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                         int cut_at = len + unique_abbrev_extra_length;
 210                         cut_at = (cut_at < 40) ? cut_at : 40;
 211                         hex[cut_at] = 0;
 212                         return hex;
 213                 }
 214                 len++;
 215         }
 216         return hex;
 217 }
 218
 219 static int ambiguous_path(const char *path, int len)
 220 {
 221         int slash = 1;
 222         int cnt;
 223
 224         for (cnt = 0; cnt < len; cnt++) {
 225                 switch (*path++) {
 226                 case '\0':
 227                         break;
 228                 case '/':
 229                         if (slash)
 230                                 break;
 231                         slash = 1;
 232                         continue;
 233                 case '.':
 234                         continue;
 235                 default:
 236                         slash = 0;
 237                         continue;
 238                 }
 239                 break;
 240         }
 241         return slash;
 242 }
 243
 244 /*
 245  * *string and *len will only be substituted, and *string returned (for
 246  * later free()ing) if the string passed in is a magic short-hand form
 247  * to name a branch.
 248  */
 249 static char *substitute_branch_name(const char **string, int *len)
 250 {
 251         struct strbuf buf = STRBUF_INIT;
 252         int ret = interpret_branch_name(*string, &buf);
 253
 254         if (ret == *len) {
 255                 size_t size;
 256                 *string = strbuf_detach(&buf, &size);
 257                 *len = size;
 258                 return (char *)*string;
 259         }
 260
 261         return NULL;
 262 }
 263
 264 int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
 265 {
 266         char *last_branch = substitute_branch_name(&str, &len);
 267         const char **p, *r;
 268         int refs_found = 0;
 269
 270         *ref = NULL;
 271         for (p = ref_rev_parse_rules; *p; p++) {
 272                 char fullref[PATH_MAX];
 273                 unsigned char sha1_from_ref[20];
 274                 unsigned char *this_result;
 275                 int flag;
 276
 277                 this_result = refs_found ? sha1_from_ref : sha1;
 278                 mksnpath(fullref, sizeof(fullref), *p, len, str);
 279                 r = resolve_ref(fullref, this_result, 1, &flag);
 280                 if (r) {
 281                         if (!refs_found++)
 282                                 *ref = xstrdup(r);
 283                         if (!warn_ambiguous_refs)
 284                                 break;
 285                 } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD"))
 286                         warning("ignoring dangling symref %s.", fullref);
 287         }
 288         free(last_branch);
 289         return refs_found;
 290 }
 291
 292 int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
 293 {
 294         char *last_branch = substitute_branch_name(&str, &len);
 295         const char **p;
 296         int logs_found = 0;
 297
 298         *log = NULL;
 299         for (p = ref_rev_parse_rules; *p; p++) {
 300                 struct stat st;
 301                 unsigned char hash[20];
 302                 char path[PATH_MAX];
 303                 const char *ref, *it;
 304
 305                 mksnpath(path, sizeof(path), *p, len, str);
 306                 ref = resolve_ref(path, hash, 1, NULL);
 307                 if (!ref)
 308                         continue;
 309                 if (!stat(git_path("logs/%s", path), &st) &&
 310                     S_ISREG(st.st_mode))
 311                         it = path;
 312                 else if (strcmp(ref, path) &&
 313                          !stat(git_path("logs/%s", ref), &st) &&
 314                          S_ISREG(st.st_mode))
 315                         it = ref;
 316                 else
 317                         continue;
 318                 if (!logs_found++) {
 319                         *log = xstrdup(it);
 320                         hashcpy(sha1, hash);
 321                 }
 322                 if (!warn_ambiguous_refs)
 323                         break;
 324         }
 325         free(last_branch);
 326         return logs_found;
 327 }
 328
 329 static inline int upstream_mark(const char *string, int len)
 330 {
 331         const char *suffix[] = { "@{upstream}", "@{u}" };
 332         int i;
 333
 334         for (i = 0; i < ARRAY_SIZE(suffix); i++) {
 335                 int suffix_len = strlen(suffix[i]);
 336                 if (suffix_len <= len
 337                     && !memcmp(string, suffix[i], suffix_len))
 338                         return suffix_len;
 339         }
 340         return 0;
 341 }
 342
 343 static int get_sha1_1(const char *name, int len, unsigned char *sha1);
