refs.c

   1 #include "cache.h"
   2 #include "refs.h"
   3 #include "object.h"
   4 #include "tag.h"
   5 #include "dir.h"
   6
   7 /* ISSYMREF=01 and ISPACKED=02 are public interfaces */
   8 #define REF_KNOWS_PEELED 04
   9
  10 struct ref_list {
  11         struct ref_list *next;
  12         unsigned char flag; /* ISSYMREF? ISPACKED? */
  13         unsigned char sha1[20];
  14         unsigned char peeled[20];
  15         char name[FLEX_ARRAY];
  16 };
  17
  18 static const char *parse_ref_line(char *line, unsigned char *sha1)
  19 {
  20         /*
  21          * 42: the answer to everything.
  22          *
  23          * In this case, it happens to be the answer to
  24          *  40 (length of sha1 hex representation)
  25          *  +1 (space in between hex and name)
  26          *  +1 (newline at the end of the line)
  27          */
  28         int len = strlen(line) - 42;
  29
  30         if (len <= 0)
  31                 return NULL;
  32         if (get_sha1_hex(line, sha1) < 0)
  33                 return NULL;
  34         if (!isspace(line[40]))
  35                 return NULL;
  36         line += 41;
  37         if (isspace(*line))
  38                 return NULL;
  39         if (line[len] != '\n')
  40                 return NULL;
  41         line[len] = 0;
  42
  43         return line;
  44 }
  45
  46 static struct ref_list *add_ref(const char *name, const unsigned char *sha1,
  47                                 int flag, struct ref_list *list,
  48                                 struct ref_list **new_entry)
  49 {
  50         int len;
  51         struct ref_list *entry;
  52
  53         /* Allocate it and add it in.. */
  54         len = strlen(name) + 1;
  55         entry = xmalloc(sizeof(struct ref_list) + len);
  56         hashcpy(entry->sha1, sha1);
  57         hashclr(entry->peeled);
  58         memcpy(entry->name, name, len);
  59         entry->flag = flag;
  60         entry->next = list;
  61         if (new_entry)
  62                 *new_entry = entry;
  63         return entry;
  64 }
  65
  66 /* merge sort the ref list */
  67 static struct ref_list *sort_ref_list(struct ref_list *list)
  68 {
  69         int psize, qsize, last_merge_count, cmp;
  70         struct ref_list *p, *q, *l, *e;
  71         struct ref_list *new_list = list;
  72         int k = 1;
  73         int merge_count = 0;
  74
  75         if (!list)
  76                 return list;
  77
  78         do {
  79                 last_merge_count = merge_count;
  80                 merge_count = 0;
  81
  82                 psize = 0;
  83
  84                 p = new_list;
  85                 q = new_list;
  86                 new_list = NULL;
  87                 l = NULL;
  88
  89                 while (p) {
  90                         merge_count++;
  91
  92                         while (psize < k && q->next) {
  93                                 q = q->next;
  94                                 psize++;
  95                         }
  96                         qsize = k;
  97
  98                         while ((psize > 0) || (qsize > 0 && q)) {
  99                                 if (qsize == 0 || !q) {
 100                                         e = p;
 101                                         p = p->next;
 102                                         psize--;
 103                                 } else if (psize == 0) {
 104                                         e = q;
 105                                         q = q->next;
 106                                         qsize--;
 107                                 } else {
 108                                         cmp = strcmp(q->name, p->name);
 109                                         if (cmp < 0) {
 110                                                 e = q;
 111                                                 q = q->next;
 112                                                 qsize--;
 113                                         } else if (cmp > 0) {
 114                                                 e = p;
 115                                                 p = p->next;
 116                                                 psize--;
 117                                         } else {
 118                                                 if (hashcmp(q->sha1, p->sha1))
 119                                                         die("Duplicated ref, and SHA1s don't match: %s",
 120                                                             q->name);
 121                                                 warning("Duplicated ref: %s", q->name);
 122                                                 e = q;
 123                                                 q = q->next;
 124                                                 qsize--;
 125                                                 free(e);
 126                                                 e = p;
 127                                                 p = p->next;
 128                                                 psize--;
 129                                         }
 130                                 }
 131
 132                                 e->next = NULL;
 133
 134                                 if (l)
 135                                         l->next = e;
 136                                 if (!new_list)
 137                                         new_list = e;
 138                                 l = e;
 139                         }
 140
 141                         p = q;
 142                 };
 143
 144                 k = k * 2;
 145         } while ((last_merge_count != merge_count) || (last_merge_count != 1));
 146
 147         return new_list;
 148 }
 149
 150 /*
 151  * Future: need to be in "struct repository"
 152  * when doing a full libification.
 153  */
 154 static struct cached_refs {
 155         char did_loose;
 156         char did_packed;
 157         struct ref_list *loose;
 158         struct ref_list *packed;
 159 } cached_refs;
 160 static struct ref_list *current_ref;
 161
 162 static struct ref_list *extra_refs;
 163
 164 static void free_ref_list(struct ref_list *list)
 165 {
 166         struct ref_list *next;
 167         for ( ; list; list = next) {
 168                 next = list->next;
 169                 free(list);
 170         }
 171 }
 172
 173 static void invalidate_cached_refs(void)
 174 {
 175         struct cached_refs *ca = &cached_refs;
 176
 177         if (ca->did_loose && ca->loose)
 178                 free_ref_list(ca->loose);
 179         if (ca->did_packed && ca->packed)
 180                 free_ref_list(ca->packed);
 181         ca->loose = ca->packed = NULL;
 182         ca->did_loose = ca->did_packed = 0;
 183 }
 184
 185 static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
 186 {
 187         struct ref_list *list = NULL;
 188         struct ref_list *last = NULL;
 189         char refline[PATH_MAX];
 190         int flag = REF_ISPACKED;
 191
 192         while (fgets(refline, sizeof(refline), f)) {
 193                 unsigned char sha1[20];
 194                 const char *name;
 195                 static const char header[] = "# pack-refs with:";
 196
 197                 if (!strncmp(refline, header, sizeof(header)-1)) {
 198                         const char *traits = refline + sizeof(header) - 1;
 199                         if (strstr(traits, " peeled "))
 200                                 flag |= REF_KNOWS_PEELED;
 201                         /* perhaps other traits later as well */
 202                         continue;
 203                 }
 204
 205                 name = parse_ref_line(refline, sha1);
 206                 if (name) {
 207                         list = add_ref(name, sha1, flag, list, &last);
 208                         continue;
 209                 }
 210                 if (last &&
 211                     refline[0] == '^' &&
 212                     strlen(refline) == 42 &&
 213                     refline[41] == '\n' &&
 214                     !get_sha1_hex(refline + 1, sha1))
 215                         hashcpy(last->peeled, sha1);
 216         }
 217         cached_refs->packed = sort_ref_list(list);
 218 }
 219
 220 void add_extra_ref(const char *name, const unsigned char *sha1, int flag)
 221 {
 222         extra_refs = add_ref(name, sha1, flag, extra_refs, NULL);
 223 }
 224
 225 void clear_extra_refs(void)
 226 {
 227         free_ref_list(extra_refs);
 228         extra_refs = NULL;
 229 }
 230
 231 static struct ref_list *get_packed_refs(void)
 232 {
 233         if (!cached_refs.did_packed) {
 234                 FILE *f = fopen(git_path("packed-refs"), "r");
 235                 cached_refs.packed = NULL;
 236                 if (f) {
 237                         read_packed_refs(f, &cached_refs);
 238                         fclose(f);
 239                 }
 240                 cached_refs.did_packed = 1;
 241         }
 242         return cached_refs.packed;
 243 }
 244
 245 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
 246 {
 247         DIR *dir = opendir(git_path("%s", base));
 248
 249         if (dir) {
 250                 struct dirent *de;
 251                 int baselen = strlen(base);
 252                 char *ref = xmalloc(baselen + 257);
 253
 254                 memcpy(ref, base, baselen);
 255                 if (baselen && base[baselen-1] != '/')
 256                         ref[baselen++] = '/';
 257
 258                 while ((de = readdir(dir)) != NULL) {
 259                         unsigned char sha1[20];
 260                         struct stat st;
 261                         int flag;
 262                         int namelen;
 263
 264                         if (de->d_name[0] == '.')
