len - used);
1329 }
1330
1331 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1332 {
1333         strbuf_branchname(sb, name, INTERPRET_BRANCH_LOCAL);
1334         if (name[0] == '-')
1335                 return -1;
1336         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1337         return check_refname_format(sb->buf, 0);
1338 }
1339
1340 /*
1341  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1342  * notably "xyz^" for "parent of xyz"
1343  */
1344 int get_sha1(const char *name, unsigned char *sha1)
1345 {
1346         struct object_context unused;
1347         return get_sha1_with_context(name, 0, sha1, &unused);
1348 }
1349
1350 /*
1351  * This is like "get_sha1()", but for struct object_id.
1352  */
1353 int get_oid(const char *name, struct object_id *oid)
1354 {
1355         return get_sha1(name, oid->hash);
1356 }
1357
1358
1359 /*
1360  * Many callers know that the user meant to name a commit-ish by
1361  * syntactical positions where the object name appears.  Calling this
1362  * function allows the machinery to disambiguate shorter-than-unique
1363  * abbreviated object names between commit-ish and others.
1364  *
1365  * Note that this does NOT error out when the named object is not a
1366  * commit-ish. It is merely to give a hint to the disambiguation
1367  * machinery.
1368  */
1369 int get_sha1_committish(const char *name, unsigned char *sha1)
1370 {
1371         struct object_context unused;
1372         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1373                                      sha1, &unused);
1374 }
1375
1376 int get_sha1_treeish(const char *name, unsigned char *sha1)
1377 {
1378         struct object_context unused;
1379         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1380                                      sha1, &unused);
1381 }
1382
1383 int get_sha1_commit(const char *name, unsigned char *sha1)
1384 {
1385         struct object_context unused;
1386         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1387                                      sha1, &unused);
1388 }
1389
1390 int get_sha1_tree(const char *name, unsigned char *sha1)
1391 {
1392         struct object_context unused;
1393         return get_sha1_with_context(name, GET_SHA1_TREE,
1394                                      sha1, &unused);
1395 }
1396
1397 int get_sha1_blob(const char *name, unsigned char *sha1)
1398 {
1399         struct object_context unused;
1400         return get_sha1_with_context(name, GET_SHA1_BLOB,
1401                                      sha1, &unused);
1402 }
1403
1404 /* Must be called only when object_name:filename doesn't exist. */
1405 static void diagnose_invalid_sha1_path(const char *prefix,
1406                                        const char *filename,
1407                                        const unsigned char *tree_sha1,
1408                                        const char *object_name,
1409                                        int object_name_len)
1410 {
1411         unsigned char sha1[20];
1412         unsigned mode;
1413
1414         if (!prefix)
1415                 prefix = "";
1416
1417         if (file_exists(filename))
1418                 die("Path '%s' exists on disk, but not in '%.*s'.",
1419                     filename, object_name_len, object_name);
1420         if (is_missing_file_error(errno)) {
1421                 char *fullname = xstrfmt("%s%s", prefix, filename);
1422
1423                 if (!get_tree_entry(tree_sha1, fullname,
1424                                     sha1, &mode)) {
1425                         die("Path '%s' exists, but not '%s'.\n"
1426                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1427                             fullname,
1428                             filename,
1429                             object_name_len, object_name,
1430                             fullname,
1431                             object_name_len, object_name,
1432                             filename);
1433                 }
1434                 die("Path '%s' does not exist in '%.*s'",
1435                     filename, object_name_len, object_name);
1436         }
1437 }
1438
1439 /* Must be called only when :stage:filename doesn't exist. */
1440 static void diagnose_invalid_index_path(int stage,
1441                                         const char *prefix,
1442                                         const char *filename)
1443 {
1444         const struct cache_entry *ce;
1445         int pos;
1446         unsigned namelen = strlen(filename);
1447         struct strbuf fullname = STRBUF_INIT;
1448
1449         if (!prefix)
1450                 prefix = "";
1451
1452         /* Wrong stage number? */
1453         pos = cache_name_pos(filename, namelen);
1454         if (pos < 0)
1455                 pos = -pos - 1;
1456         if (pos < active_nr) {
1457                 ce = active_cache[pos];
1458                 if (ce_namelen(ce) == namelen &&
1459                     !memcmp(ce->name, filename, namelen))
1460                         die("Path '%s' is in the index, but not at stage %d.\n"
1461                             "Did you mean ':%d:%s'?",
1462                             filename, stage,
1463                             ce_stage(ce), filename);
1464         }
1465
1466         /* Confusion between relative and absolute filenames? */
1467         strbuf_addstr(&fullname, prefix);
1468         strbuf_addstr(&fullname, filename);
1469         pos = cache_name_pos(fullname.buf, fullname.len);
1470         if (pos < 0)
1471                 pos = -pos - 1;
1472         if (pos < active_nr) {
1473                 ce = active_cache[pos];
1474                 if (ce_namelen(ce) == fullname.len &&
1475                     !memcmp(ce->name, fullname.buf, fullname.len))
1476                         die("Path '%s' is in the index, but not '%s'.\n"
1477                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1478                             fullname.buf, filename,
1479                             ce_stage(ce), fullname.buf,
1480                             ce_stage(ce), filename);
1481         }
1482
1483         if (file_exists(filename))
1484                 die("Path '%s' exists on disk, but not in the index.", filename);
1485         if (is_missing_file_error(errno))
1486                 die("Path '%s' does not exist (neither on disk nor in the index).",
1487                     filename);
1488
1489         strbuf_release(&fullname);
1490 }
1491
1492
1493 static char *resolve_relative_path(const char *rel)
1494 {
1495         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1496                 return NULL;
1497
1498         if (!is_inside_work_tree())
1499                 die("relative path syntax can't be used outside working tree.");
1500
1501         /* die() inside prefix_path() if resolved path is outside worktree */
1502         return prefix_path(startup_info->prefix,