 344
 345 static int get_sha1_basic(const char *str, int len, unsigned char *sha1)
 346 {
 347         static const char *warn_msg = "refname '%.*s' is ambiguous.";
 348         char *real_ref = NULL;
 349         int refs_found = 0;
 350         int at, reflog_len;
 351
 352         if (len == 40 && !get_sha1_hex(str, sha1))
 353                 return 0;
 354
 355         /* basic@{time or number or -number} format to query ref-log */
 356         reflog_len = at = 0;
 357         if (len && str[len-1] == '}') {
 358                 for (at = len-2; at >= 0; at--) {
 359                         if (str[at] == '@' && str[at+1] == '{') {
 360                                 if (!upstream_mark(str + at, len - at)) {
 361                                         reflog_len = (len-1) - (at+2);
 362                                         len = at;
 363                                 }
 364                                 break;
 365                         }
 366                 }
 367         }
 368
 369         /* Accept only unambiguous ref paths. */
 370         if (len && ambiguous_path(str, len))
 371                 return -1;
 372
 373         if (!len && reflog_len) {
 374                 struct strbuf buf = STRBUF_INIT;
 375                 int ret;
 376                 /* try the @{-N} syntax for n-th checkout */
 377                 ret = interpret_branch_name(str+at, &buf);
 378                 if (ret > 0) {
 379                         /* substitute this branch name and restart */
 380                         return get_sha1_1(buf.buf, buf.len, sha1);
 381                 } else if (ret == 0) {
 382                         return -1;
 383                 }
 384                 /* allow "@{...}" to mean the current branch reflog */
 385                 refs_found = dwim_ref("HEAD", 4, sha1, &real_ref);
 386         } else if (reflog_len)
 387                 refs_found = dwim_log(str, len, sha1, &real_ref);
 388         else
 389                 refs_found = dwim_ref(str, len, sha1, &real_ref);
 390
 391         if (!refs_found)
 392                 return -1;
 393
 394         if (warn_ambiguous_refs && refs_found > 1)
 395                 warning(warn_msg, len, str);
 396
 397         if (reflog_len) {
 398                 int nth, i;
 399                 unsigned long at_time;
 400                 unsigned long co_time;
 401                 int co_tz, co_cnt;
 402
 403                 /* a @{-N} placed anywhere except the start is an error */
 404                 if (str[at+2] == '-')
 405                         return -1;
 406
 407                 /* Is it asking for N-th entry, or approxidate? */
 408                 for (i = nth = 0; 0 <= nth && i < reflog_len; i++) {
 409                         char ch = str[at+2+i];
 410                         if ('0' <= ch && ch <= '9')
 411                                 nth = nth * 10 + ch - '0';
 412                         else
 413                                 nth = -1;
 414                 }
 415                 if (100000000 <= nth) {
 416                         at_time = nth;
 417                         nth = -1;
 418                 } else if (0 <= nth)
 419                         at_time = 0;
 420                 else {
 421                         int errors = 0;
 422                         char *tmp = xstrndup(str + at + 2, reflog_len);
 423                         at_time = approxidate_careful(tmp, &errors);
 424                         free(tmp);
 425                         if (errors)
 426                                 return -1;
 427                 }
 428                 if (read_ref_at(real_ref, at_time, nth, sha1, NULL,
 429                                 &co_time, &co_tz, &co_cnt)) {
 430                         if (at_time)
 431                                 warning("Log for '%.*s' only goes "
 432                                         "back to %s.", len, str,
 433                                         show_date(co_time, co_tz, DATE_RFC2822));
 434                         else {
 435                                 free(real_ref);
 436                                 die("Log for '%.*s' only has %d entries.",
 437                                     len, str, co_cnt);
 438                         }
 439                 }
 440         }
 441
 442         free(real_ref);
 443         return 0;
 444 }
 445
 446 static int get_parent(const char *name, int len,
 447                       unsigned char *result, int idx)
 448 {
 449         unsigned char sha1[20];
 450         int ret = get_sha1_1(name, len, sha1);
 451         struct commit *commit;
 452         struct commit_list *p;
 453
 454         if (ret)
 455                 return ret;
 456         commit = lookup_commit_reference(sha1);
 457         if (!commit)
 458                 return -1;
 459         if (parse_commit(commit))
