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         if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
 535                 if (is_null_sha1(entry->sha1))
 536                         return 0;
 537                 if (!has_sha1_file(entry->sha1)) {
 538                         error("%s does not point to a valid object!", entry->name);
 539                         return 0;
 540                 }
 541         }
 542         current_ref = entry;
 543         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 544 }
 545
 546 int peel_ref(const char *ref, unsigned char *sha1)
 547 {
 548         int flag;
 549         unsigned char base[20];
 550         struct object *o;
 551
 552         if (current_ref && (current_ref->name == ref
 553                 || !strcmp(current_ref->name, ref))) {
 554                 if (current_ref->flag & REF_KNOWS_PEELED) {
 555                         hashcpy(sha1, current_ref->peeled);
 556                         return 0;
 557                 }
 558                 hashcpy(base, current_ref->sha1);
 559                 goto fallback;
 560         }
 561
 562         if (!resolve_ref(ref, base, 1, &flag))
 563                 return -1;
 564
 565         if ((flag & REF_ISPACKED)) {
 566                 struct ref_list *list = get_packed_refs();
 567
 568                 while (list) {
 569                         if (!strcmp(list->name, ref)) {
 570                                 if (list->flag & REF_KNOWS_PEELED) {
 571                                         hashcpy(sha1, list->peeled);
 572                                         return 0;
 573                                 }
 574                                 /* older pack-refs did not leave peeled ones */
 575                                 break;
 576                         }
 577                         list = list->next;
 578                 }
 579         }
 580
 581 fallback:
 582         o = parse_object(base);
 583         if (o && o->type == OBJ_TAG) {
 584                 o = deref_tag(o, ref, 0);
 585                 if (o) {
 586                         hashcpy(sha1, o->sha1);
 587                         return 0;
 588                 }
 589         }
 590         return -1;
 591 }
 592
 593 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
 594                            int flags, void *cb_data)
 595 {
 596         int retval = 0;
 597         struct ref_list *packed = get_packed_refs();
 598         struct ref_list *loose = get_loose_refs();
 599
 600         struct ref_list *extra;
 601
 602         for (extra = extra_refs; extra; extra = extra->next)
 603                 retval = do_one_ref(base, fn, trim, flags, cb_data, extra);
 604
 605         while (packed && loose) {
 606                 struct ref_list *entry;
 607                 int cmp = strcmp(packed->name, loose->name);
 608                 if (!cmp) {
 609                         packed = packed->next;
 610                         continue;
 611                 }
 612                 if (cmp > 0) {
 613                         entry = loose;
 614                         loose = loose->next;
 615                 } else {
 616                         entry = packed;
 617                         packed = packed->next;
 618                 }
 619                 retval = do_one_ref(base, fn, trim, flags, cb_data, entry);
 620                 if (retval)
 621                         goto end_each;
 622         }
 623
 624         for (packed = packed ? packed : loose; packed; packed = packed->next) {
 625                 retval = do_one_ref(base, fn, trim, flags, cb_data, packed);
 626                 if (retval)
 627                         goto end_each;
 628         }
 629
 630 end_each:
 631         current_ref = NULL;
 632         return retval;
 633 }
 634
 635 int head_ref(each_ref_fn fn, void *cb_data)
 636 {
 637         unsigned char sha1[20];
 638         int flag;
 639
 640         if (resolve_ref("HEAD", sha1, 1, &flag))
 641                 return fn("HEAD", sha1, flag, cb_data);
 642         return 0;
 643 }
 644
 645 int for_each_ref(each_ref_fn fn, void *cb_data)
 646 {
 647         return do_for_each_ref("refs/", fn, 0, 0, cb_data);
 648 }
 649
 650 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 651 {
 652         return do_for_each_ref("refs/tags/", fn, 10, 0, cb_data);
 653 }
 654
 655 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 656 {
 657         return do_for_each_ref("refs/heads/", fn, 11, 0, cb_data);
 658 }
 659
 660 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 661 {
 662         return do_for_each_ref("refs/remotes/", fn, 13, 0, cb_data);
 663 }
 664
 665 int for_each_rawref(each_ref_fn fn, void *cb_data)
 666 {
 667         return do_for_each_ref("refs/", fn, 0,
 668                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
 669 }
 670
 671 /*
 672  * Make sure "ref" is something reasonable to have under ".git/refs/";
 673  * We do not like it if:
 674  *
 675  * - any path component of it begins with ".", or
 676  * - it has double dots "..", or
 677  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 678  * - it ends with a "/".
