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

   1 #include "cache.h"
   2 #include "tag.h"
   3 #include "commit.h"
   4 #include "tree.h"
   5 #include "blob.h"
   6 #include "tree-walk.h"
   7 #include "refs.h"
   8 #include "remote.h"
   9 #include "dir.h"
  10 #include "sha1-array.h"
  11
  12 static int get_sha1_oneline(const char *, unsigned char *, struct commit_list *);
  13
  14 typedef int (*disambiguate_hint_fn)(const unsigned char *, void *);
  15
  16 struct disambiguate_state {
  17         int len; /* length of prefix in hex chars */
  18         char hex_pfx[GIT_SHA1_HEXSZ + 1];
  19         unsigned char bin_pfx[GIT_SHA1_RAWSZ];
  20
  21         disambiguate_hint_fn fn;
  22         void *cb_data;
  23         unsigned char candidate[GIT_SHA1_RAWSZ];
  24         unsigned candidate_exists:1;
  25         unsigned candidate_checked:1;
  26         unsigned candidate_ok:1;
  27         unsigned disambiguate_fn_used:1;
  28         unsigned ambiguous:1;
  29         unsigned always_call_fn:1;
  30 };
  31
  32 static void update_candidates(struct disambiguate_state *ds, const unsigned char *current)
  33 {
  34         if (ds->always_call_fn) {
  35                 ds->ambiguous = ds->fn(current, ds->cb_data) ? 1 : 0;
  36                 return;
  37         }
  38         if (!ds->candidate_exists) {
  39                 /* this is the first candidate */
  40                 hashcpy(ds->candidate, current);
  41                 ds->candidate_exists = 1;
  42                 return;
  43         } else if (!hashcmp(ds->candidate, current)) {
  44                 /* the same as what we already have seen */
  45                 return;
  46         }
  47
  48         if (!ds->fn) {
  49                 /* cannot disambiguate between ds->candidate and current */
  50                 ds->ambiguous = 1;
  51                 return;
  52         }
  53
  54         if (!ds->candidate_checked) {
  55                 ds->candidate_ok = ds->fn(ds->candidate, ds->cb_data);
  56                 ds->disambiguate_fn_used = 1;
  57                 ds->candidate_checked = 1;
  58         }
  59
  60         if (!ds->candidate_ok) {
  61                 /* discard the candidate; we know it does not satisfy fn */
  62                 hashcpy(ds->candidate, current);
  63                 ds->candidate_checked = 0;
  64                 return;
  65         }
  66
  67         /* if we reach this point, we know ds->candidate satisfies fn */
  68         if (ds->fn(current, ds->cb_data)) {
  69                 /*
  70                  * if both current and candidate satisfy fn, we cannot
  71                  * disambiguate.
  72                  */
  73                 ds->candidate_ok = 0;
  74                 ds->ambiguous = 1;
  75         }
  76
  77         /* otherwise, current can be discarded and candidate is still good */
  78 }
  79
  80 static void find_short_object_filename(struct disambiguate_state *ds)
  81 {
  82         struct alternate_object_database *alt;
  83         char hex[GIT_SHA1_HEXSZ];
  84         static struct alternate_object_database *fakeent;
  85
  86         if (!fakeent) {
  87                 /*
  88                  * Create a "fake" alternate object database that
  89                  * points to our own object database, to make it
  90                  * easier to get a temporary working space in
  91                  * alt->name/alt->base while iterating over the
  92                  * object databases including our own.
  93                  */
  94                 fakeent = alloc_alt_odb(get_object_directory());
  95         }
  96         fakeent->next = alt_odb_list;
  97
  98         xsnprintf(hex, sizeof(hex), "%.2s", ds->hex_pfx);
  99         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 100                 struct strbuf *buf = alt_scratch_buf(alt);
 101                 struct dirent *de;
 102                 DIR *dir;
 103
 104                 strbuf_addf(buf, "%.2s/", ds->hex_pfx);
 105                 dir = opendir(buf->buf);
 106                 if (!dir)
 107                         continue;
 108
 109                 while (!ds->ambiguous && (de = readdir(dir)) != NULL) {
 110                         unsigned char sha1[20];
 111
 112                         if (strlen(de->d_name) != 38)
 113                                 continue;
 114                         if (memcmp(de->d_name, ds->hex_pfx + 2, ds->len - 2))
 115                                 continue;
 116                         memcpy(hex + 2, de->d_name, 38);
 117                         if (!get_sha1_hex(hex, sha1))
 118                                 update_candidates(ds, sha1);
 119                 }
 120                 closedir(dir);
 121         }
 122 }
 123
 124 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 125 {
 126         do {
 127                 if (*a != *b)
 128                         return 0;
 129                 a++;
 130                 b++;
 131                 len -= 2;
 132         } while (len > 1);
 133         if (len)
 134                 if ((*a ^ *b) & 0xf0)
 135                         return 0;
 136         return 1;
 137 }
 138
 139 static void unique_in_pack(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(ds->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(ds->len, ds->bin_pfx, current))
 174                         break;
 175                 update_candidates(ds, current);
 176         }
 177 }
 178
 179 static void find_short_packed_object(struct disambiguate_state *ds)
 180 {
 181         struct packed_git *p;
 182
 183         prepare_packed_git();
 184         for (p = packed_git; p && !ds->ambiguous; p = p->next)
 185                 unique_in_pack(p, ds);
 186 }
 187
 188 #define SHORT_NAME_NOT_FOUND (-1)
 189 #define SHORT_NAME_AMBIGUOUS (-2)
 190
 191 static int finish_object_disambiguation(struct disambiguate_state *ds,
 192                                         unsigned char *sha1)
 193 {
 194         if (ds->ambiguous)
 195                 return SHORT_NAME_AMBIGUOUS;
 196
 197         if (!ds->candidate_exists)
 198                 return SHORT_NAME_NOT_FOUND;
 199
 200         if (!ds->candidate_checked)
 201                 /*
 202                  * If this is the only candidate, there is no point
 203                  * calling the disambiguation hint callback.
 204                  *
 205                  * On the other hand, if the current candidate
 206                  * replaced an earlier candidate that did _not_ pass
 207                  * the disambiguation hint callback, then we do have
 208                  * more than one objects that match the short name
 209                  * given, so we should make sure this one matches;
 210                  * otherwise, if we discovered this one and the one
 211                  * that we previously discarded in the reverse order,
 212                  * we would end up showing different results in the
 213                  * same repository!
