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
  10 static int find_short_object_filename(int len, const char *name, unsigned char *sha1)
  11 {
  12         struct alternate_object_database *alt;
  13         char hex[40];
  14         int found = 0;
  15         static struct alternate_object_database *fakeent;
  16
  17         if (!fakeent) {
  18                 const char *objdir = get_object_directory();
  19                 int objdir_len = strlen(objdir);
  20                 int entlen = objdir_len + 43;
  21                 fakeent = xmalloc(sizeof(*fakeent) + entlen);
  22                 memcpy(fakeent->base, objdir, objdir_len);
  23                 fakeent->name = fakeent->base + objdir_len + 1;
  24                 fakeent->name[-1] = '/';
  25         }
  26         fakeent->next = alt_odb_list;
  27
  28         sprintf(hex, "%.2s", name);
  29         for (alt = fakeent; alt && found < 2; alt = alt->next) {
  30                 struct dirent *de;
  31                 DIR *dir;
  32                 sprintf(alt->name, "%.2s/", name);
  33                 dir = opendir(alt->base);
  34                 if (!dir)
  35                         continue;
  36                 while ((de = readdir(dir)) != NULL) {
  37                         if (strlen(de->d_name) != 38)
  38                                 continue;
  39                         if (memcmp(de->d_name, name + 2, len - 2))
  40                                 continue;
  41                         if (!found) {
  42                                 memcpy(hex + 2, de->d_name, 38);
  43                                 found++;
  44                         }
  45                         else if (memcmp(hex + 2, de->d_name, 38)) {
  46                                 found = 2;
  47                                 break;
  48                         }
  49                 }
  50                 closedir(dir);
  51         }
  52         if (found == 1)
  53                 return get_sha1_hex(hex, sha1) == 0;
  54         return found;
  55 }
  56
  57 static int match_sha(unsigned len, const unsigned char *a, const unsigned char *b)
  58 {
  59         do {
  60                 if (*a != *b)
  61                         return 0;
  62                 a++;
  63                 b++;
  64                 len -= 2;
  65         } while (len > 1);
  66         if (len)
  67                 if ((*a ^ *b) & 0xf0)
  68                         return 0;
  69         return 1;
  70 }
  71
  72 static int find_short_packed_object(int len, const unsigned char *match, unsigned char *sha1)
  73 {
  74         struct packed_git *p;
  75         const unsigned char *found_sha1 = NULL;
  76         int found = 0;
  77
  78         prepare_packed_git();
  79         for (p = packed_git; p && found < 2; p = p->next) {
  80                 uint32_t num, last;
  81                 uint32_t first = 0;
  82                 open_pack_index(p);
  83                 num = p->num_objects;
  84                 last = num;
  85                 while (first < last) {
  86                         uint32_t mid = (first + last) / 2;
  87                         const unsigned char *now;
  88                         int cmp;
  89
  90                         now = nth_packed_object_sha1(p, mid);
  91                         cmp = hashcmp(match, now);
  92                         if (!cmp) {
  93                                 first = mid;
  94                                 break;
  95                         }
  96                         if (cmp > 0) {
  97                                 first = mid+1;
  98                                 continue;
  99                         }
 100                         last = mid;
 101                 }
 102                 if (first < num) {
 103                         const unsigned char *now, *next;
 104                        now = nth_packed_object_sha1(p, first);
 105                         if (match_sha(len, match, now)) {
 106                                 next = nth_packed_object_sha1(p, first+1);
 107                                if (!next|| !match_sha(len, match, next)) {
 108                                         /* unique within this pack */
 109                                         if (!found) {
 110                                                 found_sha1 = now;
 111                                                 found++;
 112                                         }
 113                                         else if (hashcmp(found_sha1, now)) {
 114                                                 found = 2;
 115                                                 break;
 116                                         }
 117                                 }
 118                                 else {
 119                                         /* not even unique within this pack */
 120                                         found = 2;
 121                                         break;
 122                                 }
 123                         }
 124                 }
 125         }
 126         if (found == 1)
 127                 hashcpy(sha1, found_sha1);
 128         return found;
 129 }
 130
 131 #define SHORT_NAME_NOT_FOUND (-1)
 132 #define SHORT_NAME_AMBIGUOUS (-2)
 133
 134 static int find_unique_short_object(int len, char *canonical,
 135                                     unsigned char *res, unsigned char *sha1)
 136 {
 137         int has_unpacked, has_packed;
 138         unsigned char unpacked_sha1[20], packed_sha1[20];
 139
 140         prepare_alt_odb();
 141         has_unpacked = find_short_object_filename(len, canonical, unpacked_sha1);
