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 int find_unique_abbrev_r(char *hex, const unsigned char *sha1, int len)
 459 {
 460         int status, exists;
 461
 462         sha1_to_hex_r(hex, sha1);
 463         if (len == 40 || !len)
 464                 return 40;
 465         exists = has_sha1_file(sha1);
 466         while (len < 40) {
 467                 unsigned char sha1_ret[20];
 468                 status = get_short_sha1(hex, len, sha1_ret, GET_SHA1_QUIETLY);
 469                 if (exists
 470                     ? !status
 471                     : status == SHORT_NAME_NOT_FOUND) {
 472                         hex[len] = 0;
 473                         return len;
 474                 }
 475                 len++;
 476         }
 477         return len;
 478 }
 479
 480 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 481 {
 482         static char hex[GIT_SHA1_HEXSZ + 1];
 483         find_unique_abbrev_r(hex, sha1, len);
 484         return hex;
 485 }
 486
 487 static int ambiguous_path(const char *path, int len)
 488 {
 489         int slash = 1;
 490         int cnt;
 491
 492         for (cnt = 0; cnt < len; cnt++) {
 493                 switch (*path++) {
 494                 case '\0':
 495                         break;
 496                 case '/':
 497                         if (slash)
 498                                 break;
 499                         slash = 1;
 500                         continue;
 501                 case '.':
 502                         continue;
 503                 default:
 504                         slash = 0;
 505                         continue;
 506                 }
 507                 break;
 508         }
 509         return slash;
 510 }
 511
 512 static inline int at_mark(const char *string, int len,
 513                           const char **suffix, int nr)
 514 {
 515         int i;
 516
 517         for (i = 0; i < nr; i++) {
 518                 int suffix_len = strlen(suffix[i]);
 519                 if (suffix_len <= len
 520                     && !memcmp(string, suffix[i], suffix_len))
 521                         return suffix_len;
 522         }
 523         return 0;
 524 }
 525
 526 static inline int upstream_mark(const char *string, int len)
 527 {
 528         const char *suffix[] = { "@{upstream}", "@{u}" };
 529         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 530 }
 531
 532 static inline int push_mark(const char *string, int len)
 533 {
 534         const char *suffix[] = { "@{push}" };
 535         return at_mark(string, len, suffix, ARRAY_SIZE(suffix));
 536 }
 537
 538 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags);
 539 static int interpret_nth_prior_checkout(const char *name, int namelen, struct strbuf *buf);
 540
 541 static int get_sha1_basic(const char *str, int len, unsigned char *sha1,
 542                           unsigned int flags)
 543 {
 544         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 545         static const char *object_name_msg = N_(
 546         "Git normally never creates a ref that ends with 40 hex characters\n"
 547         "because it will be ignored when you just specify 40-hex. These refs\n"
 548         "may be created by mistake. For example,\n"
 549         "\n"
 550         "  git checkout -b $br $(git rev-parse ...)\n"
 551         "\n"
 552         "where \"$br\" is somehow empty and a 40-hex ref is created. Please\n"
 553         "examine these refs and maybe delete them. Turn this message off by\n"
 554         "running \"git config advice.objectNameWarning false\"");
 555         unsigned char tmp_sha1[20];
 556         char *real_ref = NULL;
 557         int refs_found = 0;
 558         int at, reflog_len, nth_prior = 0;
 559
 560         if (len == 40 && !get_sha1_hex(str, sha1)) {
 561                 if (warn_ambiguous_refs && warn_on_object_refname_ambiguity) {
 562                         refs_found = dwim_ref(str, len, tmp_sha1, &real_ref);
 563                         if (refs_found > 0) {
 564                                 warning(warn_msg, len, str);
 565                                 if (advice_object_name_warning)
 566                                         fprintf(stderr, "%s\n", _(object_name_msg));
 567                         }
 568                         free(real_ref);
 569                 }
 570                 return 0;
 571         }
 572
 573         /* basic@{time or number or -number} format to query ref-log */
 574         reflog_len = at = 0;
 575         if (len && str[len-1] == '}') {
 576                 for (at = len-4; at >= 0; at--) {
 577                         if (str[at] == '@' && str[at+1] == '{') {
 578                                 if (str[at+2] == '-') {
 579                                         if (at != 0)
 580                                                 /* @{-N} not at start */
 581                                                 return -1;
 582                                         nth_prior = 1;
 583                                         continue;
 584                                 }
 585                                 if (!upstream_mark(str + at, len - at) &&
 586                                     !push_mark(str + at, len - at)) {
 587                                         reflog_len = (len-1) - (at+2);
 588                                         len = at;
 589                                 }
 590                                 break;
 591                         }
 592                 }
 593         }
 594
 595         /* Accept only unambiguous ref paths. */
 596         if (len && ambiguous_path(str, len))
 597                 return -1;
 598
 599         if (nth_prior) {
 600                 struct strbuf buf = STRBUF_INIT;
 601                 int detached;
 602
 603                 if (interpret_nth_prior_checkout(str, len, &buf) > 0) {
 604                         detached = (buf.len == 40 && !get_sha1_hex(buf.buf, sha1));
 605                         strbuf_release(&buf);
 606                         if (detached)
 607                                 return 0;
 608                 }
 609         }
 610
 611         if (!len && reflog_len)
 612                 /* allow "@{...}" to mean the current branch reflog */
 613                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 614         else if (reflog_len)
 615                 refs_found = dwim_log(str, len, sha1, &real_ref);
 616         else
 617                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 618
 619         if (!refs_found)
 620                 return -1;
 621
 622         if (warn_ambiguous_refs && !(flags & GET_SHA1_QUIETLY) &&