 679  */
 680
 681 static inline int bad_ref_char(int ch)
 682 {
 683         if (((unsigned) ch) <= ' ' ||
 684             ch == '~' || ch == '^' || ch == ':')
 685                 return 1;
 686         /* 2.13 Pattern Matching Notation */
 687         if (ch == '?' || ch == '[') /* Unsupported */
 688                 return 1;
 689         if (ch == '*') /* Supported at the end */
 690                 return 2;
 691         return 0;
 692 }
 693
 694 int check_ref_format(const char *ref)
 695 {
 696         int ch, level, bad_type;
 697         const char *cp = ref;
 698
 699         level = 0;
 700         while (1) {
 701                 while ((ch = *cp++) == '/')
 702                         ; /* tolerate duplicated slashes */
 703                 if (!ch)
 704                         /* should not end with slashes */
 705                         return CHECK_REF_FORMAT_ERROR;
 706
 707                 /* we are at the beginning of the path component */
 708                 if (ch == '.')
 709                         return CHECK_REF_FORMAT_ERROR;
 710                 bad_type = bad_ref_char(ch);
 711                 if (bad_type) {
 712                         return (bad_type == 2 && !*cp)
 713                                 ? CHECK_REF_FORMAT_WILDCARD
 714                                 : CHECK_REF_FORMAT_ERROR;
 715                 }
 716
 717                 /* scan the rest of the path component */
 718                 while ((ch = *cp++) != 0) {
 719                         bad_type = bad_ref_char(ch);
 720                         if (bad_type) {
 721                                 return (bad_type == 2 && !*cp)
 722                                         ? CHECK_REF_FORMAT_WILDCARD
 723                                         : CHECK_REF_FORMAT_ERROR;
 724                         }
 725                         if (ch == '/')
 726                                 break;
 727                         if (ch == '.' && *cp == '.')
 728                                 return CHECK_REF_FORMAT_ERROR;
 729                 }
 730                 level++;
 731                 if (!ch) {
 732                         if (level < 2)
 733                                 return CHECK_REF_FORMAT_ONELEVEL;
 734                         return CHECK_REF_FORMAT_OK;
 735                 }
 736         }
 737 }
 738
 739 const char *prettify_ref(const struct ref *ref)
 740 {
 741         const char *name = ref->name;
 742         return name + (
 743                 !prefixcmp(name, "refs/heads/") ? 11 :
 744                 !prefixcmp(name, "refs/tags/") ? 10 :
 745                 !prefixcmp(name, "refs/remotes/") ? 13 :
 746                 0);
 747 }
 748
 749 const char *ref_rev_parse_rules[] = {
 750         "%.*s",
 751         "refs/%.*s",
 752         "refs/tags/%.*s",
 753         "refs/heads/%.*s",
 754         "refs/remotes/%.*s",
 755         "refs/remotes/%.*s/HEAD",
 756         NULL
 757 };
 758
 759 const char *ref_fetch_rules[] = {
 760         "%.*s",
 761         "refs/%.*s",
 762         "refs/heads/%.*s",
 763         NULL
 764 };
 765
 766 int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
 767 {
 768         const char **p;
 769         const int abbrev_name_len = strlen(abbrev_name);
 770
 771         for (p = rules; *p; p++) {
 772                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
 773                         return 1;
 774                 }
 775         }
 776
 777         return 0;
 778 }
 779
 780 static struct ref_lock *verify_lock(struct ref_lock *lock,
 781         const unsigned char *old_sha1, int mustexist)
 782 {
 783         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
 784                 error("Can't verify ref %s", lock->ref_name);
 785                 unlock_ref(lock);
 786                 return NULL;
 787         }
 788         if (hashcmp(lock->old_sha1, old_sha1)) {
 789                 error("Ref %s is at %s but expected %s", lock->ref_name,
 790                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 791                 unlock_ref(lock);
 792                 return NULL;
 793         }
 794         return lock;
 795 }
 796
 797 static int remove_empty_directories(const char *file)
 798 {
 799         /* we want to create a file but there is a directory there;
 800          * if that is an empty directory (or a directory that contains
 801          * only empty directories), remove them.