 460                 return -1;
 461         if (!idx) {
 462                 hashcpy(result, commit->object.sha1);
 463                 return 0;
 464         }
 465         p = commit->parents;
 466         while (p) {
 467                 if (!--idx) {
 468                         hashcpy(result, p->item->object.sha1);
 469                         return 0;
 470                 }
 471                 p = p->next;
 472         }
 473         return -1;
 474 }
 475
 476 static int get_nth_ancestor(const char *name, int len,
 477                             unsigned char *result, int generation)
 478 {
 479         unsigned char sha1[20];
 480         struct commit *commit;
 481         int ret;
 482
 483         ret = get_sha1_1(name, len, sha1);
 484         if (ret)
 485                 return ret;
 486         commit = lookup_commit_reference(sha1);
 487         if (!commit)
 488                 return -1;
 489
 490         while (generation--) {
 491                 if (parse_commit(commit) || !commit->parents)
 492                         return -1;
 493                 commit = commit->parents->item;
 494         }
 495         hashcpy(result, commit->object.sha1);
 496         return 0;
 497 }
 498
 499 struct object *peel_to_type(const char *name, int namelen,
 500                             struct object *o, enum object_type expected_type)
 501 {
 502         if (name && !namelen)
 503                 namelen = strlen(name);
 504         if (!o) {
 505                 unsigned char sha1[20];
 506                 if (get_sha1_1(name, namelen, sha1))
 507                         return NULL;
 508                 o = parse_object(sha1);
 509         }
 510         while (1) {
 511                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 512                         return NULL;
 513                 if (o->type == expected_type)
 514                         return o;
 515                 if (o->type == OBJ_TAG)
 516                         o = ((struct tag*) o)->tagged;
 517                 else if (o->type == OBJ_COMMIT)
 518                         o = &(((struct commit *) o)->tree->object);
 519                 else {
 520                         if (name)
 521                                 error("%.*s: expected %s type, but the object "
 522                                       "dereferences to %s type",
 523                                       namelen, name, typename(expected_type),
 524                                       typename(o->type));
 525                         return NULL;
 526                 }
 527         }
 528 }
 529
 530 static int peel_onion(const char *name, int len, unsigned char *sha1)
 531 {
 532         unsigned char outer[20];
 533         const char *sp;
 534         unsigned int expected_type = 0;
 535         struct object *o;
 536
 537         /*
 538          * "ref^{type}" dereferences ref repeatedly until you cannot
 539          * dereference anymore, or you get an object of given type,
 540          * whichever comes first.  "ref^{}" means just dereference
 541          * tags until you get a non-tag.  "ref^0" is a shorthand for
 542          * "ref^{commit}".  "commit^{tree}" could be used to find the
 543          * top-level tree of the given commit.
 544          */
 545         if (len < 4 || name[len-1] != '}')
 546                 return -1;
 547
 548         for (sp = name + len - 1; name <= sp; sp--) {
 549                 int ch = *sp;
 550                 if (ch == '{' && name < sp && sp[-1] == '^')
 551                         break;
 552         }
 553         if (sp <= name)
 554                 return -1;
 555
 556         sp++; /* beginning of type name, or closing brace for empty */
 557         if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
 558                 expected_type = OBJ_COMMIT;
 559         else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
 560                 expected_type = OBJ_TREE;
 561         else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
 562                 expected_type = OBJ_BLOB;
 563         else if (sp[0] == '}')
 564                 expected_type = OBJ_NONE;
 565         else
 566                 return -1;
 567
 568         if (get_sha1_1(name, sp - name - 2, outer))
 569                 return -1;
 570
 571         o = parse_object(outer);
 572         if (!o)
 573                 return -1;
 574         if (!expected_type) {
 575                 o = deref_tag(o, name, sp - name - 2);
 576                 if (!o || (!o->parsed && !parse_object(o->sha1)))
 577                         return -1;
 578                 hashcpy(sha1, o->sha1);
 579         }
 580         else {
 581                 /*
 582                  * At this point, the syntax look correct, so
 583                  * if we do not get the needed object, we should
 584                  * barf.
