refs.c

   1 #include "cache.h"
   2 #include "refs.h"
   3 #include "object.h"
   4 #include "tag.h"
   5
   6 /* ISSYMREF=01 and ISPACKED=02 are public interfaces */
   7 #define REF_KNOWS_PEELED 04
   8
   9 struct ref_list {
  10         struct ref_list *next;
  11         unsigned char flag; /* ISSYMREF? ISPACKED? */
  12         unsigned char sha1[20];
  13         unsigned char peeled[20];
  14         char name[FLEX_ARRAY];
  15 };
  16
  17 static const char *parse_ref_line(char *line, unsigned char *sha1)
  18 {
  19         /*
  20          * 42: the answer to everything.
  21          *
  22          * In this case, it happens to be the answer to
  23          *  40 (length of sha1 hex representation)
  24          *  +1 (space in between hex and name)
  25          *  +1 (newline at the end of the line)
  26          */
  27         int len = strlen(line) - 42;
  28
  29         if (len <= 0)
  30                 return NULL;
  31         if (get_sha1_hex(line, sha1) < 0)
  32                 return NULL;
  33         if (!isspace(line[40]))
  34                 return NULL;
  35         line += 41;
  36         if (isspace(*line))
  37                 return NULL;
  38         if (line[len] != '\n')
  39                 return NULL;
  40         line[len] = 0;
  41
  42         return line;
  43 }
  44
  45 static struct ref_list *add_ref(const char *name, const unsigned char *sha1,
  46                                 int flag, struct ref_list *list,
  47                                 struct ref_list **new_entry)
  48 {
  49         int len;
  50         struct ref_list **p = &list, *entry;
  51
  52         /* Find the place to insert the ref into.. */
  53         while ((entry = *p) != NULL) {
  54                 int cmp = strcmp(entry->name, name);
  55                 if (cmp > 0)
  56                         break;
  57
  58                 /* Same as existing entry? */
  59                 if (!cmp) {
  60                         if (new_entry)
  61                                 *new_entry = entry;
  62                         return list;
  63                 }
  64                 p = &entry->next;
  65         }
  66
  67         /* Allocate it and add it in.. */
  68         len = strlen(name) + 1;
  69         entry = xmalloc(sizeof(struct ref_list) + len);
  70         hashcpy(entry->sha1, sha1);
  71         hashclr(entry->peeled);
  72         memcpy(entry->name, name, len);
  73         entry->flag = flag;
  74         entry->next = *p;
  75         *p = entry;
  76         if (new_entry)
  77                 *new_entry = entry;
  78         return list;
  79 }
  80
  81 /*
  82  * Future: need to be in "struct repository"
  83  * when doing a full libification.
  84  */
  85 struct cached_refs {
  86         char did_loose;
  87         char did_packed;
  88         struct ref_list *loose;
  89         struct ref_list *packed;
  90 } cached_refs;
  91
  92 static void free_ref_list(struct ref_list *list)
  93 {
  94         struct ref_list *next;
  95         for ( ; list; list = next) {
  96                 next = list->next;
  97                 free(list);
  98         }
  99 }
 100
 101 static void invalidate_cached_refs(void)
 102 {
 103         struct cached_refs *ca = &cached_refs;
 104
 105         if (ca->did_loose && ca->loose)
 106                 free_ref_list(ca->loose);
 107         if (ca->did_packed && ca->packed)
 108                 free_ref_list(ca->packed);
 109         ca->loose = ca->packed = NULL;
 110         ca->did_loose = ca->did_packed = 0;
 111 }
 112
 113 static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
 114 {
 115         struct ref_list *list = NULL;
 116         struct ref_list *last = NULL;
 117         char refline[PATH_MAX];
 118         int flag = REF_ISPACKED;
 119
 120         while (fgets(refline, sizeof(refline), f)) {
 121                 unsigned char sha1[20];
 122                 const char *name;
 123                 static const char header[] = "# pack-refs with:";
 124
 125                 if (!strncmp(refline, header, sizeof(header)-1)) {
 126                         const char *traits = refline + sizeof(header) - 1;
 127                         if (strstr(traits, " peeled "))
 128                                 flag |= REF_KNOWS_PEELED;
 129                         /* perhaps other traits later as well */
 130                         continue;
 131                 }
 132
 133                 name = parse_ref_line(refline, sha1);
 134                 if (name) {
 135                         list = add_ref(name, sha1, flag, list, &last);
 136                         continue;
 137                 }
 138                 if (last &&
 139                     refline[0] == '^' &&
 140                     strlen(refline) == 42 &&
 141                     refline[41] == '\n' &&
 142                     !get_sha1_hex(refline + 1, sha1))
 143                         hashcpy(last->peeled, sha1);
 144         }
 145         cached_refs->packed = list;
 146 }
 147
 148 static struct ref_list *get_packed_refs(void)
 149 {
 150         if (!cached_refs.did_packed) {
 151                 FILE *f = fopen(git_path("packed-refs"), "r");
 152                 cached_refs.packed = NULL;
 153                 if (f) {
 154                         read_packed_refs(f, &cached_refs);
 155                         fclose(f);
 156                 }
 157                 cached_refs.did_packed = 1;
 158         }
 159         return cached_refs.packed;
 160 }
 161
 162 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
 163 {
 164         DIR *dir = opendir(git_path("%s", base));
 165
 166         if (dir) {
 167                 struct dirent *de;
 168                 int baselen = strlen(base);
 169                 char *ref = xmalloc(baselen + 257);
 170
 171                 memcpy(ref, base, baselen);
 172                 if (baselen && base[baselen-1] != '/')
 173                         ref[baselen++] = '/';
 174
 175                 while ((de = readdir(dir)) != NULL) {
 176                         unsigned char sha1[20];
 177                         struct stat st;
 178                         int flag;
 179                         int namelen;
 180
 181                         if (de->d_name[0] == '.')