 802          */
 803         struct strbuf path;
 804         int result;
 805
 806         strbuf_init(&path, 20);
 807         strbuf_addstr(&path, file);
 808
 809         result = remove_dir_recursively(&path, 1);
 810
 811         strbuf_release(&path);
 812
 813         return result;
 814 }
 815
 816 static int is_refname_available(const char *ref, const char *oldref,
 817                                 struct ref_list *list, int quiet)
 818 {
 819         int namlen = strlen(ref); /* e.g. 'foo/bar' */
 820         while (list) {
 821                 /* list->name could be 'foo' or 'foo/bar/baz' */
 822                 if (!oldref || strcmp(oldref, list->name)) {
 823                         int len = strlen(list->name);
 824                         int cmplen = (namlen < len) ? namlen : len;
 825                         const char *lead = (namlen < len) ? list->name : ref;
 826                         if (!strncmp(ref, list->name, cmplen) &&
 827                             lead[cmplen] == '/') {
 828                                 if (!quiet)
 829                                         error("'%s' exists; cannot create '%s'",
 830                                               list->name, ref);
 831                                 return 0;
 832                         }
 833                 }
 834                 list = list->next;
 835         }
 836         return 1;
 837 }
 838
 839 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
 840 {
 841         char *ref_file;
 842         const char *orig_ref = ref;
 843         struct ref_lock *lock;
 844         int last_errno = 0;
 845         int type, lflags;
 846         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 847         int missing = 0;
 848
 849         lock = xcalloc(1, sizeof(struct ref_lock));
 850         lock->lock_fd = -1;
 851
 852         ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
 853         if (!ref && errno == EISDIR) {
 854                 /* we are trying to lock foo but we used to
 855                  * have foo/bar which now does not exist;
 856                  * it is normal for the empty directory 'foo'
 857                  * to remain.
 858                  */
 859                 ref_file = git_path("%s", orig_ref);
 860                 if (remove_empty_directories(ref_file)) {
 861                         last_errno = errno;
 862                         error("there are still refs under '%s'", orig_ref);
 863                         goto error_return;
 864                 }
 865                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
 866         }
 867         if (type_p)
 868             *type_p = type;
 869         if (!ref) {
 870                 last_errno = errno;
 871                 error("unable to resolve reference %s: %s",
 872                         orig_ref, strerror(errno));
 873                 goto error_return;
 874         }
 875         missing = is_null_sha1(lock->old_sha1);
 876         /* When the ref did not exist and we are creating it,
 877          * make sure there is no existing ref that is packed
 878          * whose name begins with our refname, nor a ref whose
 879          * name is a proper prefix of our refname.
 880          */
 881         if (missing &&
 882             !is_refname_available(ref, NULL, get_packed_refs(), 0))
 883                 goto error_return;
 884
 885         lock->lk = xcalloc(1, sizeof(struct lock_file));
 886
 887         lflags = LOCK_DIE_ON_ERROR;
 888         if (flags & REF_NODEREF) {
 889                 ref = orig_ref;
 890                 lflags |= LOCK_NODEREF;
 891         }
 892         lock->ref_name = xstrdup(ref);
 893         lock->orig_ref_name = xstrdup(orig_ref);
 894         ref_file = git_path("%s", ref);
 895         if (missing)
 896                 lock->force_write = 1;
 897         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
 898                 lock->force_write = 1;
 899
 900         if (safe_create_leading_directories(ref_file)) {
 901                 last_errno = errno;
 902                 error("unable to create directory for %s", ref_file);
 903                 goto error_return;
 904         }
 905
 906         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
 907         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 908
 909  error_return:
 910         unlock_ref(lock);
 911         errno = last_errno;
 912         return NULL;
 913 }
 914
 915 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 916 {
 917         char refpath[PATH_MAX];
 918         if (check_ref_format(ref))
 919                 return NULL;
 920         strcpy(refpath, mkpath("refs/%s", ref));
 921         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
 922 }
 923
 924 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
 925 {
 926         switch (check_ref_format(ref)) {
 927         default:
 928                 return NULL;
 929         case 0:
 930         case CHECK_REF_FORMAT_ONELEVEL:
 931                 return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
 932         }
 933 }
 934
 935 static struct lock_file packlock;
 936
 937 static int repack_without_ref(const char *refname)
 938 {
 939         struct ref_list *list, *packed_ref_list;
 940         int fd;
 941         int found = 0;
 942
 943         packed_ref_list = get_packed_refs();
 944         for (list = packed_ref_list; list; list = list->next) {
 945                 if (!strcmp(refname, list->name)) {
 946                         found = 1;
 947                         break;
 948                 }
 949         }
 950         if (!found)
 951                 return 0;
 952         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
 953         if (fd < 0)
 954                 return error("cannot delete '%s' from packed refs", refname);
 955
 956         for (list = packed_ref_list; list; list = list->next) {
 957                 char line[PATH_MAX + 100];
 958                 int len;
 959
 960                 if (!strcmp(refname, list->name))
 961                         continue;
 962                 len = snprintf(line, sizeof(line), "%s %s\n",
 963                                sha1_to_hex(list->sha1), list->name);
 964                 /* this should not happen but just being defensive */
 965                 if (len > sizeof(line))
 966                         die("too long a refname '%s'", list->name);
 967                 write_or_die(fd, line, len);
 968         }
 969         return commit_lock_file(&packlock);
 970 }
 971
 972 int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
 973 {
 974         struct ref_lock *lock;
 975         int err, i = 0, ret = 0, flag = 0;
 976
 977         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
 978         if (!lock)
 979                 return 1;
 980         if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
 981                 /* loose */
 982                 const char *path;
 983
 984                 if (!(delopt & REF_NODEREF)) {
 985                         i = strlen(lock->lk->filename) - 5; /* .lock */
 986                         lock->lk->filename[i] = 0;
 987                         path = lock->lk->filename;
 988                 } else {
 989                         path = git_path("%s", refname);
 990                 }
 991                 err = unlink(path);
 992                 if (err && errno != ENOENT) {
 993                         ret = 1;
 994                         error("unlink(%s) failed: %s",
 995                               path, strerror(errno));
 996                 }
 997                 if (!(delopt & REF_NODEREF))
 998                         lock->lk->filename[i] = '.';
 999         }
1000         /* removing the loose one could have resurrected an earlier
1001          * packed one.  Also, if it was not loose we need to repack
1002          * without it.