 623             (refs_found > 1 ||
 624              !get_short_sha1(str, len, tmp_sha1, GET_SHA1_QUIETLY)))
 625                 warning(warn_msg, len, str);
 626
 627         if (reflog_len) {
 628                 int nth, i;
 629                 unsigned long at_time;
 630                 unsigned long co_time;
 631                 int co_tz, co_cnt;
 632
 633                 /* Is it asking for N-th entry, or approxidate? */
 634                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 635                         char ch = str[at+2+i];
 636                         if ('0' <= ch && ch <= '9')
 637                                 nth = nth * 10 + ch - '0';
 638                         else
 639                                 nth = -1;
 640                 }
 641                 if (100000000 <= nth) {
 642                         at_time = nth;
 643                         nth = -1;
 644                 } else if (0 <= nth)
 645                         at_time = 0;
 646                 else {
 647                         int errors = 0;
 648                         char *tmp = xstrndup(str + at + 2, reflog_len);
 649                         at_time = approxidate_careful(tmp, &errors);
 650                         free(tmp);
 651                         if (errors) {
 652                                 free(real_ref);
 653                                 return -1;
 654                         }
 655                 }
 656                 if (read_ref_at(real_ref, flags, at_time, nth, sha1, NULL,
 657                                 &co_time, &co_tz, &co_cnt)) {
 658                         if (!len) {
 659                                 if (starts_with(real_ref, "refs/heads/")) {
 660                                         str = real_ref + 11;
 661                                         len = strlen(real_ref + 11);
 662                                 } else {
 663                                         /* detached HEAD */
 664                                         str = "HEAD";
 665                                         len = 4;
 666                                 }
 667                         }
 668                         if (at_time) {
 669                                 if (!(flags & GET_SHA1_QUIETLY)) {
 670                                         warning("Log for '%.*s' only goes "
 671                                                 "back to %s.", len, str,
 672                                                 show_date(co_time, co_tz, DATE_MODE(RFC2822)));
 673                                 }
 674                         } else {
 675                                 if (flags & GET_SHA1_QUIETLY) {
 676                                         exit(128);
 677                                 }
 678                                 die("Log for '%.*s' only has %d entries.",
 679                                     len, str, co_cnt);
 680                         }
 681                 }
 682         }
 683
 684         free(real_ref);
 685         return 0;
 686 }
 687
 688 static int get_parent(const char *name, int len,
 689                       unsigned char *result, int idx)
 690 {
 691         unsigned char sha1[20];
 692         int ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 693         struct commit *commit;
 694         struct commit_list *p;
 695
 696         if (ret)
 697                 return ret;
 698         commit = lookup_commit_reference(sha1);
 699         if (parse_commit(commit))
 700                 return -1;
 701         if (!idx) {
 702                 hashcpy(result, commit->object.oid.hash);
 703                 return 0;
 704         }
 705         p = commit->parents;
 706         while (p) {
 707                 if (!--idx) {
 708                         hashcpy(result, p->item->object.oid.hash);
 709                         return 0;
 710                 }
 711                 p = p->next;
 712         }
 713         return -1;
 714 }
 715
 716 static int get_nth_ancestor(const char *name, int len,
 717                             unsigned char *result, int generation)
 718 {
 719         unsigned char sha1[20];
 720         struct commit *commit;
 721         int ret;
 722
 723         ret = get_sha1_1(name, len, sha1, GET_SHA1_COMMITTISH);
 724         if (ret)
 725                 return ret;
 726         commit = lookup_commit_reference(sha1);
 727         if (!commit)
 728                 return -1;
 729
 730         while (generation--) {
 731                 if (parse_commit(commit) || !commit->parents)
 732                         return -1;
 733                 commit = commit->parents->item;
 734         }
 735         hashcpy(result, commit->object.oid.hash);
 736         return 0;
 737 }
 738
 739 struct object *peel_to_type(const char *name, int namelen,
 740                             struct object *o, enum object_type expected_type)
 741 {
 742         if (name && !namelen)
 743                 namelen = strlen(name);
 744         while (1) {
 745                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 746                         return NULL;
 747                 if (expected_type == OBJ_ANY || o->type == expected_type)
 748                         return o;
 749                 if (o->type == OBJ_TAG)
 750                         o = ((struct tag*) o)->tagged;
 751                 else if (o->type == OBJ_COMMIT)
 752                         o = &(((struct commit *) o)->tree->object);
 753                 else {
 754                         if (name)
 755                                 error("%.*s: expected %s type, but the object "
 756                                       "dereferences to %s type",
 757                                       namelen, name, typename(expected_type),
 758                                       typename(o->type));
 759                         return NULL;
 760                 }
 761         }
 762 }
 763
 764 static int peel_onion(const char *name, int len, unsigned char *sha1,
 765                       unsigned lookup_flags)
 766 {
 767         unsigned char outer[20];
 768         const char *sp;
 769         unsigned int expected_type = 0;
 770         struct object *o;
 771
 772         /*
 773          * "ref^{type}" dereferences ref repeatedly until you cannot
 774          * dereference anymore, or you get an object of given type,
 775          * whichever comes first.  "ref^{}" means just dereference
 776          * tags until you get a non-tag.  "ref^0" is a shorthand for
 777          * "ref^{commit}".  "commit^{tree}" could be used to find the
 778          * top-level tree of the given commit.