 585                  */
 586                 o = peel_to_type(name, len, o, expected_type);
 587                 if (o) {
 588                         hashcpy(sha1, o->sha1);
 589                         return 0;
 590                 }
 591                 return -1;
 592         }
 593         return 0;
 594 }
 595
 596 static int get_describe_name(const char *name, int len, unsigned char *sha1)
 597 {
 598         const char *cp;
 599
 600         for (cp = name + len - 1; name + 2 <= cp; cp--) {
 601                 char ch = *cp;
 602                 if (hexval(ch) & ~0377) {
 603                         /* We must be looking at g in "SOMETHING-g"
 604                          * for it to be describe output.
 605                          */
 606                         if (ch == 'g' && cp[-1] == '-') {
 607                                 cp++;
 608                                 len -= cp - name;
 609                                 return get_short_sha1(cp, len, sha1, 1);
 610                         }
 611                 }
 612         }
 613         return -1;
 614 }
 615
 616 static int get_sha1_1(const char *name, int len, unsigned char *sha1)
 617 {
 618         int ret, has_suffix;
 619         const char *cp;
 620
 621         /*
 622          * "name~3" is "name^^^", "name~" is "name~1", and "name^" is "name^1".
 623          */
 624         has_suffix = 0;
 625         for (cp = name + len - 1; name <= cp; cp--) {
 626                 int ch = *cp;
 627                 if ('0' <= ch && ch <= '9')
 628                         continue;
 629                 if (ch == '~' || ch == '^')
 630                         has_suffix = ch;
 631                 break;
 632         }
 633
 634         if (has_suffix) {
 635                 int num = 0;
 636                 int len1 = cp - name;
 637                 cp++;
 638                 while (cp < name + len)
 639                         num = num * 10 + *cp++ - '0';
 640                 if (!num && len1 == len - 1)
 641                         num = 1;
 642                 if (has_suffix == '^')
 643                         return get_parent(name, len1, sha1, num);
 644                 /* else if (has_suffix == '~') -- goes without saying */
 645                 return get_nth_ancestor(name, len1, sha1, num);
 646         }
 647
 648         ret = peel_onion(name, len, sha1);
 649         if (!ret)
 650                 return 0;
 651
 652         ret = get_sha1_basic(name, len, sha1);
 653         if (!ret)
 654                 return 0;
 655
 656         /* It could be describe output that is "SOMETHING-gXXXX" */
 657         ret = get_describe_name(name, len, sha1);
 658         if (!ret)
 659                 return 0;
 660
 661         return get_short_sha1(name, len, sha1, 0);
 662 }
 663
 664 /*
 665  * This interprets names like ':/Initial revision of "git"' by searching
 666  * through history and returning the first commit whose message starts
 667  * the given regular expression.
 668  *
 669  * For future extension, ':/!' is reserved. If you want to match a message
 670  * beginning with a '!', you have to repeat the exclamation mark.
 671  */
 672 #define ONELINE_SEEN (1u<<20)
 673
 674 static int handle_one_ref(const char *path,
 675                 const unsigned char *sha1, int flag, void *cb_data)
 676 {
 677         struct commit_list **list = cb_data;
 678         struct object *object = parse_object(sha1);
 679         if (!object)
 680                 return 0;
 681         if (object->type == OBJ_TAG) {
 682                 object = deref_tag(object, path, strlen(path));
 683                 if (!object)
 684                         return 0;
 685         }
 686         if (object->type != OBJ_COMMIT)
 687                 return 0;
 688         insert_by_date((struct commit *)object, list);
 689         object->flags |= ONELINE_SEEN;
 690         return 0;
 691 }
 692
 693 static int get_sha1_oneline(const char *prefix, unsigned char *sha1)
 694 {
 695         struct commit_list *list = NULL, *backup = NULL, *l;
 696         int retval = -1;
 697         char *temp_commit_buffer = NULL;
 698         regex_t regex;
 699
 700         if (prefix[0] == '!') {
 701                 if (prefix[1] != '!')
