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[3 & ++bufno];
 514         find_unique_abbrev_r(hex, sha1, len);
 515         return hex;
 516 }
 517
 518 static int ambiguous_path(const char *path, int len)
 519 {
 520         int slash = 1;
 521         int cnt;
 522
 523         for (cnt = 0; cnt < len; cnt++) {
 524                 switch (*path++) {
 525                 case '\0':
 526                         break;
 527                 case '/':
 528                         if (slash)
 529                                 break;
 530                         slash = 1;
 531                         continue;
 532                 case '.':
 533                         continue;
 534                 default:
 535                         slash = 0;
 536                         continue;
 537                 }
 538                 break;
 539         }
 540         return slash;
 541 }
 542
 543 static inline int at_mark(const char *string, int len,
 544                           const char **suffix, int nr)
 545 {
 546         int i;
 547
 548         for (i = 0; i < nr; i++) {
 549                 int suffix_len = strlen(suffix[i]);
 550                 if (suffix_len <= len
 551                     && !memcmp(string, suffix[i], suffix_len))
 552                         return suffix_len;
 553         }
 554         return 0;
 555 }
 556
 557 static inline int upstream_mark(const char *string, int len)
 558 {
 559         const char *suffix[] = { "@{upstream}", "@{u}" };
 560         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 561 }
 562
 563 static inline int push_mark(const char *string, int len)
 564 {
 565         const char *suffix[] = { "@{push}" };
 566         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 567 }
 568
 569 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 570 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 571
 572 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 573                           unsigned int flags)
 574 {
 575         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 576         static const char *object_name_msg = N_(
 577         "Git normally never creates a ref that ends with 40 hex characters\n"
 578         "because it will be ignored when you just specify 40-hex. These refs\n"
 579         "may be created by mistake. For example,\n"
 580         "\n"
 581         "  git checkout -b $br $(git rev-parse ...)\n"
 582         "\n"
 583         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 584         "examine these refs and maybe delete them. Turn this message off by\n"
 585         "running \"git config advice.objectNameWarning false\"");
 586         unsigned char tmp_sha1[20];
 587         char *real_ref = NULL;
 588         int refs_found = 0;
 589         int at, reflog_len, nth_prior = 0;
 590
 591         if (len == 40 && !get_sha1_hex(str, sha1)) {
 592                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 593                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 594                         if (refs_found > 0) {
 595                                 warning(warn_msg, len, str);
 596                                 if (advice_object_name_warning)
 597                                         fprintf(stderr, "%s\n", _(object_name_msg));
 598                         }
 599                         free(real_ref);
 600                 }
 601                 return 0;
 602         }
 603
 604         /* basic@{time or number or -number} format to query ref-log */
 605         reflog_len = at = 0;
 606         if (len && str[len-1] == '}') {
 607                 for (at = len-4; at >= 0; at--) {
 608                         if (str[at] == '@' && str[at+1] == '{') {
 609                                 if (str[at+2] == '-') {
 610                                         if (at != 0)
 611                                                 /* @{-N} not at start */
 612                                                 return -1;
 613                                         nth_prior = 1;
 614                                         continue;
 615                                 }
 616                                 if (!upstream_mark(str + at, len - at) &&
 617                                     !push_mark(str + at, len - at)) {
 618                                         reflog_len = (len-1) - (at+2);
 619                                         len = at;
 620                                 }
 621                                 break;
 622                         }
 623                 }
 624         }
 625
 626         /* Accept only unambiguous ref paths. */
 627         if (len && ambiguous_path(str, len))
 628                 return -1;
 629
 630         if (nth_prior) {
 631                 struct strbuf buf = STRBUF_INIT;
 632                 int detached;
 633
 634                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 635                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 636                         strbuf_release(&buf);
 637                         if (detached)
 638                                 return 0;
 639                 }
 640         }
 641
 642         if (!len && reflog_len)
 643                 /* allow "@{...}" to mean the current branch reflog */
 644                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 645         else if (reflog_len)
 646                 refs_found = dwim_log(str, len, sha1, &real_ref);
 647         else
 648                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 649
 650         if (!refs_found)
 651                 return -1;
 652
 653         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 654             (refs_found > 1 ||
 655              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 656                 warning(warn_msg, len, str);
 657
 658         if (reflog_len) {
 659                 int nth, i;
 660                 unsigned long at_time;
 661                 unsigned long co_time;
 662                 int co_tz, co_cnt;
 663
 664                 /* Is it asking for N-th entry, or approxidate? */