 214                  */
 215                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 216                                     ds->fn(ds->candidate, ds->cb_data));
 217
 218         if (!ds->candidate_ok)
 219                 return SHORT_NAME_AMBIGUOUS;
 220
 221         hashcpy(sha1, ds->candidate);
 222         return 0;
 223 }
 224
 225 static int disambiguate_commit_only(const unsigned char *sha1, void *cb_data_unused)
 226 {
 227         int kind = sha1_object_info(sha1, NULL);
 228         return kind == OBJ_COMMIT;
 229 }
 230
 231 static int disambiguate_committish_only(const unsigned char *sha1, void *cb_data_unused)
 232 {
 233         struct object *obj;
 234         int kind;
 235
 236         kind = sha1_object_info(sha1, NULL);
 237         if (kind == OBJ_COMMIT)
 238                 return 1;
 239         if (kind != OBJ_TAG)
 240                 return 0;
 241
 242         /* We need to do this the hard way... */
 243         obj = deref_tag(parse_object(sha1), NULL, 0);
 244         if (obj && obj->type == OBJ_COMMIT)
 245                 return 1;
 246         return 0;
 247 }
 248
 249 static int disambiguate_tree_only(const unsigned char *sha1, void *cb_data_unused)
 250 {
 251         int kind = sha1_object_info(sha1, NULL);
 252         return kind == OBJ_TREE;
 253 }
 254
 255 static int disambiguate_treeish_only(const unsigned char *sha1, void *cb_data_unused)
 256 {
 257         struct object *obj;
 258         int kind;
 259
 260         kind = sha1_object_info(sha1, NULL);
 261         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 262                 return 1;
 263         if (kind != OBJ_TAG)
 264                 return 0;
 265
 266         /* We need to do this the hard way... */
 267         obj = deref_tag(parse_object(sha1), NULL, 0);
 268         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 269                 return 1;
 270         return 0;
 271 }
 272
 273 static int disambiguate_blob_only(const unsigned char *sha1, void *cb_data_unused)
 274 {
 275         int kind = sha1_object_info(sha1, NULL);
 276         return kind == OBJ_BLOB;
 277 }
 278
 279 static disambiguate_hint_fn default_disambiguate_hint;
 280
 281 int set_disambiguate_hint_config(const char *var, const char *value)
 282 {
 283         static const struct {
 284                 const char *name;
 285                 disambiguate_hint_fn fn;
 286         } hints[] = {
 287                 { "none", NULL },
 288                 { "commit", disambiguate_commit_only },
 289                 { "committish", disambiguate_committish_only },
 290                 { "tree", disambiguate_tree_only },
 291                 { "treeish", disambiguate_treeish_only },
 292                 { "blob", disambiguate_blob_only }
 293         };
 294         int i;
 295
 296         if (!value)
 297                 return config_error_nonbool(var);
 298
 299         for (i = 0; i < ARRAY_SIZE(hints); i++) {
 300                 if (!strcasecmp(value, hints[i].name)) {
 301                         default_disambiguate_hint = hints[i].fn;
 302                         return 0;
 303                 }
 304         }
 305
 306         return error("unknown hint type for '%s': %s", var, value);
 307 }
 308
 309 static int init_object_disambiguation(const char *name, int len,
 310                                       struct disambiguate_state *ds)
 311 {
 312         int i;
 313
 314         if (len < MINIMUM_ABBREV || len > GIT_SHA1_HEXSZ)
 315                 return -1;
 316
 317         memset(ds, 0, sizeof(*ds));
 318
 319         for (i = 0; i < len ;i++) {
 320                 unsigned char c = name[i];
 321                 unsigned char val;
 322                 if (c >= '0' && c <= '9')
 323                         val = c - '0';
 324                 else if (c >= 'a' && c <= 'f')
 325                         val = c - 'a' + 10;
 326                 else if (c >= 'A' && c <='F') {
 327                         val = c - 'A' + 10;
 328                         c -= 'A' - 'a';
 329                 }
 330                 else
 331                         return -1;
 332                 ds->hex_pfx[i] = c;
 333                 if (!(i & 1))
 334                         val <<= 4;
 335                 ds->bin_pfx[i >> 1] |= val;
 336         }
 337
 338         ds->len = len;
 339         ds->hex_pfx[len] = '\0';
 340         prepare_alt_odb();
 341         return 0;
 342 }
 343
 344 static int show_ambiguous_object(const unsigned char *sha1, void *data)
 345 {
 346         const struct disambiguate_state *ds = data;
 347         struct strbuf desc = STRBUF_INIT;
 348         int type;
 349
 350         if (ds->fn && !ds->fn(sha1, ds->cb_data))
 351                 return 0;
 352
 353         type = sha1_object_info(sha1, NULL);
 354         if (type == OBJ_COMMIT) {
 355                 struct commit *commit = lookup_commit(sha1);
 356                 if (commit) {
 357                         struct pretty_print_context pp = {0};
 358                         pp.date_mode.type = DATE_SHORT;
 359                         format_commit_message(commit, " %ad - %s", &desc, &pp);
 360                 }
 361         } else if (type == OBJ_TAG) {
 362                 struct tag *tag = lookup_tag(sha1);
 363                 if (!parse_tag(tag) && tag->tag)
 364                         strbuf_addf(&desc, " %s", tag->tag);
 365         }
 366
 367         advise("  %s %s%s",
 368                find_unique_abbrev(sha1, DEFAULT_ABBREV),
 369                typename(type) ? typename(type) : "unknown type",
 370                desc.buf);
 371
 372         strbuf_release(&desc);
 373         return 0;
 374 }
 375
 376 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 377                           unsigned flags)
 378 {
 379         int status;
 380         struct disambiguate_state ds;
 381         int quietly = !!(flags & GET_SHA1_QUIETLY);
 382
 383         if (init_object_disambiguation(name, len, &ds) < 0)
 384                 return -1;
 385
 386         if (HAS_MULTI_BITS(flags & GET_SHA1_DISAMBIGUATORS))
 387                 die("BUG: multiple get_short_sha1 disambiguator flags");
 388
 389         if (flags & GET_SHA1_COMMIT)
 390                 ds.fn = disambiguate_commit_only;
 391         else if (flags & GET_SHA1_COMMITTISH)
 392                 ds.fn = disambiguate_committish_only;
 393         else if (flags & GET_SHA1_TREE)
 394                 ds.fn = disambiguate_tree_only;
 395         else if (flags & GET_SHA1_TREEISH)
 396                 ds.fn = disambiguate_treeish_only;
 397         else if (flags & GET_SHA1_BLOB)
 398                 ds.fn = disambiguate_blob_only;
 399         else
 400                 ds.fn = default_disambiguate_hint;
 401
 402         find_short_object_filename(&ds);
 403         find_short_packed_object(&ds);
 404         status = finish_object_disambiguation(&ds, sha1);
 405
 406         if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
 407                 error(_("short SHA1 %s is ambiguous"), ds.hex_pfx);
 408
 409                 /*
 410                  * We may still have ambiguity if we simply saw a series of
 411                  * candidates that did not satisfy our hint function. In
 412                  * that case, we still want to show them, so disable the hint
 413                  * function entirely.