 142         has_packed = find_short_packed_object(len, res, packed_sha1);
 143         if (!has_unpacked && !has_packed)
 144                 return SHORT_NAME_NOT_FOUND;
 145         if (1 < has_unpacked || 1 < has_packed)
 146                 return SHORT_NAME_AMBIGUOUS;
 147         if (has_unpacked != has_packed) {
 148                 hashcpy(sha1, (has_packed ? packed_sha1 : unpacked_sha1));
 149                 return 0;
 150         }
 151         /* Both have unique ones -- do they match? */
 152         if (hashcmp(packed_sha1, unpacked_sha1))
 153                 return SHORT_NAME_AMBIGUOUS;
 154         hashcpy(sha1, packed_sha1);
 155         return 0;
 156 }
 157
 158 static int get_short_sha1(const char *name, int len, unsigned char *sha1,
 159                           int quietly)
 160 {
 161         int i, status;
 162         char canonical[40];
 163         unsigned char res[20];
 164
 165         if (len < MINIMUM_ABBREV || len > 40)
 166                 return -1;
 167         hashclr(res);
 168         memset(canonical, 'x', 40);
 169         for (i = 0; i < len ;i++) {
 170                 unsigned char c = name[i];
 171                 unsigned char val;
 172                 if (c >= '0' && c <= '9')
 173                         val = c - '0';
 174                 else if (c >= 'a' && c <= 'f')
 175                         val = c - 'a' + 10;
 176                 else if (c >= 'A' && c <='F') {
 177                         val = c - 'A' + 10;
 178                         c -= 'A' - 'a';
 179                 }
 180                 else
 181                         return -1;
 182                 canonical[i] = c;
 183                 if (!(i & 1))
 184                         val <<= 4;
 185                 res[i >> 1] |= val;
 186         }
 187
 188         status = find_unique_short_object(i, canonical, res, sha1);
 189         if (!quietly && (status == SHORT_NAME_AMBIGUOUS))
 190                 return error("short SHA1 %.*s is ambiguous.", len, canonical);
 191         return status;
 192 }
 193
 194 const char *find_unique_abbrev(const unsigned char *sha1, int len)
 195 {
 196         int status, exists;
 197         static char hex[41];
 198
 199         exists = has_sha1_file(sha1);
 200         memcpy(hex, sha1_to_hex(sha1), 40);
 201         if (len == 40 || !len)
 202                 return hex;
 203         while (len < 40) {
 204                 unsigned char sha1_ret[20];
 205                 status = get_short_sha1(hex, len, sha1_ret, 1);
 206                 if (exists
 207                     ? !status
 208                     : status == SHORT_NAME_NOT_FOUND) {
 209                         hex[len] = 0;
 210                         return hex;
 211                 }
 212                 len++;
 213         }
 214         return hex;
 215 }
 216
 217 static int ambiguous_path(const char *path, int len)
 218 {
 219         int slash = 1;
 220         int cnt;
 221
 222         for (cnt = 0; cnt < len; cnt++) {
 223                 switch (*path++) {
 224                 case '\0':
 225                         break;
 226                 case '/':
 227                         if (slash)
 228                                 break;
 229                         slash = 1;
 230                         continue;
 231                 case '.':
 232                         continue;
 233                 default:
 234                         slash = 0;
 235                         continue;
 236                 }
 237                 break;
 238         }
 239         return slash;
 240 }
 241
 242 /*
 243  * *string and *len will only be substituted, and *string returned (for
 244  * later free()ing) if the string passed in is a magic short-hand form
 245  * to name a branch.
 246  */
 247 static char *substitute_branch_name(const char **string, int *len)
 248 {
 249         struct strbuf buf = STRBUF_INIT;
 250         int ret = interpret_branch_name(*string, &buf);
 251
 252         if (ret == *len) {
 253                 size_t size;
 254                 *string = strbuf_detach(&buf, &size);
 255                 *len = size;
 256                 return (char *)*string;
 257         }
 258
 259         return NULL;
 260 }
 261
 262 int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
 263 {
 264         char *last_branch = substitute_branch_name(&str, &len);
 265         const char **p, *r;
 266         int refs_found = 0;
 267
 268         *ref = NULL;
 269         for (p = ref_rev_parse_rules; *p; p++) {
 270                 char fullref[PATH_MAX];
 271                 unsigned char sha1_from_ref[20];
 272                 unsigned char *this_result;
 273                 int flag;
 274
 275                 this_result = refs_found ? sha1_from_ref : sha1;
 276                 mksnpath(fullref, sizeof(fullref), *p, len, str);
 277                 r = resolve_ref(fullref, this_result, 1, &flag);
 278                 if (r) {
 279                         if (!refs_found++)
 280                                 *ref = xstrdup(r);
 281                         if (!warn_ambiguous_refs)
 282                                 break;
 283                 } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD"))
 284                         warning("ignoring dangling symref %s.", fullref);
 285         }
 286         free(last_branch);
 287         return refs_found;
 288 }
 289
 290 int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
 291 {
 292         char *last_branch = substitute_branch_name(&str, &len);
 293         const char **p;
 294         int logs_found = 0;
 295
 296         *log = NULL;
 297         for (p = ref_rev_parse_rules; *p; p++) {
 298                 struct stat st;