 182                                 continue;
 183                         namelen = strlen(de->d_name);
 184                         if (namelen > 255)
 185                                 continue;
 186                         if (has_extension(de->d_name, ".lock"))
 187                                 continue;
 188                         memcpy(ref + baselen, de->d_name, namelen+1);
 189                         if (stat(git_path("%s", ref), &st) < 0)
 190                                 continue;
 191                         if (S_ISDIR(st.st_mode)) {
 192                                 list = get_ref_dir(ref, list);
 193                                 continue;
 194                         }
 195                         if (!resolve_ref(ref, sha1, 1, &flag)) {
 196                                 error("%s points nowhere!", ref);
 197                                 continue;
 198                         }
 199                         list = add_ref(ref, sha1, flag, list, NULL);
 200                 }
 201                 free(ref);
 202                 closedir(dir);
 203         }
 204         return list;
 205 }
 206
 207 static struct ref_list *get_loose_refs(void)
 208 {
 209         if (!cached_refs.did_loose) {
 210                 cached_refs.loose = get_ref_dir("refs", NULL);
 211                 cached_refs.did_loose = 1;
 212         }
 213         return cached_refs.loose;
 214 }
 215
 216 /* We allow "recursive" symbolic refs. Only within reason, though */
 217 #define MAXDEPTH 5
 218
 219 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 220 {
 221         int depth = MAXDEPTH, len;
 222         char buffer[256];
 223         static char ref_buffer[256];
 224
 225         if (flag)
 226                 *flag = 0;
 227
 228         for (;;) {
 229                 const char *path = git_path("%s", ref);
 230                 struct stat st;
 231                 char *buf;
 232                 int fd;
 233
 234                 if (--depth < 0)
 235                         return NULL;
 236
 237                 /* Special case: non-existing file.
 238                  * Not having the refs/heads/new-branch is OK
 239                  * if we are writing into it, so is .git/HEAD
 240                  * that points at refs/heads/master still to be
 241                  * born.  It is NOT OK if we are resolving for
 242                  * reading.
 243                  */
 244                 if (lstat(path, &st) < 0) {
 245                         struct ref_list *list = get_packed_refs();
 246                         while (list) {
 247                                 if (!strcmp(ref, list->name)) {
 248                                         hashcpy(sha1, list->sha1);
 249                                         if (flag)
 250                                                 *flag |= REF_ISPACKED;
 251                                         return ref;
 252                                 }
 253                                 list = list->next;
 254                         }
 255                         if (reading || errno != ENOENT)
 256                                 return NULL;
 257                         hashclr(sha1);
 258                         return ref;
 259                 }
 260
 261                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 262                 if (S_ISLNK(st.st_mode)) {
 263                         len = readlink(path, buffer, sizeof(buffer)-1);
 264                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 265                                 buffer[len] = 0;
 266                                 strcpy(ref_buffer, buffer);
 267                                 ref = ref_buffer;
 268                                 if (flag)
 269                                         *flag |= REF_ISSYMREF;
 270                                 continue;
 271                         }
 272                 }
 273
 274                 /* Is it a directory? */
 275                 if (S_ISDIR(st.st_mode)) {
 276                         errno = EISDIR;
 277                         return NULL;
 278                 }
 279
 280                 /*
 281                  * Anything else, just open it and try to use it as
 282                  * a ref
 283                  */
 284                 fd = open(path, O_RDONLY);
 285                 if (fd < 0)
 286                         return NULL;
 287                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
 288                 close(fd);
 289
 290                 /*
 291                  * Is it a symbolic ref?