1003          */
1004         ret |= repack_without_ref(refname);
1005
1006         err = unlink(git_path("logs/%s", lock->ref_name));
1007         if (err && errno != ENOENT)
1008                 fprintf(stderr, "warning: unlink(%s) failed: %s",
1009                         git_path("logs/%s", lock->ref_name), strerror(errno));
1010         invalidate_cached_refs();
1011         unlock_ref(lock);
1012         return ret;
1013 }
1014
1015 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
1016 {
1017         static const char renamed_ref[] = "RENAMED-REF";
1018         unsigned char sha1[20], orig_sha1[20];
1019         int flag = 0, logmoved = 0;
1020         struct ref_lock *lock;
1021         struct stat loginfo;
1022         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
1023         const char *symref = NULL;
1024
1025         if (log && S_ISLNK(loginfo.st_mode))
1026                 return error("reflog for %s is a symlink", oldref);
1027
1028         symref = resolve_ref(oldref, orig_sha1, 1, &flag);
1029         if (flag & REF_ISSYMREF)
1030                 return error("refname %s is a symbolic ref, renaming it is not supported",
1031                         oldref);
1032         if (!symref)
1033                 return error("refname %s not found", oldref);
1034
1035         if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
1036                 return 1;
1037
1038         if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
1039                 return 1;
1040
1041         lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
1042         if (!lock)
1043                 return error("unable to lock %s", renamed_ref);
1044         lock->force_write = 1;
1045         if (write_ref_sha1(lock, orig_sha1, logmsg))
1046                 return error("unable to save current sha1 in %s", renamed_ref);
1047
1048         if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
1049                 return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
1050                         oldref, strerror(errno));
1051
1052         if (delete_ref(oldref, orig_sha1, REF_NODEREF)) {
1053                 error("unable to delete old %s", oldref);
1054                 goto rollback;
1055         }
1056
1057         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1, REF_NODEREF)) {
1058                 if (errno==EISDIR) {
1059                         if (remove_empty_directories(git_path("%s", newref))) {
1060                                 error("Directory not empty: %s", newref);
1061                                 goto rollback;
1062                         }
1063                 } else {
1064                         error("unable to delete existing %s", newref);
1065                         goto rollback;
1066                 }
1067         }
1068
1069         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
1070                 error("unable to create directory for %s", newref);
1071                 goto rollback;
1072         }
1073
1074  retry:
1075         if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
1076                 if (errno==EISDIR || errno==ENOTDIR) {
1077                         /*
1078                          * rename(a, b) when b is an existing
1079                          * directory ought to result in ISDIR, but
1080                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
1081                          */
1082                         if (remove_empty_directories(git_path("logs/%s", newref))) {
1083                                 error("Directory not empty: logs/%s", newref);
1084                                 goto rollback;
1085                         }
1086                         goto retry;
1087                 } else {
1088                         error("unable to move logfile tmp-renamed-log to logs/%s: %s",
1089                                 newref, strerror(errno));
1090                         goto rollback;
1091                 }
1092         }
1093         logmoved = log;
1094
1095         lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
1096         if (!lock) {
1097                 error("unable to lock %s for update", newref);
1098                 goto rollback;
1099         }
1100         lock->force_write = 1;
1101         hashcpy(lock->old_sha1, orig_sha1);
1102         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
1103                 error("unable to write current sha1 into %s", newref);
1104                 goto rollback;
1105         }
1106
1107         return 0;
1108
1109  rollback:
1110         lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
1111         if (!lock) {
1112                 error("unable to lock %s for rollback", oldref);
1113                 goto rollbacklog;
1114         }
1115
1116         lock->force_write = 1;
1117         flag = log_all_ref_updates;
1118         log_all_ref_updates = 0;
1119         if (write_ref_sha1(lock, orig_sha1, NULL))
1120                 error("unable to write current sha1 into %s", oldref);
1121         log_all_ref_updates = flag;
1122
1123  rollbacklog:
1124         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
1125                 error("unable to restore logfile %s from %s: %s",
1126                         oldref, newref, strerror(errno));
1127         if (!logmoved && log &&
1128             rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
1129                 error("unable to restore logfile %s from tmp-renamed-log: %s",
1130                         oldref, strerror(errno));
1131
1132         return 1;
1133 }
1134
1135 int close_ref(struct ref_lock *lock)
1136 {
1137         if (close_lock_file(lock->lk))
1138                 return -1;
1139         lock->lock_fd = -1;
1140         return 0;
1141 }
1142
1143 int commit_ref(struct ref_lock *lock)
1144 {
1145         if (commit_lock_file(lock->lk))
1146                 return -1;
1147         lock->lock_fd = -1;
1148         return 0;
1149 }
1150
1151 void unlock_ref(struct ref_lock *lock)
1152 {
1153         /* Do not free lock->lk -- atexit() still looks at them */
1154         if (lock->lk)
1155                 rollback_lock_file(lock->lk);
1156         free(lock->ref_name);
1157         free(lock->orig_ref_name);
1158         free(lock);
1159 }
1160
1161 /*
1162  * copy the reflog message msg to buf, which has been allocated sufficiently
1163  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1164  * because reflog file is one line per entry.