 299                 unsigned char hash[20];
 300                 char path[PATH_MAX];
 301                 const char *ref, *it;
 302
 303                 mksnpath(path, sizeof(path), *p, len, str);
 304                 ref = resolve_ref(path, hash, 1, NULL);
 305                 if (!ref)
 306                         continue;
 307                 if (!stat(git_path("logs/%s", path), &st) &&
 308                     S_ISREG(st.st_mode))
 309                         it = path;
 310                 else if (strcmp(ref, path) &&
 311                          !stat(git_path("logs/%s", ref), &st) &&
 312                          S_ISREG(st.st_mode))
 313                         it = ref;
 314                 else
 315                         continue;
 316                 if (!logs_found++) {
 317                         *log = xstrdup(it);
 318                         hashcpy(sha1, hash);
 319                 }
 320                 if (!warn_ambiguous_refs)
 321                         break;
 322         }
 323         free(last_branch);
 324         return logs_found;
 325 }
 326
 327 static inline int upstream_mark(const char *string, int len)
 328 {
 329         const char *suffix[] = { "@{upstream}", "@{u}" };
 330         int i;
 331
 332         for (i = 0; i < ARRAY_SIZE(suffix); i++) {
 333                 int suffix_len = strlen(suffix[i]);
 334                 if (suffix_len <= len
 335                     && !memcmp(string, suffix[i], suffix_len))
 336                         return suffix_len;
 337         }
 338         return 0;
 339 }
 340
 341 static int get_sha1_1(const char *name, int len, unsigned char *sha1);
 342
 343 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 344 {
 345         static const char *warning = "warning: refname '%.*s' is ambiguous.\n";
 346         char *real_ref = NULL;
 347         int refs_found = 0;
 348         int at, reflog_len;
 349
 350         if (len == 40 && !get_sha1_hex(str, sha1))
 351                 return 0;
 352
 353         /* basic@{time or number or -number} format to query ref-log */
 354         reflog_len = at = 0;
 355         if (len && str[len-1] == '}') {
 356                 for (at = len-2; at >= 0; at--) {
 357                         if (str[at] == '@' && str[at+1] == '{') {
 358                                 if (!upstream_mark(str + at, len - at)) {
 359                                         reflog_len = (len-1) - (at+2);
 360                                         len = at;
 361                                 }
 362                                 break;
 363                         }
 364                 }
 365         }
 366
 367         /* Accept only unambiguous ref paths. */
 368         if (len && ambiguous_path(str, len))
 369                 return -1;
 370
 371         if (!len && reflog_len) {
 372                 struct strbuf buf = STRBUF_INIT;
 373                 int ret;
 374                 /* try the @{-N} syntax for n-th checkout */
 375                 ret = interpret_branch_name(str+at, &buf);
 376                 if (ret > 0) {
 377                         /* substitute this branch name and restart */
 378                         return get_sha1_1(buf.buf, buf.len, sha1);
 379                 } else if (ret == 0) {
 380                         return -1;
 381                 }
 382                 /* allow "@{...}" to mean the current branch reflog */
 383                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 384         } else if (reflog_len)
 385                 refs_found = dwim_log(str, len, sha1, &real_ref);
 386         else
 387                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 388
 389         if (!refs_found)
 390                 return -1;
 391
 392         if (warn_ambiguous_refs && refs_found > 1)
 393                 fprintf(stderr, warning, len, str);
 394
 395         if (reflog_len) {
 396                 int nth, i;
 397                 unsigned long at_time;
 398                 unsigned long co_time;
 399                 int co_tz, co_cnt;
 400
 401                 /* a @{-N} placed anywhere except the start is an error */
 402                 if (str[at+2] == '-')
 403                         return -1;
 404
 405                 /* Is it asking for N-th entry, or approxidate? */
 406                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 407                         char ch = str[at+2+i];
 408                         if ('0' <= ch && ch <= '9')
 409                                 nth = nth * 10 + ch - '0';
 410                         else
 411                                 nth = -1;
 412                 }
 413                 if (100000000 <= nth) {
 414                         at_time = nth;
 415                         nth = -1;
 416                 } else if (0 <= nth)
 417                         at_time = 0;
 418                 else {
 419                         int errors = 0;
 420                         char *tmp = xstrndup(str + at + 2, reflog_len);
 421                         at_time = approxidate_careful(tmp, &errors);
 422                         free(tmp);
 423                         if (errors)
 424                                 return -1;
 425                 }
 426                 if (read_ref_at(real_ref, at_time, nth, sha1, NULL,
 427                                 &co_time, &co_tz, &co_cnt)) {
 428                         if (at_time)
 429                                 fprintf(stderr,
 430                                         "warning: Log for '%.*s' only goes "
 431                                         "back to %s.\n", len, str,
 432                                         show_date(co_time, co_tz, DATE_RFC2822));