 665                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 666                         char ch = str[at+2+i];
 667                         if ('0' <= ch && ch <= '9')
 668                                 nth = nth * 10 + ch - '0';
 669                         else
 670                                 nth = -1;
 671                 }
 672                 if (100000000 <= nth) {
 673                         at_time = nth;
 674                         nth = -1;
 675                 } else if (0 <= nth)
 676                         at_time = 0;
 677                 else {
 678                         int errors = 0;
 679                         char *tmp = xstrndup(str + at + 2, reflog_len);
 680                         at_time = approxidate_careful(tmp, &errors);
 681                         free(tmp);
 682                         if (errors) {
 683                                 free(real_ref);
 684                                 return -1;
 685                         }
 686                 }
 687                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 688                                 &co_time, &co_tz, &co_cnt)) {
 689                         if (!len) {
 690                                 if (starts_with(real_ref, "refs/heads/")) {
 691                                         str = real_ref + 11;
 692                                         len = strlen(real_ref + 11);
 693                                 } else {
 694                                         /* detached HEAD */
 695                                         str = "HEAD";
 696                                         len = 4;
 697                                 }
 698                         }
 699                         if (at_time) {
 700                                 if (!(flags & GET_SHA1_QUIETLY)) {
 701                                         warning("Log for '%.*s' only goes "
 702                                                 "back to %s.", len, str,
 703                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 704                                 }
 705                         } else {
 706                                 if (flags & GET_SHA1_QUIETLY) {
 707                                         exit(128);
 708                                 }
 709                                 die("Log for '%.*s' only has %d entries.",
 710                                     len, str, co_cnt);
 711                         }
 712                 }
 713         }
 714
 715         free(real_ref);
 716         return 0;
 717 }
 718
 719 static int get_parent(const char *name, int len,
 720                       unsigned char *result, int idx)
 721 {
 722         unsigned char sha1[20];
 723         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 724         struct commit *commit;
 725         struct commit_list *p;
 726
 727         if (ret)
 728                 return ret;
 729         commit = lookup_commit_reference(sha1);
 730         if (parse_commit(commit))
 731                 return -1;
 732         if (!idx) {
 733                 hashcpy(result, commit->object.oid.hash);
 734                 return 0;
 735         }
 736         p = commit->parents;
 737         while (p) {
 738                 if (!--idx) {
 739                         hashcpy(result, p->item->object.oid.hash);
 740                         return 0;
 741                 }
 742                 p = p->next;
 743         }
 744         return -1;
 745 }
 746
 747 static int get_nth_ancestor(const char *name, int len,
 748                             unsigned char *result, int generation)
 749 {
 750         unsigned char sha1[20];
 751         struct commit *commit;
 752         int ret;
 753
 754         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 755         if (ret)
 756                 return ret;
 757         commit = lookup_commit_reference(sha1);
 758         if (!commit)
 759                 return -1;
 760
 761         while (generation--) {
 762                 if (parse_commit(commit) || !commit->parents)
 763                         return -1;
 764                 commit = commit->parents->item;
 765         }
 766         hashcpy(result, commit->object.oid.hash);
 767         return 0;
 768 }
 769
 770 struct object *peel_to_type(const char *name, int namelen,
 771                             struct object *o, enum object_type expected_type)
 772 {
 773         if (name && !namelen)
 774                 namelen = strlen(name);
 775         while (1) {
 776                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 777                         return NULL;
 778                 if (expected_type == OBJ_ANY || o->type == expected_type)
 779                         return o;
 780                 if (o->type == OBJ_TAG)
 781                         o = ((struct tag*) o)->tagged;
 782                 else if (o->type == OBJ_COMMIT)
 783                         o = &(((struct commit *) o)->tree->object);
 784                 else {
 785                         if (name)
 786                                 error("%.*s: expected %s type, but the object "
 787                                       "dereferences to %s type",
 788                                       namelen, name, typename(expected_type),
 789                                       typename(o->type));
 790                         return NULL;
 791                 }
 792         }
 793 }
 794
 795 static int peel_onion(const char *name, int len, unsigned char *sha1,
 796                       unsigned lookup_flags)
 797 {
 798         unsigned char outer[20];
 799         const char *sp;
 800         unsigned int expected_type = 0;
 801         struct object *o;
 802
 803         /*
 804          * "ref^{type}" dereferences ref repeatedly until you cannot
 805          * dereference anymore, or you get an object of given type,
 806          * whichever comes first.  "ref^{}" means just dereference
 807          * tags until you get a non-tag.  "ref^0" is a shorthand for
 808          * "ref^{commit}".  "commit^{tree}" could be used to find the
 809          * top-level tree of the given commit.