 779          */
 780         if (len < 4 || name[len-1] != '}')
 781                 return -1;
 782
 783         for (sp = name + len - 1; name <= sp; sp--) {
 784                 int ch = *sp;
 785                 if (ch == '{' && name < sp && sp[-1] == '^')
 786                         break;
 787         }
 788         if (sp <= name)
 789                 return -1;
 790
 791         sp++; /* beginning of type name, or closing brace for empty */
 792         if (starts_with(sp, "commit}"))
 793                 expected_type = OBJ_COMMIT;
 794         else if (starts_with(sp, "tag}"))
 795                 expected_type = OBJ_TAG;
 796         else if (starts_with(sp, "tree}"))
 797                 expected_type = OBJ_TREE;
 798         else if (starts_with(sp, "blob}"))
 799                 expected_type = OBJ_BLOB;
 800         else if (starts_with(sp, "object}"))
 801                 expected_type = OBJ_ANY;
 802         else if (sp[0] == '}')
 803                 expected_type = OBJ_NONE;
 804         else if (sp[0] == '/')
 805                 expected_type = OBJ_COMMIT;
 806         else
 807                 return -1;
 808
 809         lookup_flags &= ~GET_SHA1_DISAMBIGUATORS;
 810         if (expected_type == OBJ_COMMIT)
 811                 lookup_flags |= GET_SHA1_COMMITTISH;
 812         else if (expected_type == OBJ_TREE)
 813                 lookup_flags |= GET_SHA1_TREEISH;
 814
 815         if (get_sha1_1(name, sp - name - 2, outer, lookup_flags))
 816                 return -1;
 817
 818         o = parse_object(outer);
 819         if (!o)
 820                 return -1;
 821         if (!expected_type) {
 822                 o = deref_tag(o, name, sp - name - 2);
 823                 if (!o || (!o->parsed && !parse_object(o->oid.hash)))
 824                         return -1;
 825                 hashcpy(sha1, o->oid.hash);
 826                 return 0;
 827         }
 828
 829         /*
 830          * At this point, the syntax look correct, so
 831          * if we do not get the needed object, we should
 832          * barf.
 833          */
 834         o = peel_to_type(name, len, o, expected_type);
 835         if (!o)
 836                 return -1;
 837
 838         hashcpy(sha1, o->oid.hash);
 839         if (sp[0] == '/') {
 840                 /* "$commit^{/foo}" */
 841                 char *prefix;
 842                 int ret;
 843                 struct commit_list *list = NULL;
 844
 845                 /*
 846                  * $commit^{/}. Some regex implementation may reject.
 847                  * We don't need regex anyway. '' pattern always matches.
 848                  */
 849                 if (sp[1] == '}')
 850                         return 0;
 851
 852                 prefix = xstrndup(sp + 1, name + len - 1 - (sp + 1));
 853                 commit_list_insert((struct commit *)o, &list);
 854                 ret = get_sha1_oneline(prefix, sha1, list);
 855                 free(prefix);
 856                 return ret;
 857         }
 858         return 0;
 859 }
 860
 861 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 862 {
 863         const char *cp;
 864         unsigned flags = GET_SHA1_QUIETLY | GET_SHA1_COMMIT;
 865
 866         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 867                 char ch = *cp;
 868                 if (!isxdigit(ch)) {
 869                         /* We must be looking at g in "SOMETHING-g"
 870                          * for it to be describe output.