 265                                 continue;
 266                         namelen = strlen(de->d_name);
 267                         if (namelen > 255)
 268                                 continue;
 269                         if (has_extension(de->d_name, ".lock"))
 270                                 continue;
 271                         memcpy(ref + baselen, de->d_name, namelen+1);
 272                         if (stat(git_path("%s", ref), &st) < 0)
 273                                 continue;
 274                         if (S_ISDIR(st.st_mode)) {
 275                                 list = get_ref_dir(ref, list);
 276                                 continue;
 277                         }
 278                         if (!resolve_ref(ref, sha1, 1, &flag))
 279                                 hashclr(sha1);
 280                         list = add_ref(ref, sha1, flag, list, NULL);
 281                 }
 282                 free(ref);
 283                 closedir(dir);
 284         }
 285         return sort_ref_list(list);
 286 }
 287
 288 struct warn_if_dangling_data {
 289         const char *refname;
 290         const char *msg_fmt;
 291 };
 292
 293 static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
 294                                    int flags, void *cb_data)
 295 {
 296         struct warn_if_dangling_data *d = cb_data;
 297         const char *resolves_to;
 298         unsigned char junk[20];
 299
 300         if (!(flags & REF_ISSYMREF))
 301                 return 0;
 302
 303         resolves_to = resolve_ref(refname, junk, 0, NULL);
 304         if (!resolves_to || strcmp(resolves_to, d->refname))
 305                 return 0;
 306
 307         printf(d->msg_fmt, refname);
 308         return 0;
 309 }
 310
 311 void warn_dangling_symref(const char *msg_fmt, const char *refname)
 312 {
 313         struct warn_if_dangling_data data = { refname, msg_fmt };
 314         for_each_rawref(warn_if_dangling_symref, &data);
 315 }
 316
 317 static struct ref_list *get_loose_refs(void)
 318 {
 319         if (!cached_refs.did_loose) {
 320                 cached_refs.loose = get_ref_dir("refs", NULL);
 321                 cached_refs.did_loose = 1;
 322         }
 323         return cached_refs.loose;
 324 }
 325
 326 /* We allow "recursive" symbolic refs. Only within reason, though */
 327 #define MAXDEPTH 5
 328 #define MAXREFLEN (1024)
 329
 330 static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
 331 {
 332         FILE *f;
 333         struct cached_refs refs;
 334         struct ref_list *ref;
 335         int retval;
 336
 337         strcpy(name + pathlen, "packed-refs");
 338         f = fopen(name, "r");
 339         if (!f)
 340                 return -1;
 341         read_packed_refs(f, &refs);
 342         fclose(f);
 343         ref = refs.packed;
 344         retval = -1;
 345         while (ref) {
 346                 if (!strcmp(ref->name, refname)) {
 347                         retval = 0;
 348                         memcpy(result, ref->sha1, 20);
 349                         break;
 350                 }
 351                 ref = ref->next;
 352         }
 353         free_ref_list(refs.packed);
 354         return retval;
 355 }
 356
 357 static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
 358 {
 359         int fd, len = strlen(refname);
 360         char buffer[128], *p;
 361
 362         if (recursion > MAXDEPTH || len > MAXREFLEN)
 363                 return -1;
 364         memcpy(name + pathlen, refname, len+1);
 365         fd = open(name, O_RDONLY);
 366         if (fd < 0)
 367                 return resolve_gitlink_packed_ref(name, pathlen, refname, result);
 368
 369         len = read(fd, buffer, sizeof(buffer)-1);
 370         close(fd);
 371         if (len < 0)
 372                 return -1;
 373         while (len && isspace(buffer[len-1]))
 374                 len--;
 375         buffer[len] = 0;
 376
 377         /* Was it a detached head or an old-fashioned symlink? */
 378         if (!get_sha1_hex(buffer, result))
 379                 return 0;
 380
 381         /* Symref? */
 382         if (strncmp(buffer, "ref:", 4))
 383                 return -1;
 384         p = buffer + 4;
 385         while (isspace(*p))
 386                 p++;
 387
 388         return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
 389 }
 390
 391 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
 392 {
 393         int len = strlen(path), retval;
 394         char *gitdir;
 395         const char *tmp;
 396
 397         while (len && path[len-1] == '/')
 398                 len--;
 399         if (!len)
 400                 return -1;
 401         gitdir = xmalloc(len + MAXREFLEN + 8);
 402         memcpy(gitdir, path, len);
 403         memcpy(gitdir + len, "/.git", 6);
 404         len += 5;
 405
 406         tmp = read_gitfile_gently(gitdir);
 407         if (tmp) {
 408                 free(gitdir);
 409                 len = strlen(tmp);
 410                 gitdir = xmalloc(len + MAXREFLEN + 3);
 411                 memcpy(gitdir, tmp, len);
 412         }
 413         gitdir[len] = '/';
 414         gitdir[++len] = '\0';
 415         retval = resolve_gitlink_ref_recursive(gitdir, len, refname, result, 0);
 416         free(gitdir);
 417         return retval;
 418 }
 419
 420 /*
 421  * If the "reading" argument is set, this function finds out what _object_
 422  * the ref points at by "reading" the ref.  The ref, if it is not symbolic,
 423  * has to exist, and if it is symbolic, it has to point at an existing ref,
 424  * because the "read" goes through the symref to the ref it points at.
 425  *
 426  * The access that is not "reading" may often be "writing", but does not
 427  * have to; it can be merely checking _where it leads to_. If it is a
 428  * prelude to "writing" to the ref, a write to a symref that points at
 429  * yet-to-be-born ref will create the real ref pointed by the symref.
 430  * reading=0 allows the caller to check where such a symref leads to.