 810          */
 811         if (len < 4 || name[len-1] != '}')
 812                 return -1;
 813
 814         for (sp = name + len - 1; name <= sp; sp--) {
 815                 int ch = *sp;
 816                 if (ch == '{' && name < sp && sp[-1] == '^')
 817                         break;
 818         }
 819         if (sp <= name)
 820                 return -1;
 821
 822         sp++; /* beginning of type name, or closing brace for empty */
 823         if (starts_with(sp, "commit}"))
 824                 expected_type = OBJ_COMMIT;
 825         else if (starts_with(sp, "tag}"))
 826                 expected_type = OBJ_TAG;
 827         else if (starts_with(sp, "tree}"))
 828                 expected_type = OBJ_TREE;
 829         else if (starts_with(sp, "blob}"))
 830                 expected_type = OBJ_BLOB;
 831         else if (starts_with(sp, "object}"))
 832                 expected_type = OBJ_ANY;
 833         else if (sp[0] == '}')
 834                 expected_type = OBJ_NONE;
 835         else if (sp[0] == '/')
 836                 expected_type = OBJ_COMMIT;
 837         else
 838                 return -1;
 839
 840         lookup_flags &= ~GET_SHA1_DISAMBIGUATORS;
 841         if (expected_type == OBJ_COMMIT)
 842                 lookup_flags |= GET_SHA1_COMMITTISH;
 843         else if (expected_type == OBJ_TREE)
 844                 lookup_flags |= GET_SHA1_TREEISH;
 845
 846         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 847                 return -1;
 848
 849         o = parse_object(outer);
 850         if (!o)
 851                 return -1;
 852         if (!expected_type) {
 853                 o = deref_tag(o, name, sp - name - 2);
 854                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 855                         return -1;
 856                 hashcpy(sha1, o->oid.hash);
 857                 return 0;
 858         }
 859
 860         /*
 861          * At this point, the syntax look correct, so
 862          * if we do not get the needed object, we should
 863          * barf.
 864          */
 865         o = peel_to_type(name, len, o, expected_type);
 866         if (!o)
 867                 return -1;
 868
 869         hashcpy(sha1, o->oid.hash);
 870         if (sp[0] == '/') {
 871                 /* "$commit^{/foo}" */
 872                 char *prefix;
 873                 int ret;
 874                 struct commit_list *list = NULL;
 875
 876                 /*
 877                  * $commit^{/}. Some regex implementation may reject.
 878                  * We don't need regex anyway. '' pattern always matches.
 879                  */
 880                 if (sp[1] == '}')
 881                         return 0;
 882
 883                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 884                 commit_list_insert((struct commit *)o, &list);
 885                 ret = get_sha1_oneline(prefix, sha1, list);
 886                 free(prefix);
 887                 return ret;
 888         }
 889         return 0;
 890 }
 891
 892 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 893 {
 894         const char *cp;
 895         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 896
 897         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 898                 char ch = *cp;
 899                 if (!isxdigit(ch)) {
 900                         /* We must be looking at g in "SOMETHING-g"
 901                          * for it to be describe output.
 902                          */
 903                         if (ch == 'g' && cp[-1] == '-') {
 904                                 cp++;
 905                                 len -= cp - name;
 906                                 return get_short_sha1(cp, len, sha1, flags);
 907                         }
 908                 }
 909         }
 910         return -1;
 911 }
 912
 913 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 914 {
 915         int ret, has_suffix;
 916         const char *cp;
 917
 918         /*
 919          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 920          */
 921         has_suffix = 0;
 922         for (cp = name + len - 1; name <= cp; cp--) {
 923                 int ch = *cp;
 924                 if ('0' <= ch && ch <= '9')
 925                         continue;
 926                 if (ch == '~' || ch == '^')
 927                         has_suffix = ch;
 928                 break;
 929         }
 930
 931         if (has_suffix) {
 932                 int num = 0;
 933                 int len1 = cp - name;
 934                 cp++;
 935                 while (cp < name + len)
 936                         num = num * 10 + *cp++ - '0';
 937                 if (!num && len1 == len - 1)
 938                         num = 1;
 939                 if (has_suffix == '^')
 940                         return get_parent(name, len1, sha1, num);
 941                 /* else if (has_suffix == '~') -- goes without saying */
 942                 return get_nth_ancestor(name, len1, sha1, num);
 943         }
 944
 945         ret = peel_onion(name, len, sha1, lookup_flags);
 946         if (!ret)
 947                 return 0;
 948
 949         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 950         if (!ret)
 951                 return 0;
 952
 953         /* It could be describe output that is "SOMETHING-gXXXX" */
 954         ret = get_describe_name(name, len, sha1);
 955         if (!ret)
 956                 return 0;
 957
 958         return get_short_sha1(name, len, sha1, lookup_flags);
 959 }
 960
 961 /*
 962  * This interprets names like ':/Initial revision of "git"' by searching
 963  * through history and returning the first commit whose message starts
 964  * the given regular expression.