 871                          */
 872                         if (ch == 'g' && cp[-1] == '-') {
 873                                 cp++;
 874                                 len -= cp - name;
 875                                 return get_short_sha1(cp, len, sha1, flags);
 876                         }
 877                 }
 878         }
 879         return -1;
 880 }
 881
 882 static int get_sha1_1(const char *name, int len, unsigned char *sha1, unsigned lookup_flags)
 883 {
 884         int ret, has_suffix;
 885         const char *cp;
 886
 887         /*
 888          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 889          */
 890         has_suffix = 0;
 891         for (cp = name + len - 1; name <= cp; cp--) {
 892                 int ch = *cp;
 893                 if ('0' <= ch && ch <= '9')
 894                         continue;
 895                 if (ch == '~' || ch == '^')
 896                         has_suffix = ch;
 897                 break;
 898         }
 899
 900         if (has_suffix) {
 901                 int num = 0;
 902                 int len1 = cp - name;
 903                 cp++;
 904                 while (cp < name + len)
 905                         num = num * 10 + *cp++ - '0';
 906                 if (!num && len1 == len - 1)
 907                         num = 1;
 908                 if (has_suffix == '^')
 909                         return get_parent(name, len1, sha1, num);
 910                 /* else if (has_suffix == '~') -- goes without saying */
 911                 return get_nth_ancestor(name, len1, sha1, num);
 912         }
 913
 914         ret = peel_onion(name, len, sha1, lookup_flags);
 915         if (!ret)
 916                 return 0;
 917
 918         ret = get_sha1_basic(name, len, sha1, lookup_flags);
 919         if (!ret)
 920                 return 0;
 921
 922         /* It could be describe output that is "SOMETHING-gXXXX" */
 923         ret = get_describe_name(name, len, sha1);
 924         if (!ret)
 925                 return 0;
 926
 927         return get_short_sha1(name, len, sha1, lookup_flags);
 928 }
 929
 930 /*
 931  * This interprets names like ':/Initial revision of "git"' by searching
 932  * through history and returning the first commit whose message starts
 933  * the given regular expression.
 934  *
 935  * For negative-matching, prefix the pattern-part with '!-', like: ':/!-WIP'.
 936  *
 937  * For a literal '!' character at the beginning of a pattern, you have to repeat
 938  * that, like: ':/!!foo'
 939  *
 940  * For future extension, all other sequences beginning with ':/!' are reserved.
 941  */
 942
 943 /* Remember to update object flag allocation in object.h */
 944 #define ONELINE_SEEN (1u<<20)
 945
 946 static int handle_one_ref(const char *path, const struct object_id *oid,
 947                           int flag, void *cb_data)
 948 {
 949         struct commit_list **list = cb_data;
 950         struct object *object = parse_object(oid->hash);
 951         if (!object)
 952                 return 0;
 953         if (object->type == OBJ_TAG) {
 954                 object = deref_tag(object, path, strlen(path));
 955                 if (!object)
 956                         return 0;
 957         }
 958         if (object->type != OBJ_COMMIT)
 959                 return 0;
 960         commit_list_insert((struct commit *)object, list);
 961         return 0;
 962 }
 963
 964 static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 965                             struct commit_list *list)
 966 {
 967         struct commit_list *backup = NULL, *l;
 968         int found = 0;
 969         int negative = 0;
 970         regex_t regex;
 971
 972         if (prefix[0] == '!') {
 973                 prefix++;
 974
 975                 if (prefix[0] == '-') {
 976                         prefix++;
 977                         negative = 1;
 978                 } else if (prefix[0] != '!') {
 979                         return -1;
 980                 }
 981         }
 982
 983         if (regcomp(&regex, prefix, REG_EXTENDED))
 984                 return -1;
 985
 986         for (l = list; l; l = l->next) {
 987                 l->item->object.flags |= ONELINE_SEEN;
 988                 commit_list_insert(l->item, &backup);
 989         }
 990         while (list) {
 991                 const char *p, *buf;
 992                 struct commit *commit;
 993                 int matches;
 994
 995                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 996                 if (!parse_object(commit->object.oid.hash))
 997                         continue;
 998                 buf = get_commit_buffer(commit, NULL);
 999                 p = strstr(buf, "\n\n");
1000                 matches = negative ^ (p && !regexec(&regex, p + 2, 0, NULL, 0));
1001                 unuse_commit_buffer(commit, buf);
1002
1003                 if (matches) {
1004                         hashcpy(sha1, commit->object.oid.hash);
1005                         found = 1;
1006                         break;
1007                 }
1008         }
1009         regfree(&regex);
1010         free_commit_list(list);
1011         for (l = backup; l; l = l->next)
1012                 clear_commit_marks(l->item, ONELINE_SEEN);
1013         free_commit_list(backup);
1014         return found ? 0 : -1;
1015 }
1016
1017 struct grab_nth_branch_switch_cbdata {
1018         int remaining;
1019         struct strbuf buf;
1020 };
1021
1022 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
1023                                   const char *email, unsigned long timestamp, int tz,
1024                                   const char *message, void *cb_data)
1025 {
1026         struct grab_nth_branch_switch_cbdata *cb = cb_data;
1027         const char *match = NULL, *target = NULL;
1028         size_t len;
1029
1030         if (skip_prefix(message, "checkout: moving from ", &match))
1031                 target = strstr(match, " to ");
1032
1033         if (!match || !target)
1034                 return 0;
1035         if (--(cb->remaining) == 0) {
1036                 len = target - match;
1037                 strbuf_reset(&cb->buf);
1038                 strbuf_add(&cb->buf, match, len);
1039                 return 1; /* we are done */
1040         }
1041         return 0;
1042 }
1043
1044 /*
1045  * Parse @{-N} syntax, return the number of characters parsed
1046  * if successful; otherwise signal an error with negative value.