 431  */
 432 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 433 {
 434         int depth = MAXDEPTH;
 435         ssize_t len;
 436         char buffer[256];
 437         static char ref_buffer[256];
 438
 439         if (flag)
 440                 *flag = 0;
 441
 442         for (;;) {
 443                 char path[PATH_MAX];
 444                 struct stat st;
 445                 char *buf;
 446                 int fd;
 447
 448                 if (--depth < 0)
 449                         return NULL;
 450
 451                 git_snpath(path, sizeof(path), "%s", ref);
 452                 /* Special case: non-existing file. */
 453                 if (lstat(path, &st) < 0) {
 454                         struct ref_list *list = get_packed_refs();
 455                         while (list) {
 456                                 if (!strcmp(ref, list->name)) {
 457                                         hashcpy(sha1, list->sha1);
 458                                         if (flag)
 459                                                 *flag |= REF_ISPACKED;
 460                                         return ref;
 461                                 }
 462                                 list = list->next;
 463                         }
 464                         if (reading || errno != ENOENT)
 465                                 return NULL;
 466                         hashclr(sha1);
 467                         return ref;
 468                 }
 469
 470                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 471                 if (S_ISLNK(st.st_mode)) {
 472                         len = readlink(path, buffer, sizeof(buffer)-1);
 473                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 474                                 buffer[len] = 0;
 475                                 strcpy(ref_buffer, buffer);
 476                                 ref = ref_buffer;
 477                                 if (flag)
 478                                         *flag |= REF_ISSYMREF;
 479                                 continue;
 480                         }
 481                 }
 482
 483                 /* Is it a directory? */
 484                 if (S_ISDIR(st.st_mode)) {
 485                         errno = EISDIR;
 486                         return NULL;
 487                 }
 488
 489                 /*
 490                  * Anything else, just open it and try to use it as
 491                  * a ref
 492                  */
 493                 fd = open(path, O_RDONLY);
 494                 if (fd < 0)
 495                         return NULL;
 496                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
 497                 close(fd);
 498
 499                 /*
 500                  * Is it a symbolic ref?
 501                  */
 502                 if (len < 4 || memcmp("ref:", buffer, 4))
 503                         break;
 504                 buf = buffer + 4;
 505                 len -= 4;
 506                 while (len && isspace(*buf))
 507                         buf++, len--;
 508                 while (len && isspace(buf[len-1]))
 509                         len--;
 510                 buf[len] = 0;
 511                 memcpy(ref_buffer, buf, len + 1);
 512                 ref = ref_buffer;
 513                 if (flag)
 514                         *flag |= REF_ISSYMREF;
 515         }
 516         if (len < 40 || get_sha1_hex(buffer, sha1))
 517                 return NULL;
 518         return ref;
 519 }
 520
 521 int read_ref(const char *ref, unsigned char *sha1)
 522 {
 523         if (resolve_ref(ref, sha1, 1, NULL))
 524                 return 0;
 525         return -1;
 526 }
 527
 528 #define DO_FOR_EACH_INCLUDE_BROKEN 01
 529 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
 530                       int flags, void *cb_data, struct ref_list *entry)
 531 {
 532         if (strncmp(base, entry->name, trim))
 533                 return 0;
 534         /* Is this a "negative ref" that represents a deleted ref? */
 535         if (is_null_sha1(entry->sha1))
 536                 return 0;
 537         if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
 538                 if (!has_sha1_file(entry->sha1)) {
 539                         error("%s does not point to a valid object!", entry->name);
 540                         return 0;
 541                 }
 542         }
 543         current_ref = entry;
 544         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 545 }
 546
 547 int peel_ref(const char *ref, unsigned char *sha1)
 548 {
 549         int flag;
 550         unsigned char base[20];
 551         struct object *o;
 552
 553         if (current_ref && (current_ref->name == ref
 554                 || !strcmp(current_ref->name, ref))) {
 555                 if (current_ref->flag & REF_KNOWS_PEELED) {
 556                         hashcpy(sha1, current_ref->peeled);
 557                         return 0;
 558                 }
 559                 hashcpy(base, current_ref->sha1);
 560                 goto fallback;
 561         }
 562
 563         if (!resolve_ref(ref, base, 1, &flag))
 564                 return -1;
 565
 566         if ((flag & REF_ISPACKED)) {
 567                 struct ref_list *list = get_packed_refs();
 568
 569                 while (list) {
 570                         if (!strcmp(list->name, ref)) {
 571                                 if (list->flag & REF_KNOWS_PEELED) {
 572                                         hashcpy(sha1, list->peeled);
 573                                         return 0;
 574                                 }
 575                                 /* older pack-refs did not leave peeled ones */
 576                                 break;
 577                         }
 578                         list = list->next;
 579                 }
 580         }
 581
 582 fallback:
 583         o = parse_object(base);
 584         if (o && o->type == OBJ_TAG) {
 585                 o = deref_tag(o, ref, 0);
 586                 if (o) {
 587                         hashcpy(sha1, o->sha1);
 588                         return 0;
 589                 }
 590         }
 591         return -1;
 592 }
 593
 594 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
 595                            int flags, void *cb_data)
 596 {
 597         int retval = 0;
 598         struct ref_list *packed = get_packed_refs();
 599         struct ref_list *loose = get_loose_refs();
 600
 601         struct ref_list *extra;
 602
 603         for (extra = extra_refs; extra; extra = extra->next)
 604                 retval = do_one_ref(base, fn, trim, flags, cb_data, extra);
 605
 606         while (packed && loose) {
 607                 struct ref_list *entry;
 608                 int cmp = strcmp(packed->name, loose->name);
 609                 if (!cmp) {
 610                         packed = packed->next;
 611                         continue;
 612                 }
 613                 if (cmp > 0) {
 614                         entry = loose;
 615                         loose = loose->next;
 616                 } else {
 617                         entry = packed;
 618                         packed = packed->next;
 619                 }
 620                 retval = do_one_ref(base, fn, trim, flags, cb_data, entry);
 621                 if (retval)
 622                         goto end_each;
 623         }
 624
 625         for (packed = packed ? packed : loose; packed; packed = packed->next) {
 626                 retval = do_one_ref(base, fn, trim, flags, cb_data, packed);
 627                 if (retval)
 628                         goto end_each;
 629         }
 630
 631 end_each:
 632         current_ref = NULL;
 633         return retval;
 634 }
 635
 636 int head_ref(each_ref_fn fn, void *cb_data)
 637 {
 638         unsigned char sha1[20];
 639         int flag;
 640
 641         if (resolve_ref("HEAD", sha1, 1, &flag))
 642                 return fn("HEAD", sha1, flag, cb_data);
 643         return 0;
 644 }
 645
 646 int for_each_ref(each_ref_fn fn, void *cb_data)
 647 {
 648         return do_for_each_ref("refs/", fn, 0, 0, cb_data);
 649 }
 650
 651 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
 652 {
 653         return do_for_each_ref(prefix, fn, strlen(prefix), 0, cb_data);
 654 }
 655
 656 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 657 {
 658         return for_each_ref_in("refs/tags/", fn, cb_data);
 659 }
 660
 661 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 662 {
 663         return for_each_ref_in("refs/heads/", fn, cb_data);
 664 }
 665
 666 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 667 {
 668         return for_each_ref_in("refs/remotes/", fn, cb_data);
 669 }
 670
 671 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
 672 {
 673         return do_for_each_ref("refs/replace/", fn, 13, 0, cb_data);
 674 }
 675
 676 int for_each_rawref(each_ref_fn fn, void *cb_data)
 677 {
 678         return do_for_each_ref("refs/", fn, 0,
 679                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
 680 }
 681
 682 /*
 683  * Make sure "ref" is something reasonable to have under ".git/refs/";
 684  * We do not like it if:
 685  *
 686  * - any path component of it begins with ".", or
 687  * - it has double dots "..", or
 688  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 689  * - it ends with a "/".