 414                  */
 415                 if (!ds.ambiguous)
 416                         ds.fn = NULL;
 417
 418                 advise(_("The candidates are:"));
 419                 for_each_abbrev(ds.hex_pfx, show_ambiguous_object, &ds);
 420         }
 421
 422         return status;
 423 }
 424
 425 static int collect_ambiguous(const unsigned char *sha1, void *data)
 426 {
 427         sha1_array_append(data, sha1);
 428         return 0;
 429 }
 430
 431 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 432 {
 433         struct sha1_array collect = SHA1_ARRAY_INIT;
 434         struct disambiguate_state ds;
 435         int ret;
 436
 437         if (init_object_disambiguation(prefix, strlen(prefix), &ds) < 0)
 438                 return -1;
 439
 440         ds.always_call_fn = 1;
 441         ds.fn = collect_ambiguous;
 442         ds.cb_data = &collect;
 443         find_short_object_filename(&ds);
 444         find_short_packed_object(&ds);
 445
 446         ret = sha1_array_for_each_unique(&collect, fn, cb_data);
 447         sha1_array_clear(&collect);
 448         return ret;
 449 }
 450
 451 /*
 452  * Return the slot of the most-significant bit set in "val". There are various
 453  * ways to do this quickly with fls() or __builtin_clzl(), but speed is
 454  * probably not a big deal here.
 455  */
 456 static unsigned msb(unsigned long val)
 457 {
 458         unsigned r = 0;
 459         while (val >>= 1)
 460                 r++;
 461         return r;
 462 }
 463
 464 int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 465 {
 466         int status, exists;
 467
 468         if (len < 0) {
 469                 unsigned long count = approximate_object_count();
 470                 /*
 471                  * Add one because the MSB only tells us the highest bit set,
 472                  * not including the value of all the _other_ bits (so "15"
 473                  * is only one off of 2^4, but the MSB is the 3rd bit.
 474                  */
 475                 len = msb(count) + 1;
 476                 /*
 477                  * We now know we have on the order of 2^len objects, which
 478                  * expects a collision at 2^(len/2). But we also care about hex
 479                  * chars, not bits, and there are 4 bits per hex. So all
 480                  * together we need to divide by 2; but we also want to round
 481                  * odd numbers up, hence adding one before dividing.
 482                  */
 483                 len = (len + 1) / 2;
 484                 /*
 485                  * For very small repos, we stick with our regular fallback.
 486                  */
 487                 if (len < FALLBACK_DEFAULT_ABBREV)
 488                         len = FALLBACK_DEFAULT_ABBREV;
 489         }
 490
 491         sha1_to_hex_r(hex, sha1);
 492         if (len == 40 || !len)
 493                 return 40;
 494         exists = has_sha1_file(sha1);
 495         while (len < 40) {
 496                 unsigned char sha1_ret[20];
 497                 status = get_short_sha1(hex, len, sha1_ret, GET_SHA1_QUIETLY);
 498                 if (exists
 499                     ? !status
 500                     : status == SHORT_NAME_NOT_FOUND) {
 501                         hex[len] = 0;
 502                         return len;
 503                 }
 504                 len++;
 505         }
 506         return len;
 507 }
 508
 509 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 510 {
 511         static int bufno;
 512         static char hexbuffer[4][GIT_SHA1_HEXSZ + 1];
 513         char *hex = hexbuffer[bufno];
 514         bufno = (bufno + 1) % ARRAY_SIZE(hexbuffer);
 515         find_unique_abbrev_r(hex, sha1, len);
 516         return hex;
 517 }
 518
 519 static int ambiguous_path(const char *path, int len)
 520 {
 521         int slash = 1;
 522         int cnt;
 523
 524         for (cnt = 0; cnt < len; cnt++) {
 525                 switch (*path++) {
 526                 case '\0':
 527                         break;
 528                 case '/':
 529                         if (slash)
 530                                 break;
 531                         slash = 1;
 532                         continue;
 533                 case '.':
 534                         continue;
 535                 default:
 536                         slash = 0;
 537                         continue;
 538                 }
 539                 break;
 540         }
 541         return slash;
 542 }
 543
 544 static inline int at_mark(const char *string, int len,
 545                           const char **suffix, int nr)
 546 {
 547         int i;
 548
 549         for (i = 0; i < nr; i++) {
 550                 int suffix_len = strlen(suffix[i]);
 551                 if (suffix_len <= len
 552                     && !memcmp(string, suffix[i], suffix_len))
 553                         return suffix_len;
 554         }
 555         return 0;
 556 }
 557
 558 static inline int upstream_mark(const char *string, int len)
 559 {
 560         const char *suffix[] = { "@{upstream}", "@{u}" };
 561         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 562 }
 563
 564 static inline int push_mark(const char *string, int len)
 565 {
 566         const char *suffix[] = { "@{push}" };
 567         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 568 }
 569
 570 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 571 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 572
 573 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 574                           unsigned int flags)
 575 {
 576         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 577         static const char *object_name_msg = N_(
 578         "Git normally never creates a ref that ends with 40 hex characters\n"
 579         "because it will be ignored when you just specify 40-hex. These refs\n"
 580         "may be created by mistake. For example,\n"
 581         "\n"
 582         "  git checkout -b $br $(git rev-parse ...)\n"
 583         "\n"
 584         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 585         "examine these refs and maybe delete them. Turn this message off by\n"
 586         "running \"git config advice.objectNameWarning false\"");
 587         unsigned char tmp_sha1[20];
 588         char *real_ref = NULL;
 589         int refs_found = 0;
 590         int at, reflog_len, nth_prior = 0;
 591
 592         if (len == 40 && !get_sha1_hex(str, sha1)) {
 593                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 594                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 595                         if (refs_found > 0) {
 596                                 warning(warn_msg, len, str);
 597                                 if (advice_object_name_warning)
 598                                         fprintf(stderr, "%s\n", _(object_name_msg));
 599                         }
 600                         free(real_ref);
 601                 }
 602                 return 0;
 603         }
 604
 605         /* basic@{time or number or -number} format to query ref-log */
 606         reflog_len = at = 0;
 607         if (len && str[len-1] == '}') {
 608                 for (at = len-4; at >= 0; at--) {
 609                         if (str[at] == '@' && str[at+1] == '{') {
 610                                 if (str[at+2] == '-') {
 611                                         if (at != 0)
 612                                                 /* @{-N} not at start */
 613                                                 return -1;
 614                                         nth_prior = 1;
 615                                         continue;
 616                                 }
 617                                 if (!upstream_mark(str + at, len - at) &&
 618                                     !push_mark(str + at, len - at)) {