 292                  */
 293                 if (len < 4 || memcmp("ref:", buffer, 4))
 294                         break;
 295                 buf = buffer + 4;
 296                 len -= 4;
 297                 while (len && isspace(*buf))
 298                         buf++, len--;
 299                 while (len && isspace(buf[len-1]))
 300                         len--;
 301                 buf[len] = 0;
 302                 memcpy(ref_buffer, buf, len + 1);
 303                 ref = ref_buffer;
 304                 if (flag)
 305                         *flag |= REF_ISSYMREF;
 306         }
 307         if (len < 40 || get_sha1_hex(buffer, sha1))
 308                 return NULL;
 309         return ref;
 310 }
 311
 312 int create_symref(const char *ref_target, const char *refs_heads_master)
 313 {
 314         const char *lockpath;
 315         char ref[1000];
 316         int fd, len, written;
 317         const char *git_HEAD = git_path("%s", ref_target);
 318
 319 #ifndef NO_SYMLINK_HEAD
 320         if (prefer_symlink_refs) {
 321                 unlink(git_HEAD);
 322                 if (!symlink(refs_heads_master, git_HEAD))
 323                         return 0;
 324                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
 325         }
 326 #endif
 327
 328         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
 329         if (sizeof(ref) <= len) {
 330                 error("refname too long: %s", refs_heads_master);
 331                 return -1;
 332         }
 333         lockpath = mkpath("%s.lock", git_HEAD);
 334         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
 335         if (fd < 0) {
 336                 error("Unable to open %s for writing", lockpath);
 337                 return -5;
 338         }
 339         written = write_in_full(fd, ref, len);
 340         close(fd);
 341         if (written != len) {
 342                 unlink(lockpath);
 343                 error("Unable to write to %s", lockpath);
 344                 return -2;
 345         }
 346         if (rename(lockpath, git_HEAD) < 0) {
 347                 unlink(lockpath);
 348                 error("Unable to create %s", git_HEAD);
 349                 return -3;
 350         }
 351         if (adjust_shared_perm(git_HEAD)) {
 352                 unlink(lockpath);
 353                 error("Unable to fix permissions on %s", lockpath);
 354                 return -4;
 355         }
 356         return 0;
 357 }
 358
 359 int read_ref(const char *ref, unsigned char *sha1)
 360 {
 361         if (resolve_ref(ref, sha1, 1, NULL))
 362                 return 0;
 363         return -1;
 364 }
 365
 366 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
 367                       void *cb_data, struct ref_list *entry)
 368 {
 369         if (strncmp(base, entry->name, trim))
 370                 return 0;
 371         if (is_null_sha1(entry->sha1))
 372                 return 0;
 373         if (!has_sha1_file(entry->sha1)) {
 374                 error("%s does not point to a valid object!", entry->name);
 375                 return 0;
 376         }
 377         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 378 }
 379
 380 int peel_ref(const char *ref, unsigned char *sha1)
 381 {
 382         int flag;
 383         unsigned char base[20];
 384         struct object *o;
 385
 386         if (!resolve_ref(ref, base, 1, &flag))
 387                 return -1;
 388
 389         if ((flag & REF_ISPACKED)) {
 390                 struct ref_list *list = get_packed_refs();
 391
 392                 while (list) {
 393                         if (!strcmp(list->name, ref)) {
 394                                 if (list->flag & REF_KNOWS_PEELED) {
 395                                         hashcpy(sha1, list->peeled);
 396                                         return 0;
 397                                 }
 398                                 /* older pack-refs did not leave peeled ones */
 399                                 break;
 400                         }
 401                         list = list->next;
 402                 }
 403         }
 404
 405         /* fallback - callers should not call this for unpacked refs */
 406         o = parse_object(base);
 407         if (o->type == OBJ_TAG) {
 408                 o = deref_tag(o, ref, 0);
 409                 if (o) {
 410                         hashcpy(sha1, o->sha1);
 411                         return 0;
 412                 }
 413         }
 414         return -1;
 415 }
 416
 417 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
 418                            void *cb_data)
 419 {
 420         int retval;
 421         struct ref_list *packed = get_packed_refs();
 422         struct ref_list *loose = get_loose_refs();
 423
 424         while (packed && loose) {
 425                 struct ref_list *entry;
 426                 int cmp = strcmp(packed->name, loose->name);
 427                 if (!cmp) {
 428                         packed = packed->next;
 429                         continue;
 430                 }
 431                 if (cmp > 0) {
 432                         entry = loose;
 433                         loose = loose->next;
 434                 } else {
 435                         entry = packed;
 436                         packed = packed->next;
 437                 }
 438                 retval = do_one_ref(base, fn, trim, cb_data, entry);
 439                 if (retval)
 440                         return retval;
 441         }
 442
 443         for (packed = packed ? packed : loose; packed; packed = packed->next) {
 444                 retval = do_one_ref(base, fn, trim, cb_data, packed);
 445                 if (retval)
 446                         return retval;
 447         }
 448         return 0;
 449 }
 450
 451 int head_ref(each_ref_fn fn, void *cb_data)
 452 {
 453         unsigned char sha1[20];
 454         int flag;
 455
 456         if (resolve_ref("HEAD", sha1, 1, &flag))
 457                 return fn("HEAD", sha1, flag, cb_data);
 458         return 0;
 459 }
 460
 461 int for_each_ref(each_ref_fn fn, void *cb_data)
 462 {
 463         return do_for_each_ref("refs/", fn, 0, cb_data);
 464 }
 465
 466 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 467 {
 468         return do_for_each_ref("refs/tags/", fn, 10, cb_data);
 469 }
 470
 471 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 472 {
 473         return do_for_each_ref("refs/heads/", fn, 11, cb_data);
 474 }
 475
 476 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 477 {
 478         return do_for_each_ref("refs/remotes/", fn, 13, cb_data);
 479 }
 480
 481 /* NEEDSWORK: This is only used by ssh-upload and it should go; the
 482  * caller should do resolve_ref or read_ref like everybody else.  Or
 483  * maybe everybody else should use get_ref_sha1() instead of doing
 484  * read_ref().