 690  * - it ends with ".lock"
 691  * - it contains a "\" (backslash)
 692  */
 693
 694 static inline int bad_ref_char(int ch)
 695 {
 696         if (((unsigned) ch) <= ' ' ||
 697             ch == '~' || ch == '^' || ch == ':' || ch == '\\')
 698                 return 1;
 699         /* 2.13 Pattern Matching Notation */
 700         if (ch == '?' || ch == '[') /* Unsupported */
 701                 return 1;
 702         if (ch == '*') /* Supported at the end */
 703                 return 2;
 704         return 0;
 705 }
 706
 707 int check_ref_format(const char *ref)
 708 {
 709         int ch, level, bad_type, last;
 710         int ret = CHECK_REF_FORMAT_OK;
 711         const char *cp = ref;
 712
 713         level = 0;
 714         while (1) {
 715                 while ((ch = *cp++) == '/')
 716                         ; /* tolerate duplicated slashes */
 717                 if (!ch)
 718                         /* should not end with slashes */
 719                         return CHECK_REF_FORMAT_ERROR;
 720
 721                 /* we are at the beginning of the path component */
 722                 if (ch == '.')
 723                         return CHECK_REF_FORMAT_ERROR;
 724                 bad_type = bad_ref_char(ch);
 725                 if (bad_type) {
 726                         if (bad_type == 2 && (!*cp || *cp == '/') &&
 727                             ret == CHECK_REF_FORMAT_OK)
 728                                 ret = CHECK_REF_FORMAT_WILDCARD;
 729                         else
 730                                 return CHECK_REF_FORMAT_ERROR;
 731                 }
 732
 733                 last = ch;
 734                 /* scan the rest of the path component */
 735                 while ((ch = *cp++) != 0) {
 736                         bad_type = bad_ref_char(ch);
 737                         if (bad_type)
 738                                 return CHECK_REF_FORMAT_ERROR;
 739                         if (ch == '/')
 740                                 break;
 741                         if (last == '.' && ch == '.')
 742                                 return CHECK_REF_FORMAT_ERROR;
 743                         if (last == '@' && ch == '{')
 744                                 return CHECK_REF_FORMAT_ERROR;
 745                         last = ch;
 746                 }
 747                 level++;
 748                 if (!ch) {
 749                         if (ref <= cp - 2 && cp[-2] == '.')
 750                                 return CHECK_REF_FORMAT_ERROR;
 751                         if (level < 2)
 752                                 return CHECK_REF_FORMAT_ONELEVEL;
 753                         if (has_extension(ref, ".lock"))
 754                                 return CHECK_REF_FORMAT_ERROR;
 755                         return ret;
 756                 }
 757         }
 758 }
 759
 760 const char *prettify_refname(const char *name)
 761 {
 762         return name + (
 763                 !prefixcmp(name, "refs/heads/") ? 11 :
 764                 !prefixcmp(name, "refs/tags/") ? 10 :
 765                 !prefixcmp(name, "refs/remotes/") ? 13 :
 766                 0);
 767 }
 768
 769 const char *ref_rev_parse_rules[] = {
 770         "%.*s",
 771         "refs/%.*s",
 772         "refs/tags/%.*s",
 773         "refs/heads/%.*s",
 774         "refs/remotes/%.*s",
 775         "refs/remotes/%.*s/HEAD",
 776         NULL
 777 };
 778
 779 const char *ref_fetch_rules[] = {
 780         "%.*s",
 781         "refs/%.*s",
 782         "refs/heads/%.*s",
 783         NULL
 784 };
 785
 786 int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
 787 {
 788         const char **p;
 789         const int abbrev_name_len = strlen(abbrev_name);
 790
 791         for (p = rules; *p; p++) {
 792                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
 793                         return 1;
 794                 }
 795         }
 796
 797         return 0;
 798 }
 799
 800 static struct ref_lock *verify_lock(struct ref_lock *lock,
 801         const unsigned char *old_sha1, int mustexist)
 802 {
 803         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
 804                 error("Can't verify ref %s", lock->ref_name);
 805                 unlock_ref(lock);
 806                 return NULL;
 807         }
 808         if (hashcmp(lock->old_sha1, old_sha1)) {
 809                 error("Ref %s is at %s but expected %s", lock->ref_name,
 810                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 811                 unlock_ref(lock);
 812                 return NULL;
 813         }
 814         return lock;
 815 }
 816
 817 static int remove_empty_directories(const char *file)
 818 {
 819         /* we want to create a file but there is a directory there;
 820          * if that is an empty directory (or a directory that contains
 821          * only empty directories), remove them.
 822          */
 823         struct strbuf path;
 824         int result;
 825
 826         strbuf_init(&path, 20);
 827         strbuf_addstr(&path, file);
 828
 829         result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
 830
 831         strbuf_release(&path);
 832
 833         return result;
 834 }
 835
 836 static int is_refname_available(const char *ref, const char *oldref,
 837                                 struct ref_list *list, int quiet)
 838 {
 839         int namlen = strlen(ref); /* e.g. 'foo/bar' */
 840         while (list) {
 841                 /* list->name could be 'foo' or 'foo/bar/baz' */
 842                 if (!oldref || strcmp(oldref, list->name)) {
 843                         int len = strlen(list->name);
 844                         int cmplen = (namlen < len) ? namlen : len;
 845                         const char *lead = (namlen < len) ? list->name : ref;
 846                         if (!strncmp(ref, list->name, cmplen) &&
 847                             lead[cmplen] == '/') {
 848                                 if (!quiet)
 849                                         error("'%s' exists; cannot create '%s'",
 850                                               list->name, ref);
 851                                 return 0;
 852                         }
 853                 }
 854                 list = list->next;
 855         }
 856         return 1;
 857 }
 858
 859 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
 860 {
 861         char *ref_file;
 862         const char *orig_ref = ref;
 863         struct ref_lock *lock;
 864         int last_errno = 0;
 865         int type, lflags;
 866         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 867         int missing = 0;
 868
 869         lock = xcalloc(1, sizeof(struct ref_lock));
 870         lock->lock_fd = -1;
 871
 872         ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
 873         if (!ref && errno == EISDIR) {
 874                 /* we are trying to lock foo but we used to
 875                  * have foo/bar which now does not exist;
 876                  * it is normal for the empty directory 'foo'
 877                  * to remain.
 878                  */
 879                 ref_file = git_path("%s", orig_ref);
 880                 if (remove_empty_directories(ref_file)) {
 881                         last_errno = errno;
 882                         error("there are still refs under '%s'", orig_ref);
 883                         goto error_return;
 884                 }
 885                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
 886         }
 887         if (type_p)
 888             *type_p = type;
 889         if (!ref) {
 890                 last_errno = errno;
 891                 error("unable to resolve reference %s: %s",
 892                         orig_ref, strerror(errno));
 893                 goto error_return;
 894         }
 895         missing = is_null_sha1(lock->old_sha1);
 896         /* When the ref did not exist and we are creating it,
 897          * make sure there is no existing ref that is packed
 898          * whose name begins with our refname, nor a ref whose
 899          * name is a proper prefix of our refname.