1047  */
1048 static int interpret_nth_prior_checkout(const char *name, int namelen,
1049                                         struct strbuf *buf)
1050 {
1051         long nth;
1052         int retval;
1053         struct grab_nth_branch_switch_cbdata cb;
1054         const char *brace;
1055         char *num_end;
1056
1057         if (namelen < 4)
1058                 return -1;
1059         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
1060                 return -1;
1061         brace = memchr(name, '}', namelen);
1062         if (!brace)
1063                 return -1;
1064         nth = strtol(name + 3, &num_end, 10);
1065         if (num_end != brace)
1066                 return -1;
1067         if (nth <= 0)
1068                 return -1;
1069         cb.remaining = nth;
1070         strbuf_init(&cb.buf, 20);
1071
1072         retval = 0;
1073         if (0 < for_each_reflog_ent_reverse("HEAD", grab_nth_branch_switch, &cb)) {
1074                 strbuf_reset(buf);
1075                 strbuf_addbuf(buf, &cb.buf);
1076                 retval = brace - name + 1;
1077         }
1078
1079         strbuf_release(&cb.buf);
1080         return retval;
1081 }
1082
1083 int get_oid_mb(const char *name, struct object_id *oid)
1084 {
1085         struct commit *one, *two;
1086         struct commit_list *mbs;
1087         struct object_id oid_tmp;
1088         const char *dots;
1089         int st;
1090
1091         dots = strstr(name, "...");
1092         if (!dots)
1093                 return get_oid(name, oid);
1094         if (dots == name)
1095                 st = get_oid("HEAD", &oid_tmp);
1096         else {
1097                 struct strbuf sb;
1098                 strbuf_init(&sb, dots - name);
1099                 strbuf_add(&sb, name, dots - name);
1100                 st = get_sha1_committish(sb.buf, oid_tmp.hash);
1101                 strbuf_release(&sb);
1102         }
1103         if (st)
1104                 return st;
1105         one = lookup_commit_reference_gently(oid_tmp.hash, 0);
1106         if (!one)
1107                 return -1;
1108
1109         if (get_sha1_committish(dots[3] ? (dots + 3) : "HEAD", oid_tmp.hash))
1110                 return -1;
1111         two = lookup_commit_reference_gently(oid_tmp.hash, 0);
1112         if (!two)
1113                 return -1;
1114         mbs = get_merge_bases(one, two);
1115         if (!mbs || mbs->next)
1116                 st = -1;
1117         else {
1118                 st = 0;
1119                 oidcpy(oid, &mbs->item->object.oid);
1120         }
1121         free_commit_list(mbs);
1122         return st;
1123 }
1124
1125 /* parse @something syntax, when 'something' is not {.*} */
1126 static int interpret_empty_at(const char *name, int namelen, int len, struct strbuf *buf)
1127 {
1128         const char *next;
1129
1130         if (len || name[1] == '{')
1131                 return -1;
1132
1133         /* make sure it's a single @, or @@{.*}, not @foo */
1134         next = memchr(name + len + 1, '@', namelen - len - 1);
1135         if (next && next[1] != '{')
1136                 return -1;
1137         if (!next)
1138                 next = name + namelen;
1139         if (next != name + 1)
1140                 return -1;
1141
1142         strbuf_reset(buf);
1143         strbuf_add(buf, "HEAD", 4);
1144         return 1;
1145 }
1146
1147 static int reinterpret(const char *name, int namelen, int len, struct strbuf *buf)
1148 {
1149         /* we have extra data, which might need further processing */
1150         struct strbuf tmp = STRBUF_INIT;
1151         int used = buf->len;
1152         int ret;
1153
1154         strbuf_add(buf, name + len, namelen - len);
1155         ret = interpret_branch_name(buf->buf, buf->len, &tmp);
1156         /* that data was not interpreted, remove our cruft */
1157         if (ret < 0) {
1158                 strbuf_setlen(buf, used);
1159                 return len;
1160         }
1161         strbuf_reset(buf);
1162         strbuf_addbuf(buf, &tmp);
1163         strbuf_release(&tmp);
1164         /* tweak for size of {-N} versus expanded ref name */
1165         return ret - used + len;
1166 }
1167
1168 static void set_shortened_ref(struct strbuf *buf, const char *ref)
1169 {
1170         char *s = shorten_unambiguous_ref(ref, 0);
1171         strbuf_reset(buf);
1172         strbuf_addstr(buf, s);
1173         free(s);
1174 }
1175
1176 static int interpret_branch_mark(const char *name, int namelen,
1177                                  int at, struct strbuf *buf,
1178                                  int (*get_mark)(const char *, int),
1179                                  const char *(*get_data)(struct branch *,
1180                                                          struct strbuf *))
1181 {
1182         int len;
1183         struct branch *branch;
1184         struct strbuf err = STRBUF_INIT;
1185         const char *value;
1186
1187         len = get_mark(name + at, namelen - at);
1188         if (!len)
1189                 return -1;
1190
1191         if (memchr(name, ':', at))
1192                 return -1;
1193
1194         if (at) {
1195                 char *name_str = xmemdupz(name, at);
1196                 branch = branch_get(name_str);
1197                 free(name_str);
1198         } else
1199                 branch = branch_get(NULL);
1200
1201         value = get_data(branch, &err);
1202         if (!value)
1203                 die("%s", err.buf);
1204
1205         set_shortened_ref(buf, value);
1206         return len + at;
1207 }
1208
1209 /*
1210  * This reads short-hand syntax that not only evaluates to a commit
1211  * object name, but also can act as if the end user spelled the name
1212  * of the branch from the command line.