 485  */
 486 int get_ref_sha1(const char *ref, unsigned char *sha1)
 487 {
 488         if (check_ref_format(ref))
 489                 return -1;
 490         return read_ref(mkpath("refs/%s", ref), sha1);
 491 }
 492
 493 /*
 494  * Make sure "ref" is something reasonable to have under ".git/refs/";
 495  * We do not like it if:
 496  *
 497  * - any path component of it begins with ".", or
 498  * - it has double dots "..", or
 499  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 500  * - it ends with a "/".
 501  */
 502
 503 static inline int bad_ref_char(int ch)
 504 {
 505         return (((unsigned) ch) <= ' ' ||
 506                 ch == '~' || ch == '^' || ch == ':' ||
 507                 /* 2.13 Pattern Matching Notation */
 508                 ch == '?' || ch == '*' || ch == '[');
 509 }
 510
 511 int check_ref_format(const char *ref)
 512 {
 513         int ch, level;
 514         const char *cp = ref;
 515
 516         level = 0;
 517         while (1) {
 518                 while ((ch = *cp++) == '/')
 519                         ; /* tolerate duplicated slashes */
 520                 if (!ch)
 521                         return -1; /* should not end with slashes */
 522
 523                 /* we are at the beginning of the path component */
 524                 if (ch == '.' || bad_ref_char(ch))
 525                         return -1;
 526
 527                 /* scan the rest of the path component */
 528                 while ((ch = *cp++) != 0) {
 529                         if (bad_ref_char(ch))
 530                                 return -1;
 531                         if (ch == '/')
 532                                 break;
 533                         if (ch == '.' && *cp == '.')
 534                                 return -1;
 535                 }
 536                 level++;
 537                 if (!ch) {
 538                         if (level < 2)
 539                                 return -2; /* at least of form "heads/blah" */
 540                         return 0;
 541                 }
 542         }
 543 }
 544
 545 static struct ref_lock *verify_lock(struct ref_lock *lock,
 546         const unsigned char *old_sha1, int mustexist)
 547 {
 548         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
 549                 error("Can't verify ref %s", lock->ref_name);
 550                 unlock_ref(lock);
 551                 return NULL;
 552         }
 553         if (hashcmp(lock->old_sha1, old_sha1)) {
 554                 error("Ref %s is at %s but expected %s", lock->ref_name,
 555                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 556                 unlock_ref(lock);
 557                 return NULL;
 558         }
 559         return lock;
 560 }
 561
 562 static int remove_empty_dir_recursive(char *path, int len)
 563 {
 564         DIR *dir = opendir(path);
 565         struct dirent *e;
 566         int ret = 0;
 567
 568         if (!dir)
 569                 return -1;
 570         if (path[len-1] != '/')
 571                 path[len++] = '/';
 572         while ((e = readdir(dir)) != NULL) {
 573                 struct stat st;
 574                 int namlen;
 575                 if ((e->d_name[0] == '.') &&
 576                     ((e->d_name[1] == 0) ||
 577                      ((e->d_name[1] == '.') && e->d_name[2] == 0)))
 578                         continue; /* "." and ".." */
 579
 580                 namlen = strlen(e->d_name);
 581                 if ((len + namlen < PATH_MAX) &&
 582                     strcpy(path + len, e->d_name) &&
 583                     !lstat(path, &st) &&
 584                     S_ISDIR(st.st_mode) &&
 585                     !remove_empty_dir_recursive(path, len + namlen))
 586                         continue; /* happy */
 587
 588                 /* path too long, stat fails, or non-directory still exists */
 589                 ret = -1;
 590                 break;
 591         }
 592         closedir(dir);
 593         if (!ret) {
 594                 path[len] = 0;
 595                 ret = rmdir(path);
 596         }
 597         return ret;
 598 }
 599
 600 static int remove_empty_directories(char *file)
 601 {
 602         /* we want to create a file but there is a directory there;
 603          * if that is an empty directory (or a directory that contains
 604          * only empty directories), remove them.