 900          */
 901         if (missing &&
 902              !is_refname_available(ref, NULL, get_packed_refs(), 0)) {
 903                 last_errno = ENOTDIR;
 904                 goto error_return;
 905         }
 906
 907         lock->lk = xcalloc(1, sizeof(struct lock_file));
 908
 909         lflags = LOCK_DIE_ON_ERROR;
 910         if (flags & REF_NODEREF) {
 911                 ref = orig_ref;
 912                 lflags |= LOCK_NODEREF;
 913         }
 914         lock->ref_name = xstrdup(ref);
 915         lock->orig_ref_name = xstrdup(orig_ref);
 916         ref_file = git_path("%s", ref);
 917         if (missing)
 918                 lock->force_write = 1;
 919         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
 920                 lock->force_write = 1;
 921
 922         if (safe_create_leading_directories(ref_file)) {
 923                 last_errno = errno;
 924                 error("unable to create directory for %s", ref_file);
 925                 goto error_return;
 926         }
 927
 928         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
 929         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 930
 931  error_return:
 932         unlock_ref(lock);
 933         errno = last_errno;
 934         return NULL;
 935 }
 936
 937 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 938 {
 939         char refpath[PATH_MAX];
 940         if (check_ref_format(ref))
 941                 return NULL;
 942         strcpy(refpath, mkpath("refs/%s", ref));
 943         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
 944 }
 945
 946 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
 947 {
 948         switch (check_ref_format(ref)) {
 949         default:
 950                 return NULL;
 951         case 0:
 952         case CHECK_REF_FORMAT_ONELEVEL:
 953                 return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
 954         }
 955 }
 956
 957 static struct lock_file packlock;
 958
 959 static int repack_without_ref(const char *refname)
 960 {
 961         struct ref_list *list, *packed_ref_list;
 962         int fd;
 963         int found = 0;
 964
 965         packed_ref_list = get_packed_refs();
 966         for (list = packed_ref_list; list; list = list->next) {
 967                 if (!strcmp(refname, list->name)) {
 968                         found = 1;
 969                         break;
 970                 }
 971         }
 972         if (!found)
 973                 return 0;
 974         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
 975         if (fd < 0) {
 976                 unable_to_lock_error(git_path("packed-refs"), errno);
 977                 return error("cannot delete '%s' from packed refs", refname);
 978         }
 979
 980         for (list = packed_ref_list; list; list = list->next) {
 981                 char line[PATH_MAX + 100];
 982                 int len;
 983
 984                 if (!strcmp(refname, list->name))
 985                         continue;
 986                 len = snprintf(line, sizeof(line), "%s %s\n",
 987                                sha1_to_hex(list->sha1), list->name);
 988                 /* this should not happen but just being defensive */
 989                 if (len > sizeof(line))
 990                         die("too long a refname '%s'", list->name);
 991                 write_or_die(fd, line, len);
 992         }
 993         return commit_lock_file(&packlock);
 994 }
 995
 996 int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
 997 {
 998         struct ref_lock *lock;
 999         int err, i = 0, ret = 0, flag = 0;
1000
1001         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
1002         if (!lock)
1003                 return 1;
1004         if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
1005                 /* loose */
1006                 const char *path;
1007
1008                 if (!(delopt & REF_NODEREF)) {
1009                         i = strlen(lock->lk->filename) - 5; /* .lock */
1010                         lock->lk->filename[i] = 0;
1011                         path = lock->lk->filename;
1012                 } else {
1013                         path = git_path("%s", refname);
1014                 }
1015                 err = unlink_or_warn(path);
1016                 if (err && errno != ENOENT)
1017                         ret = 1;
1018
1019                 if (!(delopt & REF_NODEREF))
1020                         lock->lk->filename[i] = '.';
1021         }
1022         /* removing the loose one could have resurrected an earlier
1023          * packed one.  Also, if it was not loose we need to repack
1024          * without it.
1025          */
1026         ret |= repack_without_ref(refname);
1027
1028         unlink_or_warn(git_path("logs/%s", lock->ref_name));
1029         invalidate_cached_refs();
1030         unlock_ref(lock);
1031         return ret;
1032 }
1033
1034 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
1035 {
1036         static const char renamed_ref[] = "RENAMED-REF";
1037         unsigned char sha1[20], orig_sha1[20];
1038         int flag = 0, logmoved = 0;
1039         struct ref_lock *lock;
1040         struct stat loginfo;
1041         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
1042         const char *symref = NULL;
1043
1044         if (log && S_ISLNK(loginfo.st_mode))
1045                 return error("reflog for %s is a symlink", oldref);
1046
1047         symref = resolve_ref(oldref, orig_sha1, 1, &flag);
1048         if (flag & REF_ISSYMREF)
1049                 return error("refname %s is a symbolic ref, renaming it is not supported",
1050                         oldref);
1051         if (!symref)
1052                 return error("refname %s not found", oldref);
1053
1054         if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
1055                 return 1;
1056
1057         if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
1058                 return 1;
1059
1060         lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
1061         if (!lock)
1062                 return error("unable to lock %s", renamed_ref);
1063         lock->force_write = 1;
1064         if (write_ref_sha1(lock, orig_sha1, logmsg))
1065                 return error("unable to save current sha1 in %s", renamed_ref);
1066
1067         if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
1068                 return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
1069                         oldref, strerror(errno));
1070
1071         if (delete_ref(oldref, orig_sha1, REF_NODEREF)) {
1072                 error("unable to delete old %s", oldref);
1073                 goto rollback;
1074         }
1075
1076         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1, REF_NODEREF)) {
1077                 if (errno==EISDIR) {
1078                         if (remove_empty_directories(git_path("%s", newref))) {
1079                                 error("Directory not empty: %s", newref);
1080                                 goto rollback;
1081                         }
1082                 } else {
1083                         error("unable to delete existing %s", newref);
1084                         goto rollback;
1085                 }
1086         }
1087
1088         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
1089                 error("unable to create directory for %s", newref);
1090                 goto rollback;
1091         }
1092
1093  retry:
1094         if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
1095                 if (errno==EISDIR || errno==ENOTDIR) {
1096                         /*
1097                          * rename(a, b) when b is an existing
1098                          * directory ought to result in ISDIR, but
1099                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
1100                          */
1101                         if (remove_empty_directories(git_path("logs/%s", newref))) {
1102                                 error("Directory not empty: logs/%s", newref);
1103                                 goto rollback;
1104                         }
1105                         goto retry;
1106                 } else {
1107                         error("unable to move logfile tmp-renamed-log to logs/%s: %s",
1108                                 newref, strerror(errno));
1109                         goto rollback;
1110                 }
1111         }
1112         logmoved = log;
1113
1114         lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
1115         if (!lock) {
1116                 error("unable to lock %s for update", newref);
1117                 goto rollback;
1118         }
1119         lock->force_write = 1;
1120         hashcpy(lock->old_sha1, orig_sha1);
1121         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
1122                 error("unable to write current sha1 into %s", newref);
1123                 goto rollback;
1124         }
1125
1126         return 0;
1127
1128  rollback:
1129         lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
1130         if (!lock) {
1131                 error("unable to lock %s for rollback", oldref);
1132                 goto rollbacklog;
1133         }
1134
1135         lock->force_write = 1;
1136         flag = log_all_ref_updates;
1137         log_all_ref_updates = 0;
1138         if (write_ref_sha1(lock, orig_sha1, NULL))
1139                 error("unable to write current sha1 into %s", oldref);
1140         log_all_ref_updates = flag;
1141
1142  rollbacklog:
1143         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
1144                 error("unable to restore logfile %s from %s: %s",
1145                         oldref, newref, strerror(errno));
1146         if (!logmoved && log &&
1147             rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
1148                 error("unable to restore logfile %s from tmp-renamed-log: %s",
1149                         oldref, strerror(errno));
1150
1151         return 1;
1152 }
1153
1154 int close_ref(struct ref_lock *lock)
1155 {
1156         if (close_lock_file(lock->lk))
1157                 return -1;
1158         lock->lock_fd = -1;
1159         return 0;
1160 }
1161
1162 int commit_ref(struct ref_lock *lock)
1163 {
1164         if (commit_lock_file(lock->lk))
1165                 return -1;
1166         lock->lock_fd = -1;
1167         return 0;
1168 }
1169
1170 void unlock_ref(struct ref_lock *lock)
1171 {
1172         /* Do not free lock->lk -- atexit() still looks at them */
1173         if (lock->lk)
1174                 rollback_lock_file(lock->lk);
1175         free(lock->ref_name);
1176         free(lock->orig_ref_name);
1177         free(lock);
1178 }
1179
1180 /*
1181  * copy the reflog message msg to buf, which has been allocated sufficiently
1182  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1183  * because reflog file is one line per entry.
