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                 const char *objdir = get_object_directory();
  95                 size_t objdir_len = strlen(objdir);
  96                 fakeent = xmalloc(st_add3(sizeof(*fakeent), objdir_len, 43));
  97                 memcpy(fakeent->base, objdir, objdir_len);
  98                 fakeent->name = fakeent->base + objdir_len + 1;
  99                 fakeent->name[-1] = '/';
 100         }
 101         fakeent->next = alt_odb_list;
 102
 103         xsnprintf(hex, sizeof(hex), "%.2s", ds->hex_pfx);
 104         for (alt = fakeent; alt && !ds->ambiguous; alt = alt->next) {
 105                 struct dirent *de;
 106                 DIR *dir;
 107                 /*
 108                  * every alt_odb struct has 42 extra bytes after the base
 109                  * for exactly this purpose
 110                  */
 111                 xsnprintf(alt->name, 42, "%.2s/", ds->hex_pfx);
 112                 dir = opendir(alt->base);
 113                 if (!dir)
 114                         continue;
 115
 116                 while (!ds->ambiguous && (de = readdir(dir)) != NULL) {
 117                         unsigned char sha1[20];
 118
 119                         if (strlen(de->d_name) != 38)
 120                                 continue;
 121                         if (memcmp(de->d_name, ds->hex_pfx + 2, ds->len - 2))
 122                                 continue;
 123                         memcpy(hex + 2, de->d_name, 38);
 124                         if (!get_sha1_hex(hex, sha1))
 125                                 update_candidates(ds, sha1);
 126                 }
 127                 closedir(dir);
 128         }
 129 }
 130
 131 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
 132 {
 133         do {
 134                 if (*a != *b)
 135                         return 0;
 136                 a++;
 137                 b++;
 138                 len -= 2;
 139         } while (len > 1);
 140         if (len)
 141                 if ((*a ^ *b) & 0xf0)
 142                         return 0;
 143         return 1;
 144 }
 145
 146 static void unique_in_pack(struct packed_git *p,
 147                            struct disambiguate_state *ds)
 148 {
 149         uint32_t num, last, i, first = 0;
 150         const unsigned char *current = NULL;
 151
 152         open_pack_index(p);
 153         num = p->num_objects;
 154         last = num;
 155         while (first < last) {
 156                 uint32_t mid = (first + last) / 2;
 157                 const unsigned char *current;
 158                 int cmp;
 159
 160                 current = nth_packed_object_sha1(p, mid);
 161                 cmp = hashcmp(ds->bin_pfx, current);
 162                 if (!cmp) {
 163                         first = mid;
 164                         break;
 165                 }
 166                 if (cmp > 0) {
 167                         first = mid+1;
 168                         continue;
 169                 }
 170                 last = mid;
 171         }
 172
 173         /*
 174          * At this point, "first" is the location of the lowest object
 175          * with an object name that could match "bin_pfx".  See if we have
 176          * 0, 1 or more objects that actually match(es).
 177          */
 178         for (i = first; i < num && !ds->ambiguous; i++) {
 179                 current = nth_packed_object_sha1(p, i);
 180                 if (!match_sha(ds->len, ds->bin_pfx, current))
 181                         break;
 182                 update_candidates(ds, current);
 183         }
 184 }
 185
 186 static void find_short_packed_object(struct disambiguate_state *ds)
 187 {
 188         struct packed_git *p;
 189
 190         prepare_packed_git();
 191         for (p = packed_git; p && !ds->ambiguous; p = p->next)
 192                 unique_in_pack(p, ds);
 193 }
 194
 195 #define SHORT_NAME_NOT_FOUND (-1)
 196 #define SHORT_NAME_AMBIGUOUS (-2)
 197
 198 static int finish_object_disambiguation(struct disambiguate_state *ds,
 199                                         unsigned char *sha1)
 200 {
 201         if (ds->ambiguous)
 202                 return SHORT_NAME_AMBIGUOUS;
 203
 204         if (!ds->candidate_exists)
 205                 return SHORT_NAME_NOT_FOUND;
 206
 207         if (!ds->candidate_checked)
 208                 /*
 209                  * If this is the only candidate, there is no point
 210                  * calling the disambiguation hint callback.
 211                  *
 212                  * On the other hand, if the current candidate
 213                  * replaced an earlier candidate that did _not_ pass
 214                  * the disambiguation hint callback, then we do have
 215                  * more than one objects that match the short name
 216                  * given, so we should make sure this one matches;
 217                  * otherwise, if we discovered this one and the one
 218                  * that we previously discarded in the reverse order,
 219                  * we would end up showing different results in the
 220                  * same repository!