 605          */
 606         char path[PATH_MAX];
 607         int len = strlen(file);
 608
 609         if (len >= PATH_MAX) /* path too long ;-) */
 610                 return -1;
 611         strcpy(path, file);
 612         return remove_empty_dir_recursive(path, len);
 613 }
 614
 615 static int is_refname_available(const char *ref, const char *oldref,
 616                                 struct ref_list *list, int quiet)
 617 {
 618         int namlen = strlen(ref); /* e.g. 'foo/bar' */
 619         while (list) {
 620                 /* list->name could be 'foo' or 'foo/bar/baz' */
 621                 if (!oldref || strcmp(oldref, list->name)) {
 622                         int len = strlen(list->name);
 623                         int cmplen = (namlen < len) ? namlen : len;
 624                         const char *lead = (namlen < len) ? list->name : ref;
 625                         if (!strncmp(ref, list->name, cmplen) &&
 626                             lead[cmplen] == '/') {
 627                                 if (!quiet)
 628                                         error("'%s' exists; cannot create '%s'",
 629                                               list->name, ref);
 630                                 return 0;
 631                         }
 632                 }
 633                 list = list->next;
 634         }
 635         return 1;
 636 }
 637
 638 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int *flag)
 639 {
 640         char *ref_file;
 641         const char *orig_ref = ref;
 642         struct ref_lock *lock;
 643         struct stat st;
 644         int last_errno = 0;
 645         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 646
 647         lock = xcalloc(1, sizeof(struct ref_lock));
 648         lock->lock_fd = -1;
 649
 650         ref = resolve_ref(ref, lock->old_sha1, mustexist, flag);
 651         if (!ref && errno == EISDIR) {
 652                 /* we are trying to lock foo but we used to
 653                  * have foo/bar which now does not exist;
 654                  * it is normal for the empty directory 'foo'
 655                  * to remain.
 656                  */
 657                 ref_file = git_path("%s", orig_ref);
 658                 if (remove_empty_directories(ref_file)) {
 659                         last_errno = errno;
 660                         error("there are still refs under '%s'", orig_ref);
 661                         goto error_return;
 662                 }
 663                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, flag);
 664         }
 665         if (!ref) {
 666                 last_errno = errno;
 667                 error("unable to resolve reference %s: %s",
 668                         orig_ref, strerror(errno));
 669                 goto error_return;
 670         }
 671         /* When the ref did not exist and we are creating it,
 672          * make sure there is no existing ref that is packed
 673          * whose name begins with our refname, nor a ref whose
 674          * name is a proper prefix of our refname.
 675          */
 676         if (is_null_sha1(lock->old_sha1) &&
 677             !is_refname_available(ref, NULL, get_packed_refs(), 0))
 678                 goto error_return;
 679
 680         lock->lk = xcalloc(1, sizeof(struct lock_file));
 681
 682         lock->ref_name = xstrdup(ref);
 683         lock->log_file = xstrdup(git_path("logs/%s", ref));
 684         ref_file = git_path("%s", ref);
 685         lock->force_write = lstat(ref_file, &st) && errno == ENOENT;
 686
 687         if (safe_create_leading_directories(ref_file)) {
 688                 last_errno = errno;
 689                 error("unable to create directory for %s", ref_file);
 690                 goto error_return;
 691         }
 692         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, 1);
 693
 694         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 695
 696  error_return:
 697         unlock_ref(lock);
 698         errno = last_errno;
 699         return NULL;
 700 }
 701
 702 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 703 {
 704         char refpath[PATH_MAX];
 705         if (check_ref_format(ref))
 706                 return NULL;
 707         strcpy(refpath, mkpath("refs/%s", ref));
 708         return lock_ref_sha1_basic(refpath, old_sha1, NULL);
 709 }
 710
 711 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1)
 712 {
 713         return lock_ref_sha1_basic(ref, old_sha1, NULL);
 714 }
 715
 716 static struct lock_file packlock;
 717
 718 static int repack_without_ref(const char *refname)
 719 {
 720         struct ref_list *list, *packed_ref_list;
 721         int fd;
 722         int found = 0;
 723
 724         packed_ref_list = get_packed_refs();
 725         for (list = packed_ref_list; list; list = list->next) {
 726                 if (!strcmp(refname, list->name)) {
 727                         found = 1;
 728                         break;
 729                 }
 730         }
 731         if (!found)
 732                 return 0;
 733         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
 734         if (fd < 0)
 735                 return error("cannot delete '%s' from packed refs", refname);
 736
 737         for (list = packed_ref_list; list; list = list->next) {
 738                 char line[PATH_MAX + 100];
 739                 int len;
 740
 741                 if (!strcmp(refname, list->name))
 742                         continue;
 743                 len = snprintf(line, sizeof(line), "%s %s\n",
 744                                sha1_to_hex(list->sha1), list->name);
 745                 /* this should not happen but just being defensive */
 746                 if (len > sizeof(line))
 747                         die("too long a refname '%s'", list->name);
 748                 write_or_die(fd, line, len);
 749         }
 750         return commit_lock_file(&packlock);
 751 }
 752
 753 int delete_ref(const char *refname, unsigned char *sha1)
 754 {
 755         struct ref_lock *lock;
 756         int err, i, ret = 0, flag = 0;
 757
 758         lock = lock_ref_sha1_basic(refname, sha1, &flag);
 759         if (!lock)
 760                 return 1;
 761         if (!(flag & REF_ISPACKED)) {
 762                 /* loose */
 763                 i = strlen(lock->lk->filename) - 5; /* .lock */
 764                 lock->lk->filename[i] = 0;
 765                 err = unlink(lock->lk->filename);
 766                 if (err) {
 767                         ret = 1;
 768                         error("unlink(%s) failed: %s",
 769                               lock->lk->filename, strerror(errno));
 770                 }
 771                 lock->lk->filename[i] = '.';
 772         }
 773         /* removing the loose one could have resurrected an earlier
 774          * packed one.  Also, if it was not loose we need to repack
 775          * without it.