 433                         else
 434                                 fprintf(stderr,
 435                                         "warning: Log for '%.*s' only has "
 436                                         "%d entries.\n", len, str, co_cnt);
 437                 }
 438         }
 439
 440         free(real_ref);
 441         return 0;
 442 }
 443
 444 static int get_parent(const char *name, int len,
 445                       unsigned char *result, int idx)
 446 {
 447         unsigned char sha1[20];
 448         int ret = get_sha1_1(name, len, sha1);
 449         struct commit *commit;
 450         struct commit_list *p;
 451
 452         if (ret)
 453                 return ret;
 454         commit = lookup_commit_reference(sha1);
 455         if (!commit)
 456                 return -1;
 457         if (parse_commit(commit))
 458                 return -1;
 459         if (!idx) {
 460                 hashcpy(result, commit->object.sha1);
 461                 return 0;
 462         }
 463         p = commit->parents;
 464         while (p) {
 465                 if (!--idx) {
 466                         hashcpy(result, p->item->object.sha1);
 467                         return 0;
 468                 }
 469                 p = p->next;
 470         }
 471         return -1;
 472 }
 473
 474 static int get_nth_ancestor(const char *name, int len,
 475                             unsigned char *result, int generation)
 476 {
 477         unsigned char sha1[20];
 478         struct commit *commit;
 479         int ret;
 480
 481         ret = get_sha1_1(name, len, sha1);
 482         if (ret)
 483                 return ret;
 484         commit = lookup_commit_reference(sha1);
 485         if (!commit)
 486                 return -1;
 487
 488         while (generation--) {
 489                 if (parse_commit(commit) || !commit->parents)
 490                         return -1;
 491                 commit = commit->parents->item;
 492         }
 493         hashcpy(result, commit->object.sha1);
 494         return 0;
 495 }
 496
 497 struct object *peel_to_type(const char *name, int namelen,
 498                             struct object *o, enum object_type expected_type)
 499 {
 500         if (name && !namelen)
 501                 namelen = strlen(name);
 502         if (!o) {
 503                 unsigned char sha1[20];
 504                 if (get_sha1_1(name, namelen, sha1))
 505                         return NULL;
 506                 o = parse_object(sha1);
 507         }
 508         while (1) {
 509                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 510                         return NULL;
 511                 if (o->type == expected_type)
 512                         return o;
 513                 if (o->type == OBJ_TAG)
 514                         o = ((struct tag*) o)->tagged;
 515                 else if (o->type == OBJ_COMMIT)
 516                         o = &(((struct commit *) o)->tree->object);
 517                 else {
 518                         if (name)
 519                                 error("%.*s: expected %s type, but the object "
 520                                       "dereferences to %s type",
 521                                       namelen, name, typename(expected_type),
 522                                       typename(o->type));
 523                         return NULL;
 524                 }
 525         }
 526 }
 527
 528 static int peel_onion(const char *name, int len, unsigned char *sha1)
 529 {
 530         unsigned char outer[20];
 531         const char *sp;
 532         unsigned int expected_type = 0;
 533         struct object *o;
 534
 535         /*
 536          * "ref^{type}" dereferences ref repeatedly until you cannot
 537          * dereference anymore, or you get an object of given type,
 538          * whichever comes first.  "ref^{}" means just dereference
 539          * tags until you get a non-tag.  "ref^0" is a shorthand for
 540          * "ref^{commit}".  "commit^{tree}" could be used to find the
 541          * top-level tree of the given commit.
 542          */
 543         if (len < 4 || name[len-1] != '}')
 544                 return -1;
 545
 546         for (sp = name + len - 1; name <= sp; sp--) {
 547                 int ch = *sp;
 548                 if (ch == '{' && name < sp && sp[-1] == '^')
 549                         break;
 550         }
 551         if (sp <= name)
 552                 return -1;
 553
 554         sp++; /* beginning of type name, or closing brace for empty */
 555         if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
 556                 expected_type = OBJ_COMMIT;
 557         else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
 558                 expected_type = OBJ_TREE;
 559         else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
 560                 expected_type = OBJ_BLOB;
 561         else if (sp[0] == '}')
 562                 expected_type = OBJ_NONE;
 563         else
 564                 return -1;
 565
 566         if (get_sha1_1(name, sp - name - 2, outer))
 567                 return -1;
 568
 569         o = parse_object(outer);
 570         if (!o)
 571                 return -1;
 572         if (!expected_type) {
 573                 o = deref_tag(o, name, sp - name - 2);
 574                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 575                         return -1;
 576                 hashcpy(sha1, o->sha1);
 577         }
 578         else {
 579                 /*
 580                  * At this point, the syntax look correct, so
 581                  * if we do not get the needed object, we should
 582                  * barf.