 619                                         reflog_len = (len-1) - (at+2);
 620                                         len = at;
 621                                 }
 622                                 break;
 623                         }
 624                 }
 625         }
 626
 627         /* Accept only unambiguous ref paths. */
 628         if (len && ambiguous_path(str, len))
 629                 return -1;
 630
 631         if (nth_prior) {
 632                 struct strbuf buf = STRBUF_INIT;
 633                 int detached;
 634
 635                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 636                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 637                         strbuf_release(&buf);
 638                         if (detached)
 639                                 return 0;
 640                 }
 641         }
 642
 643         if (!len && reflog_len)
 644                 /* allow "@{...}" to mean the current branch reflog */
 645                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 646         else if (reflog_len)
 647                 refs_found = dwim_log(str, len, sha1, &real_ref);
 648         else
 649                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 650
 651         if (!refs_found)
 652                 return -1;
 653
 654         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 655             (refs_found > 1 ||
 656              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 657                 warning(warn_msg, len, str);
 658
 659         if (reflog_len) {
 660                 int nth, i;
 661                 unsigned long at_time;
 662                 unsigned long co_time;
 663                 int co_tz, co_cnt;
 664
 665                 /* Is it asking for N-th entry, or approxidate? */
 666                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 667                         char ch = str[at+2+i];
 668                         if ('0' <= ch && ch <= '9')
 669                                 nth = nth * 10 + ch - '0';
 670                         else
 671                                 nth = -1;
 672                 }
 673                 if (100000000 <= nth) {
 674                         at_time = nth;
 675                         nth = -1;
 676                 } else if (0 <= nth)
 677                         at_time = 0;
 678                 else {
 679                         int errors = 0;
 680                         char *tmp = xstrndup(str + at + 2, reflog_len);
 681                         at_time = approxidate_careful(tmp, &errors);
 682                         free(tmp);
 683                         if (errors) {
 684                                 free(real_ref);
 685                                 return -1;
 686                         }
 687                 }
 688                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 689                                 &co_time, &co_tz, &co_cnt)) {
 690                         if (!len) {
 691                                 if (starts_with(real_ref, "refs/heads/")) {
 692                                         str = real_ref + 11;
 693                                         len = strlen(real_ref + 11);
 694                                 } else {
 695                                         /* detached HEAD */
 696                                         str = "HEAD";
 697                                         len = 4;
 698                                 }
 699                         }
 700                         if (at_time) {
 701                                 if (!(flags & GET_SHA1_QUIETLY)) {
 702                                         warning("Log for '%.*s' only goes "
 703                                                 "back to %s.", len, str,
 704                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 705                                 }
 706                         } else {
 707                                 if (flags & GET_SHA1_QUIETLY) {
 708                                         exit(128);
 709                                 }
 710                                 die("Log for '%.*s' only has %d entries.",
 711                                     len, str, co_cnt);
 712                         }
 713                 }
 714         }
 715
 716         free(real_ref);
 717         return 0;
 718 }
 719
 720 static int get_parent(const char *name, int len,
 721                       unsigned char *result, int idx)
 722 {
 723         unsigned char sha1[20];
 724         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 725         struct commit *commit;
 726         struct commit_list *p;
 727
 728         if (ret)
 729                 return ret;
 730         commit = lookup_commit_reference(sha1);
 731         if (parse_commit(commit))
 732                 return -1;
 733         if (!idx) {
 734                 hashcpy(result, commit->object.oid.hash);
 735                 return 0;
 736         }
 737         p = commit->parents;
 738         while (p) {
 739                 if (!--idx) {
 740                         hashcpy(result, p->item->object.oid.hash);
 741                         return 0;
 742                 }
 743                 p = p->next;
 744         }
 745         return -1;
 746 }
 747
 748 static int get_nth_ancestor(const char *name, int len,
 749                             unsigned char *result, int generation)
 750 {
 751         unsigned char sha1[20];
 752         struct commit *commit;
 753         int ret;
 754
 755         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 756         if (ret)
 757                 return ret;
 758         commit = lookup_commit_reference(sha1);
 759         if (!commit)
 760                 return -1;
 761
 762         while (generation--) {
 763                 if (parse_commit(commit) || !commit->parents)
 764                         return -1;
 765                 commit = commit->parents->item;
 766         }
 767         hashcpy(result, commit->object.oid.hash);
 768         return 0;
 769 }
 770
 771 struct object *peel_to_type(const char *name, int namelen,
 772                             struct object *o, enum object_type expected_type)
 773 {
 774         if (name && !namelen)
 775                 namelen = strlen(name);
 776         while (1) {
 777                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 778                         return NULL;
 779                 if (expected_type == OBJ_ANY || o->type == expected_type)
 780                         return o;
 781                 if (o->type == OBJ_TAG)
 782                         o = ((struct tag*) o)->tagged;
 783                 else if (o->type == OBJ_COMMIT)
 784                         o = &(((struct commit *) o)->tree->object);
 785                 else {
 786                         if (name)
 787                                 error("%.*s: expected %s type, but the object "
 788                                       "dereferences to %s type",
 789                                       namelen, name, typename(expected_type),
 790                                       typename(o->type));
 791                         return NULL;
 792                 }
 793         }
 794 }
 795
 796 static int peel_onion(const char *name, int len, unsigned char *sha1,
 797                       unsigned lookup_flags)
 798 {
 799         unsigned char outer[20];
 800         const char *sp;
 801         unsigned int expected_type = 0;
 802         struct object *o;
 803
 804         /*
 805          * "ref^{type}" dereferences ref repeatedly until you cannot
 806          * dereference anymore, or you get an object of given type,
 807          * whichever comes first.  "ref^{}" means just dereference
 808          * tags until you get a non-tag.  "ref^0" is a shorthand for
 809          * "ref^{commit}".  "commit^{tree}" could be used to find the
 810          * top-level tree of the given commit.