1213  *
1214  * - "@{-N}" finds the name of the Nth previous branch we were on, and
1215  *   places the name of the branch in the given buf and returns the
1216  *   number of characters parsed if successful.
1217  *
1218  * - "<branch>@{upstream}" finds the name of the other ref that
1219  *   <branch> is configured to merge with (missing <branch> defaults
1220  *   to the current branch), and places the name of the branch in the
1221  *   given buf and returns the number of characters parsed if
1222  *   successful.
1223  *
1224  * If the input is not of the accepted format, it returns a negative
1225  * number to signal an error.
1226  *
1227  * If the input was ok but there are not N branch switches in the
1228  * reflog, it returns 0.
1229  */
1230 int interpret_branch_name(const char *name, int namelen, struct strbuf *buf)
1231 {
1232         char *at;
1233         const char *start;
1234         int len = interpret_nth_prior_checkout(name, namelen, buf);
1235
1236         if (!namelen)
1237                 namelen = strlen(name);
1238
1239         if (!len) {
1240                 return len; /* syntax Ok, not enough switches */
1241         } else if (len > 0) {
1242                 if (len == namelen)
1243                         return len; /* consumed all */
1244                 else
1245                         return reinterpret(name, namelen, len, buf);
1246         }
1247
1248         for (start = name;
1249              (at = memchr(start, '@', namelen - (start - name)));
1250              start = at + 1) {
1251
1252                 len = interpret_empty_at(name, namelen, at - name, buf);
1253                 if (len > 0)
1254                         return reinterpret(name, namelen, len, buf);
1255
1256                 len = interpret_branch_mark(name, namelen, at - name, buf,
1257                                             upstream_mark, branch_get_upstream);
1258                 if (len > 0)
1259                         return len;
1260
1261                 len = interpret_branch_mark(name, namelen, at - name, buf,
1262                                             push_mark, branch_get_push);
1263                 if (len > 0)
1264                         return len;
1265         }
1266
1267         return -1;
1268 }
1269
1270 int strbuf_branchname(struct strbuf *sb, const char *name)
1271 {
1272         int len = strlen(name);
1273         int used = interpret_branch_name(name, len, sb);
1274
1275         if (used == len)
1276                 return 0;
1277         if (used < 0)
1278                 used = 0;
1279         strbuf_add(sb, name + used, len - used);
1280         return len;
1281 }
1282
1283 int strbuf_check_branch_ref(struct strbuf *sb, const char *name)
1284 {
1285         strbuf_branchname(sb, name);
1286         if (name[0] == '-')
1287                 return -1;
1288         strbuf_splice(sb, 0, 0, "refs/heads/", 11);
1289         return check_refname_format(sb->buf, 0);
1290 }
1291
1292 /*
1293  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
1294  * notably "xyz^" for "parent of xyz"
1295  */
1296 int get_sha1(const char *name, unsigned char *sha1)
1297 {
1298         struct object_context unused;
1299         return get_sha1_with_context(name, 0, sha1, &unused);
1300 }
1301
1302 /*
1303  * This is like "get_sha1()", but for struct object_id.
1304  */
1305 int get_oid(const char *name, struct object_id *oid)
1306 {
1307         return get_sha1(name, oid->hash);
1308 }
1309
1310
1311 /*
1312  * Many callers know that the user meant to name a commit-ish by
1313  * syntactical positions where the object name appears.  Calling this
1314  * function allows the machinery to disambiguate shorter-than-unique
1315  * abbreviated object names between commit-ish and others.
1316  *
1317  * Note that this does NOT error out when the named object is not a
1318  * commit-ish. It is merely to give a hint to the disambiguation
1319  * machinery.