 583                  */
 584                 o = peel_to_type(name, len, o, expected_type);
 585                 if (o) {
 586                         hashcpy(sha1, o->sha1);
 587                         return 0;
 588                 }
 589                 return -1;
 590         }
 591         return 0;
 592 }
 593
 594 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 595 {
 596         const char *cp;
 597
 598         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 599                 char ch = *cp;
 600                 if (hexval(ch) & ~0377) {
 601                         /* We must be looking at g in "SOMETHING-g"
 602                          * for it to be describe output.
 603                          */
 604                         if (ch == 'g' && cp[-1] == '-') {
 605                                 cp++;
 606                                 len -= cp - name;
 607                                 return get_short_sha1(cp, len, sha1, 1);
 608                         }
 609                 }
 610         }
 611         return -1;
 612 }
 613
 614 static int get_sha1_1(const char *name, int len, unsigned char *sha1)
 615 {
 616         int ret, has_suffix;
 617         const char *cp;
 618
 619         /*
 620          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 621          */
 622         has_suffix = 0;
 623         for (cp = name + len - 1; name <= cp; cp--) {
 624                 int ch = *cp;
 625                 if ('0' <= ch && ch <= '9')
 626                         continue;
 627                 if (ch == '~' || ch == '^')
 628                         has_suffix = ch;
 629                 break;
 630         }
 631
 632         if (has_suffix) {
 633                 int num = 0;
 634                 int len1 = cp - name;
 635                 cp++;
 636                 while (cp < name + len)
 637                         num = num * 10 + *cp++ - '0';
 638                 if (!num && len1 == len - 1)
 639                         num = 1;
 640                 if (has_suffix == '^')
 641                         return get_parent(name, len1, sha1, num);
 642                 /* else if (has_suffix == '~') -- goes without saying */
 643                 return get_nth_ancestor(name, len1, sha1, num);
 644         }
 645
 646         ret = peel_onion(name, len, sha1);
 647         if (!ret)
 648                 return 0;
 649
 650         ret = get_sha1_basic(name, len, sha1);
 651         if (!ret)
 652                 return 0;
 653
 654         /* It could be describe output that is "SOMETHING-gXXXX" */
 655         ret = get_describe_name(name, len, sha1);
 656         if (!ret)
 657                 return 0;
 658
 659         return get_short_sha1(name, len, sha1, 0);
 660 }
 661
 662 /*
 663  * This interprets names like ':/Initial revision of "git"' by searching
 664  * through history and returning the first commit whose message starts
 665  * the given regular expression.
 666  *
 667  * For future extension, ':/!' is reserved. If you want to match a message
 668  * beginning with a '!', you have to repeat the exclamation mark.
 669  */
 670 #define ONELINE_SEEN (1u<<20)
 671
 672 static int handle_one_ref(const char *path,
 673                 const unsigned char *sha1, int flag, void *cb_data)
 674 {
 675         struct commit_list **list = cb_data;
 676         struct object *object = parse_object(sha1);
 677         if (!object)
 678                 return 0;
 679         if (object->type == OBJ_TAG) {
 680                 object = deref_tag(object, path, strlen(path));
 681                 if (!object)
 682                         return 0;
 683         }
 684         if (object->type != OBJ_COMMIT)
 685                 return 0;
 686         insert_by_date((struct commit *)object, list);
 687         object->flags |= ONELINE_SEEN;
 688         return 0;
 689 }
 690
 691 static int get_sha1_oneline(const char *prefix, unsigned char *sha1)
 692 {
 693         struct commit_list *list = NULL, *backup = NULL, *l;
 694         int retval = -1;
 695         char *temp_commit_buffer = NULL;
 696         regex_t regex;
 697
 698         if (prefix[0] == '!') {
 699                 if (prefix[1] != '!')
 700                         die ("Invalid search pattern: %s", prefix);
 701                 prefix++;
 702         }
 703
 704         if (regcomp(&regex, prefix, REG_EXTENDED))
 705                 die("Invalid search pattern: %s", prefix);
 706
 707         for_each_ref(handle_one_ref, &list);
 708         for (l = list; l; l = l->next)
 709                 commit_list_insert(l->item, &backup);
 710         while (list) {
 711                 char *p;
 712                 struct commit *commit;
 713                 enum object_type type;
 714                 unsigned long size;
 715
 716                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 717                 if (!parse_object(commit->object.sha1))
 718                         continue;
 719                 free(temp_commit_buffer);
 720                 if (commit->buffer)
 721                         p = commit->buffer;
 722                 else {
 723                         p = read_sha1_file(commit->object.sha1, &type, &size);
 724                         if (!p)
 725                                 continue;
 726                         temp_commit_buffer = p;
 727                 }
 728                 if (!(p = strstr(p, "\n\n")))
 729                         continue;
 730                 if (!regexec(&regex, p + 2, 0, NULL, 0)) {
 731                         hashcpy(sha1, commit->object.sha1);
 732                         retval = 0;
 733                         break;
 734                 }
 735         }
 736         regfree(&regex);
 737         free(temp_commit_buffer);
 738         free_commit_list(list);
 739         for (l = backup; l; l = l->next)
 740                 clear_commit_marks(l->item, ONELINE_SEEN);
 741         return retval;
 742 }
 743
 744 struct grab_nth_branch_switch_cbdata {
 745         long cnt, alloc;
 746         struct strbuf *buf;
 747 };
 748
 749 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 750                                   const char *email, unsigned long timestamp, int tz,
 751                                   const char *message, void *cb_data)
 752 {
 753         struct grab_nth_branch_switch_cbdata *cb = cb_data;
 754         const char *match = NULL, *target = NULL;
 755         size_t len;
 756         int nth;
 757
 758         if (!prefixcmp(message, "checkout: moving from ")) {
 759                 match = message + strlen("checkout: moving from ");
 760                 target = strstr(match, " to ");
 761         }
 762
 763         if (!match || !target)
 764                 return 0;
 765
 766         len = target - match;
 767         nth = cb->cnt++ % cb->alloc;
 768         strbuf_reset(&cb->buf[nth]);
 769         strbuf_add(&cb->buf[nth], match, len);
 770         return 0;
 771 }
 772
 773 /*
 774  * Parse @{-N} syntax, return the number of characters parsed
 775  * if successful; otherwise signal an error with negative value.