1184  */
1185 static int copy_msg(char *buf, const char *msg)
1186 {
1187         char *cp = buf;
1188         char c;
1189         int wasspace = 1;
1190
1191         *cp++ = '\t';
1192         while ((c = *msg++)) {
1193                 if (wasspace && isspace(c))
1194                         continue;
1195                 wasspace = isspace(c);
1196                 if (wasspace)
1197                         c = ' ';
1198                 *cp++ = c;
1199         }
1200         while (buf < cp && isspace(cp[-1]))
1201                 cp--;
1202         *cp++ = '\n';
1203         return cp - buf;
1204 }
1205
1206 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1207                          const unsigned char *new_sha1, const char *msg)
1208 {
1209         int logfd, written, oflags = O_APPEND | O_WRONLY;
1210         unsigned maxlen, len;
1211         int msglen;
1212         char log_file[PATH_MAX];
1213         char *logrec;
1214         const char *committer;
1215
1216         if (log_all_ref_updates < 0)
1217                 log_all_ref_updates = !is_bare_repository();
1218
1219         git_snpath(log_file, sizeof(log_file), "logs/%s", ref_name);
1220
1221         if (log_all_ref_updates &&
1222             (!prefixcmp(ref_name, "refs/heads/") ||
1223              !prefixcmp(ref_name, "refs/remotes/") ||
1224              !strcmp(ref_name, "HEAD"))) {
1225                 if (safe_create_leading_directories(log_file) < 0)
1226                         return error("unable to create directory for %s",
1227                                      log_file);
1228                 oflags |= O_CREAT;
1229         }
1230
1231         logfd = open(log_file, oflags, 0666);
1232         if (logfd < 0) {
1233                 if (!(oflags & O_CREAT) && errno == ENOENT)
1234                         return 0;
1235
1236                 if ((oflags & O_CREAT) && errno == EISDIR) {
1237                         if (remove_empty_directories(log_file)) {
1238                                 return error("There are still logs under '%s'",
1239                                              log_file);
1240                         }
1241                         logfd = open(log_file, oflags, 0666);
1242                 }
1243
1244                 if (logfd < 0)
1245                         return error("Unable to append to %s: %s",
1246                                      log_file, strerror(errno));
1247         }
1248
1249         adjust_shared_perm(log_file);
1250
1251         msglen = msg ? strlen(msg) : 0;
1252         committer = git_committer_info(0);
1253         maxlen = strlen(committer) + msglen + 100;
1254         logrec = xmalloc(maxlen);
1255         len = sprintf(logrec, "%s %s %s\n",
1256                       sha1_to_hex(old_sha1),
1257                       sha1_to_hex(new_sha1),
1258                       committer);
1259         if (msglen)
1260                 len += copy_msg(logrec + len - 1, msg) - 1;
1261         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1262         free(logrec);
1263         if (close(logfd) != 0 || written != len)
1264                 return error("Unable to append to %s", log_file);
1265         return 0;
1266 }
1267
1268 static int is_branch(const char *refname)
1269 {
1270         return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
1271 }
1272
1273 int write_ref_sha1(struct ref_lock *lock,
1274         const unsigned char *sha1, const char *logmsg)
1275 {
1276         static char term = '\n';
1277         struct object *o;
1278
1279         if (!lock)
1280                 return -1;
1281         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1282                 unlock_ref(lock);
1283                 return 0;
1284         }
1285         o = parse_object(sha1);
1286         if (!o) {
1287                 error("Trying to write ref %s with nonexistant object %s",
1288                         lock->ref_name, sha1_to_hex(sha1));
1289                 unlock_ref(lock);
1290                 return -1;
1291         }
1292         if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1293                 error("Trying to write non-commit object %s to branch %s",
1294                         sha1_to_hex(sha1), lock->ref_name);
1295                 unlock_ref(lock);
1296                 return -1;
1297         }
1298         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1299             write_in_full(lock->lock_fd, &term, 1) != 1
1300                 || close_ref(lock) < 0) {
1301                 error("Couldn't write %s", lock->lk->filename);
1302                 unlock_ref(lock);
1303                 return -1;
1304         }
1305         invalidate_cached_refs();
1306         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1307             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1308              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1309                 unlock_ref(lock);
1310                 return -1;
1311         }
1312         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1313                 /*
1314                  * Special hack: If a branch is updated directly and HEAD
1315                  * points to it (may happen on the remote side of a push
1316                  * for example) then logically the HEAD reflog should be
1317                  * updated too.
1318                  * A generic solution implies reverse symref information,
1319                  * but finding all symrefs pointing to the given branch
1320                  * would be rather costly for this rare event (the direct
1321                  * update of a branch) to be worth it.  So let's cheat and
1322                  * check with HEAD only which should cover 99% of all usage
1323                  * scenarios (even 100% of the default ones).