 221                  */
 222                 ds->candidate_ok = (!ds->disambiguate_fn_used ||
 223                                     ds->fn(ds->candidate, ds->cb_data));
 224
 225         if (!ds->candidate_ok)
 226                 return SHORT_NAME_AMBIGUOUS;
 227
 228         hashcpy(sha1, ds->candidate);
 229         return 0;
 230 }
 231
 232 static int disambiguate_commit_only(const unsigned char *sha1, void *cb_data_unused)
 233 {
 234         int kind = sha1_object_info(sha1, NULL);
 235         return kind == OBJ_COMMIT;
 236 }
 237
 238 static int disambiguate_committish_only(const unsigned char *sha1, void *cb_data_unused)
 239 {
 240         struct object *obj;
 241         int kind;
 242
 243         kind = sha1_object_info(sha1, NULL);
 244         if (kind == OBJ_COMMIT)
 245                 return 1;
 246         if (kind != OBJ_TAG)
 247                 return 0;
 248
 249         /* We need to do this the hard way... */
 250         obj = deref_tag(parse_object(sha1), NULL, 0);
 251         if (obj && obj->type == OBJ_COMMIT)
 252                 return 1;
 253         return 0;
 254 }
 255
 256 static int disambiguate_tree_only(const unsigned char *sha1, void *cb_data_unused)
 257 {
 258         int kind = sha1_object_info(sha1, NULL);
 259         return kind == OBJ_TREE;
 260 }
 261
 262 static int disambiguate_treeish_only(const unsigned char *sha1, void *cb_data_unused)
 263 {
 264         struct object *obj;
 265         int kind;
 266
 267         kind = sha1_object_info(sha1, NULL);
 268         if (kind == OBJ_TREE || kind == OBJ_COMMIT)
 269                 return 1;
 270         if (kind != OBJ_TAG)
 271                 return 0;
 272
 273         /* We need to do this the hard way... */
 274         obj = deref_tag(parse_object(sha1), NULL, 0);
 275         if (obj && (obj->type == OBJ_TREE || obj->type == OBJ_COMMIT))
 276                 return 1;
 277         return 0;
 278 }
 279
 280 static int disambiguate_blob_only(const unsigned char *sha1, void *cb_data_unused)
 281 {
 282         int kind = sha1_object_info(sha1, NULL);
 283         return kind == OBJ_BLOB;
 284 }
 285
 286 static disambiguate_hint_fn default_disambiguate_hint;
 287
 288 int set_disambiguate_hint_config(const char *var, const char *value)
 289 {
 290         static const struct {
 291                 const char *name;
 292                 disambiguate_hint_fn fn;
 293         } hints[] = {
 294                 { "none", NULL },
 295                 { "commit", disambiguate_commit_only },
 296                 { "committish", disambiguate_committish_only },
 297                 { "tree", disambiguate_tree_only },
 298                 { "treeish", disambiguate_treeish_only },
 299                 { "blob", disambiguate_blob_only }
 300         };
 301         int i;
 302
 303         if (!value)
 304                 return config_error_nonbool(var);
 305
 306         for (i = 0; i < ARRAY_SIZE(hints); i++) {
 307                 if (!strcasecmp(value, hints[i].name)) {
 308                         default_disambiguate_hint = hints[i].fn;
 309                         return 0;
 310                 }
 311         }
 312
 313         return error("unknown hint type for '%s': %s", var, value);
 314 }
 315
 316 static int init_object_disambiguation(const char *name, int len,
 317                                       struct disambiguate_state *ds)
 318 {
 319         int i;
 320
 321         if (len < MINIMUM_ABBREV || len > GIT_SHA1_HEXSZ)
 322                 return -1;
 323
 324         memset(ds, 0, sizeof(*ds));
 325
 326         for (i = 0; i < len ;i++) {
 327                 unsigned char c = name[i];
 328                 unsigned char val;
 329                 if (c >= '0' && c <= '9')
 330                         val = c - '0';
 331                 else if (c >= 'a' && c <= 'f')
 332                         val = c - 'a' + 10;
 333                 else if (c >= 'A' && c <='F') {
 334                         val = c - 'A' + 10;
 335                         c -= 'A' - 'a';
 336                 }
 337                 else
 338                         return -1;
 339                 ds->hex_pfx[i] = c;
 340                 if (!(i & 1))
 341                         val <<= 4;
 342                 ds->bin_pfx[i >> 1] |= val;
 343         }
 344
 345         ds->len = len;
 346         ds->hex_pfx[len] = '\0';
 347         prepare_alt_odb();
 348         return 0;
 349 }
 350
 351 static int show_ambiguous_object(const unsigned char *sha1, void *data)
 352 {
 353         const struct disambiguate_state *ds = data;
 354         struct strbuf desc = STRBUF_INIT;
 355         int type;
 356
 357         if (ds->fn && !ds->fn(sha1, ds->cb_data))
 358                 return 0;
 359
 360         type = sha1_object_info(sha1, NULL);
 361         if (type == OBJ_COMMIT) {
 362                 struct commit *commit = lookup_commit(sha1);
 363                 if (commit) {
 364                         struct pretty_print_context pp = {0};
 365                         pp.date_mode.type = DATE_SHORT;
 366                         format_commit_message(commit, " %ad - %s", &desc, &pp);
 367                 }
 368         } else if (type == OBJ_TAG) {
 369                 struct tag *tag = lookup_tag(sha1);
 370                 if (!parse_tag(tag) && tag->tag)
 371                         strbuf_addf(&desc, " %s", tag->tag);
 372         }
 373
 374         advise("  %s %s%s",
 375                find_unique_abbrev(sha1, DEFAULT_ABBREV),
 376                typename(type) ? typename(type) : "unknown type",
 377                desc.buf);
 378
 379         strbuf_release(&desc);
 380         return 0;
 381 }
 382
 383 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 384                           unsigned flags)
 385 {
 386         int status;
 387         struct disambiguate_state ds;
 388         int quietly = !!(flags & GET_SHA1_QUIETLY);
 389
 390         if (init_object_disambiguation(name, len, &ds) < 0)
 391                 return -1;
 392
 393         if (HAS_MULTI_BITS(flags & GET_SHA1_DISAMBIGUATORS))
 394                 die("BUG: multiple get_short_sha1 disambiguator flags");
 395
 396         if (flags & GET_SHA1_COMMIT)
 397                 ds.fn = disambiguate_commit_only;
 398         else if (flags & GET_SHA1_COMMITTISH)
 399                 ds.fn = disambiguate_committish_only;
 400         else if (flags & GET_SHA1_TREE)
 401                 ds.fn = disambiguate_tree_only;
 402         else if (flags & GET_SHA1_TREEISH)
 403                 ds.fn = disambiguate_treeish_only;
 404         else if (flags & GET_SHA1_BLOB)
 405                 ds.fn = disambiguate_blob_only;
 406         else
 407                 ds.fn = default_disambiguate_hint;
 408
 409         find_short_object_filename(&ds);
 410         find_short_packed_object(&ds);
 411         status = finish_object_disambiguation(&ds, sha1);
 412
 413         if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
 414                 error(_("short SHA1 %s is ambiguous"), ds.hex_pfx);
 415
 416                 /*
 417                  * We may still have ambiguity if we simply saw a series of
 418                  * candidates that did not satisfy our hint function. In
 419                  * that case, we still want to show them, so disable the hint
 420                  * function entirely.
 421                  */
 422                 if (!ds.ambiguous)
 423                         ds.fn = NULL;
 424
 425                 advise(_("The candidates are:"));
 426                 for_each_abbrev(ds.hex_pfx, show_ambiguous_object, &ds);
 427         }
 428
 429         return status;
 430 }
 431
 432 static int collect_ambiguous(const unsigned char *sha1, void *data)
 433 {
 434         sha1_array_append(data, sha1);
 435         return 0;
 436 }
 437
 438 int for_each_abbrev(const char *prefix, each_abbrev_fn fn, void *cb_data)
 439 {
 440         struct sha1_array collect = SHA1_ARRAY_INIT;
 441         struct disambiguate_state ds;
 442         int ret;
 443
 444         if (init_object_disambiguation(prefix, strlen(prefix), &ds) < 0)
 445                 return -1;
 446
 447         ds.always_call_fn = 1;
 448         ds.fn = collect_ambiguous;
 449         ds.cb_data = &collect;
 450         find_short_object_filename(&ds);
 451         find_short_packed_object(&ds);
 452
 453         ret = sha1_array_for_each_unique(&collect, fn, cb_data);
 454         sha1_array_clear(&collect);
 455         return ret;
 456 }
 457
 458 /*
 459  * Return the slot of the most-significant bit set in "val". There are various
 460  * ways to do this quickly with fls() or __builtin_clzl(), but speed is
 461  * probably not a big deal here.