1165  */
1166 static int copy_msg(char *buf, const char *msg)
1167 {
1168         char *cp = buf;
1169         char c;
1170         int wasspace = 1;
1171
1172         *cp++ = '\t';
1173         while ((c = *msg++)) {
1174                 if (wasspace && isspace(c))
1175                         continue;
1176                 wasspace = isspace(c);
1177                 if (wasspace)
1178                         c = ' ';
1179                 *cp++ = c;
1180         }
1181         while (buf < cp && isspace(cp[-1]))
1182                 cp--;
1183         *cp++ = '\n';
1184         return cp - buf;
1185 }
1186
1187 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1188                          const unsigned char *new_sha1, const char *msg)
1189 {
1190         int logfd, written, oflags = O_APPEND | O_WRONLY;
1191         unsigned maxlen, len;
1192         int msglen;
1193         char log_file[PATH_MAX];
1194         char *logrec;
1195         const char *committer;
1196
1197         if (log_all_ref_updates < 0)
1198                 log_all_ref_updates = !is_bare_repository();
1199
1200         git_snpath(log_file, sizeof(log_file), "logs/%s", ref_name);
1201
1202         if (log_all_ref_updates &&
1203             (!prefixcmp(ref_name, "refs/heads/") ||
1204              !prefixcmp(ref_name, "refs/remotes/") ||
1205              !strcmp(ref_name, "HEAD"))) {
1206                 if (safe_create_leading_directories(log_file) < 0)
1207                         return error("unable to create directory for %s",
1208                                      log_file);
1209                 oflags |= O_CREAT;
1210         }
1211
1212         logfd = open(log_file, oflags, 0666);
1213         if (logfd < 0) {
1214                 if (!(oflags & O_CREAT) && errno == ENOENT)
1215                         return 0;
1216
1217                 if ((oflags & O_CREAT) && errno == EISDIR) {
1218                         if (remove_empty_directories(log_file)) {
1219                                 return error("There are still logs under '%s'",
1220                                              log_file);
1221                         }
1222                         logfd = open(log_file, oflags, 0666);
1223                 }
1224
1225                 if (logfd < 0)
1226                         return error("Unable to append to %s: %s",
1227                                      log_file, strerror(errno));
1228         }
1229
1230         adjust_shared_perm(log_file);
1231
1232         msglen = msg ? strlen(msg) : 0;
1233         committer = git_committer_info(0);
1234         maxlen = strlen(committer) + msglen + 100;
1235         logrec = xmalloc(maxlen);
1236         len = sprintf(logrec, "%s %s %s\n",
1237                       sha1_to_hex(old_sha1),
1238                       sha1_to_hex(new_sha1),
1239                       committer);
1240         if (msglen)
1241                 len += copy_msg(logrec + len - 1, msg) - 1;
1242         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1243         free(logrec);
1244         if (close(logfd) != 0 || written != len)
1245                 return error("Unable to append to %s", log_file);
1246         return 0;
1247 }
1248
1249 static int is_branch(const char *refname)
1250 {
1251         return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
1252 }
1253
1254 int write_ref_sha1(struct ref_lock *lock,
1255         const unsigned char *sha1, const char *logmsg)
1256 {
1257         static char term = '\n';
1258         struct object *o;
1259
1260         if (!lock)
1261                 return -1;
1262         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1263                 unlock_ref(lock);
1264                 return 0;
1265         }
1266         o = parse_object(sha1);
1267         if (!o) {
1268                 error("Trying to write ref %s with nonexistant object %s",
1269                         lock->ref_name, sha1_to_hex(sha1));
1270                 unlock_ref(lock);
1271                 return -1;
1272         }
1273         if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1274                 error("Trying to write non-commit object %s to branch %s",
1275                         sha1_to_hex(sha1), lock->ref_name);
1276                 unlock_ref(lock);
1277                 return -1;
1278         }
1279         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1280             write_in_full(lock->lock_fd, &term, 1) != 1
1281                 || close_ref(lock) < 0) {
1282                 error("Couldn't write %s", lock->lk->filename);
1283                 unlock_ref(lock);
1284                 return -1;
1285         }
1286         invalidate_cached_refs();
1287         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1288             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1289              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1290                 unlock_ref(lock);
1291                 return -1;
1292         }
1293         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1294                 /*
1295                  * Special hack: If a branch is updated directly and HEAD
1296                  * points to it (may happen on the remote side of a push
1297                  * for example) then logically the HEAD reflog should be
1298                  * updated too.