 702                         die ("Invalid search pattern: %s", prefix);
 703                 prefix++;
 704         }
 705
 706         if (regcomp(&regex, prefix, REG_EXTENDED))
 707                 die("Invalid search pattern: %s", prefix);
 708
 709         for_each_ref(handle_one_ref, &list);
 710         for (l = list; l; l = l->next)
 711                 commit_list_insert(l->item, &backup);
 712         while (list) {
 713                 char *p;
 714                 struct commit *commit;
 715                 enum object_type type;
 716                 unsigned long size;
 717
 718                 commit = pop_most_recent_commit(&list, ONELINE_SEEN);
 719                 if (!parse_object(commit->object.sha1))
 720                         continue;
 721                 free(temp_commit_buffer);
 722                 if (commit->buffer)
 723                         p = commit->buffer;
 724                 else {
 725                         p = read_sha1_file(commit->object.sha1, &type, &size);
 726                         if (!p)
 727                                 continue;
 728                         temp_commit_buffer = p;
 729                 }
 730                 if (!(p = strstr(p, "\n\n")))
 731                         continue;
 732                 if (!regexec(&regex, p + 2, 0, NULL, 0)) {
 733                         hashcpy(sha1, commit->object.sha1);
 734                         retval = 0;
 735                         break;
 736                 }
 737         }
 738         regfree(&regex);
 739         free(temp_commit_buffer);
 740         free_commit_list(list);
 741         for (l = backup; l; l = l->next)
 742                 clear_commit_marks(l->item, ONELINE_SEEN);
 743         return retval;
 744 }
 745
 746 struct grab_nth_branch_switch_cbdata {
 747         long cnt, alloc;
 748         struct strbuf *buf;
 749 };
 750
 751 static int grab_nth_branch_switch(unsigned char *osha1, unsigned char *nsha1,
 752                                   const char *email, unsigned long timestamp, int tz,
 753                                   const char *message, void *cb_data)
 754 {
 755         struct grab_nth_branch_switch_cbdata *cb = cb_data;
 756         const char *match = NULL, *target = NULL;
 757         size_t len;
 758         int nth;
 759
 760         if (!prefixcmp(message, "checkout: moving from ")) {
 761                 match = message + strlen("checkout: moving from ");
 762                 target = strstr(match, " to ");
 763         }
 764
 765         if (!match || !target)
 766                 return 0;
 767
 768         len = target - match;
 769         nth = cb->cnt++ % cb->alloc;
 770         strbuf_reset(&cb->buf[nth]);
 771         strbuf_add(&cb->buf[nth], match, len);
 772         return 0;
 773 }
 774
 775 /*
 776  * Parse @{-N} syntax, return the number of characters parsed
 777  * if successful; otherwise signal an error with negative value.
 778  */
 779 static int interpret_nth_prior_checkout(const char *name, struct strbuf *buf)
 780 {
 781         long nth;
 782         int i, retval;
 783         struct grab_nth_branch_switch_cbdata cb;
 784         const char *brace;
 785         char *num_end;
 786
 787         if (name[0] != '@' || name[1] != '{' || name[2] != '-')
 788                 return -1;
 789         brace = strchr(name, '}');
 790         if (!brace)
 791                 return -1;
 792         nth = strtol(name+3, &num_end, 10);
 793         if (num_end != brace)
 794                 return -1;
 795         if (nth <= 0)
 796                 return -1;
 797         cb.alloc = nth;
 798         cb.buf = xmalloc(nth * sizeof(struct strbuf));
 799         for (i = 0; i < nth; i++)
 800                 strbuf_init(&cb.buf[i], 20);
 801         cb.cnt = 0;
 802         retval = 0;
 803         for_each_recent_reflog_ent("HEAD", grab_nth_branch_switch, 40960, &cb);
 804         if (cb.cnt < nth) {
 805                 cb.cnt = 0;
 806                 for_each_reflog_ent("HEAD", grab_nth_branch_switch, &cb);
 807         }
 808         if (cb.cnt < nth)
 809                 goto release_return;
 810         i = cb.cnt % nth;
 811         strbuf_reset(buf);
 812         strbuf_add(buf, cb.buf[i].buf, cb.buf[i].len);
 813         retval = brace-name+1;
 814
 815 release_return:
 816         for (i = 0; i < nth; i++)
 817                 strbuf_release(&cb.buf[i]);
 818         free(cb.buf);
 819