 776  */
 777 static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf)
 778 {
 779         long nth;
 780         int i, retval;
 781         struct grab_nth_branch_switch_cbdata cb;
 782         const char *brace;
 783         char *num_end;
 784
 785         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
 786                 return -1;
 787         brace = strchr(name, '}');
 788         if (!brace)
 789                 return -1;
 790         nth = strtol(name+3, &num_end, 10);
 791         if (num_end != brace)
 792                 return -1;
 793         if (nth <= 0)
 794                 return -1;
 795         cb.alloc = nth;
 796         cb.buf = xmalloc(nth * sizeof(struct strbuf));
 797         for (i = 0; i < nth; i++)
 798                 strbuf_init(&cb.buf[i], 20);
 799         cb.cnt = 0;
 800         retval = 0;
 801         for_each_recent_reflog_ent("HEAD", grab_nth_branch_switch, 40960, &cb);
 802         if (cb.cnt < nth) {
 803                 cb.cnt = 0;
 804                 for_each_reflog_ent("HEAD", grab_nth_branch_switch, &cb);
 805         }
 806         if (cb.cnt < nth)
 807                 goto release_return;
 808         i = cb.cnt % nth;
 809         strbuf_reset(buf);
 810         strbuf_add(buf, cb.buf[i].buf, cb.buf[i].len);
 811         retval = brace-name+1;
 812
 813 release_return:
 814         for (i = 0; i < nth; i++)
 815                 strbuf_release(&cb.buf[i]);
 816         free(cb.buf);
 817
 818         return retval;
 819 }
 820
 821 int get_sha1_mb(const char *name, unsigned char *sha1)
 822 {
 823         struct commit *one, *two;
 824         struct commit_list *mbs;
 825         unsigned char sha1_tmp[20];
 826         const char *dots;
 827         int st;
 828
 829         dots = strstr(name, "...");
 830         if (!dots)
 831                 return get_sha1(name, sha1);
 832         if (dots == name)
 833                 st = get_sha1("HEAD", sha1_tmp);
 834         else {
 835                 struct strbuf sb;
 836                 strbuf_init(&sb, dots - name);
 837                 strbuf_add(&sb, name, dots - name);
 838                 st = get_sha1(sb.buf, sha1_tmp);
 839                 strbuf_release(&sb);
 840         }
 841         if (st)
 842                 return st;
 843         one = lookup_commit_reference_gently(sha1_tmp, 0);
 844         if (!one)
 845                 return -1;
 846
 847         if (get_sha1(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
 848                 return -1;
 849         two = lookup_commit_reference_gently(sha1_tmp, 0);
 850         if (!two)
 851                 return -1;
 852         mbs = get_merge_bases(one, two, 1);
 853         if (!mbs || mbs->next)
 854                 st = -1;
 855         else {
 856                 st = 0;
 857                 hashcpy(sha1, mbs->item->object.sha1);
 858         }
 859         free_commit_list(mbs);
 860         return st;
 861 }
 862
 863 /*
 864  * This reads short-hand syntax that not only evaluates to a commit
 865  * object name, but also can act as if the end user spelled the name
 866  * of the branch from the command line.
 867  *
 868  * - "@{-N}" finds the name of the Nth previous branch we were on, and
 869  *   places the name of the branch in the given buf and returns the
 870  *   number of characters parsed if successful.
 871  *
 872  * - "<branch>@{upstream}" finds the name of the other ref that
 873  *   <branch> is configured to merge with (missing <branch> defaults
 874  *   to the current branch), and places the name of the branch in the
 875  *   given buf and returns the number of characters parsed if
 876  *   successful.
 877  *
 878  * If the input is not of the accepted format, it returns a negative
 879  * number to signal an error.