1299                  * A generic solution implies reverse symref information,
1300                  * but finding all symrefs pointing to the given branch
1301                  * would be rather costly for this rare event (the direct
1302                  * update of a branch) to be worth it.  So let's cheat and
1303                  * check with HEAD only which should cover 99% of all usage
1304                  * scenarios (even 100% of the default ones).
1305                  */
1306                 unsigned char head_sha1[20];
1307                 int head_flag;
1308                 const char *head_ref;
1309                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1310                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1311                     !strcmp(head_ref, lock->ref_name))
1312                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1313         }
1314         if (commit_ref(lock)) {
1315                 error("Couldn't set %s", lock->ref_name);
1316                 unlock_ref(lock);
1317                 return -1;
1318         }
1319         unlock_ref(lock);
1320         return 0;
1321 }
1322
1323 int create_symref(const char *ref_target, const char *refs_heads_master,
1324                   const char *logmsg)
1325 {
1326         const char *lockpath;
1327         char ref[1000];
1328         int fd, len, written;
1329         char *git_HEAD = git_pathdup("%s", ref_target);
1330         unsigned char old_sha1[20], new_sha1[20];
1331
1332         if (logmsg && read_ref(ref_target, old_sha1))
1333                 hashclr(old_sha1);
1334
1335         if (safe_create_leading_directories(git_HEAD) < 0)
1336                 return error("unable to create directory for %s", git_HEAD);
1337
1338 #ifndef NO_SYMLINK_HEAD
1339         if (prefer_symlink_refs) {
1340                 unlink(git_HEAD);
1341                 if (!symlink(refs_heads_master, git_HEAD))
1342                         goto done;
1343                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1344         }
1345 #endif
1346
1347         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1348         if (sizeof(ref) <= len) {
1349                 error("refname too long: %s", refs_heads_master);
1350                 goto error_free_return;
1351         }
1352         lockpath = mkpath("%s.lock", git_HEAD);
1353         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1354         if (fd < 0) {
1355                 error("Unable to open %s for writing", lockpath);
1356                 goto error_free_return;
1357         }
1358         written = write_in_full(fd, ref, len);
1359         if (close(fd) != 0 || written != len) {
1360                 error("Unable to write to %s", lockpath);
1361                 goto error_unlink_return;
1362         }
1363         if (rename(lockpath, git_HEAD) < 0) {
1364                 error("Unable to create %s", git_HEAD);
1365                 goto error_unlink_return;
1366         }
1367         if (adjust_shared_perm(git_HEAD)) {
1368                 error("Unable to fix permissions on %s", lockpath);
1369         error_unlink_return:
1370                 unlink(lockpath);
1371         error_free_return:
1372                 free(git_HEAD);
1373                 return -1;
1374         }
1375
1376 #ifndef NO_SYMLINK_HEAD
1377         done:
1378 #endif
1379         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1380                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1381
1382         free(git_HEAD);
1383         return 0;
1384 }
1385
1386 static char *ref_msg(const char *line, const char *endp)
1387 {
1388         const char *ep;
1389         line += 82;
1390         ep = memchr(line, '\n', endp - line);
1391         if (!ep)
1392                 ep = endp;
1393         return xmemdupz(line, ep - line);
1394 }
1395
1396 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)
1397 {
1398         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1399         char *tz_c;
1400         int logfd, tz, reccnt = 0;
1401         struct stat st;
1402         unsigned long date;
1403         unsigned char logged_sha1[20];
1404         void *log_mapped;
1405         size_t mapsz;
1406
1407         logfile = git_path("logs/%s", ref);
1408         logfd = open(logfile, O_RDONLY, 0);
1409         if (logfd < 0)
1410                 die("Unable to read log %s: %s", logfile, strerror(errno));
1411         fstat(logfd, &st);
1412         if (!st.st_size)
1413                 die("Log %s is empty.", logfile);
1414         mapsz = xsize_t(st.st_size);
1415         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1416         logdata = log_mapped;
1417         close(logfd);
1418
1419         lastrec = NULL;
1420         rec = logend = logdata + st.st_size;
1421         while (logdata < rec) {
1422                 reccnt++;
1423                 if (logdata < rec && *(rec-1) == '\n')