 811          */
 812         if (len < 4 || name[len-1] != '}')
 813                 return -1;
 814
 815         for (sp = name + len - 1; name <= sp; sp--) {
 816                 int ch = *sp;
 817                 if (ch == '{' && name < sp && sp[-1] == '^')
 818                         break;
 819         }
 820         if (sp <= name)
 821                 return -1;
 822
 823         sp++; /* beginning of type name, or closing brace for empty */
 824         if (starts_with(sp, "commit}"))
 825                 expected_type = OBJ_COMMIT;
 826         else if (starts_with(sp, "tag}"))
 827                 expected_type = OBJ_TAG;
 828         else if (starts_with(sp, "tree}"))
 829                 expected_type = OBJ_TREE;
 830         else if (starts_with(sp, "blob}"))
 831                 expected_type = OBJ_BLOB;
 832         else if (starts_with(sp, "object}"))
 833                 expected_type = OBJ_ANY;
 834         else if (sp[0] == '}')
 835                 expected_type = OBJ_NONE;
 836         else if (sp[0] == '/')
 837                 expected_type = OBJ_COMMIT;
 838         else
 839                 return -1;
 840
 841         lookup_flags &= ~GET_SHA1_DISAMBIGUATORS;
 842         if (expected_type == OBJ_COMMIT)
 843                 lookup_flags |= GET_SHA1_COMMITTISH;
 844         else if (expected_type == OBJ_TREE)
 845                 lookup_flags |= GET_SHA1_TREEISH;
 846
 847         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 848                 return -1;
 849
 850         o = parse_object(outer);
 851         if (!o)
 852                 return -1;
 853         if (!expected_type) {
 854                 o = deref_tag(o, name, sp - name - 2);
 855                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 856                         return -1;
 857                 hashcpy(sha1, o->oid.hash);
 858                 return 0;
 859         }
 860
 861         /*
 862          * At this point, the syntax look correct, so
 863          * if we do not get the needed object, we should
 864          * barf.
 865          */
 866         o = peel_to_type(name, len, o, expected_type);
 867         if (!o)
 868                 return -1;
 869
 870         hashcpy(sha1, o->oid.hash);
 871         if (sp[0] == '/') {
 872                 /* "$commit^{/foo}" */
 873                 char *prefix;
 874                 int ret;
 875                 struct commit_list *list = NULL;
 876
 877                 /*
 878                  * $commit^{/}. Some regex implementation may reject.
 879                  * We don't need regex anyway. '' pattern always matches.
 880                  */
 881                 if (sp[1] == '}')
 882                         return 0;
 883
 884                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 885                 commit_list_insert((struct commit *)o, &list);
 886                 ret = get_sha1_oneline(prefix, sha1, list);
 887                 free(prefix);
 888                 return ret;
 889         }
 890         return 0;
 891 }
 892
 893 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 894 {
 895         const char *cp;
 896         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 897
 898         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 899                 char ch = *cp;
 900                 if (!isxdigit(ch)) {
 901                         /* We must be looking at g in "SOMETHING-g"
 902                          * for it to be describe output.
 903                          */
 904                         if (ch == 'g' && cp[-1] == '-') {
 905                                 cp++;
 906                                 len -= cp - name;
 907                                 return get_short_sha1(cp, len, sha1, flags);
 908                         }
 909                 }
 910         }
 911         return -1;
 912 }
 913
 914 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 915 {
 916         int ret, has_suffix;
 917         const char *cp;
 918
 919         /*
 920          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 921          */
 922         has_suffix = 0;
 923         for (cp = name + len - 1; name <= cp; cp--) {
 924                 int ch = *cp;
 925                 if ('0' <= ch && ch <= '9')
 926                         continue;
 927                 if (ch == '~' || ch == '^')
 928                         has_suffix = ch;
 929                 break;
 930         }
 931
 932         if (has_suffix) {
 933                 int num = 0;
 934                 int len1 = cp - name;
 935                 cp++;
 936                 while (cp < name + len)
 937                         num = num * 10 + *cp++ - '0';
 938                 if (!num && len1 == len - 1)
 939                         num = 1;
 940                 if (has_suffix == '^')
 941                         return get_parent(name, len1, sha1, num);
 942                 /* else if (has_suffix == '~') -- goes without saying */
 943                 return get_nth_ancestor(name, len1, sha1, num);
 944         }
 945
 946         ret = peel_onion(name, len, sha1, lookup_flags);
 947         if (!ret)
 948                 return 0;
 949
 950         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 951         if (!ret)
 952                 return 0;
 953
 954         /* It could be describe output that is "SOMETHING-gXXXX" */
 955         ret = get_describe_name(name, len, sha1);
 956         if (!ret)
 957                 return 0;
 958
 959         return get_short_sha1(name, len, sha1, lookup_flags);
 960 }
 961
 962 /*
 963  * This interprets names like ':/Initial revision of "git"' by searching
 964  * through history and returning the first commit whose message starts
 965  * the given regular expression.
 966  *
 967  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
 968  *
 969  * For a literal '!' character at the beginning of a pattern, you have to repeat
 970  * that, like: ':/!!foo'
 971  *
 972  * For future extension, all other sequences beginning with ':/!' are reserved.
 973  */
 974
 975 /* Remember to update object flag allocation in object.h */
 976 #define ONELINE_SEEN (1u<<20)
 977
 978 static int handle_one_ref(const char *path, const struct object_id *oid,
 979                           int flag, void *cb_data)
 980 {
 981         struct commit_list **list = cb_data;
 982         struct object *object = parse_object(oid->hash);
 983         if (!object)
 984                 return 0;
 985         if (object->type == OBJ_TAG) {
 986                 object = deref_tag(object, path, strlen(path));
 987                 if (!object)
 988                         return 0;
 989         }
 990         if (object->type != OBJ_COMMIT)
 991                 return 0;
 992         commit_list_insert((struct commit *)object, list);
 993         return 0;
 994 }
 995
 996 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 997                             struct commit_list *list)
 998 {
 999         struct commit_list *backup = NULL, *l;
1000         int found = 0;
1001         int negative = 0;
1002         regex_t regex;
1003
1004         if (prefix[0] == '!') {
1005                 prefix++;
1006
1007                 if (prefix[0] == '-') {
1008                         prefix++;
1009                         negative = 1;
1010                 } else if (prefix[0] != '!') {
1011                         return -1;
1012                 }
1013         }
1014
1015         if (regcomp(&regex, prefix, REG_EXTENDED))
1016                 return -1;
1017
1018         for (l = list; l; l = l->next) {
1019                 l->item->object.flags |= ONELINE_SEEN;
1020                 commit_list_insert(l->item, &backup);
1021         }
1022         while (list) {
1023                 const char *p, *buf;
1024                 struct commit *commit;
1025                 int matches;
1026
1027                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
1028                 if (!parse_object(commit->object.oid.hash))
1029                         continue;
1030                 buf = get_commit_buffer(commit, NULL);
1031                 p = strstr(buf, "\n\n");
1032                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
1033                 unuse_commit_buffer(commit, buf);
1034
1035                 if (matches) {
1036                         hashcpy(sha1, commit->object.oid.hash);
1037                         found = 1;
1038                         break;
1039                 }
1040         }
1041         regfree(&regex);
1042         free_commit_list(list);
1043         for (l = backup; l; l = l->next)
1044                 clear_commit_marks(l->item, ONELINE_SEEN);
1045         free_commit_list(backup);
1046         return found ? 0 : -1;
1047 }
1048
1049 struct grab_nth_branch_switch_cbdata {
1050         int remaining;
1051         struct strbuf buf;
1052 };
1053
1054 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
1055                                   const char *email, unsigned long timestamp, int tz,
1056                                   const char *message, void *cb_data)
1057 {
1058         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1059         const char *match = NULL, *target = NULL;
1060         size_t len;
1061
1062         if (skip_prefix(message, "checkout: moving from ", &match))
1063                 target = strstr(match, " to ");
1064
1065         if (!match || !target)
1066                 return 0;
1067         if (--(cb->remaining) == 0) {
1068                 len = target - match;
1069                 strbuf_reset(&cb->buf);
1070                 strbuf_add(&cb->buf, match, len);
1071                 return 1; /* we are done */
1072         }
1073         return 0;
1074 }
1075
1076 /*
1077  * Parse @{-N} syntax, return the number of characters parsed
1078  * if successful; otherwise signal an error with negative value.