 880  *
 881  * If the input was ok but there are not N branch switches in the
 882  * reflog, it returns 0.
 883  */
 884 int interpret_branch_name(const char *name, struct strbuf *buf)
 885 {
 886         char *cp;
 887         struct branch *upstream;
 888         int namelen = strlen(name);
 889         int len = interpret_nth_prior_checkout(name, buf);
 890         int tmp_len;
 891
 892         if (!len)
 893                 return len; /* syntax Ok, not enough switches */
 894         if (0 < len && len == namelen)
 895                 return len; /* consumed all */
 896         else if (0 < len) {
 897                 /* we have extra data, which might need further processing */
 898                 struct strbuf tmp = STRBUF_INIT;
 899                 int used = buf->len;
 900                 int ret;
 901
 902                 strbuf_add(buf, name + len, namelen - len);
 903                 ret = interpret_branch_name(buf->buf, &tmp);
 904                 /* that data was not interpreted, remove our cruft */
 905                 if (ret < 0) {
 906                         strbuf_setlen(buf, used);
 907                         return len;
 908                 }
 909                 strbuf_reset(buf);
 910                 strbuf_addbuf(buf, &tmp);
 911                 strbuf_release(&tmp);
 912                 /* tweak for size of {-N} versus expanded ref name */
 913                 return ret - used + len;
 914         }
 915
 916         cp = strchr(name, '@');
 917         if (!cp)
 918                 return -1;
 919         tmp_len = upstream_mark(cp, namelen - (cp - name));
 920         if (!tmp_len)
 921                 return -1;
 922         len = cp + tmp_len - name;
 923         cp = xstrndup(name, cp - name);
 924         upstream = branch_get(*cp ? cp : NULL);
 925         if (!upstream
 926             || !upstream->merge
 927             || !upstream->merge[0]->dst)
 928                 return error("No upstream branch found for '%s'", cp);
 929         free(cp);
 930         cp = shorten_unambiguous_ref(upstream->merge[0]->dst, 0);
 931         strbuf_reset(buf);
 932         strbuf_addstr(buf, cp);
 933         free(cp);
 934         return len;
 935 }
 936
 937 /*
 938  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
 939  * notably "xyz^" for "parent of xyz"
 940  */
 941 int get_sha1(const char *name, unsigned char *sha1)
 942 {
 943         struct object_context unused;
 944         return get_sha1_with_context(name, sha1, &unused);
 945 }
 946
 947 /* Must be called only when object_name:filename doesn't exist. */
 948 static void diagnose_invalid_sha1_path(const char *prefix,
 949                                        const char *filename,
 950                                        const unsigned char *tree_sha1,
 951                                        const char *object_name)
 952 {
 953         struct stat st;
 954         unsigned char sha1[20];
 955         unsigned mode;
 956
 957         if (!prefix)
 958                 prefix = "";
 959
 960         if (!lstat(filename, &st))
 961                 die("Path '%s' exists on disk, but not in '%s'.",
 962                     filename, object_name);
 963         if (errno == ENOENT || errno == ENOTDIR) {
 964                 char *fullname = xmalloc(strlen(filename)
 965                                              + strlen(prefix) + 1);
 966                 strcpy(fullname, prefix);
 967                 strcat(fullname, filename);
 968
 969                 if (!get_tree_entry(tree_sha1, fullname,
 970                                     sha1, &mode)) {
 971                         die("Path '%s' exists, but not '%s'.\n"
 972                             "Did you mean '%s:%s'?",
 973                             fullname,
 974                             filename,
 975                             object_name,
 976                             fullname);
 977                 }
 978                 die("Path '%s' does not exist in '%s'",
 979                     filename, object_name);
 980         }
 981 }
 982
 983 /* Must be called only when :stage:filename doesn't exist. */
 984 static void diagnose_invalid_index_path(int stage,
 985                                         const char *prefix,
 986                                         const char *filename)
 987 {
 988         struct stat st;
 989         struct cache_entry *ce;
 990         int pos;
 991         unsigned namelen = strlen(filename);
 992         unsigned fullnamelen;
 993         char *fullname;
 994
 995         if (!prefix)
 996                 prefix = "";
 997
 998         /* Wrong stage number? */
 999         pos = cache_name_pos(filename, namelen);
1000         if (pos < 0)
1001                 pos = -pos - 1;
1002         if (pos < active_nr) {
1003                 ce = active_cache[pos];
1004                 if (ce_namelen(ce) == namelen &&
1005                     !memcmp(ce->name, filename, namelen))
1006                         die("Path '%s' is in the index, but not at stage %d.\n"
1007                             "Did you mean ':%d:%s'?",
1008                             filename, stage,
1009                             ce_stage(ce), filename);
1010         }
1011
1012         /* Confusion between relative and absolute filenames? */
1013         fullnamelen = namelen + strlen(prefix);
1014         fullname = xmalloc(fullnamelen + 1);
1015         strcpy(fullname, prefix);
1016         strcat(fullname, filename);