1424                         rec--;
1425                 lastgt = NULL;
1426                 while (logdata < rec && *(rec-1) != '\n') {
1427                         rec--;
1428                         if (*rec == '>')
1429                                 lastgt = rec;
1430                 }
1431                 if (!lastgt)
1432                         die("Log %s is corrupt.", logfile);
1433                 date = strtoul(lastgt + 1, &tz_c, 10);
1434                 if (date <= at_time || cnt == 0) {
1435                         tz = strtoul(tz_c, NULL, 10);
1436                         if (msg)
1437                                 *msg = ref_msg(rec, logend);
1438                         if (cutoff_time)
1439                                 *cutoff_time = date;
1440                         if (cutoff_tz)
1441                                 *cutoff_tz = tz;
1442                         if (cutoff_cnt)
1443                                 *cutoff_cnt = reccnt - 1;
1444                         if (lastrec) {
1445                                 if (get_sha1_hex(lastrec, logged_sha1))
1446                                         die("Log %s is corrupt.", logfile);
1447                                 if (get_sha1_hex(rec + 41, sha1))
1448                                         die("Log %s is corrupt.", logfile);
1449                                 if (hashcmp(logged_sha1, sha1)) {
1450                                         fprintf(stderr,
1451                                                 "warning: Log %s has gap after %s.\n",
1452                                                 logfile, show_date(date, tz, DATE_RFC2822));
1453                                 }
1454                         }
1455                         else if (date == at_time) {
1456                                 if (get_sha1_hex(rec + 41, sha1))
1457                                         die("Log %s is corrupt.", logfile);
1458                         }
1459                         else {
1460                                 if (get_sha1_hex(rec + 41, logged_sha1))
1461                                         die("Log %s is corrupt.", logfile);
1462                                 if (hashcmp(logged_sha1, sha1)) {
1463                                         fprintf(stderr,
1464                                                 "warning: Log %s unexpectedly ended on %s.\n",
1465                                                 logfile, show_date(date, tz, DATE_RFC2822));
1466                                 }
1467                         }
1468                         munmap(log_mapped, mapsz);
1469                         return 0;
1470                 }
1471                 lastrec = rec;
1472                 if (cnt > 0)
1473                         cnt--;
1474         }
1475
1476         rec = logdata;
1477         while (rec < logend && *rec != '>' && *rec != '\n')
1478                 rec++;
1479         if (rec == logend || *rec == '\n')
1480                 die("Log %s is corrupt.", logfile);
1481         date = strtoul(rec + 1, &tz_c, 10);
1482         tz = strtoul(tz_c, NULL, 10);
1483         if (get_sha1_hex(logdata, sha1))
1484                 die("Log %s is corrupt.", logfile);
1485         if (is_null_sha1(sha1)) {
1486                 if (get_sha1_hex(logdata + 41, sha1))
1487                         die("Log %s is corrupt.", logfile);
1488         }
1489         if (msg)
1490                 *msg = ref_msg(logdata, logend);
1491         munmap(log_mapped, mapsz);
1492
1493         if (cutoff_time)
1494                 *cutoff_time = date;
1495         if (cutoff_tz)
1496                 *cutoff_tz = tz;
1497         if (cutoff_cnt)
1498                 *cutoff_cnt = reccnt;
1499         return 1;
1500 }
1501
1502 int for_each_recent_reflog_ent(const char *ref, each_reflog_ent_fn fn, long ofs, void *cb_data)
1503 {
1504         const char *logfile;
1505         FILE *logfp;
1506         char buf[1024];
1507         int ret = 0;
1508
1509         logfile = git_path("logs/%s", ref);
1510         logfp = fopen(logfile, "r");
1511         if (!logfp)
1512                 return -1;
1513
1514         if (ofs) {
1515                 struct stat statbuf;
1516                 if (fstat(fileno(logfp), &statbuf) ||
1517                     statbuf.st_size < ofs ||
1518                     fseek(logfp, -ofs, SEEK_END) ||
1519                     fgets(buf, sizeof(buf), logfp))
1520                         return -1;
1521         }
1522
1523         while (fgets(buf, sizeof(buf), logfp)) {
1524                 unsigned char osha1[20], nsha1[20];
1525                 char *email_end, *message;
1526                 unsigned long timestamp;
1527                 int len, tz;
1528
1529                 /* old SP new SP name <email> SP time TAB msg LF */
1530                 len = strlen(buf);
1531                 if (len < 83 || buf[len-1] != '\n' ||