 820         return retval;
 821 }
 822
 823 int get_sha1_mb(const char *name, unsigned char *sha1)
 824 {
 825         struct commit *one, *two;
 826         struct commit_list *mbs;
 827         unsigned char sha1_tmp[20];
 828         const char *dots;
 829         int st;
 830
 831         dots = strstr(name, "...");
 832         if (!dots)
 833                 return get_sha1(name, sha1);
 834         if (dots == name)
 835                 st = get_sha1("HEAD", sha1_tmp);
 836         else {
 837                 struct strbuf sb;
 838                 strbuf_init(&sb, dots - name);
 839                 strbuf_add(&sb, name, dots - name);
 840                 st = get_sha1(sb.buf, sha1_tmp);
 841                 strbuf_release(&sb);
 842         }
 843         if (st)
 844                 return st;
 845         one = lookup_commit_reference_gently(sha1_tmp, 0);
 846         if (!one)
 847                 return -1;
 848
 849         if (get_sha1(dots[3] ? (dots + 3) : "HEAD", sha1_tmp))
 850                 return -1;
 851         two = lookup_commit_reference_gently(sha1_tmp, 0);
 852         if (!two)
 853                 return -1;
 854         mbs = get_merge_bases(one, two, 1);
 855         if (!mbs || mbs->next)
 856                 st = -1;
 857         else {
 858                 st = 0;
 859                 hashcpy(sha1, mbs->item->object.sha1);
 860         }
 861         free_commit_list(mbs);
 862         return st;
 863 }
 864
 865 /*
 866  * This reads short-hand syntax that not only evaluates to a commit
 867  * object name, but also can act as if the end user spelled the name
 868  * of the branch from the command line.
 869  *
 870  * - "@{-N}" finds the name of the Nth previous branch we were on, and
 871  *   places the name of the branch in the given buf and returns the
 872  *   number of characters parsed if successful.
 873  *
 874  * - "<branch>@{upstream}" finds the name of the other ref that
 875  *   <branch> is configured to merge with (missing <branch> defaults
 876  *   to the current branch), and places the name of the branch in the
 877  *   given buf and returns the number of characters parsed if
 878  *   successful.
 879  *
 880  * If the input is not of the accepted format, it returns a negative
 881  * number to signal an error.
 882  *
 883  * If the input was ok but there are not N branch switches in the
 884  * reflog, it returns 0.
 885  */
 886 int interpret_branch_name(const char *name, struct strbuf *buf)
 887 {
 888         char *cp;
 889         struct branch *upstream;
 890         int namelen = strlen(name);
 891         int len = interpret_nth_prior_checkout(name, buf);
 892         int tmp_len;
 893
 894         if (!len)
 895                 return len; /* syntax Ok, not enough switches */
 896         if (0 < len && len == namelen)
 897                 return len; /* consumed all */
 898         else if (0 < len) {
 899                 /* we have extra data, which might need further processing */
 900                 struct strbuf tmp = STRBUF_INIT;
 901                 int used = buf->len;
 902                 int ret;
 903
 904                 strbuf_add(buf, name + len, namelen - len);
 905                 ret = interpret_branch_name(buf->buf, &tmp);
 906                 /* that data was not interpreted, remove our cruft */
 907                 if (ret < 0) {
 908                         strbuf_setlen(buf, used);
 909                         return len;
 910                 }
 911                 strbuf_reset(buf);
 912                 strbuf_addbuf(buf, &tmp);
 913                 strbuf_release(&tmp);
 914                 /* tweak for size of {-N} versus expanded ref name */
 915                 return ret - used + len;
 916         }
 917
 918         cp = strchr(name, '@');
 919         if (!cp)
 920                 return -1;
 921         tmp_len = upstream_mark(cp, namelen - (cp - name));
 922         if (!tmp_len)
 923                 return -1;
 924         len = cp + tmp_len - name;
 925         cp = xstrndup(name, cp - name);
 926         upstream = branch_get(*cp ? cp : NULL);
 927         if (!upstream
 928             || !upstream->merge
 929             || !upstream->merge[0]->dst)
 930                 return error("No upstream branch found for '%s'", cp);
 931         free(cp);
 932         cp = shorten_unambiguous_ref(upstream->merge[0]->dst, 0);
 933         strbuf_reset(buf);