 965  *
 966  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
 967  *
 968  * For a literal '!' character at the beginning of a pattern, you have to repeat
 969  * that, like: ':/!!foo'
 970  *
 971  * For future extension, all other sequences beginning with ':/!' are reserved.
 972  */
 973
 974 /* Remember to update object flag allocation in object.h */
 975 #define ONELINE_SEEN (1u<<20)
 976
 977 static int handle_one_ref(const char *path, const struct object_id *oid,
 978                           int flag, void *cb_data)
 979 {
 980         struct commit_list **list = cb_data;
 981         struct object *object = parse_object(oid->hash);
 982         if (!object)
 983                 return 0;
 984         if (object->type == OBJ_TAG) {
 985                 object = deref_tag(object, path, strlen(path));
 986                 if (!object)
 987                         return 0;
 988         }
 989         if (object->type != OBJ_COMMIT)
 990                 return 0;
 991         commit_list_insert((struct commit *)object, list);
 992         return 0;
 993 }
 994
 995 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 996                             struct commit_list *list)
 997 {
 998         struct commit_list *backup = NULL, *l;
 999         int found = 0;
1000         int negative = 0;
1001         regex_t regex;
1002
1003         if (prefix[0] == '!') {
1004                 prefix++;
1005
1006                 if (prefix[0] == '-') {
1007                         prefix++;
1008                         negative = 1;
1009                 } else if (prefix[0] != '!') {
1010                         return -1;
1011                 }
1012         }
1013
1014         if (regcomp(&regex, prefix, REG_EXTENDED))
1015                 return -1;
1016
1017         for (l = list; l; l = l->next) {
1018                 l->item->object.flags |= ONELINE_SEEN;
1019                 commit_list_insert(l->item, &backup);
1020         }
1021         while (list) {
1022                 const char *p, *buf;
1023                 struct commit *commit;
1024                 int matches;
1025
1026                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
1027                 if (!parse_object(commit->object.oid.hash))
1028                         continue;
1029                 buf = get_commit_buffer(commit, NULL);
1030                 p = strstr(buf, "\n\n");
1031                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
1032                 unuse_commit_buffer(commit, buf);
1033
1034                 if (matches) {
1035                         hashcpy(sha1, commit->object.oid.hash);
1036                         found = 1;
1037                         break;
1038                 }
1039         }
1040         regfree(&regex);
1041         free_commit_list(list);
1042         for (l = backup; l; l = l->next)
1043                 clear_commit_marks(l->item, ONELINE_SEEN);
1044         free_commit_list(backup);
1045         return found ? 0 : -1;
1046 }
1047
1048 struct grab_nth_branch_switch_cbdata {
1049         int remaining;
1050         struct strbuf buf;
1051 };
1052
1053 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
1054                                   const char *email, unsigned long timestamp, int tz,
1055                                   const char *message, void *cb_data)
1056 {
1057         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1058         const char *match = NULL, *target = NULL;
1059         size_t len;
1060
1061         if (skip_prefix(message, "checkout: moving from ", &match))
1062                 target = strstr(match, " to ");
1063
1064         if (!match || !target)
1065                 return 0;
1066         if (--(cb->remaining) == 0) {
1067                 len = target - match;
1068                 strbuf_reset(&cb->buf);
1069                 strbuf_add(&cb->buf, match, len);
1070                 return 1; /* we are done */
1071         }
1072         return 0;
1073 }
1074
1075 /*
1076  * Parse @{-N} syntax, return the number of characters parsed
1077  * if successful; otherwise signal an error with negative value.