 462  */
 463 static unsigned msb(unsigned long val)
 464 {
 465         unsigned r = 0;
 466         while (val >>= 1)
 467                 r++;
 468         return r;
 469 }
 470
 471 int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 472 {
 473         int status, exists;
 474
 475         if (len < 0) {
 476                 unsigned long count = approximate_object_count();
 477                 /*
 478                  * Add one because the MSB only tells us the highest bit set,
 479                  * not including the value of all the _other_ bits (so "15"
 480                  * is only one off of 2^4, but the MSB is the 3rd bit.
 481                  */
 482                 len = msb(count) + 1;
 483                 /*
 484                  * We now know we have on the order of 2^len objects, which
 485                  * expects a collision at 2^(len/2). But we also care about hex
 486                  * chars, not bits, and there are 4 bits per hex. So all
 487                  * together we need to divide by 2; but we also want to round
 488                  * odd numbers up, hence adding one before dividing.
 489                  */
 490                 len = (len + 1) / 2;
 491                 /*
 492                  * For very small repos, we stick with our regular fallback.
 493                  */
 494                 if (len < FALLBACK_DEFAULT_ABBREV)
 495                         len = FALLBACK_DEFAULT_ABBREV;
 496         }
 497
 498         sha1_to_hex_r(hex, sha1);
 499         if (len == 40 || !len)
 500                 return 40;
 501         exists = has_sha1_file(sha1);
 502         while (len < 40) {
 503                 unsigned char sha1_ret[20];
 504                 status = get_short_sha1(hex, len, sha1_ret, GET_SHA1_QUIETLY);
 505                 if (exists
 506                     ? !status
 507                     : status == SHORT_NAME_NOT_FOUND) {
 508                         hex[len] = 0;
 509                         return len;
 510                 }
 511                 len++;
 512         }
 513         return len;
 514 }
 515
 516 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 517 {
 518         static char hex[GIT_SHA1_HEXSZ + 1];
 519         find_unique_abbrev_r(hex, sha1, len);
 520         return hex;
 521 }
 522
 523 static int ambiguous_path(const char *path, int len)
 524 {
 525         int slash = 1;
 526         int cnt;
 527
 528         for (cnt = 0; cnt < len; cnt++) {
 529                 switch (*path++) {
 530                 case '\0':
 531                         break;
 532                 case '/':
 533                         if (slash)
 534                                 break;
 535                         slash = 1;
 536                         continue;
 537                 case '.':
 538                         continue;
 539                 default:
 540                         slash = 0;
 541                         continue;
 542                 }
 543                 break;
 544         }
 545         return slash;
 546 }
 547
 548 static inline int at_mark(const char *string, int len,
 549                           const char **suffix, int nr)
 550 {
 551         int i;
 552
 553         for (i = 0; i < nr; i++) {
 554                 int suffix_len = strlen(suffix[i]);
 555                 if (suffix_len <= len
 556                     && !memcmp(string, suffix[i], suffix_len))
 557                         return suffix_len;
 558         }
 559         return 0;
 560 }
 561
 562 static inline int upstream_mark(const char *string, int len)
 563 {
 564         const char *suffix[] = { "@{upstream}", "@{u}" };
 565         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 566 }
 567
 568 static inline int push_mark(const char *string, int len)
 569 {
 570         const char *suffix[] = { "@{push}" };
 571         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 572 }
 573
 574 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 575 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 576
 577 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 578                           unsigned int flags)
 579 {
 580         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 581         static const char *object_name_msg = N_(
 582         "Git normally never creates a ref that ends with 40 hex characters\n"
 583         "because it will be ignored when you just specify 40-hex. These refs\n"
 584         "may be created by mistake. For example,\n"
 585         "\n"
 586         "  git checkout -b $br $(git rev-parse ...)\n"
 587         "\n"
 588         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 589         "examine these refs and maybe delete them. Turn this message off by\n"
 590         "running \"git config advice.objectNameWarning false\"");
 591         unsigned char tmp_sha1[20];
 592         char *real_ref = NULL;
 593         int refs_found = 0;
 594         int at, reflog_len, nth_prior = 0;
 595
 596         if (len == 40 && !get_sha1_hex(str, sha1)) {
 597                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 598                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 599                         if (refs_found > 0) {
 600                                 warning(warn_msg, len, str);
 601                                 if (advice_object_name_warning)
 602                                         fprintf(stderr, "%s\n", _(object_name_msg));
 603                         }
 604                         free(real_ref);
 605                 }
 606                 return 0;
 607         }
 608
 609         /* basic@{time or number or -number} format to query ref-log */
 610         reflog_len = at = 0;
 611         if (len && str[len-1] == '}') {
 612                 for (at = len-4; at >= 0; at--) {
 613                         if (str[at] == '@' && str[at+1] == '{') {
 614                                 if (str[at+2] == '-') {
 615                                         if (at != 0)
 616                                                 /* @{-N} not at start */
 617                                                 return -1;
 618                                         nth_prior = 1;
 619                                         continue;
 620                                 }
 621                                 if (!upstream_mark(str + at, len - at) &&
 622                                     !push_mark(str + at, len - at)) {
 623                                         reflog_len = (len-1) - (at+2);
 624                                         len = at;
 625                                 }
 626                                 break;
 627                         }
 628                 }
 629         }
 630
 631         /* Accept only unambiguous ref paths. */
 632         if (len && ambiguous_path(str, len))
 633                 return -1;
 634
 635         if (nth_prior) {
 636                 struct strbuf buf = STRBUF_INIT;
 637                 int detached;
 638
 639                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 640                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 641                         strbuf_release(&buf);
 642                         if (detached)
 643                                 return 0;
 644                 }
 645         }
 646
 647         if (!len && reflog_len)
 648                 /* allow "@{...}" to mean the current branch reflog */
 649                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 650         else if (reflog_len)
 651                 refs_found = dwim_log(str, len, sha1, &real_ref);
 652         else
 653                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 654
 655         if (!refs_found)
 656                 return -1;
 657
 658         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 659             (refs_found > 1 ||
 660              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 661                 warning(warn_msg, len, str);
 662
 663         if (reflog_len) {
 664                 int nth, i;
 665                 unsigned long at_time;
 666                 unsigned long co_time;
 667                 int co_tz, co_cnt;
 668
 669                 /* Is it asking for N-th entry, or approxidate? */