 934         strbuf_addstr(buf, cp);
 935         free(cp);
 936         return len;
 937 }
 938
 939 /*
 940  * This is like "get_sha1_basic()", except it allows "sha1 expressions",
 941  * notably "xyz^" for "parent of xyz"
 942  */
 943 int get_sha1(const char *name, unsigned char *sha1)
 944 {
 945         struct object_context unused;
 946         return get_sha1_with_context(name, sha1, &unused);
 947 }
 948
 949 /* Must be called only when object_name:filename doesn't exist. */
 950 static void diagnose_invalid_sha1_path(const char *prefix,
 951                                        const char *filename,
 952                                        const unsigned char *tree_sha1,
 953                                        const char *object_name)
 954 {
 955         struct stat st;
 956         unsigned char sha1[20];
 957         unsigned mode;
 958
 959         if (!prefix)
 960                 prefix = "";
 961
 962         if (!lstat(filename, &st))
 963                 die("Path '%s' exists on disk, but not in '%s'.",
 964                     filename, object_name);
 965         if (errno == ENOENT || errno == ENOTDIR) {
 966                 char *fullname = xmalloc(strlen(filename)
 967                                              + strlen(prefix) + 1);
 968                 strcpy(fullname, prefix);
 969                 strcat(fullname, filename);
 970
 971                 if (!get_tree_entry(tree_sha1, fullname,
 972                                     sha1, &mode)) {
 973                         die("Path '%s' exists, but not '%s'.\n"
 974                             "Did you mean '%s:%s'?",
 975                             fullname,
 976                             filename,
 977                             object_name,
 978                             fullname);
 979                 }
 980                 die("Path '%s' does not exist in '%s'",
 981                     filename, object_name);
 982         }
 983 }
 984
 985 /* Must be called only when :stage:filename doesn't exist. */
 986 static void diagnose_invalid_index_path(int stage,
 987                                         const char *prefix,
 988                                         const char *filename)
 989 {
 990         struct stat st;
 991         struct cache_entry *ce;
 992         int pos;
 993         unsigned namelen = strlen(filename);
 994         unsigned fullnamelen;
 995         char *fullname;
 996
 997         if (!prefix)
 998                 prefix = "";
 999
1000         /* Wrong stage number? */
1001         pos = cache_name_pos(filename, namelen);
1002         if (pos < 0)
1003                 pos = -pos - 1;
1004         if (pos < active_nr) {
1005                 ce = active_cache[pos];
1006                 if (ce_namelen(ce) == namelen &&
1007                     !memcmp(ce->name, filename, namelen))
1008                         die("Path '%s' is in the index, but not at stage %d.\n"
1009                             "Did you mean ':%d:%s'?",
1010                             filename, stage,
1011                             ce_stage(ce), filename);
1012         }
1013
1014         /* Confusion between relative and absolute filenames? */
1015         fullnamelen = namelen + strlen(prefix);
1016         fullname = xmalloc(fullnamelen + 1);
1017         strcpy(fullname, prefix);
1018         strcat(fullname, filename);
1019         pos = cache_name_pos(fullname, fullnamelen);
1020         if (pos < 0)
1021                 pos = -pos - 1;
1022         if (pos < active_nr) {
1023                 ce = active_cache[pos];
1024                 if (ce_namelen(ce) == fullnamelen &&
1025                     !memcmp(ce->name, fullname, fullnamelen))
1026                         die("Path '%s' is in the index, but not '%s'.\n"
1027                             "Did you mean ':%d:%s'?",
1028                             fullname, filename,
1029                             ce_stage(ce), fullname);
1030         }
1031
1032         if (!lstat(filename, &st))
1033                 die("Path '%s' exists on disk, but not in the index.", filename);
1034         if (errno == ENOENT || errno == ENOTDIR)
1035                 die("Path '%s' does not exist (neither on disk nor in the index).",
1036                     filename);
1037
1038         free(fullname);
1039 }
1040
1041
1042 int get_sha1_with_mode_1(const char *name, unsigned char *sha1, unsigned *mode, int gently, const char *prefix)
