refs.c

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