1532                     get_sha1_hex(buf, osha1) || buf[40] != ' ' ||
1533                     get_sha1_hex(buf + 41, nsha1) || buf[81] != ' ' ||
1534                     !(email_end = strchr(buf + 82, '>')) ||
1535                     email_end[1] != ' ' ||
1536                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1537                     !message || message[0] != ' ' ||
1538                     (message[1] != '+' && message[1] != '-') ||
1539                     !isdigit(message[2]) || !isdigit(message[3]) ||
1540                     !isdigit(message[4]) || !isdigit(message[5]))
1541                         continue; /* corrupt? */
1542                 email_end[1] = '\0';
1543                 tz = strtol(message + 1, NULL, 10);
1544                 if (message[6] != '\t')
1545                         message += 6;
1546                 else
1547                         message += 7;
1548                 ret = fn(osha1, nsha1, buf+82, timestamp, tz, message, cb_data);
1549                 if (ret)
1550                         break;
1551         }
1552         fclose(logfp);
1553         return ret;
1554 }
1555
1556 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1557 {
1558         return for_each_recent_reflog_ent(ref, fn, 0, cb_data);
1559 }
1560
1561 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1562 {
1563         DIR *dir = opendir(git_path("logs/%s", base));
1564         int retval = 0;
1565
1566         if (dir) {
1567                 struct dirent *de;
1568                 int baselen = strlen(base);
1569                 char *log = xmalloc(baselen + 257);
1570
1571                 memcpy(log, base, baselen);
1572                 if (baselen && base[baselen-1] != '/')
1573                         log[baselen++] = '/';
1574
1575                 while ((de = readdir(dir)) != NULL) {
1576                         struct stat st;
1577                         int namelen;
1578
1579                         if (de->d_name[0] == '.')
1580                                 continue;
1581                         namelen = strlen(de->d_name);
1582                         if (namelen > 255)
1583                                 continue;
1584                         if (has_extension(de->d_name, ".lock"))
1585                                 continue;
1586                         memcpy(log + baselen, de->d_name, namelen+1);
1587                         if (stat(git_path("logs/%s", log), &st) < 0)
1588                                 continue;
1589                         if (S_ISDIR(st.st_mode)) {
1590                                 retval = do_for_each_reflog(log, fn, cb_data);
1591                         } else {
1592                                 unsigned char sha1[20];
1593                                 if (!resolve_ref(log, sha1, 0, NULL))
1594                                         retval = error("bad ref for %s", log);
1595                                 else
1596                                         retval = fn(log, sha1, 0, cb_data);
1597                         }
1598                         if (retval)
1599                                 break;
1600                 }
1601                 free(log);
1602                 closedir(dir);
1603         }
1604         else if (*base)
1605                 return errno;
1606         return retval;
1607 }
1608
1609 int for_each_reflog(each_ref_fn fn, void *cb_data)
1610 {
1611         return do_for_each_reflog("", fn, cb_data);
1612 }
1613
1614 int update_ref(const char *action, const char *refname,
1615                 const unsigned char *sha1, const unsigned char *oldval,
1616                 int flags, enum action_on_err onerr)
1617 {
1618         static struct ref_lock *lock;
1619         lock = lock_any_ref_for_update(refname, oldval, flags);
1620         if (!lock) {
1621                 const char *str = "Cannot lock the ref '%s'.";
1622                 switch (onerr) {
1623                 case MSG_ON_ERR: error(str, refname); break;
1624                 case DIE_ON_ERR: die(str, refname); break;
1625                 case QUIET_ON_ERR: break;
1626                 }
1627                 return 1;
1628         }
1629         if (write_ref_sha1(lock, sha1, action) < 0) {
1630                 const char *str = "Cannot update the ref '%s'.";
1631                 switch (onerr) {
1632                 case MSG_ON_ERR: error(str, refname); break;
1633                 case DIE_ON_ERR: die(str, refname); break;
1634                 case QUIET_ON_ERR: break;
1635                 }
1636                 return 1;
1637         }
1638         return 0;
1639 }
1640
1641 struct ref *find_ref_by_name(const struct ref *list, const char *name)
1642 {
1643         for ( ; list; list = list->next)
1644                 if (!strcmp(list->name, name))
1645                         return (struct ref *)list;
1646         return NULL;
1647 }