1320  */
1321 int get_sha1_committish(const char *name, unsigned char *sha1)
1322 {
1323         struct object_context unused;
1324         return get_sha1_with_context(name, GET_SHA1_COMMITTISH,
1325                                      sha1, &unused);
1326 }
1327
1328 int get_sha1_treeish(const char *name, unsigned char *sha1)
1329 {
1330         struct object_context unused;
1331         return get_sha1_with_context(name, GET_SHA1_TREEISH,
1332                                      sha1, &unused);
1333 }
1334
1335 int get_sha1_commit(const char *name, unsigned char *sha1)
1336 {
1337         struct object_context unused;
1338         return get_sha1_with_context(name, GET_SHA1_COMMIT,
1339                                      sha1, &unused);
1340 }
1341
1342 int get_sha1_tree(const char *name, unsigned char *sha1)
1343 {
1344         struct object_context unused;
1345         return get_sha1_with_context(name, GET_SHA1_TREE,
1346                                      sha1, &unused);
1347 }
1348
1349 int get_sha1_blob(const char *name, unsigned char *sha1)
1350 {
1351         struct object_context unused;
1352         return get_sha1_with_context(name, GET_SHA1_BLOB,
1353                                      sha1, &unused);
1354 }
1355
1356 /* Must be called only when object_name:filename doesn't exist. */
1357 static void diagnose_invalid_sha1_path(const char *prefix,
1358                                        const char *filename,
1359                                        const unsigned char *tree_sha1,
1360                                        const char *object_name,
1361                                        int object_name_len)
1362 {
1363         unsigned char sha1[20];
1364         unsigned mode;
1365
1366         if (!prefix)
1367                 prefix = "";
1368
1369         if (file_exists(filename))
1370                 die("Path '%s' exists on disk, but not in '%.*s'.",
1371                     filename, object_name_len, object_name);
1372         if (errno == ENOENT || errno == ENOTDIR) {
1373                 char *fullname = xstrfmt("%s%s", prefix, filename);
1374
1375                 if (!get_tree_entry(tree_sha1, fullname,
1376                                     sha1, &mode)) {
1377                         die("Path '%s' exists, but not '%s'.\n"
1378                             "Did you mean '%.*s:%s' aka '%.*s:./%s'?",
1379                             fullname,
1380                             filename,
1381                             object_name_len, object_name,
1382                             fullname,
1383                             object_name_len, object_name,
1384                             filename);
1385                 }
1386                 die("Path '%s' does not exist in '%.*s'",
1387                     filename, object_name_len, object_name);
1388         }
1389 }
1390
1391 /* Must be called only when :stage:filename doesn't exist. */
1392 static void diagnose_invalid_index_path(int stage,
1393                                         const char *prefix,
1394                                         const char *filename)
1395 {
1396         const struct cache_entry *ce;
1397         int pos;
1398         unsigned namelen = strlen(filename);
1399         struct strbuf fullname = STRBUF_INIT;
1400
1401         if (!prefix)
1402                 prefix = "";
1403
1404         /* Wrong stage number? */
1405         pos = cache_name_pos(filename, namelen);
1406         if (pos < 0)
1407                 pos = -pos - 1;
1408         if (pos < active_nr) {
1409                 ce = active_cache[pos];
1410                 if (ce_namelen(ce) == namelen &&
1411                     !memcmp(ce->name, filename, namelen))
1412                         die("Path '%s' is in the index, but not at stage %d.\n"
1413                             "Did you mean ':%d:%s'?",
1414                             filename, stage,
1415                             ce_stage(ce), filename);
1416         }
1417
1418         /* Confusion between relative and absolute filenames? */
1419         strbuf_addstr(&fullname, prefix);
1420         strbuf_addstr(&fullname, filename);
1421         pos = cache_name_pos(fullname.buf, fullname.len);
1422         if (pos < 0)
1423                 pos = -pos - 1;
1424         if (pos < active_nr) {
1425                 ce = active_cache[pos];
1426                 if (ce_namelen(ce) == fullname.len &&
1427                     !memcmp(ce->name, fullname.buf, fullname.len))
1428                         die("Path '%s' is in the index, but not '%s'.\n"
1429                             "Did you mean ':%d:%s' aka ':%d:./%s'?",
1430                             fullname.buf, filename,
1431                             ce_stage(ce), fullname.buf,
1432                             ce_stage(ce), filename);
1433         }
1434
1435         if (file_exists(filename))
1436                 die("Path '%s' exists on disk, but not in the index.", filename);
1437         if (errno == ENOENT || errno == ENOTDIR)
1438                 die("Path '%s' does not exist (neither on disk nor in the index).",
1439                     filename);
1440
1441         strbuf_release(&fullname);
1442 }
1443
1444
1445 static char *resolve_relative_path(const char *rel)
1446 {
1447         if (!starts_with(rel, "./") && !starts_with(rel, "../"))
1448                 return NULL;
1449
1450         if (!is_inside_work_tree())
1451                 die("relative path syntax can't be used outside working tree.");
1452
1453         /* die() inside prefix_path() if resolved path is outside worktree */
1454         return prefix_path(startup_info->prefix,
1455                            startup_info->prefix ? strlen(startup_info->prefix) : 0,
1456                            rel);
1457 }
1458
1459 static int get_sha1_with_context_1(const char *name,
1460                                    unsigned flags,
1461                                    const char *prefix,
1462                                    unsigned char *sha1,
1463                                    struct object_context *oc)
1464 {
1465         int ret, bracket_depth;
1466         int namelen = strlen(name);
1467         const char *cp;
1468         int only_to_die = flags & GET_SHA1_ONLY_TO_DIE;
1469
1470         if (only_to_die)
1471                 flags |= GET_SHA1_QUIETLY;
1472