1078  */
1079 static int interpret_nth_prior_checkout(const char *name, int namelen,
1080                                         struct strbuf *buf)
1081 {
1082         long nth;
1083         int retval;
1084         struct grab_nth_branch_switch_cbdata cb;
1085         const char *brace;
1086         char *num_end;
1087
1088         if (namelen < 4)
1089                 return -1;
1090         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1091                 return -1;
1092         brace = memchr(name, '}', namelen);
1093         if (!brace)
1094                 return -1;
1095         nth = strtol(name + 3, &num_end, 10);
1096         if (num_end != brace)
1097                 return -1;
1098         if (nth <= 0)
1099                 return -1;
1100         cb.remaining = nth;
1101         strbuf_init(&cb.buf, 20);
1102
1103         retval = 0;
1104         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1105                 strbuf_reset(buf);
1106                 strbuf_addbuf(buf, &cb.buf);
1107                 retval = brace - name + 1;
1108         }
1109
1110         strbuf_release(&cb.buf);
1111         return retval;
1112 }
1113
1114 int get_oid_mb(const char *name, struct object_id *oid)
1115 {
1116         struct commit *one, *two;
1117         struct commit_list *mbs;
1118         struct object_id oid_tmp;
1119         const char *dots;
1120         int st;
1121
1122         dots = strstr(name, "...");
1123         if (!dots)
1124                 return get_oid(name, oid);
1125         if (dots == name)
1126                 st = get_oid("HEAD", &oid_tmp);
1127         else {
1128                 struct strbuf sb;
1129                 strbuf_init(&sb, dots - name);
1130                 strbuf_add(&sb, name, dots - name);
1131                 st = get_sha1_committish(sb.buf, oid_tmp.hash);
1132                 strbuf_release(&sb);
1133         }
1134         if (st)
1135                 return st;
1136         one = lookup_commit_reference_gently(oid_tmp.hash, 0);
1137         if (!one)
1138                 return -1;
1139
1140         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", oid_tmp.hash))
1141                 return -1;
1142         two = lookup_commit_reference_gently(oid_tmp.hash, 0);
1143         if (!two)
1144                 return -1;
1145         mbs = get_merge_bases(one, two);
1146         if (!mbs || mbs->next)
1147                 st = -1;
1148         else {
1149                 st = 0;
1150                 oidcpy(oid, &mbs->item->object.oid);
1151         }
1152         free_commit_list(mbs);
1153         return st;
1154 }
1155
1156 /* parse @something syntax, when 'something' is not {.*} */
1157 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1158 {
1159         const char *next;
1160
1161         if (len || name[1] == '{')
1162                 return -1;
1163
1164         /* make sure it's a single @, or @@{.*}, not @foo */
1165         next = memchr(name + len + 1, '@', namelen - len - 1);
1166         if (next && next[1] != '{')
1167                 return -1;
1168         if (!next)
1169                 next = name + namelen;
1170         if (next != name + 1)
1171                 return -1;
1172
1173         strbuf_reset(buf);
1174         strbuf_add(buf, "HEAD", 4);
1175         return 1;
1176 }
1177
1178 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1179 {
1180         /* we have extra data, which might need further processing */
1181         struct strbuf tmp = STRBUF_INIT;
1182         int used = buf->len;
1183         int ret;
1184
1185         strbuf_add(buf, name + len, namelen - len);
1186         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1187         /* that data was not interpreted, remove our cruft */
1188         if (ret < 0) {
1189                 strbuf_setlen(buf, used);
1190                 return len;
1191         }
1192         strbuf_reset(buf);
1193         strbuf_addbuf(buf, &tmp);
1194         strbuf_release(&tmp);
1195         /* tweak for size of {-N} versus expanded ref name */
1196         return ret - used + len;
1197 }
1198
1199 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1200 {
1201         char *s = shorten_unambiguous_ref(ref, 0);
1202         strbuf_reset(buf);
1203         strbuf_addstr(buf, s);
1204         free(s);
1205 }
1206
1207 static int interpret_branch_mark(const char *name, int namelen,
1208                                  int at, struct strbuf *buf,
1209                                  int (*get_mark)(const char *, int),
1210                                  const char *(*get_data)(struct branch *,
1211                                                          struct strbuf *))
1212 {
1213         int len;
1214         struct branch *branch;
1215         struct strbuf err = STRBUF_INIT;
1216         const char *value;
1217
1218         len = get_mark(name + at, namelen - at);
1219         if (!len)
1220                 return -1;
1221
1222         if (memchr(name, ':', at))
1223                 return -1;
1224
1225         if (at) {
1226                 char *name_str = xmemdupz(name, at);
1227                 branch = branch_get(name_str);
1228                 free(name_str);
1229         } else
1230                 branch = branch_get(NULL);
1231
1232         value = get_data(branch, &err);
1233         if (!value)
1234                 die("%s", err.buf);
1235
1236         set_shortened_ref(buf, value);
1237         return len + at;
1238 }
1239
1240 /*
1241  * This reads short-hand syntax that not only evaluates to a commit
1242  * object name, but also can act as if the end user spelled the name
1243  * of the branch from the command line.