1079  */
1080 static int interpret_nth_prior_checkout(const char *name, int namelen,
1081                                         struct strbuf *buf)
1082 {
1083         long nth;
1084         int retval;
1085         struct grab_nth_branch_switch_cbdata cb;
1086         const char *brace;
1087         char *num_end;
1088
1089         if (namelen < 4)
1090                 return -1;
1091         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1092                 return -1;
1093         brace = memchr(name, '}', namelen);
1094         if (!brace)
1095                 return -1;
1096         nth = strtol(name + 3, &num_end, 10);
1097         if (num_end != brace)
1098                 return -1;
1099         if (nth <= 0)
1100                 return -1;
1101         cb.remaining = nth;
1102         strbuf_init(&cb.buf, 20);
1103
1104         retval = 0;
1105         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1106                 strbuf_reset(buf);
1107                 strbuf_addbuf(buf, &cb.buf);
1108                 retval = brace - name + 1;
1109         }
1110
1111         strbuf_release(&cb.buf);
1112         return retval;
1113 }
1114
1115 int get_oid_mb(const char *name, struct object_id *oid)
1116 {
1117         struct commit *one, *two;
1118         struct commit_list *mbs;
1119         struct object_id oid_tmp;
1120         const char *dots;
1121         int st;
1122
1123         dots = strstr(name, "...");
1124         if (!dots)
1125                 return get_oid(name, oid);
1126         if (dots == name)
1127                 st = get_oid("HEAD", &oid_tmp);
1128         else {
1129                 struct strbuf sb;
1130                 strbuf_init(&sb, dots - name);
1131                 strbuf_add(&sb, name, dots - name);
1132                 st = get_sha1_committish(sb.buf, oid_tmp.hash);
1133                 strbuf_release(&sb);
1134         }
1135         if (st)
1136                 return st;
1137         one = lookup_commit_reference_gently(oid_tmp.hash, 0);
1138         if (!one)
1139                 return -1;
1140
1141         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", oid_tmp.hash))
1142                 return -1;
1143         two = lookup_commit_reference_gently(oid_tmp.hash, 0);
1144         if (!two)
1145                 return -1;
1146         mbs = get_merge_bases(one, two);
1147         if (!mbs || mbs->next)
1148                 st = -1;
1149         else {
1150                 st = 0;
1151                 oidcpy(oid, &mbs->item->object.oid);
1152         }
1153         free_commit_list(mbs);
1154         return st;
1155 }
1156
1157 /* parse @something syntax, when 'something' is not {.*} */
1158 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1159 {
1160         const char *next;
1161
1162         if (len || name[1] == '{')
1163                 return -1;
1164
1165         /* make sure it's a single @, or @@{.*}, not @foo */
1166         next = memchr(name + len + 1, '@', namelen - len - 1);
1167         if (next && next[1] != '{')
1168                 return -1;
1169         if (!next)
1170                 next = name + namelen;
1171         if (next != name + 1)
1172                 return -1;
1173
1174         strbuf_reset(buf);
1175         strbuf_add(buf, "HEAD", 4);
1176         return 1;
1177 }
1178
1179 static int reinterpret(const char *name, int namelen, int len,
1180                        struct strbuf *buf, unsigned allowed)
1181 {
1182         /* we have extra data, which might need further processing */
1183         struct strbuf tmp = STRBUF_INIT;
1184         int used = buf->len;
1185         int ret;
1186
1187         strbuf_add(buf, name + len, namelen - len);
1188         ret = interpret_branch_name(buf->buf, buf->len, &tmp, allowed);
1189         /* that data was not interpreted, remove our cruft */
1190         if (ret < 0) {
1191                 strbuf_setlen(buf, used);
1192                 return len;
1193         }
1194         strbuf_reset(buf);
1195         strbuf_addbuf(buf, &tmp);
1196         strbuf_release(&tmp);
1197         /* tweak for size of {-N} versus expanded ref name */
1198         return ret - used + len;
1199 }
1200
1201 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1202 {
1203         char *s = shorten_unambiguous_ref(ref, 0);
1204         strbuf_reset(buf);
1205         strbuf_addstr(buf, s);
1206         free(s);
1207 }
1208
1209 static int branch_interpret_allowed(const char *refname, unsigned allowed)
1210 {
1211         if (!allowed)
1212                 return 1;
1213
1214         if ((allowed & INTERPRET_BRANCH_LOCAL) &&
1215             starts_with(refname, "refs/heads/"))
1216                 return 1;
1217         if ((allowed & INTERPRET_BRANCH_REMOTE) &&
1218             starts_with(refname, "refs/remotes/"))
1219                 return 1;
1220
1221         return 0;
1222 }
1223
1224 static int interpret_branch_mark(const char *name, int namelen,
1225                                  int at, struct strbuf *buf,
1226                                  int (*get_mark)(const char *, int),
1227                                  const char *(*get_data)(struct branch *,
1228                                                          struct strbuf *),
1229                                  unsigned allowed)
1230 {
1231         int len;
1232         struct branch *branch;
1233         struct strbuf err = STRBUF_INIT;
1234         const char *value;
1235
1236         len = get_mark(name + at, namelen - at);
1237         if (!len)
1238                 return -1;
1239
1240         if (memchr(name, ':', at))
1241                 return -1;
1242
1243         if (at) {
1244                 char *name_str = xmemdupz(name, at);
1245                 branch = branch_get(name_str);
1246                 free(name_str);
1247         } else
1248                 branch = branch_get(NULL);
1249
1250         value = get_data(branch, &err);
1251         if (!value)
1252                 die("%s", err.buf);
1253
1254         if (!branch_interpret_allowed(value, allowed))
1255                 return -1;
1256
1257         set_shortened_ref(buf, value);
1258         return len + at;
1259 }
1260
1261 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf,
1262                           unsigned allowed)
1263 {
1264         char *at;
1265         const char *start;
1266         int len;
1267
1268         if (!namelen)
1269                 namelen = strlen(name);
1270
1271         if (!allowed || (allowed & INTERPRET_BRANCH_LOCAL)) {
1272                 len = interpret_nth_prior_checkout(name, namelen, buf);
1273                 if (!len) {
1274                         return len; /* syntax Ok, not enough switches */
1275                 } else if (len > 0) {
1276                         if (len == namelen)
1277                                 return len; /* consumed all */
1278                         else
1279                                 return reinterpret(name, namelen, len, buf, allowed);
1280                 }
1281         }
1282
1283         for (start = name;
1284              (at = memchr(start, '@', namelen - (start - name)));
1285              start = at + 1) {
1286
1287                 if (!allowed || (allowed & INTERPRET_BRANCH_HEAD)) {
1288                         len = interpret_empty_at(name, namelen, at - name, buf);
1289                         if (len > 0)
1290                                 return reinterpret(name, namelen, len, buf,