1324                  */
1325                 unsigned char head_sha1[20];
1326                 int head_flag;
1327                 const char *head_ref;
1328                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1329                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1330                     !strcmp(head_ref, lock->ref_name))
1331                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1332         }
1333         if (commit_ref(lock)) {
1334                 error("Couldn't set %s", lock->ref_name);
1335                 unlock_ref(lock);
1336                 return -1;
1337         }
1338         unlock_ref(lock);
1339         return 0;
1340 }
1341
1342 int create_symref(const char *ref_target, const char *refs_heads_master,
1343                   const char *logmsg)
1344 {
1345         const char *lockpath;
1346         char ref[1000];
1347         int fd, len, written;
1348         char *git_HEAD = git_pathdup("%s", ref_target);
1349         unsigned char old_sha1[20], new_sha1[20];
1350
1351         if (logmsg && read_ref(ref_target, old_sha1))
1352                 hashclr(old_sha1);
1353
1354         if (safe_create_leading_directories(git_HEAD) < 0)
1355                 return error("unable to create directory for %s", git_HEAD);
1356
1357 #ifndef NO_SYMLINK_HEAD
1358         if (prefer_symlink_refs) {
1359                 unlink(git_HEAD);
1360                 if (!symlink(refs_heads_master, git_HEAD))
1361                         goto done;
1362                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1363         }
1364 #endif
1365
1366         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1367         if (sizeof(ref) <= len) {
1368                 error("refname too long: %s", refs_heads_master);
1369                 goto error_free_return;
1370         }
1371         lockpath = mkpath("%s.lock", git_HEAD);
1372         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1373         if (fd < 0) {
1374                 error("Unable to open %s for writing", lockpath);
1375                 goto error_free_return;
1376         }
1377         written = write_in_full(fd, ref, len);
1378         if (close(fd) != 0 || written != len) {
1379                 error("Unable to write to %s", lockpath);
1380                 goto error_unlink_return;
1381         }
1382         if (rename(lockpath, git_HEAD) < 0) {
1383                 error("Unable to create %s", git_HEAD);
1384                 goto error_unlink_return;
1385         }
1386         if (adjust_shared_perm(git_HEAD)) {
1387                 error("Unable to fix permissions on %s", lockpath);
1388         error_unlink_return:
1389                 unlink_or_warn(lockpath);
1390         error_free_return:
1391                 free(git_HEAD);
1392                 return -1;
1393         }
1394
1395 #ifndef NO_SYMLINK_HEAD
1396         done:
1397 #endif
1398         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1399                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1400
1401         free(git_HEAD);
1402         return 0;
1403 }
1404
1405 static char *ref_msg(const char *line, const char *endp)
1406 {
1407         const char *ep;
1408         line += 82;
1409         ep = memchr(line, '\n', endp - line);
1410         if (!ep)
1411                 ep = endp;
1412         return xmemdupz(line, ep - line);
1413 }
1414
1415 int read_ref_at(const char *ref, unsigned long at_time, int cnt, unsigned char *sha1, char **msg, unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
1416 {
1417         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1418         char *tz_c;
1419         int logfd, tz, reccnt = 0;
1420         struct stat st;
1421         unsigned long date;
1422         unsigned char logged_sha1[20];
1423         void *log_mapped;
1424         size_t mapsz;
1425
1426         logfile = git_path("logs/%s", ref);
1427         logfd = open(logfile, O_RDONLY, 0);
1428         if (logfd < 0)
1429                 die_errno("Unable to read log '%s'", logfile);
1430         fstat(logfd, &st);
1431         if (!st.st_size)
1432                 die("Log %s is empty.", logfile);
1433         mapsz = xsize_t(st.st_size);
1434         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1435         logdata = log_mapped;
1436         close(logfd);
1437
1438         lastrec = NULL;
1439         rec = logend = logdata + st.st_size;
1440         while (logdata < rec) {
1441                 reccnt++;
1442                 if (logdata < rec && *(rec-1) == '\n')
1443                         rec--;
1444                 lastgt = NULL;
1445                 while (logdata < rec && *(rec-1) != '\n') {
1446                         rec--;
1447                         if (*rec == '>')
1448                                 lastgt = rec;
1449                 }
1450                 if (!lastgt)
1451                         die("Log %s is corrupt.", logfile);
1452                 date = strtoul(lastgt + 1, &tz_c, 10);
1453                 if (date <= at_time || cnt == 0) {
1454                         tz = strtoul(tz_c, NULL, 10);
1455                         if (msg)
1456                                 *msg = ref_msg(rec, logend);
1457                         if (cutoff_time)
1458                                 *cutoff_time = date;
1459                         if (cutoff_tz)
1460                                 *cutoff_tz = tz;
1461                         if (cutoff_cnt)
1462                                 *cutoff_cnt = reccnt - 1;
1463                         if (lastrec) {
1464                                 if (get_sha1_hex(lastrec, logged_sha1))
1465                                         die("Log %s is corrupt.", logfile);
1466                                 if (get_sha1_hex(rec + 41, sha1))
1467                                         die("Log %s is corrupt.", logfile);
1468                                 if (hashcmp(logged_sha1, sha1)) {
1469                                         warning("Log %s has gap after %s.",
1470                                                 logfile, show_date(date, tz, DATE_RFC2822));
1471                                 }
1472                         }
1473                         else if (date == at_time) {
1474                                 if (get_sha1_hex(rec + 41, sha1))
1475                                         die("Log %s is corrupt.", logfile);
1476                         }
1477                         else {
1478                                 if (get_sha1_hex(rec + 41, logged_sha1))
1479                                         die("Log %s is corrupt.", logfile);
1480                                 if (hashcmp(logged_sha1, sha1)) {
1481                                         warning("Log %s unexpectedly ended on %s.",
1482                                                 logfile, show_date(date, tz, DATE_RFC2822));
1483                                 }
1484                         }
1485                         munmap(log_mapped, mapsz);
1486                         return 0;
1487                 }
1488                 lastrec = rec;
1489                 if (cnt > 0)
1490                         cnt--;
1491         }
1492
1493         rec = logdata;
1494         while (rec < logend && *rec != '>' && *rec != '\n')
1495                 rec++;
1496         if (rec == logend || *rec == '\n')
1497                 die("Log %s is corrupt.", logfile);
1498         date = strtoul(rec + 1, &tz_c, 10);
1499         tz = strtoul(tz_c, NULL, 10);
1500         if (get_sha1_hex(logdata, sha1))
1501                 die("Log %s is corrupt.", logfile);
1502         if (is_null_sha1(sha1)) {
1503                 if (get_sha1_hex(logdata + 41, sha1))
1504                         die("Log %s is corrupt.", logfile);
1505         }
1506         if (msg)
1507                 *msg = ref_msg(logdata, logend);
1508         munmap(log_mapped, mapsz);
1509
1510         if (cutoff_time)
1511                 *cutoff_time = date;
1512         if (cutoff_tz)
1513                 *cutoff_tz = tz;
1514         if (cutoff_cnt)
1515                 *cutoff_cnt = reccnt;
1516         return 1;
1517 }
1518
1519 int for_each_recent_reflog_ent(const char *ref, each_reflog_ent_fn fn, long ofs, void *cb_data)
1520 {
1521         const char *logfile;
1522         FILE *logfp;
1523         char buf[1024];
1524         int ret = 0;
1525
1526         logfile = git_path("logs/%s", ref);
1527         logfp = fopen(logfile, "r");
1528         if (!logfp)
1529                 return -1;
1530
1531         if (ofs) {
1532                 struct stat statbuf;
1533                 if (fstat(fileno(logfp), &statbuf) ||
1534                     statbuf.st_size < ofs ||
1535                     fseek(logfp, -ofs, SEEK_END) ||
1536                     fgets(buf, sizeof(buf), logfp)) {
1537                         fclose(logfp);
1538                         return -1;
1539                 }
1540         }
1541
1542         while (fgets(buf, sizeof(buf), logfp)) {
1543                 unsigned char osha1[20], nsha1[20];
1544                 char *email_end, *message;
1545                 unsigned long timestamp;
1546                 int len, tz;
1547
1548                 /* old SP new SP name <email> SP time TAB msg LF */
1549                 len = strlen(buf);
1550                 if (len < 83 || buf[len-1] != '\n' ||
1551                     get_sha1_hex(buf, osha1) || buf[40] != ' ' ||
1552                     get_sha1_hex(buf + 41, nsha1) || buf[81] != ' ' ||
1553                     !(email_end = strchr(buf + 82, '>')) ||
1554                     email_end[1] != ' ' ||
1555                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1556                     !message || message[0] != ' ' ||
1557                     (message[1] != '+' && message[1] != '-') ||
1558                     !isdigit(message[2]) || !isdigit(message[3]) ||
1559                     !isdigit(message[4]) || !isdigit(message[5]))
1560                         continue; /* corrupt? */
1561                 email_end[1] = '\0';
1562                 tz = strtol(message + 1, NULL, 10);
1563                 if (message[6] != '\t')
1564                         message += 6;
1565                 else
1566                         message += 7;
1567                 ret = fn(osha1, nsha1, buf+82, timestamp, tz, message, cb_data);
1568                 if (ret)
1569                         break;
1570         }
1571         fclose(logfp);
1572         return ret;
1573 }
1574
1575 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1576 {
1577         return for_each_recent_reflog_ent(ref, fn, 0, cb_data);
1578 }
1579
1580 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1581 {
1582         DIR *dir = opendir(git_path("logs/%s", base));
1583         int retval = 0;
1584
1585         if (dir) {
1586                 struct dirent *de;
1587                 int baselen = strlen(base);
1588                 char *log = xmalloc(baselen + 257);
1589
1590                 memcpy(log, base, baselen);
1591                 if (baselen && base[baselen-1] != '/')
1592                         log[baselen++] = '/';
1593
1594                 while ((de = readdir(dir)) != NULL) {
1595                         struct stat st;
1596                         int namelen;
1597
1598                         if (de->d_name[0] == '.')