 670                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 671                         char ch = str[at+2+i];
 672                         if ('0' <= ch && ch <= '9')
 673                                 nth = nth * 10 + ch - '0';
 674                         else
 675                                 nth = -1;
 676                 }
 677                 if (100000000 <= nth) {
 678                         at_time = nth;
 679                         nth = -1;
 680                 } else if (0 <= nth)
 681                         at_time = 0;
 682                 else {
 683                         int errors = 0;
 684                         char *tmp = xstrndup(str + at + 2, reflog_len);
 685                         at_time = approxidate_careful(tmp, &errors);
 686                         free(tmp);
 687                         if (errors) {
 688                                 free(real_ref);
 689                                 return -1;
 690                         }
 691                 }
 692                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 693                                 &co_time, &co_tz, &co_cnt)) {
 694                         if (!len) {
 695                                 if (starts_with(real_ref, "refs/heads/")) {
 696                                         str = real_ref + 11;
 697                                         len = strlen(real_ref + 11);
 698                                 } else {
 699                                         /* detached HEAD */
 700                                         str = "HEAD";
 701                                         len = 4;
 702                                 }
 703                         }
 704                         if (at_time) {
 705                                 if (!(flags & GET_SHA1_QUIETLY)) {
 706                                         warning("Log for '%.*s' only goes "
 707                                                 "back to %s.", len, str,
 708                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 709                                 }
 710                         } else {
 711                                 if (flags & GET_SHA1_QUIETLY) {
 712                                         exit(128);
 713                                 }
 714                                 die("Log for '%.*s' only has %d entries.",
 715                                     len, str, co_cnt);
 716                         }
 717                 }
 718         }
 719
 720         free(real_ref);
 721         return 0;
 722 }
 723
 724 static int get_parent(const char *name, int len,
 725                       unsigned char *result, int idx)
 726 {
 727         unsigned char sha1[20];
 728         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 729         struct commit *commit;
 730         struct commit_list *p;
 731
 732         if (ret)
 733                 return ret;
 734         commit = lookup_commit_reference(sha1);
 735         if (parse_commit(commit))
 736                 return -1;
 737         if (!idx) {
 738                 hashcpy(result, commit->object.oid.hash);
 739                 return 0;
 740         }
 741         p = commit->parents;
 742         while (p) {
 743                 if (!--idx) {
 744                         hashcpy(result, p->item->object.oid.hash);
 745                         return 0;
 746                 }
 747                 p = p->next;
 748         }
 749         return -1;
 750 }
 751
 752 static int get_nth_ancestor(const char *name, int len,
 753                             unsigned char *result, int generation)
 754 {
 755         unsigned char sha1[20];
 756         struct commit *commit;
 757         int ret;
 758
 759         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 760         if (ret)
 761                 return ret;
 762         commit = lookup_commit_reference(sha1);
 763         if (!commit)
 764                 return -1;
 765
 766         while (generation--) {
 767                 if (parse_commit(commit) || !commit->parents)
 768                         return -1;
 769                 commit = commit->parents->item;
 770         }
 771         hashcpy(result, commit->object.oid.hash);
 772         return 0;
 773 }
 774
 775 struct object *peel_to_type(const char *name, int namelen,
 776                             struct object *o, enum object_type expected_type)
 777 {
 778         if (name && !namelen)
 779                 namelen = strlen(name);
 780         while (1) {
 781                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 782                         return NULL;
 783                 if (expected_type == OBJ_ANY || o->type == expected_type)
 784                         return o;
 785                 if (o->type == OBJ_TAG)
 786                         o = ((struct tag*) o)->tagged;
 787                 else if (o->type == OBJ_COMMIT)
 788                         o = &(((struct commit *) o)->tree->object);
 789                 else {
 790                         if (name)
 791                                 error("%.*s: expected %s type, but the object "
 792                                       "dereferences to %s type",
 793                                       namelen, name, typename(expected_type),
 794                                       typename(o->type));
 795                         return NULL;
 796                 }
 797         }
 798 }
 799
 800 static int peel_onion(const char *name, int len, unsigned char *sha1,
 801                       unsigned lookup_flags)
 802 {
 803         unsigned char outer[20];
 804         const char *sp;
 805         unsigned int expected_type = 0;
 806         struct object *o;
 807
 808         /*
 809          * "ref^{type}" dereferences ref repeatedly until you cannot
 810          * dereference anymore, or you get an object of given type,
 811          * whichever comes first.  "ref^{}" means just dereference
 812          * tags until you get a non-tag.  "ref^0" is a shorthand for
 813          * "ref^{commit}".  "commit^{tree}" could be used to find the
 814          * top-level tree of the given commit.
 815          */
 816         if (len < 4 || name[len-1] != '}')
 817                 return -1;
 818
 819         for (sp = name + len - 1; name <= sp; sp--) {
 820                 int ch = *sp;
 821                 if (ch == '{' && name < sp && sp[-1] == '^')
 822                         break;
 823         }
 824         if (sp <= name)
 825                 return -1;
 826
 827         sp++; /* beginning of type name, or closing brace for empty */
 828         if (starts_with(sp, "commit}"))
 829                 expected_type = OBJ_COMMIT;
 830         else if (starts_with(sp, "tag}"))
 831                 expected_type = OBJ_TAG;
 832         else if (starts_with(sp, "tree}"))
 833                 expected_type = OBJ_TREE;
 834         else if (starts_with(sp, "blob}"))
 835                 expected_type = OBJ_BLOB;
 836         else if (starts_with(sp, "object}"))
 837                 expected_type = OBJ_ANY;
 838         else if (sp[0] == '}')
 839                 expected_type = OBJ_NONE;
 840         else if (sp[0] == '/')
 841                 expected_type = OBJ_COMMIT;
 842         else
 843                 return -1;
 844
 845         lookup_flags &= ~GET_SHA1_DISAMBIGUATORS;
 846         if (expected_type == OBJ_COMMIT)
 847                 lookup_flags |= GET_SHA1_COMMITTISH;
 848         else if (expected_type == OBJ_TREE)
 849                 lookup_flags |= GET_SHA1_TREEISH;
 850
 851         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 852                 return -1;
 853
 854         o = parse_object(outer);
 855         if (!o)
 856                 return -1;
 857         if (!expected_type) {
 858                 o = deref_tag(o, name, sp - name - 2);
 859                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 860                         return -1;
 861                 hashcpy(sha1, o->oid.hash);
 862                 return 0;
 863         }
 864
 865         /*
 866          * At this point, the syntax look correct, so
 867          * if we do not get the needed object, we should
 868          * barf.