1473         memset(oc, 0, sizeof(*oc));
1474         oc->mode = S_IFINVALID;
1475         ret = get_sha1_1(name, namelen, sha1, flags);
1476         if (!ret)
1477                 return ret;
1478         /*
1479          * sha1:path --> object name of path in ent sha1
1480          * :path -> object name of absolute path in index
1481          * :./path -> object name of path relative to cwd in index
1482          * :[0-3]:path -> object name of path in index at stage
1483          * :/foo -> recent commit matching foo
1484          */
1485         if (name[0] == ':') {
1486                 int stage = 0;
1487                 const struct cache_entry *ce;
1488                 char *new_path = NULL;
1489                 int pos;
1490                 if (!only_to_die && namelen > 2 && name[1] == '/') {
1491                         struct commit_list *list = NULL;
1492
1493                         for_each_ref(handle_one_ref, &list);
1494                         commit_list_sort_by_date(&list);
1495                         return get_sha1_oneline(name + 2, sha1, list);
1496                 }
1497                 if (namelen < 3 ||
1498                     name[2] != ':' ||
1499                     name[1] < '0' || '3' < name[1])
1500                         cp = name + 1;
1501                 else {
1502                         stage = name[1] - '0';
1503                         cp = name + 3;
1504                 }
1505                 new_path = resolve_relative_path(cp);
1506                 if (!new_path) {
1507                         namelen = namelen - (cp - name);
1508                 } else {
1509                         cp = new_path;
1510                         namelen = strlen(cp);
1511                 }
1512
1513                 strlcpy(oc->path, cp, sizeof(oc->path));
1514
1515                 if (!active_cache)
1516                         read_cache();
1517                 pos = cache_name_pos(cp, namelen);
1518                 if (pos < 0)
1519                         pos = -pos - 1;
1520                 while (pos < active_nr) {
1521                         ce = active_cache[pos];
1522                         if (ce_namelen(ce) != namelen ||
1523                             memcmp(ce->name, cp, namelen))
1524                                 break;
1525                         if (ce_stage(ce) == stage) {
1526                                 hashcpy(sha1, ce->oid.hash);
1527                                 oc->mode = ce->ce_mode;
1528                                 free(new_path);
1529                                 return 0;
1530                         }
1531                         pos++;
1532                 }
1533                 if (only_to_die && name[1] && name[1] != '/')
1534                         diagnose_invalid_index_path(stage, prefix, cp);
1535                 free(new_path);
1536                 return -1;
1537         }
1538         for (cp = name, bracket_depth = 0; *cp; cp++) {
1539                 if (*cp == '{')
1540                         bracket_depth++;
1541                 else if (bracket_depth && *cp == '}')
1542                         bracket_depth--;
1543                 else if (!bracket_depth && *cp == ':')
1544                         break;
1545         }
1546         if (*cp == ':') {
1547                 unsigned char tree_sha1[20];
1548                 int len = cp - name;
1549                 unsigned sub_flags = flags;
1550
1551                 sub_flags &= ~GET_SHA1_DISAMBIGUATORS;
1552                 sub_flags |= GET_SHA1_TREEISH;
1553
1554                 if (!get_sha1_1(name, len, tree_sha1, sub_flags)) {
1555                         const char *filename = cp+1;
1556                         char *new_filename = NULL;
1557
1558                         new_filename = resolve_relative_path(filename);
1559                         if (new_filename)
1560                                 filename = new_filename;
1561                         if (flags & GET_SHA1_FOLLOW_SYMLINKS) {
1562                                 ret = get_tree_entry_follow_symlinks(tree_sha1,
1563                                         filename, sha1, &oc->symlink_path,
1564                                         &oc->mode);
1565                         } else {
1566                                 ret = get_tree_entry(tree_sha1, filename,
1567                                                      sha1, &oc->mode);
1568                                 if (ret && only_to_die) {
1569                                         diagnose_invalid_sha1_path(prefix,
1570                                                                    filename,
1571                                                                    tree_sha1,
1572                                                                    name, len);
1573                                 }
1574                         }
1575                         hashcpy(oc->tree, tree_sha1);
1576                         strlcpy(oc->path, filename, sizeof(oc->path));
1577
1578                         free(new_filename);
1579                         return ret;
1580                 } else {
1581                         if (only_to_die)
1582                                 die("Invalid object name '%.*s'.", len, name);
1583                 }
1584         }
1585         return ret;
1586 }
1587
1588 /*
1589  * Call this function when you know "name" given by the end user must
1590  * name an object but it doesn't; the function _may_ die with a better
1591  * diagnostic message than "no such object 'name'", e.g. "Path 'doc' does not
1592  * exist in 'HEAD'" when given "HEAD:doc", or it may return in which case
1593  * you have a chance to diagnose the error further.
1594  */
1595 void maybe_die_on_misspelt_object_name(const char *name, const char *prefix)
1596 {
1597         struct object_context oc;
1598         unsigned char sha1[20];
1599         get_sha1_with_context_1(name, GET_SHA1_ONLY_TO_DIE, prefix, sha1, &oc);
1600 }
1601
1602 int get_sha1_with_context(const char *str, unsigned flags, unsigned char *sha1, struct object_context *orc)
1603 {
1604         if (flags & GET_SHA1_FOLLOW_SYMLINKS && flags & GET_SHA1_ONLY_TO_DIE)
1605                 die("BUG: incompatible flags for get_sha1_with_context");
1606         return get_sha1_with_context_1(str, flags, NULL, sha1, orc);
1607 }