 776          */
 777         ret |= repack_without_ref(refname);
 778
 779         err = unlink(lock->log_file);
 780         if (err && errno != ENOENT)
 781                 fprintf(stderr, "warning: unlink(%s) failed: %s",
 782                         lock->log_file, strerror(errno));
 783         invalidate_cached_refs();
 784         unlock_ref(lock);
 785         return ret;
 786 }
 787
 788 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 789 {
 790         static const char renamed_ref[] = "RENAMED-REF";
 791         unsigned char sha1[20], orig_sha1[20];
 792         int flag = 0, logmoved = 0;
 793         struct ref_lock *lock;
 794         struct stat loginfo;
 795         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
 796
 797         if (S_ISLNK(loginfo.st_mode))
 798                 return error("reflog for %s is a symlink", oldref);
 799
 800         if (!resolve_ref(oldref, orig_sha1, 1, &flag))
 801                 return error("refname %s not found", oldref);
 802
 803         if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
 804                 return 1;
 805
 806         if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
 807                 return 1;
 808
 809         lock = lock_ref_sha1_basic(renamed_ref, NULL, NULL);
 810         if (!lock)
 811                 return error("unable to lock %s", renamed_ref);
 812         lock->force_write = 1;
 813         if (write_ref_sha1(lock, orig_sha1, logmsg))
 814                 return error("unable to save current sha1 in %s", renamed_ref);
 815
 816         if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
 817                 return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
 818                         oldref, strerror(errno));
 819
 820         if (delete_ref(oldref, orig_sha1)) {
 821                 error("unable to delete old %s", oldref);
 822                 goto rollback;
 823         }
 824
 825         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1)) {
 826                 if (errno==EISDIR) {
 827                         if (remove_empty_directories(git_path("%s", newref))) {
 828                                 error("Directory not empty: %s", newref);
 829                                 goto rollback;
 830                         }
 831                 } else {
 832                         error("unable to delete existing %s", newref);
 833                         goto rollback;
 834                 }
 835         }
 836
 837         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
 838                 error("unable to create directory for %s", newref);
 839                 goto rollback;
 840         }
 841
 842  retry:
 843         if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
 844                 if (errno==EISDIR || errno==ENOTDIR) {
 845                         /*
 846                          * rename(a, b) when b is an existing
 847                          * directory ought to result in ISDIR, but
 848                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
 849                          */
 850                         if (remove_empty_directories(git_path("logs/%s", newref))) {
 851                                 error("Directory not empty: logs/%s", newref);
 852                                 goto rollback;
 853                         }
 854                         goto retry;
 855                 } else {
 856                         error("unable to move logfile tmp-renamed-log to logs/%s: %s",
 857                                 newref, strerror(errno));
 858                         goto rollback;
 859                 }
 860         }
 861         logmoved = log;
 862
 863         lock = lock_ref_sha1_basic(newref, NULL, NULL);
 864         if (!lock) {
 865                 error("unable to lock %s for update", newref);
 866                 goto rollback;
 867         }
 868
 869         lock->force_write = 1;
 870         hashcpy(lock->old_sha1, orig_sha1);
 871         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
 872                 error("unable to write current sha1 into %s", newref);
 873                 goto rollback;
 874         }
 875
 876         if (!strncmp(oldref, "refs/heads/", 11) &&
 877                         !strncmp(newref, "refs/heads/", 11)) {
 878                 char oldsection[1024], newsection[1024];
 879
 880                 snprintf(oldsection, 1024, "branch.%s", oldref + 11);
 881                 snprintf(newsection, 1024, "branch.%s", newref + 11);
 882                 if (git_config_rename_section(oldsection, newsection) < 0)
 883                         return 1;
 884         }
 885
 886         return 0;
 887
 888  rollback:
 889         lock = lock_ref_sha1_basic(oldref, NULL, NULL);
 890         if (!lock) {
 891                 error("unable to lock %s for rollback", oldref);
 892                 goto rollbacklog;
 893         }
 894
 895         lock->force_write = 1;
 896         flag = log_all_ref_updates;
 897         log_all_ref_updates = 0;
 898         if (write_ref_sha1(lock, orig_sha1, NULL))
 899                 error("unable to write current sha1 into %s", oldref);
 900         log_all_ref_updates = flag;
 901
 902  rollbacklog:
 903         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
 904                 error("unable to restore logfile %s from %s: %s",
 905                         oldref, newref, strerror(errno));
 906         if (!logmoved && log &&
 907             rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
 908                 error("unable to restore logfile %s from tmp-renamed-log: %s",
 909                         oldref, strerror(errno));
 910
 911         return 1;