1244  *
1245  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1246  *   places the name of the branch in the given buf and returns the
1247  *   number of characters parsed if successful.
1248  *
1249  * - "<branch>@{upstream}" finds the name of the other ref that
1250  *   <branch> is configured to merge with (missing <branch> defaults
1251  *   to the current branch), and places the name of the branch in the
1252  *   given buf and returns the number of characters parsed if
1253  *   successful.
1254  *
1255  * If the input is not of the accepted format, it returns a negative
1256  * number to signal an error.
1257  *
1258  * If the input was ok but there are not N branch switches in the
1259  * reflog, it returns 0.
1260  */
1261 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1262 {
1263         char *at;
1264         const char *start;
1265         int len = interpret_nth_prior_checkout(name, namelen, buf);
1266
1267         if (!namelen)
1268                 namelen = strlen(name);
1269
1270         if (!len) {
1271                 return len; /* syntax Ok, not enough switches */
1272         } else if (len > 0) {
1273                 if (len == namelen)
1274                         return len; /* consumed all */
1275                 else
1276                         return reinterpret(name, namelen, len, buf);
1277         }
1278
1279         for (start = name;
1280              (at = memchr(start, '@', namelen - (start - name)));
1281              start = at + 1) {
1282
1283                 len = interpret_empty_at(name, namelen, at - name, buf);
1284                 if (len > 0)
1285                         return reinterpret(name, namelen, len, buf);
1286
1287                 len = interpret_branch_mark(name, namelen, at - name, buf,
1288                                             upstream_mark, branch_get_upstream);
1289                 if (len > 0)
1290                         return len;
1291
1292                 len = interpret_branch_mark(name, namelen, at - name, buf,
1293                                             push_mark, branch_get_push);
1294                 if (len > 0)
1295                         return len;
1296         }
1297
1298         return -1;
1299 }
1300
1301 int strbuf_branchname(struct strbuf *sb, const char *name)
1302 {
1303         int len = strlen(name);
1304         int used = interpret_branch_name(name, len, sb);
1305
1306         if (used == len)
1307                 return 0;
1308         if (used < 0)
1309                 used = 0;
1310         strbuf_add(sb, name + used, len - used);
1311         return len;
1312 }
1313
1314 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1315 {
1316         strbuf_branchname(sb, name);
1317         if (name[0] == '-')
1318                 return -1;
1319         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1320         return check_refname_format(sb->buf, 0);
1321 }
1322
1323 /*
1324  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1325  * notably "xyz^" for "parent of xyz"
1326  */
1327 int get_sha1(const char *name, unsigned char *sha1)
1328 {
1329         struct object_context unused;
1330         return get_sha1_with_context(name, 0, sha1, &unused);
1331 }
1332
1333 /*
1334  * This is like "get_sha1()", but for struct object_id.
1335  */
1336 int get_oid(const char *name, struct object_id *oid)
1337 {
1338         return get_sha1(name, oid->hash);
1339 }
1340
1341
1342 /*
1343  * Many callers know that the user meant to name a commit-ish by
1344  * syntactical positions where the object name appears.  Calling this
1345  * function allows the machinery to disambiguate shorter-than-unique
1346  * abbreviated object names between commit-ish and others.
1347  *
1348  * Note that this does NOT error out when the named object is not a
1349  * commit-ish. It is merely to give a hint to the disambiguation
1350  * machinery.