1043 {
1044         struct object_context oc;
1045         int ret;
1046         ret = get_sha1_with_context_1(name, sha1, &oc, gently, prefix);
1047         *mode = oc.mode;
1048         return ret;
1049 }
1050
1051 int get_sha1_with_context_1(const char *name, unsigned char *sha1,
1052                             struct object_context *oc,
1053                             int gently, const char *prefix)
1054 {
1055         int ret, bracket_depth;
1056         int namelen = strlen(name);
1057         const char *cp;
1058
1059         memset(oc, 0, sizeof(*oc));
1060         oc->mode = S_IFINVALID;
1061         ret = get_sha1_1(name, namelen, sha1);
1062         if (!ret)
1063                 return ret;
1064         /* sha1:path --> object name of path in ent sha1
1065          * :path -> object name of path in index
1066          * :[0-3]:path -> object name of path in index at stage
1067          * :/foo -> recent commit matching foo
1068          */
1069         if (name[0] == ':') {
1070                 int stage = 0;
1071                 struct cache_entry *ce;
1072                 int pos;
1073                 if (namelen > 2 && name[1] == '/')
1074                         return get_sha1_oneline(name + 2, sha1);
1075                 if (namelen < 3 ||
1076                     name[2] != ':' ||
1077                     name[1] < '0' || '3' < name[1])
1078                         cp = name + 1;
1079                 else {
1080                         stage = name[1] - '0';
1081                         cp = name + 3;
1082                 }
1083                 namelen = namelen - (cp - name);
1084
1085                 strncpy(oc->path, cp,
1086                         sizeof(oc->path));
1087                 oc->path[sizeof(oc->path)-1] = '\0';
1088
1089                 if (!active_cache)
1090                         read_cache();
1091                 pos = cache_name_pos(cp, namelen);
1092                 if (pos < 0)
1093                         pos = -pos - 1;
1094                 while (pos < active_nr) {
1095                         ce = active_cache[pos];
1096                         if (ce_namelen(ce) != namelen ||
1097                             memcmp(ce->name, cp, namelen))
1098                                 break;
1099                         if (ce_stage(ce) == stage) {
1100                                 hashcpy(sha1, ce->sha1);
1101                                 return 0;
1102                         }
1103                         pos++;
1104                 }
1105                 if (!gently)
1106                         diagnose_invalid_index_path(stage, prefix, cp);
1107                 return -1;
1108         }
1109         for (cp = name, bracket_depth = 0; *cp; cp++) {
1110                 if (*cp == '{')
1111                         bracket_depth++;
1112                 else if (bracket_depth && *cp == '}')
1113                         bracket_depth--;
1114                 else if (!bracket_depth && *cp == ':')
1115                         break;
1116         }
1117         if (*cp == ':') {
1118                 unsigned char tree_sha1[20];
1119                 char *object_name = NULL;
1120                 if (!gently) {
1121                         object_name = xmalloc(cp-name+1);
1122                         strncpy(object_name, name, cp-name);
1123                         object_name[cp-name] = '\0';
1124                 }
1125                 if (!get_sha1_1(name, cp-name, tree_sha1)) {
1126                         const char *filename = cp+1;
1127                         ret = get_tree_entry(tree_sha1, filename, sha1, &oc->mode);
1128                         if (!gently) {
1129                                 diagnose_invalid_sha1_path(prefix, filename,
1130                                                            tree_sha1, object_name);
1131                                 free(object_name);
1132                         }
1133                         hashcpy(oc->tree, tree_sha1);
1134                         strncpy(oc->path, filename,
1135                                 sizeof(oc->path));
1136                         oc->path[sizeof(oc->path)-1] = '\0';
1137
1138                         return ret;
1139                 } else {
1140                         if (!gently)
1141                                 die("Invalid object name '%s'.", object_name);
1142                 }
1143         }
1144         return ret;
1145 }