1291                                                    allowed);
1292                 }
1293
1294                 len = interpret_branch_mark(name, namelen, at - name, buf,
1295                                             upstream_mark, branch_get_upstream,
1296                                             allowed);
1297                 if (len > 0)
1298                         return len;
1299
1300                 len = interpret_branch_mark(name, namelen, at - name, buf,
1301                                             push_mark, branch_get_push,
1302                                             allowed);
1303                 if (len > 0)
1304                         return len;
1305         }
1306
1307         return -1;
1308 }
1309
1310 void strbuf_branchname(struct strbuf *sb, const char *name, unsigned allowed)
1311 {
1312         int len = strlen(name);
1313         int used = interpret_branch_name(name, len, sb, allowed);
1314
1315         if (used < 0)
1316                 used = 0;
1317         strbuf_add(sb, name + used, len - used);
1318 }
1319
1320 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1321 {
1322         strbuf_branchname(sb, name, INTERPRET_BRANCH_LOCAL);
1323         if (name[0] == '-')
1324                 return -1;
1325         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1326         return check_refname_format(sb->buf, 0);
1327 }
1328
1329 /*
1330  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1331  * notably "xyz^" for "parent of xyz"
1332  */
1333 int get_sha1(const char *name, unsigned char *sha1)
1334 {
1335         struct object_context unused;
1336         return get_sha1_with_context(name, 0, sha1, &unused);
1337 }
1338
1339 /*
1340  * This is like "get_sha1()", but for struct object_id.
1341  */
1342 int get_oid(const char *name, struct object_id *oid)
1343 {
1344         return get_sha1(name, oid->hash);
1345 }
1346
1347
1348 /*
1349  * Many callers know that the user meant to name a commit-ish by
1350  * syntactical positions where the object name appears.  Calling this
1351  * function allows the machinery to disambiguate shorter-than-unique
1352  * abbreviated object names between commit-ish and others.
1353  *
1354  * Note that this does NOT error out when the named object is not a
1355  * commit-ish. It is merely to give a hint to the disambiguation
1356  * machinery.
1357  */
1358 int get_sha1_committish(const char *name, unsigned char *sha1)
1359 {
1360         struct object_context unused;
1361         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1362                                      sha1, &unused);
1363 }
1364
1365 int get_sha1_treeish(const char *name, unsigned char *sha1)
1366 {
1367         struct object_context unused;
1368         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1369                                      sha1, &unused);
1370 }
1371
1372 int get_sha1_commit(const char *name, unsigned char *sha1)
1373 {
1374         struct object_context unused;
1375         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1376                                      sha1, &unused);
1377 }
1378
1379 int get_sha1_tree(const char *name, unsigned char *sha1)
1380 {
1381         struct object_context unused;
1382         return get_sha1_with_context(name, GET_SHA1_TREE,
1383                                      sha1, &unused);
1384 }
1385
1386 int get_sha1_blob(const char *name, unsigned char *sha1)
1387 {
1388         struct object_context unused;
1389         return get_sha1_with_context(name, GET_SHA1_BLOB,
1390                                      sha1, &unused);
1391 }
1392
1393 /* Must be called only when object_name:filename doesn't exist. */
1394 static void diagnose_invalid_sha1_path(const char *prefix,
1395                                        const char *filename,
1396                                        const unsigned char *tree_sha1,
1397                                        const char *object_name,
1398                                        int object_name_len)
1399 {
1400         unsigned char sha1[20];
1401         unsigned mode;
1402
1403         if (!prefix)
1404                 prefix = "";
1405
1406         if (file_exists(filename))
1407                 die("Path '%s' exists on disk, but not in '%.*s'.",
1408                     filename, object_name_len, object_name);
1409         if (errno == ENOENT || errno == ENOTDIR) {
1410                 char *fullname = xstrfmt("%s%s", prefix, filename);
1411
1412                 if (!get_tree_entry(tree_sha1, fullname,
1413                                     sha1, &mode)) {
1414                         die("Path '%s' exists, but not '%s'.\n"
1415                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1416                             fullname,
1417                             filename,
1418                             object_name_len, object_name,
1419                             fullname,
1420                             object_name_len, object_name,
1421                             filename);
1422                 }
1423                 die("Path '%s' does not exist in '%.*s'",
1424                     filename, object_name_len, object_name);
1425         }
1426 }
1427
1428 /* Must be called only when :stage:filename doesn't exist. */
1429 static void diagnose_invalid_index_path(int stage,
1430                                         const char *prefix,
1431                                         const char *filename)
1432 {
1433         const struct cache_entry *ce;
1434         int pos;
1435         unsigned namelen = strlen(filename);
1436         struct strbuf fullname = STRBUF_INIT;
1437
1438         if (!prefix)
1439                 prefix = "";
1440
1441         /* Wrong stage number? */
1442         pos = cache_name_pos(filename, namelen);
1443         if (pos < 0)
1444                 pos = -pos - 1;
1445         if (pos < active_nr) {
1446                 ce = active_cache[pos];
1447                 if (ce_namelen(ce) == namelen &&
1448                     !memcmp(ce->name, filename, namelen))
1449                         die("Path '%s' is in the index, but not at stage %d.\n"
1450                             "Did you mean ':%d:%s'?",
1451                             filename, stage,
1452                             ce_stage(ce), filename);
1453         }
1454
1455         /* Confusion between relative and absolute filenames? */
1456         strbuf_addstr(&fullname, prefix);
1457         strbuf_addstr(&fullname, filename);
1458         pos = cache_name_pos(fullname.buf, fullname.len);
1459         if (pos < 0)
1460                 pos = -pos - 1;
1461         if (pos < active_nr) {
1462                 ce = active_cache[pos];
1463                 if (ce_namelen(ce) == fullname.len &&
1464                     !memcmp(ce->name, fullname.buf, fullname.len))
1465                         die("Path '%s' is in the index, but not '%s'.\n"
1466                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1467                             fullname.buf, filename,
1468                             ce_stage(ce), fullname.buf,
1469                             ce_stage(ce), filename);
1470         }
1471
1472         if (file_exists(filename))
1473                 die("Path '%s' exists on disk, but not in the index.", filename);
1474         if (errno == ENOENT || errno == ENOTDIR)
1475                 die("Path '%s' does not exist (neither on disk nor in the index).",