1351  */
1352 int get_sha1_committish(const char *name, unsigned char *sha1)
1353 {
1354         struct object_context unused;
1355         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1356                                      sha1, &unused);
1357 }
1358
1359 int get_sha1_treeish(const char *name, unsigned char *sha1)
1360 {
1361         struct object_context unused;
1362         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1363                                      sha1, &unused);
1364 }
1365
1366 int get_sha1_commit(const char *name, unsigned char *sha1)
1367 {
1368         struct object_context unused;
1369         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1370                                      sha1, &unused);
1371 }
1372
1373 int get_sha1_tree(const char *name, unsigned char *sha1)
1374 {
1375         struct object_context unused;
1376         return get_sha1_with_context(name, GET_SHA1_TREE,
1377                                      sha1, &unused);
1378 }
1379
1380 int get_sha1_blob(const char *name, unsigned char *sha1)
1381 {
1382         struct object_context unused;
1383         return get_sha1_with_context(name, GET_SHA1_BLOB,
1384                                      sha1, &unused);
1385 }
1386
1387 /* Must be called only when object_name:filename doesn't exist. */
1388 static void diagnose_invalid_sha1_path(const char *prefix,
1389                                        const char *filename,
1390                                        const unsigned char *tree_sha1,
1391                                        const char *object_name,
1392                                        int object_name_len)
1393 {
1394         unsigned char sha1[20];
1395         unsigned mode;
1396
1397         if (!prefix)
1398                 prefix = "";
1399
1400         if (file_exists(filename))
1401                 die("Path '%s' exists on disk, but not in '%.*s'.",
1402                     filename, object_name_len, object_name);
1403         if (errno == ENOENT || errno == ENOTDIR) {
1404                 char *fullname = xstrfmt("%s%s", prefix, filename);
1405
1406                 if (!get_tree_entry(tree_sha1, fullname,
1407                                     sha1, &mode)) {
1408                         die("Path '%s' exists, but not '%s'.\n"
1409                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1410                             fullname,
1411                             filename,
1412                             object_name_len, object_name,
1413                             fullname,
1414                             object_name_len, object_name,
1415                             filename);
1416                 }
1417                 die("Path '%s' does not exist in '%.*s'",
1418                     filename, object_name_len, object_name);
1419         }
1420 }
1421
1422 /* Must be called only when :stage:filename doesn't exist. */
1423 static void diagnose_invalid_index_path(int stage,
1424                                         const char *prefix,
1425                                         const char *filename)
1426 {
1427         const struct cache_entry *ce;
1428         int pos;
1429         unsigned namelen = strlen(filename);
1430         struct strbuf fullname = STRBUF_INIT;
1431
1432         if (!prefix)
1433                 prefix = "";
1434
1435         /* Wrong stage number? */
1436         pos = cache_name_pos(filename, namelen);
1437         if (pos < 0)
1438                 pos = -pos - 1;
1439         if (pos < active_nr) {
1440                 ce = active_cache[pos];
1441                 if (ce_namelen(ce) == namelen &&
1442                     !memcmp(ce->name, filename, namelen))
1443                         die("Path '%s' is in the index, but not at stage %d.\n"
1444                             "Did you mean ':%d:%s'?",
1445                             filename, stage,
1446                             ce_stage(ce), filename);
1447         }
1448
1449         /* Confusion between relative and absolute filenames? */
1450         strbuf_addstr(&fullname, prefix);
1451         strbuf_addstr(&fullname, filename);
1452         pos = cache_name_pos(fullname.buf, fullname.len);
1453         if (pos < 0)
1454                 pos = -pos - 1;
1455         if (pos < active_nr) {
1456                 ce = active_cache[pos];
1457                 if (ce_namelen(ce) == fullname.len &&
1458                     !memcmp(ce->name, fullname.buf, fullname.len))
1459                         die("Path '%s' is in the index, but not '%s'.\n"
1460                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1461                             fullname.buf, filename,
1462                             ce_stage(ce), fullname.buf,
1463                             ce_stage(ce), filename);
1464         }
1465
1466         if (file_exists(filename))
1467                 die("Path '%s' exists on disk, but not in the index.", filename);
1468         if (errno == ENOENT || errno == ENOTDIR)
1469                 die("Path '%s' does not exist (neither on disk nor in the index).",
1470                     filename);
1471
1472         strbuf_release(&fullname);
1473 }
1474
1475
1476 static char *resolve_relative_path(const char *rel)
1477 {
1478         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1479                 return NULL;
1480
1481         if (!is_inside_work_tree())
1482                 die("relative path syntax can't be used outside working tree.");
1483
1484         /* die() inside prefix_path() if resolved path is outside worktree */
1485         return prefix_path(startup_info->prefix,
1486                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1487                            rel);
1488 }
1489
1490 static int get_sha1_with_context_1(const char *name,
1491                                    unsigned flags,
1492                                    const char *prefix,
1493                                    unsigned char *sha1,
1494                                    struct object_context *oc)
1495 {
1496         int ret, bracket_depth;
1497         int namelen = strlen(name);
1498         const char *cp;
1499         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1500