 912 }
 913
 914 void unlock_ref(struct ref_lock *lock)
 915 {
 916         if (lock->lock_fd >= 0) {
 917                 close(lock->lock_fd);
 918                 /* Do not free lock->lk -- atexit() still looks at them */
 919                 if (lock->lk)
 920                         rollback_lock_file(lock->lk);
 921         }
 922         free(lock->ref_name);
 923         free(lock->log_file);
 924         free(lock);
 925 }
 926
 927 static int log_ref_write(struct ref_lock *lock,
 928         const unsigned char *sha1, const char *msg)
 929 {
 930         int logfd, written, oflags = O_APPEND | O_WRONLY;
 931         unsigned maxlen, len;
 932         int msglen;
 933         char *logrec;
 934         const char *committer;
 935
 936         if (log_all_ref_updates < 0)
 937                 log_all_ref_updates = !is_bare_repository();
 938
 939         if (log_all_ref_updates &&
 940             (!strncmp(lock->ref_name, "refs/heads/", 11) ||
 941              !strncmp(lock->ref_name, "refs/remotes/", 13))) {
 942                 if (safe_create_leading_directories(lock->log_file) < 0)
 943                         return error("unable to create directory for %s",
 944                                 lock->log_file);
 945                 oflags |= O_CREAT;
 946         }
 947
 948         logfd = open(lock->log_file, oflags, 0666);
 949         if (logfd < 0) {
 950                 if (!(oflags & O_CREAT) && errno == ENOENT)
 951                         return 0;
 952
 953                 if ((oflags & O_CREAT) && errno == EISDIR) {
 954                         if (remove_empty_directories(lock->log_file)) {
 955                                 return error("There are still logs under '%s'",
 956                                              lock->log_file);
 957                         }
 958                         logfd = open(lock->log_file, oflags, 0666);
 959                 }
 960
 961                 if (logfd < 0)
 962                         return error("Unable to append to %s: %s",
 963                                      lock->log_file, strerror(errno));
 964         }
 965
 966         msglen = 0;
 967         if (msg) {
 968                 /* clean up the message and make sure it is a single line */
 969                 for ( ; *msg; msg++)
 970                         if (!isspace(*msg))
 971                                 break;
 972                 if (*msg) {
 973                         const char *ep = strchr(msg, '\n');
 974                         if (ep)
 975                                 msglen = ep - msg;
 976                         else
 977                                 msglen = strlen(msg);
 978                 }
 979         }
 980
 981         committer = git_committer_info(-1);
 982         maxlen = strlen(committer) + msglen + 100;
 983         logrec = xmalloc(maxlen);
 984         len = sprintf(logrec, "%s %s %s\n",
 985                       sha1_to_hex(lock->old_sha1),
 986                       sha1_to_hex(sha1),
 987                       committer);
 988         if (msglen)
 989                 len += sprintf(logrec + len - 1, "\t%.*s\n", msglen, msg) - 1;
 990         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
 991         free(logrec);
 992         close(logfd);
 993         if (written != len)
 994                 return error("Unable to append to %s", lock->log_file);
 995         return 0;
 996 }
 997
 998 int write_ref_sha1(struct ref_lock *lock,
 999         const unsigned char *sha1, const char *logmsg)
1000 {
1001         static char term = '\n';
1002
1003         if (!lock)
1004                 return -1;
1005         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1006                 unlock_ref(lock);
1007                 return 0;
1008         }
1009         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1010             write_in_full(lock->lock_fd, &term, 1) != 1
1011                 || close(lock->lock_fd) < 0) {
1012                 error("Couldn't write %s", lock->lk->filename);
1013                 unlock_ref(lock);
1014                 return -1;
1015         }
1016         invalidate_cached_refs();
1017         if (log_ref_write(lock, sha1, logmsg) < 0) {
1018                 unlock_ref(lock);
1019                 return -1;
1020         }
1021         if (commit_lock_file(lock->lk)) {
1022                 error("Couldn't set %s", lock->ref_name);
1023                 unlock_ref(lock);
1024                 return -1;
1025         }
1026         lock->lock_fd = -1;
1027         unlock_ref(lock);
1028         return 0;
1029 }
1030
1031 static char *ref_msg(const char *line, const char *endp)
1032 {
1033         const char *ep;
1034         char *msg;
1035
1036         line += 82;
1037         for (ep = line; ep < endp && *ep != '\n'; ep++)
1038                 ;
1039         msg = xmalloc(ep - line + 1);
1040         memcpy(msg, line, ep - line);
1041         msg[ep - line] = 0;
1042         return msg;
1043 }
1044
1045 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)
1046 {
1047         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1048         char *tz_c;
1049         int logfd, tz, reccnt = 0;
1050         struct stat st;
1051         unsigned long date;
1052         unsigned char logged_sha1[20];
1053         void *log_mapped;
1054
1055         logfile = git_path("logs/%s", ref);
1056         logfd = open(logfile, O_RDONLY, 0);
1057         if (logfd < 0)
1058                 die("Unable to read log %s: %s", logfile, strerror(errno));
1059         fstat(logfd, &st);
1060         if (!st.st_size)
1061                 die("Log %s is empty.", logfile);
1062         log_mapped = xmmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, logfd, 0);