1476                     filename);
1477
1478         strbuf_release(&fullname);
1479 }
1480
1481
1482 static char *resolve_relative_path(const char *rel)
1483 {
1484         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1485                 return NULL;
1486
1487         if (!is_inside_work_tree())
1488                 die("relative path syntax can't be used outside working tree.");
1489
1490         /* die() inside prefix_path() if resolved path is outside worktree */
1491         return prefix_path(startup_info->prefix,
1492                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1493                            rel);
1494 }
1495
1496 static int get_sha1_with_context_1(const char *name,
1497                                    unsigned flags,
1498                                    const char *prefix,
1499                                    unsigned char *sha1,
1500                                    struct object_context *oc)
1501 {
1502         int ret, bracket_depth;
1503         int namelen = strlen(name);
1504         const char *cp;
1505         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1506
1507         if (only_to_die)
1508                 flags |= GET_SHA1_QUIETLY;
1509
1510         memset(oc, 0, sizeof(*oc));
1511         oc->mode = S_IFINVALID;
1512         ret = get_sha1_1(name, namelen, sha1, flags);
1513         if (!ret)
1514                 return ret;
1515         /*
1516          * sha1:path --> object name of path in ent sha1
1517          * :path -> object name of absolute path in index
1518          * :./path -> object name of path relative to cwd in index
1519          * :[0-3]:path -> object name of path in index at stage
1520          * :/foo -> recent commit matching foo
1521          */
1522         if (name[0] == ':') {
1523                 int stage = 0;
1524                 const struct cache_entry *ce;
1525                 char *new_path = NULL;
1526                 int pos;
1527                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1528                         struct commit_list *list = NULL;
1529
1530                         for_each_ref(handle_one_ref, &list);
1531                         commit_list_sort_by_date(&list);
1532                         return get_sha1_oneline(name + 2, sha1, list);
1533                 }
1534                 if (namelen < 3 ||
1535                     name[2] != ':' ||
1536                     name[1] < '0' || '3' < name[1])
1537                         cp = name + 1;
1538                 else {
1539                         stage = name[1] - '0';
1540                         cp = name + 3;
1541                 }
1542                 new_path = resolve_relative_path(cp);
1543                 if (!new_path) {
1544                         namelen = namelen - (cp - name);
1545                 } else {
1546                         cp = new_path;
1547                         namelen = strlen(cp);
1548                 }
1549
1550                 strlcpy(oc->path, cp, sizeof(oc->path));
1551
1552                 if (!active_cache)
1553                         read_cache();
1554                 pos = cache_name_pos(cp, namelen);
1555                 if (pos < 0)
1556                         pos = -pos - 1;
1557                 while (pos < active_nr) {
1558                         ce = active_cache[pos];
1559                         if (ce_namelen(ce) != namelen ||
1560                             memcmp(ce->name, cp, namelen))
1561                                 break;
1562                         if (ce_stage(ce) == stage) {
1563                                 hashcpy(sha1, ce->oid.hash);
1564                                 oc->mode = ce->ce_mode;
1565                                 free(new_path);
1566                                 return 0;
1567                         }
1568                         pos++;
1569                 }
1570                 if (only_to_die && name[1] && name[1] != '/')
1571                         diagnose_invalid_index_path(stage, prefix, cp);
1572                 free(new_path);
1573                 return -1;
1574         }
1575         for (cp = name, bracket_depth = 0; *cp; cp++) {
1576                 if (*cp == '{')
1577                         bracket_depth++;
1578                 else if (bracket_depth && *cp == '}')
1579                         bracket_depth--;
1580                 else if (!bracket_depth && *cp == ':')
1581                         break;
1582         }
1583         if (*cp == ':') {
1584                 unsigned char tree_sha1[20];
1585                 int len = cp - name;
1586                 unsigned sub_flags = flags;
1587
1588                 sub_flags &= ~GET_SHA1_DISAMBIGUATORS;
1589                 sub_flags |= GET_SHA1_TREEISH;
1590
1591                 if (!get_sha1_1(name, len, tree_sha1, sub_flags)) {
1592                         const char *filename = cp+1;
1593                         char *new_filename = NULL;
1594
1595                         new_filename = resolve_relative_path(filename);
1596                         if (new_filename)
1597                                 filename = new_filename;
1598                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1599                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1600                                         filename, sha1, &oc->symlink_path,
1601                                         &oc->mode);
1602                         } else {
1603                                 ret = get_tree_entry(tree_sha1, filename,
1604                                                      sha1, &oc->mode);
1605                                 if (ret && only_to_die) {
1606                                         diagnose_invalid_sha1_path(prefix,
1607                                                                    filename,
1608                                                                    tree_sha1,
1609                                                                    name, len);
1610                                 }
1611                         }
1612                         hashcpy(oc->tree, tree_sha1);
1613                         strlcpy(oc->path, filename, sizeof(oc->path));
1614
1615                         free(new_filename);
1616                         return ret;
1617                 } else {
1618                         if (only_to_die)
1619                                 die("Invalid object name '%.*s'.", len, name);
1620                 }
1621         }
1622         return ret;
1623 }
1624
1625 /*
1626  * Call this function when you know "name" given by the end user must
1627  * name an object but it doesn't; the function _may_ die with a better
1628  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1629  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1630  * you have a chance to diagnose the error further.
1631  */
1632 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1633 {
1634         struct object_context oc;
1635         unsigned char sha1[20];
1636         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1637 }
1638
1639 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1640 {
1641         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1642                 die("BUG: incompatible flags for get_sha1_with_context");
1643         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1644 }