1017         pos = cache_name_pos(fullname, fullnamelen);
1018         if (pos < 0)
1019                 pos = -pos - 1;
1020         if (pos < active_nr) {
1021                 ce = active_cache[pos];
1022                 if (ce_namelen(ce) == fullnamelen &&
1023                     !memcmp(ce->name, fullname, fullnamelen))
1024                         die("Path '%s' is in the index, but not '%s'.\n"
1025                             "Did you mean ':%d:%s'?",
1026                             fullname, filename,
1027                             ce_stage(ce), fullname);
1028         }
1029
1030         if (!lstat(filename, &st))
1031                 die("Path '%s' exists on disk, but not in the index.", filename);
1032         if (errno == ENOENT || errno == ENOTDIR)
1033                 die("Path '%s' does not exist (neither on disk nor in the index).",
1034                     filename);
1035
1036         free(fullname);
1037 }
1038
1039
1040 int get_sha1_with_mode_1(const char *name, unsigned char *sha1, unsigned *mode, int gently, const char *prefix)
1041 {
1042         struct object_context oc;
1043         int ret;
1044         ret = get_sha1_with_context_1(name, sha1, &oc, gently, prefix);
1045         *mode = oc.mode;
1046         return ret;
1047 }
1048
1049 int get_sha1_with_context_1(const char *name, unsigned char *sha1,
1050                             struct object_context *oc,
1051                             int gently, const char *prefix)
1052 {
1053         int ret, bracket_depth;
1054         int namelen = strlen(name);
1055         const char *cp;
1056
1057         memset(oc, 0, sizeof(*oc));
1058         oc->mode = S_IFINVALID;
1059         ret = get_sha1_1(name, namelen, sha1);
1060         if (!ret)
1061                 return ret;
1062         /* sha1:path --> object name of path in ent sha1
1063          * :path -> object name of path in index
1064          * :[0-3]:path -> object name of path in index at stage
1065          */
1066         if (name[0] == ':') {
1067                 int stage = 0;
1068                 struct cache_entry *ce;
1069                 int pos;
1070                 if (namelen > 2 && name[1] == '/')
1071                         return get_sha1_oneline(name + 2, sha1);
1072                 if (namelen < 3 ||
1073                     name[2] != ':' ||
1074                     name[1] < '0' || '3' < name[1])
1075                         cp = name + 1;
1076                 else {
1077                         stage = name[1] - '0';
1078                         cp = name + 3;
1079                 }
1080                 namelen = namelen - (cp - name);
1081
1082                 strncpy(oc->path, cp,
1083                         sizeof(oc->path));
1084                 oc->path[sizeof(oc->path)-1] = '\0';
1085
1086                 if (!active_cache)
1087                         read_cache();
1088                 pos = cache_name_pos(cp, namelen);
1089                 if (pos < 0)
1090                         pos = -pos - 1;
1091                 while (pos < active_nr) {
1092                         ce = active_cache[pos];
1093                         if (ce_namelen(ce) != namelen ||
1094                             memcmp(ce->name, cp, namelen))
1095                                 break;
1096                         if (ce_stage(ce) == stage) {
1097                                 hashcpy(sha1, ce->sha1);
1098                                 return 0;
1099                         }
1100                         pos++;
1101                 }
1102                 if (!gently)
1103                         diagnose_invalid_index_path(stage, prefix, cp);
1104                 return -1;
1105         }
1106         for (cp = name, bracket_depth = 0; *cp; cp++) {
1107                 if (*cp == '{')
1108                         bracket_depth++;
1109                 else if (bracket_depth && *cp == '}')
1110                         bracket_depth--;
1111                 else if (!bracket_depth && *cp == ':')
1112                         break;
1113         }
1114         if (*cp == ':') {
1115                 unsigned char tree_sha1[20];
1116                 char *object_name = NULL;
1117                 if (!gently) {
1118                         object_name = xmalloc(cp-name+1);
1119                         strncpy(object_name, name, cp-name);
1120                         object_name[cp-name] = '\0';
1121                 }
1122                 if (!get_sha1_1(name, cp-name, tree_sha1)) {
1123                         const char *filename = cp+1;
1124                         ret = get_tree_entry(tree_sha1, filename, sha1, &oc->mode);
1125                         if (!gently) {
1126                                 diagnose_invalid_sha1_path(prefix, filename,
1127                                                            tree_sha1, object_name);
1128                                 free(object_name);
1129                         }
1130                         hashcpy(oc->tree, tree_sha1);
1131                         strncpy(oc->path, filename,
1132                                 sizeof(oc->path));
1133                         oc->path[sizeof(oc->path)-1] = '\0';
1134
1135                         return ret;
1136                 } else {
1137                         if (!gently)
1138                                 die("Invalid object name '%s'.", object_name);
1139                 }
1140         }
1141         return ret;
1142 }