 869          */
 870         o = peel_to_type(name, len, o, expected_type);
 871         if (!o)
 872                 return -1;
 873
 874         hashcpy(sha1, o->oid.hash);
 875         if (sp[0] == '/') {
 876                 /* "$commit^{/foo}" */
 877                 char *prefix;
 878                 int ret;
 879                 struct commit_list *list = NULL;
 880
 881                 /*
 882                  * $commit^{/}. Some regex implementation may reject.
 883                  * We don't need regex anyway. '' pattern always matches.
 884                  */
 885                 if (sp[1] == '}')
 886                         return 0;
 887
 888                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 889                 commit_list_insert((struct commit *)o, &list);
 890                 ret = get_sha1_oneline(prefix, sha1, list);
 891                 free(prefix);
 892                 return ret;
 893         }
 894         return 0;
 895 }
 896
 897 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 898 {
 899         const char *cp;
 900         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 901
 902         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 903                 char ch = *cp;
 904                 if (!isxdigit(ch)) {
 905                         /* We must be looking at g in "SOMETHING-g"
 906                          * for it to be describe output.
 907                          */
 908                         if (ch == 'g' && cp[-1] == '-') {
 909                                 cp++;
 910                                 len -= cp - name;
 911                                 return get_short_sha1(cp, len, sha1, flags);
 912                         }
 913                 }
 914         }
 915         return -1;
 916 }
 917
 918 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 919 {
 920         int ret, has_suffix;
 921         const char *cp;
 922
 923         /*
 924          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 925          */
 926         has_suffix = 0;
 927         for (cp = name + len - 1; name <= cp; cp--) {
 928                 int ch = *cp;
 929                 if ('0' <= ch && ch <= '9')
 930                         continue;
 931                 if (ch == '~' || ch == '^')
 932                         has_suffix = ch;
 933                 break;
 934         }
 935
 936         if (has_suffix) {
 937                 int num = 0;
 938                 int len1 = cp - name;
 939                 cp++;
 940                 while (cp < name + len)
 941                         num = num * 10 + *cp++ - '0';
 942                 if (!num && len1 == len - 1)
 943                         num = 1;
 944                 if (has_suffix == '^')
 945                         return get_parent(name, len1, sha1, num);
 946                 /* else if (has_suffix == '~') -- goes without saying */
 947                 return get_nth_ancestor(name, len1, sha1, num);
 948         }
 949
 950         ret = peel_onion(name, len, sha1, lookup_flags);
 951         if (!ret)
 952                 return 0;
 953
 954         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 955         if (!ret)
 956                 return 0;
 957
 958         /* It could be describe output that is "SOMETHING-gXXXX" */
 959         ret = get_describe_name(name, len, sha1);
 960         if (!ret)
 961                 return 0;
 962
 963         return get_short_sha1(name, len, sha1, lookup_flags);
 964 }
 965
 966 /*
 967  * This interprets names like ':/Initial revision of "git"' by searching
 968  * through history and returning the first commit whose message starts
 969  * the given regular expression.
 970  *
 971  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
 972  *
 973  * For a literal '!' character at the beginning of a pattern, you have to repeat
 974  * that, like: ':/!!foo'
 975  *
 976  * For future extension, all other sequences beginning with ':/!' are reserved.
 977  */
 978
 979 /* Remember to update object flag allocation in object.h */
 980 #define ONELINE_SEEN (1u<<20)
 981
 982 static int handle_one_ref(const char *path, const struct object_id *oid,
 983                           int flag, void *cb_data)
 984 {
 985         struct commit_list **list = cb_data;
 986         struct object *object = parse_object(oid->hash);
 987         if (!object)
 988                 return 0;
 989         if (object->type == OBJ_TAG) {
 990                 object = deref_tag(object, path, strlen(path));
 991                 if (!object)
 992                         return 0;
 993         }
 994         if (object->type != OBJ_COMMIT)
 995                 return 0;
 996         commit_list_insert((struct commit *)object, list);
 997         return 0;
 998 }
 999
1000 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
1001                             struct commit_list *list)
1002 {
1003         struct commit_list *backup = NULL, *l;
1004         int found = 0;
1005         int negative = 0;
1006         regex_t regex;
1007
1008         if (prefix[0] == '!') {
1009                 prefix++;
1010
1011                 if (prefix[0] == '-') {
1012                         prefix++;
1013                         negative = 1;
1014                 } else if (prefix[0] != '!') {
1015                         return -1;
1016                 }
1017         }
1018
1019         if (regcomp(&regex, prefix, REG_EXTENDED))
1020                 return -1;
1021
1022         for (l = list; l; l = l->next) {
1023                 l->item->object.flags |= ONELINE_SEEN;
1024                 commit_list_insert(l->item, &backup);
1025         }
1026         while (list) {
1027                 const char *p, *buf;
1028                 struct commit *commit;
1029                 int matches;
1030
1031                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
1032                 if (!parse_object(commit->object.oid.hash))
1033                         continue;
1034                 buf = get_commit_buffer(commit, NULL);
1035                 p = strstr(buf, "\n\n");
1036                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
1037                 unuse_commit_buffer(commit, buf);
1038
1039                 if (matches) {
1040                         hashcpy(sha1, commit->object.oid.hash);
1041                         found = 1;
1042                         break;
1043                 }
1044         }
1045         regfree(&regex);
1046         free_commit_list(list);
1047         for (l = backup; l; l = l->next)
1048                 clear_commit_marks(l->item, ONELINE_SEEN);
1049         free_commit_list(backup);
1050         return found ? 0 : -1;
1051 }
1052
1053 struct grab_nth_branch_switch_cbdata {
1054         int remaining;
1055         struct strbuf buf;
1056 };
1057
1058 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
1059                                   const char *email, unsigned long timestamp, int tz,
1060                                   const char *message, void *cb_data)
1061 {
1062         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1063         const char *match = NULL, *target = NULL;
1064         size_t len;
1065
1066         if (skip_prefix(message, "checkout: moving from ", &match))
1067                 target = strstr(match, " to ");
1068
1069         if (!match || !target)
1070                 return 0;
1071         if (--(cb->remaining) == 0) {
1072                 len = target - match;
1073                 strbuf_reset(&cb->buf);
1074                 strbuf_add(&cb->buf, match, len);
1075                 return 1; /* we are done */
1076         }
1077         return 0;
1078 }
1079
1080 /*
1081  * Parse @{-N} syntax, return the number of characters parsed
1082  * if successful; otherwise signal an error with negative value.