1599                                 continue;
1600                         namelen = strlen(de->d_name);
1601                         if (namelen > 255)
1602                                 continue;
1603                         if (has_extension(de->d_name, ".lock"))
1604                                 continue;
1605                         memcpy(log + baselen, de->d_name, namelen+1);
1606                         if (stat(git_path("logs/%s", log), &st) < 0)
1607                                 continue;
1608                         if (S_ISDIR(st.st_mode)) {
1609                                 retval = do_for_each_reflog(log, fn, cb_data);
1610                         } else {
1611                                 unsigned char sha1[20];
1612                                 if (!resolve_ref(log, sha1, 0, NULL))
1613                                         retval = error("bad ref for %s", log);
1614                                 else
1615                                         retval = fn(log, sha1, 0, cb_data);
1616                         }
1617                         if (retval)
1618                                 break;
1619                 }
1620                 free(log);
1621                 closedir(dir);
1622         }
1623         else if (*base)
1624                 return errno;
1625         return retval;
1626 }
1627
1628 int for_each_reflog(each_ref_fn fn, void *cb_data)
1629 {
1630         return do_for_each_reflog("", fn, cb_data);
1631 }
1632
1633 int update_ref(const char *action, const char *refname,
1634                 const unsigned char *sha1, const unsigned char *oldval,
1635                 int flags, enum action_on_err onerr)
1636 {
1637         static struct ref_lock *lock;
1638         lock = lock_any_ref_for_update(refname, oldval, flags);
1639         if (!lock) {
1640                 const char *str = "Cannot lock the ref '%s'.";
1641                 switch (onerr) {
1642                 case MSG_ON_ERR: error(str, refname); break;
1643                 case DIE_ON_ERR: die(str, refname); break;
1644                 case QUIET_ON_ERR: break;
1645                 }
1646                 return 1;
1647         }
1648         if (write_ref_sha1(lock, sha1, action) < 0) {
1649                 const char *str = "Cannot update the ref '%s'.";
1650                 switch (onerr) {
1651                 case MSG_ON_ERR: error(str, refname); break;
1652                 case DIE_ON_ERR: die(str, refname); break;
1653                 case QUIET_ON_ERR: break;
1654                 }
1655                 return 1;
1656         }
1657         return 0;
1658 }
1659
1660 struct ref *find_ref_by_name(const struct ref *list, const char *name)
1661 {
1662         for ( ; list; list = list->next)
1663                 if (!strcmp(list->name, name))
1664                         return (struct ref *)list;
1665         return NULL;
1666 }
1667
1668 /*
1669  * generate a format suitable for scanf from a ref_rev_parse_rules
1670  * rule, that is replace the "%.*s" spec with a "%s" spec
1671  */
1672 static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
1673 {
1674         char *spec;
1675
1676         spec = strstr(rule, "%.*s");
1677         if (!spec || strstr(spec + 4, "%.*s"))
1678                 die("invalid rule in ref_rev_parse_rules: %s", rule);
1679
1680         /* copy all until spec */
1681         strncpy(scanf_fmt, rule, spec - rule);
1682         scanf_fmt[spec - rule] = '\0';
1683         /* copy new spec */
1684         strcat(scanf_fmt, "%s");
1685         /* copy remaining rule */
1686         strcat(scanf_fmt, spec + 4);
1687
1688         return;
1689 }
1690
1691 char *shorten_unambiguous_ref(const char *ref, int strict)
1692 {
1693         int i;
1694         static char **scanf_fmts;
1695         static int nr_rules;
1696         char *short_name;
1697
1698         /* pre generate scanf formats from ref_rev_parse_rules[] */
1699         if (!nr_rules) {
1700                 size_t total_len = 0;
1701
1702                 /* the rule list is NULL terminated, count them first */
1703                 for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
1704                         /* no +1 because strlen("%s") < strlen("%.*s") */
1705                         total_len += strlen(ref_rev_parse_rules[nr_rules]);
1706
1707                 scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
1708
1709                 total_len = 0;
1710                 for (i = 0; i < nr_rules; i++) {
1711                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
1712                                         + total_len;
1713                         gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
1714                         total_len += strlen(ref_rev_parse_rules[i]);
1715                 }
1716         }
1717
1718         /* bail out if there are no rules */
1719         if (!nr_rules)
1720                 return xstrdup(ref);
1721
1722         /* buffer for scanf result, at most ref must fit */
1723         short_name = xstrdup(ref);
1724
1725         /* skip first rule, it will always match */
1726         for (i = nr_rules - 1; i > 0 ; --i) {
1727                 int j;
1728                 int rules_to_fail = i;
1729                 int short_name_len;
1730
1731                 if (1 != sscanf(ref, scanf_fmts[i], short_name))
1732                         continue;
1733
1734                 short_name_len = strlen(short_name);
1735
1736                 /*
1737                  * in strict mode, all (except the matched one) rules
1738                  * must fail to resolve to a valid non-ambiguous ref
1739                  */
1740                 if (strict)
1741                         rules_to_fail = nr_rules;
1742
1743                 /*
1744                  * check if the short name resolves to a valid ref,
1745                  * but use only rules prior to the matched one
1746                  */
1747                 for (j = 0; j < rules_to_fail; j++) {
1748                         const char *rule = ref_rev_parse_rules[j];
1749                         unsigned char short_objectname[20];
1750                         char refname[PATH_MAX];
1751
1752                         /* skip matched rule */
1753                         if (i == j)
1754                                 continue;
1755
1756                         /*
1757                          * the short name is ambiguous, if it resolves
1758                          * (with this previous rule) to a valid ref
1759                          * read_ref() returns 0 on success
1760                          */
1761                         mksnpath(refname, sizeof(refname),
1762                                  rule, short_name_len, short_name);
1763                         if (!read_ref(refname, short_objectname))
1764                                 break;
1765                 }
1766
1767                 /*
1768                  * short name is non-ambiguous if all previous rules
1769                  * haven't resolved to a valid ref
1770                  */
1771                 if (j == rules_to_fail)
1772                         return short_name;
1773         }
1774
1775         free(short_name);
1776         return xstrdup(ref);
1777 }