1063         logdata = log_mapped;
1064         close(logfd);
1065
1066         lastrec = NULL;
1067         rec = logend = logdata + st.st_size;
1068         while (logdata < rec) {
1069                 reccnt++;
1070                 if (logdata < rec && *(rec-1) == '\n')
1071                         rec--;
1072                 lastgt = NULL;
1073                 while (logdata < rec && *(rec-1) != '\n') {
1074                         rec--;
1075                         if (*rec == '>')
1076                                 lastgt = rec;
1077                 }
1078                 if (!lastgt)
1079                         die("Log %s is corrupt.", logfile);
1080                 date = strtoul(lastgt + 1, &tz_c, 10);
1081                 if (date <= at_time || cnt == 0) {
1082                         tz = strtoul(tz_c, NULL, 10);
1083                         if (msg)
1084                                 *msg = ref_msg(rec, logend);
1085                         if (cutoff_time)
1086                                 *cutoff_time = date;
1087                         if (cutoff_tz)
1088                                 *cutoff_tz = tz;
1089                         if (cutoff_cnt)
1090                                 *cutoff_cnt = reccnt - 1;
1091                         if (lastrec) {
1092                                 if (get_sha1_hex(lastrec, logged_sha1))
1093                                         die("Log %s is corrupt.", logfile);
1094                                 if (get_sha1_hex(rec + 41, sha1))
1095                                         die("Log %s is corrupt.", logfile);
1096                                 if (hashcmp(logged_sha1, sha1)) {
1097                                         fprintf(stderr,
1098                                                 "warning: Log %s has gap after %s.\n",
1099                                                 logfile, show_rfc2822_date(date, tz));
1100                                 }
1101                         }
1102                         else if (date == at_time) {
1103                                 if (get_sha1_hex(rec + 41, sha1))
1104                                         die("Log %s is corrupt.", logfile);
1105                         }
1106                         else {
1107                                 if (get_sha1_hex(rec + 41, logged_sha1))
1108                                         die("Log %s is corrupt.", logfile);
1109                                 if (hashcmp(logged_sha1, sha1)) {
1110                                         fprintf(stderr,
1111                                                 "warning: Log %s unexpectedly ended on %s.\n",
1112                                                 logfile, show_rfc2822_date(date, tz));
1113                                 }
1114                         }
1115                         munmap(log_mapped, st.st_size);
1116                         return 0;
1117                 }
1118                 lastrec = rec;
1119                 if (cnt > 0)
1120                         cnt--;
1121         }
1122
1123         rec = logdata;
1124         while (rec < logend && *rec != '>' && *rec != '\n')
1125                 rec++;
1126         if (rec == logend || *rec == '\n')
1127                 die("Log %s is corrupt.", logfile);
1128         date = strtoul(rec + 1, &tz_c, 10);
1129         tz = strtoul(tz_c, NULL, 10);
1130         if (get_sha1_hex(logdata, sha1))
1131                 die("Log %s is corrupt.", logfile);
1132         if (msg)
1133                 *msg = ref_msg(logdata, logend);
1134         munmap(log_mapped, st.st_size);
1135
1136         if (cutoff_time)
1137                 *cutoff_time = date;
1138         if (cutoff_tz)
1139                 *cutoff_tz = tz;
1140         if (cutoff_cnt)
1141                 *cutoff_cnt = reccnt;
1142         return 1;
1143 }
1144
1145 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1146 {
1147         const char *logfile;
1148         FILE *logfp;
1149         char buf[1024];
1150         int ret = 0;
1151
1152         logfile = git_path("logs/%s", ref);
1153         logfp = fopen(logfile, "r");
1154         if (!logfp)
1155                 return -1;
1156         while (fgets(buf, sizeof(buf), logfp)) {
1157                 unsigned char osha1[20], nsha1[20];
1158                 char *email_end, *message;
1159                 unsigned long timestamp;
1160                 int len, tz;
1161
1162                 /* old SP new SP name <email> SP time TAB msg LF */
1163                 len = strlen(buf);
1164                 if (len < 83 || buf[len-1] != '\n' ||
1165                     get_sha1_hex(buf, osha1) || buf[40] != ' ' ||
1166                     get_sha1_hex(buf + 41, nsha1) || buf[81] != ' ' ||
1167                     !(email_end = strchr(buf + 82, '>')) ||
1168                     email_end[1] != ' ' ||
1169                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1170                     !message || message[0] != ' ' ||
1171                     (message[1] != '+' && message[1] != '-') ||
1172                     !isdigit(message[2]) || !isdigit(message[3]) ||
1173                     !isdigit(message[4]) || !isdigit(message[5]) ||
1174                     message[6] != '\t')
1175                         continue; /* corrupt? */
1176                 email_end[1] = '\0';
1177                 tz = strtol(message + 1, NULL, 10);
1178                 message += 7;
1179                 ret = fn(osha1, nsha1, buf+82, timestamp, tz, message, cb_data);
1180                 if (ret)
1181                         break;
1182         }
1183         fclose(logfp);
1184         return ret;
1185 }
1186