1083  */
1084 static int interpret_nth_prior_checkout(const char *name, int namelen,
1085                                         struct strbuf *buf)
1086 {
1087         long nth;
1088         int retval;
1089         struct grab_nth_branch_switch_cbdata cb;
1090         const char *brace;
1091         char *num_end;
1092
1093         if (namelen < 4)
1094                 return -1;
1095         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1096                 return -1;
1097         brace = memchr(name, '}', namelen);
1098         if (!brace)
1099                 return -1;
1100         nth = strtol(name + 3, &num_end, 10);
1101         if (num_end != brace)
1102                 return -1;
1103         if (nth <= 0)
1104                 return -1;
1105         cb.remaining = nth;
1106         strbuf_init(&cb.buf, 20);
1107
1108         retval = 0;
1109         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1110                 strbuf_reset(buf);
1111                 strbuf_addbuf(buf, &cb.buf);
1112                 retval = brace - name + 1;
1113         }
1114
1115         strbuf_release(&cb.buf);
1116         return retval;
1117 }
1118
1119 int get_oid_mb(const char *name, struct object_id *oid)
1120 {
1121         struct commit *one, *two;
1122         struct commit_list *mbs;
1123         struct object_id oid_tmp;
1124         const char *dots;
1125         int st;
1126
1127         dots = strstr(name, "...");
1128         if (!dots)
1129                 return get_oid(name, oid);
1130         if (dots == name)
1131                 st = get_oid("HEAD", &oid_tmp);
1132         else {
1133                 struct strbuf sb;
1134                 strbuf_init(&sb, dots - name);
1135                 strbuf_add(&sb, name, dots - name);
1136                 st = get_sha1_committish(sb.buf, oid_tmp.hash);
1137                 strbuf_release(&sb);
1138         }
1139         if (st)
1140                 return st;
1141         one = lookup_commit_reference_gently(oid_tmp.hash, 0);
1142         if (!one)
1143                 return -1;
1144
1145         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", oid_tmp.hash))
1146                 return -1;
1147         two = lookup_commit_reference_gently(oid_tmp.hash, 0);
1148         if (!two)
1149                 return -1;
1150         mbs = get_merge_bases(one, two);
1151         if (!mbs || mbs->next)
1152                 st = -1;
1153         else {
1154                 st = 0;
1155                 oidcpy(oid, &mbs->item->object.oid);
1156         }
1157         free_commit_list(mbs);
1158         return st;
1159 }
1160
1161 /* parse @something syntax, when 'something' is not {.*} */
1162 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1163 {
1164         const char *next;
1165
1166         if (len || name[1] == '{')
1167                 return -1;
1168
1169         /* make sure it's a single @, or @@{.*}, not @foo */
1170         next = memchr(name + len + 1, '@', namelen - len - 1);
1171         if (next && next[1] != '{')
1172                 return -1;
1173         if (!next)
1174                 next = name + namelen;
1175         if (next != name + 1)
1176                 return -1;
1177
1178         strbuf_reset(buf);
1179         strbuf_add(buf, "HEAD", 4);
1180         return 1;
1181 }
1182
1183 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1184 {
1185         /* we have extra data, which might need further processing */
1186         struct strbuf tmp = STRBUF_INIT;
1187         int used = buf->len;
1188         int ret;
1189
1190         strbuf_add(buf, name + len, namelen - len);
1191         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1192         /* that data was not interpreted, remove our cruft */
1193         if (ret < 0) {
1194                 strbuf_setlen(buf, used);
1195                 return len;
1196         }
1197         strbuf_reset(buf);
1198         strbuf_addbuf(buf, &tmp);
1199         strbuf_release(&tmp);
1200         /* tweak for size of {-N} versus expanded ref name */
1201         return ret - used + len;
1202 }
1203
1204 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1205 {
1206         char *s = shorten_unambiguous_ref(ref, 0);
1207         strbuf_reset(buf);
1208         strbuf_addstr(buf, s);
1209         free(s);
1210 }
1211
1212 static int interpret_branch_mark(const char *name, int namelen,
1213                                  int at, struct strbuf *buf,
1214                                  int (*get_mark)(const char *, int),
1215                                  const char *(*get_data)(struct branch *,
1216                                                          struct strbuf *))
1217 {
1218         int len;
1219         struct branch *branch;
1220         struct strbuf err = STRBUF_INIT;
1221         const char *value;
1222
1223         len = get_mark(name + at, namelen - at);
1224         if (!len)
1225                 return -1;
1226
1227         if (memchr(name, ':', at))
1228                 return -1;
1229
1230         if (at) {
1231                 char *name_str = xmemdupz(name, at);
1232                 branch = branch_get(name_str);
1233                 free(name_str);
1234         } else
1235                 branch = branch_get(NULL);
1236
1237         value = get_data(branch, &err);
1238         if (!value)
1239                 die("%s", err.buf);
1240
1241         set_shortened_ref(buf, value);
1242         return len + at;
1243 }
1244
1245 /*
1246  * This reads short-hand syntax that not only evaluates to a commit
1247  * object name, but also can act as if the end user spelled the name
1248  * of the branch from the command line.
1249  *
1250  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1251  *   places the name of the branch in the given buf and returns the
1252  *   number of characters parsed if successful.
1253  *
1254  * - "<branch>@{upstream}" finds the name of the other ref that
1255  *   <branch> is configured to merge with (missing <branch> defaults
1256  *   to the current branch), and places the name of the branch in the
1257  *   given buf and returns the number of characters parsed if
1258  *   successful.