1501         if (only_to_die)
1502                 flags |= GET_SHA1_QUIETLY;
1503
1504         memset(oc, 0, sizeof(*oc));
1505         oc->mode = S_IFINVALID;
1506         ret = get_sha1_1(name, namelen, sha1, flags);
1507         if (!ret)
1508                 return ret;
1509         /*
1510          * sha1:path --> object name of path in ent sha1
1511          * :path -> object name of absolute path in index
1512          * :./path -> object name of path relative to cwd in index
1513          * :[0-3]:path -> object name of path in index at stage
1514          * :/foo -> recent commit matching foo
1515          */
1516         if (name[0] == ':') {
1517                 int stage = 0;
1518                 const struct cache_entry *ce;
1519                 char *new_path = NULL;
1520                 int pos;
1521                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1522                         struct commit_list *list = NULL;
1523
1524                         for_each_ref(handle_one_ref, &list);
1525                         commit_list_sort_by_date(&list);
1526                         return get_sha1_oneline(name + 2, sha1, list);
1527                 }
1528                 if (namelen < 3 ||
1529                     name[2] != ':' ||
1530                     name[1] < '0' || '3' < name[1])
1531                         cp = name + 1;
1532                 else {
1533                         stage = name[1] - '0';
1534                         cp = name + 3;
1535                 }
1536                 new_path = resolve_relative_path(cp);
1537                 if (!new_path) {
1538                         namelen = namelen - (cp - name);
1539                 } else {
1540                         cp = new_path;
1541                         namelen = strlen(cp);
1542                 }
1543
1544                 strlcpy(oc->path, cp, sizeof(oc->path));
1545
1546                 if (!active_cache)
1547                         read_cache();
1548                 pos = cache_name_pos(cp, namelen);
1549                 if (pos < 0)
1550                         pos = -pos - 1;
1551                 while (pos < active_nr) {
1552                         ce = active_cache[pos];
1553                         if (ce_namelen(ce) != namelen ||
1554                             memcmp(ce->name, cp, namelen))
1555                                 break;
1556                         if (ce_stage(ce) == stage) {
1557                                 hashcpy(sha1, ce->oid.hash);
1558                                 oc->mode = ce->ce_mode;
1559                                 free(new_path);
1560                                 return 0;
1561                         }
1562                         pos++;
1563                 }
1564                 if (only_to_die && name[1] && name[1] != '/')
1565                         diagnose_invalid_index_path(stage, prefix, cp);
1566                 free(new_path);
1567                 return -1;
1568         }
1569         for (cp = name, bracket_depth = 0; *cp; cp++) {
1570                 if (*cp == '{')
1571                         bracket_depth++;
1572                 else if (bracket_depth && *cp == '}')
1573                         bracket_depth--;
1574                 else if (!bracket_depth && *cp == ':')
1575                         break;
1576         }
1577         if (*cp == ':') {
1578                 unsigned char tree_sha1[20];
1579                 int len = cp - name;
1580                 unsigned sub_flags = flags;
1581
1582                 sub_flags &= ~GET_SHA1_DISAMBIGUATORS;
1583                 sub_flags |= GET_SHA1_TREEISH;
1584
1585                 if (!get_sha1_1(name, len, tree_sha1, sub_flags)) {
1586                         const char *filename = cp+1;
1587                         char *new_filename = NULL;
1588
1589                         new_filename = resolve_relative_path(filename);
1590                         if (new_filename)
1591                                 filename = new_filename;
1592                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1593                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1594                                         filename, sha1, &oc->symlink_path,
1595                                         &oc->mode);
1596                         } else {
1597                                 ret = get_tree_entry(tree_sha1, filename,
1598                                                      sha1, &oc->mode);
1599                                 if (ret && only_to_die) {
1600                                         diagnose_invalid_sha1_path(prefix,
1601                                                                    filename,
1602                                                                    tree_sha1,
1603                                                                    name, len);
1604                                 }
1605                         }
1606                         hashcpy(oc->tree, tree_sha1);
1607                         strlcpy(oc->path, filename, sizeof(oc->path));
1608
1609                         free(new_filename);
1610                         return ret;
1611                 } else {
1612                         if (only_to_die)
1613                                 die("Invalid object name '%.*s'.", len, name);
1614                 }
1615         }
1616         return ret;
1617 }
1618
1619 /*
1620  * Call this function when you know "name" given by the end user must
1621  * name an object but it doesn't; the function _may_ die with a better
1622  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1623  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1624  * you have a chance to diagnose the error further.
1625  */
1626 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1627 {
1628         struct object_context oc;
1629         unsigned char sha1[20];
1630         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1631 }
1632
1633 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1634 {
1635         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1636                 die("BUG: incompatible flags for get_sha1_with_context");
1637         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1638 }