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