1259  *
1260  * If the input is not of the accepted format, it returns a negative
1261  * number to signal an error.
1262  *
1263  * If the input was ok but there are not N branch switches in the
1264  * reflog, it returns 0.
1265  */
1266 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1267 {
1268         char *at;
1269         const char *start;
1270         int len = interpret_nth_prior_checkout(name, namelen, buf);
1271
1272         if (!namelen)
1273                 namelen = strlen(name);
1274
1275         if (!len) {
1276                 return len; /* syntax Ok, not enough switches */
1277         } else if (len > 0) {
1278                 if (len == namelen)
1279                         return len; /* consumed all */
1280                 else
1281                         return reinterpret(name, namelen, len, buf);
1282         }
1283
1284         for (start = name;
1285              (at = memchr(start, '@', namelen - (start - name)));
1286              start = at + 1) {
1287
1288                 len = interpret_empty_at(name, namelen, at - name, buf);
1289                 if (len > 0)
1290                         return reinterpret(name, namelen, len, buf);
1291
1292                 len = interpret_branch_mark(name, namelen, at - name, buf,
1293                                             upstream_mark, branch_get_upstream);
1294                 if (len > 0)
1295                         return len;
1296
1297                 len = interpret_branch_mark(name, namelen, at - name, buf,
1298                                             push_mark, branch_get_push);
1299                 if (len > 0)
1300                         return len;
1301         }
1302
1303         return -1;
1304 }
1305
1306 int strbuf_branchname(struct strbuf *sb, const char *name)
1307 {
1308         int len = strlen(name);
1309         int used = interpret_branch_name(name, len, sb);
1310
1311         if (used == len)
1312                 return 0;
1313         if (used < 0)
1314                 used = 0;
1315         strbuf_add(sb, name + used, len - used);
1316         return len;
1317 }
1318
1319 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1320 {
1321         strbuf_branchname(sb, name);
1322         if (name[0] == '-')
1323                 return -1;
1324         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1325         return check_refname_format(sb->buf, 0);
1326 }
1327
1328 /*
1329  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1330  * notably "xyz^" for "parent of xyz"
1331  */
1332 int get_sha1(const char *name, unsigned char *sha1)
1333 {
1334         struct object_context unused;
1335         return get_sha1_with_context(name, 0, sha1, &unused);
1336 }
1337
1338 /*
1339  * This is like "get_sha1()", but for struct object_id.
1340  */
1341 int get_oid(const char *name, struct object_id *oid)
1342 {
1343         return get_sha1(name, oid->hash);
1344 }
1345
1346
1347 /*
1348  * Many callers know that the user meant to name a commit-ish by
1349  * syntactical positions where the object name appears.  Calling this
1350  * function allows the machinery to disambiguate shorter-than-unique
1351  * abbreviated object names between commit-ish and others.
1352  *
1353  * Note that this does NOT error out when the named object is not a
1354  * commit-ish. It is merely to give a hint to the disambiguation
1355  * machinery.
1356  */
1357 int get_sha1_committish(const char *name, unsigned char *sha1)
1358 {
1359         struct object_context unused;
1360         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1361                                      sha1, &unused);
1362 }
1363
1364 int get_sha1_treeish(const char *name, unsigned char *sha1)
1365 {
1366         struct object_context unused;
1367         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1368                                      sha1, &unused);
1369 }
1370
1371 int get_sha1_commit(const char *name, unsigned char *sha1)
1372 {
1373         struct object_context unused;
1374         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1375                                      sha1, &unused);
1376 }
1377
1378 int get_sha1_tree(const char *name, unsigned char *sha1)
1379 {
1380         struct object_context unused;
1381         return get_sha1_with_context(name, GET_SHA1_TREE,
1382                                      sha1, &unused);
1383 }
1384
1385 int get_sha1_blob(const char *name, unsigned char *sha1)
1386 {
1387         struct object_context unused;
1388         return get_sha1_with_context(name, GET_SHA1_BLOB,
1389                                      sha1, &unused);
1390 }
1391
1392 /* Must be called only when object_name:filename doesn't exist. */
1393 static void diagnose_invalid_sha1_path(const char *prefix,
1394                                        const char *filename,
1395                                        const unsigned char *tree_sha1,
1396                                        const char *object_name,
1397                                        int object_name_len)
1398 {
1399         unsigned char sha1[20];
1400         unsigned mode;
1401
1402         if (!prefix)
1403                 prefix = "";
1404
1405         if (file_exists(filename))
1406                 die("Path '%s' exists on disk, but not in '%.*s'.",
1407                     filename, object_name_len, object_name);
1408         if (errno == ENOENT || errno == ENOTDIR) {
1409                 char *fullname = xstrfmt("%s%s", prefix, filename);
1410
1411                 if (!get_tree_entry(tree_sha1, fullname,
1412                                     sha1, &mode)) {
1413                         die("Path '%s' exists, but not '%s'.\n"
1414                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1415                             fullname,
1416                             filename,
1417                             object_name_len, object_name,
1418                             fullname,
1419                             object_name_len, object_name,
1420                             filename);
1421                 }
1422                 die("Path '%s' does not exist in '%.*s'",
1423                     filename, object_name_len, object_name);
1424         }
1425 }
1426
1427 /* Must be called only when :stage:filename doesn't exist. */
1428 static void diagnose_invalid_index_path(int stage,
1429                                         const char *prefix,
1430                                         const char *filename)
1431 {
1432         const struct cache_entry *ce;
1433         int pos;
1434         unsigned namelen = strlen(filename);
1435         struct strbuf fullname = STRBUF_INIT;
1436
1437         if (!prefix)
1438                 prefix = "";
1439
1440         /* Wrong stage number? */
1441         pos = cache_name_pos(filename, namelen);
1442         if (pos < 0)
1443                 pos = -pos - 1;
1444         if (pos < active_nr) {
1445                 ce = active_cache[pos];
1446                 if (ce_namelen(ce) == namelen &&
1447                     !memcmp(ce->name, filename, namelen))
1448                         die("Path '%s' is in the index, but not at stage %d.\n"
1449                             "Did you mean ':%d:%s'?",
1450                             filename, stage,
1451                             ce_stage(ce), filename);
1452         }
1453
1454         /* Confusion between relative and absolute filenames? */
1455         strbuf_addstr(&fullname, prefix);
1456         strbuf_addstr(&fullname, filename);
1457         pos = cache_name_pos(fullname.buf, fullname.len);
1458         if (pos < 0)
1459                 pos = -pos - 1;
1460         if (pos < active_nr) {
1461                 ce = active_cache[pos];
1462                 if (ce_namelen(ce) == fullname.len &&
1463                     !memcmp(ce->name, fullname.buf, fullname.len))
1464                         die("Path '%s' is in the index, but not '%s'.\n"