1503                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1504                            rel);
1505 }
1506
1507 static int get_sha1_with_context_1(const char *name,
1508                                    unsigned flags,
1509                                    const char *prefix,
1510                                    unsigned char *sha1,
1511                                    struct object_context *oc)
1512 {
1513         int ret, bracket_depth;
1514         int namelen = strlen(name);
1515         const char *cp;
1516         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1517
1518         if (only_to_die)
1519                 flags |= GET_SHA1_QUIETLY;
1520
1521         memset(oc, 0, sizeof(*oc));
1522         oc->mode = S_IFINVALID;
1523         strbuf_init(&oc->symlink_path, 0);
1524         ret = get_sha1_1(name, namelen, sha1, flags);
1525         if (!ret)
1526                 return ret;
1527         /*
1528          * sha1:path --> object name of path in ent sha1
1529          * :path -> object name of absolute path in index
1530          * :./path -> object name of path relative to cwd in index
1531          * :[0-3]:path -> object name of path in index at stage
1532          * :/foo -> recent commit matching foo
1533          */
1534         if (name[0] == ':') {
1535                 int stage = 0;
1536                 const struct cache_entry *ce;
1537                 char *new_path = NULL;
1538                 int pos;
1539                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1540                         struct commit_list *list = NULL;
1541
1542                         for_each_ref(handle_one_ref, &list);
1543                         commit_list_sort_by_date(&list);
1544                         return get_sha1_oneline(name + 2, sha1, list);
1545                 }
1546                 if (namelen < 3 ||
1547                     name[2] != ':' ||
1548                     name[1] < '0' || '3' < name[1])
1549                         cp = name + 1;
1550                 else {
1551                         stage = name[1] - '0';
1552                         cp = name + 3;
1553                 }
1554                 new_path = resolve_relative_path(cp);
1555                 if (!new_path) {
1556                         namelen = namelen - (cp - name);
1557                 } else {
1558                         cp = new_path;
1559                         namelen = strlen(cp);
1560                 }
1561
1562                 if (flags & GET_SHA1_RECORD_PATH)
1563                         oc->path = xstrdup(cp);
1564
1565                 if (!active_cache)
1566                         read_cache();
1567                 pos = cache_name_pos(cp, namelen);
1568                 if (pos < 0)
1569                         pos = -pos - 1;
1570                 while (pos < active_nr) {
1571                         ce = active_cache[pos];
1572                         if (ce_namelen(ce) != namelen ||
1573                             memcmp(ce->name, cp, namelen))
1574                                 break;
1575                         if (ce_stage(ce) == stage) {
1576                                 hashcpy(sha1, ce->oid.hash);
1577                                 oc->mode = ce->ce_mode;
1578                                 free(new_path);
1579                                 return 0;
1580                         }
1581                         pos++;
1582                 }
1583                 if (only_to_die && name[1] && name[1] != '/')
1584                         diagnose_invalid_index_path(stage, prefix, cp);
1585                 free(new_path);
1586                 return -1;
1587         }
1588         for (cp = name, bracket_depth = 0; *cp; cp++) {
1589                 if (*cp == '{')
1590                         bracket_depth++;
1591                 else if (bracket_depth && *cp == '}')
1592                         bracket_depth--;
1593                 else if (!bracket_depth && *cp == ':')
1594                         break;
1595         }
1596         if (*cp == ':') {
1597                 unsigned char tree_sha1[20];
1598                 int len = cp - name;
1599                 unsigned sub_flags = flags;
1600
1601                 sub_flags &= ~GET_SHA1_DISAMBIGUATORS;
1602                 sub_flags |= GET_SHA1_TREEISH;
1603
1604                 if (!get_sha1_1(name, len, tree_sha1, sub_flags)) {
1605                         const char *filename = cp+1;
1606                         char *new_filename = NULL;
1607
1608                         new_filename = resolve_relative_path(filename);
1609                         if (new_filename)
1610                                 filename = new_filename;
1611                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1612                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1613                                         filename, sha1, &oc->symlink_path,
1614                                         &oc->mode);
1615                         } else {
1616                                 ret = get_tree_entry(tree_sha1, filename,
1617                                                      sha1, &oc->mode);
1618                                 if (ret && only_to_die) {
1619                                         diagnose_invalid_sha1_path(prefix,
1620                                                                    filename,
1621                                                                    tree_sha1,
1622                                                                    name, len);
1623                                 }
1624                         }
1625                         hashcpy(oc->tree, tree_sha1);
1626                         if (flags & GET_SHA1_RECORD_PATH)
1627                                 oc->path = xstrdup(filename);
1628
1629                         free(new_filename);
1630                         return ret;
1631                 } else {
1632                         if (only_to_die)
1633                                 die("Invalid object name '%.*s'.", len, name);
1634                 }
1635         }
1636         return ret;
1637 }
1638
1639 /*
1640  * Call this function when you know "name" given by the end user must
1641  * name an object but it doesn't; the function _may_ die with a better
1642  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1643  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1644  * you have a chance to diagnose the error further.
1645  */
1646 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1647 {
1648         struct object_context oc;
1649         unsigned char sha1[20];
1650         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1651 }
1652
1653 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *oc)
1654 {
1655         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1656                 die("BUG: incompatible flags for get_sha1_with_context");
1657         return get_sha1_with_context_1(str, flags, NULL, sha1, oc);
1658 }