1465                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1466                             fullname.buf, filename,
1467                             ce_stage(ce), fullname.buf,
1468                             ce_stage(ce), filename);
1469         }
1470
1471         if (file_exists(filename))
1472                 die("Path '%s' exists on disk, but not in the index.", filename);
1473         if (errno == ENOENT || errno == ENOTDIR)
1474                 die("Path '%s' does not exist (neither on disk nor in the index).",
1475                     filename);
1476
1477         strbuf_release(&fullname);
1478 }
1479
1480
1481 static char *resolve_relative_path(const char *rel)
1482 {
1483         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1484                 return NULL;
1485
1486         if (!is_inside_work_tree())
1487                 die("relative path syntax can't be used outside working tree.");
1488
1489         /* die() inside prefix_path() if resolved path is outside worktree */
1490         return prefix_path(startup_info->prefix,
1491                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1492                            rel);
1493 }
1494
1495 static int get_sha1_with_context_1(const char *name,
1496                                    unsigned flags,
1497                                    const char *prefix,
1498                                    unsigned char *sha1,
1499                                    struct object_context *oc)
1500 {
1501         int ret, bracket_depth;
1502         int namelen = strlen(name);
1503         const char *cp;
1504         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1505
1506         if (only_to_die)
1507                 flags |= GET_SHA1_QUIETLY;
1508
1509         memset(oc, 0, sizeof(*oc));
1510         oc->mode = S_IFINVALID;
1511         ret = get_sha1_1(name, namelen, sha1, flags);
1512         if (!ret)
1513                 return ret;
1514         /*
1515          * sha1:path --> object name of path in ent sha1
1516          * :path -> object name of absolute path in index
1517          * :./path -> object name of path relative to cwd in index
1518          * :[0-3]:path -> object name of path in index at stage
1519          * :/foo -> recent commit matching foo
1520          */
1521         if (name[0] == ':') {
1522                 int stage = 0;
1523                 const struct cache_entry *ce;
1524                 char *new_path = NULL;
1525                 int pos;
1526                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1527                         struct commit_list *list = NULL;
1528
1529                         for_each_ref(handle_one_ref, &list);
1530                         commit_list_sort_by_date(&list);
1531                         return get_sha1_oneline(name + 2, sha1, list);
1532                 }
1533                 if (namelen < 3 ||
1534                     name[2] != ':' ||
1535                     name[1] < '0' || '3' < name[1])
1536                         cp = name + 1;
1537                 else {
1538                         stage = name[1] - '0';
1539                         cp = name + 3;
1540                 }
1541                 new_path = resolve_relative_path(cp);
1542                 if (!new_path) {
1543                         namelen = namelen - (cp - name);
1544                 } else {
1545                         cp = new_path;
1546                         namelen = strlen(cp);
1547                 }
1548
1549                 strlcpy(oc->path, cp, sizeof(oc->path));
1550
1551                 if (!active_cache)
1552                         read_cache();
1553                 pos = cache_name_pos(cp, namelen);
1554                 if (pos < 0)
1555                         pos = -pos - 1;
1556                 while (pos < active_nr) {
1557                         ce = active_cache[pos];
1558                         if (ce_namelen(ce) != namelen ||
1559                             memcmp(ce->name, cp, namelen))
1560                                 break;
1561                         if (ce_stage(ce) == stage) {
1562                                 hashcpy(sha1, ce->oid.hash);
1563                                 oc->mode = ce->ce_mode;
1564                                 free(new_path);
1565                                 return 0;
1566                         }
1567                         pos++;
1568                 }
1569                 if (only_to_die && name[1] && name[1] != '/')
1570                         diagnose_invalid_index_path(stage, prefix, cp);
1571                 free(new_path);
1572                 return -1;
1573         }
1574         for (cp = name, bracket_depth = 0; *cp; cp++) {
1575                 if (*cp == '{')
1576                         bracket_depth++;
1577                 else if (bracket_depth && *cp == '}')
1578                         bracket_depth--;
1579                 else if (!bracket_depth && *cp == ':')
1580                         break;
1581         }
1582         if (*cp == ':') {
1583                 unsigned char tree_sha1[20];
1584                 int len = cp - name;
1585                 unsigned sub_flags = flags;
1586
1587                 sub_flags &= ~GET_SHA1_DISAMBIGUATORS;
1588                 sub_flags |= GET_SHA1_TREEISH;
1589
1590                 if (!get_sha1_1(name, len, tree_sha1, sub_flags)) {
1591                         const char *filename = cp+1;
1592                         char *new_filename = NULL;
1593
1594                         new_filename = resolve_relative_path(filename);
1595                         if (new_filename)
1596                                 filename = new_filename;
1597                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1598                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1599                                         filename, sha1, &oc->symlink_path,
1600                                         &oc->mode);
1601                         } else {
1602                                 ret = get_tree_entry(tree_sha1, filename,
1603                                                      sha1, &oc->mode);
1604                                 if (ret && only_to_die) {
1605                                         diagnose_invalid_sha1_path(prefix,
1606                                                                    filename,
1607                                                                    tree_sha1,
1608                                                                    name, len);
1609                                 }
1610                         }
1611                         hashcpy(oc->tree, tree_sha1);
1612                         strlcpy(oc->path, filename, sizeof(oc->path));
1613
1614                         free(new_filename);
1615                         return ret;
1616                 } else {
1617                         if (only_to_die)
1618                                 die("Invalid object name '%.*s'.", len, name);
1619                 }
1620         }
1621         return ret;
1622 }
1623
1624 /*
1625  * Call this function when you know "name" given by the end user must
1626  * name an object but it doesn't; the function _may_ die with a better
1627  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1628  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1629  * you have a chance to diagnose the error further.
1630  */
1631 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1632 {
1633         struct object_context oc;
1634         unsigned char sha1[20];
1635         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1636 }
1637
1638 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1639 {
1640         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1641                 die("BUG: incompatible flags for get_sha1_with_context");
1642         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1643 }