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 #define MAXREFLEN (1024)
 219
 220 static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
 221 {
 222         FILE *f;
 223         struct cached_refs refs;
 224         struct ref_list *ref;
 225         int retval;
 226
 227         strcpy(name + pathlen, "packed-refs");
 228         f = fopen(name, "r");
 229         if (!f)
 230                 return -1;
 231         read_packed_refs(f, &refs);
 232         fclose(f);
 233         ref = refs.packed;
 234         retval = -1;
 235         while (ref) {
 236                 if (!strcmp(ref->name, refname)) {
 237                         retval = 0;
 238                         memcpy(result, ref->sha1, 20);
 239                         break;
 240                 }
 241                 ref = ref->next;
 242         }
 243         free_ref_list(refs.packed);
 244         return retval;
 245 }
 246
 247 static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
 248 {
 249         int fd, len = strlen(refname);
 250         char buffer[128], *p;
 251
 252         if (recursion > MAXDEPTH || len > MAXREFLEN)
 253                 return -1;
 254         memcpy(name + pathlen, refname, len+1);
 255         fd = open(name, O_RDONLY);
 256         if (fd < 0)
 257                 return resolve_gitlink_packed_ref(name, pathlen, refname, result);
 258
 259         len = read(fd, buffer, sizeof(buffer)-1);
 260         close(fd);
 261         if (len < 0)
 262                 return -1;
 263         while (len && isspace(buffer[len-1]))
 264                 len--;
 265         buffer[len] = 0;
 266
 267         /* Was it a detached head or an old-fashioned symlink? */
 268         if (!get_sha1_hex(buffer, result))
 269                 return 0;
 270
 271         /* Symref? */
 272         if (strncmp(buffer, "ref:", 4))
 273                 return -1;
 274         p = buffer + 4;
 275         while (isspace(*p))
 276                 p++;
 277
 278         return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
 279 }
 280
 281 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
 282 {
 283         int len = strlen(path), retval;
 284         char *gitdir;
 285
 286         while (len && path[len-1] == '/')
 287                 len--;
 288         if (!len)
 289                 return -1;
 290         gitdir = xmalloc(len + MAXREFLEN + 8);
 291         memcpy(gitdir, path, len);
 292         memcpy(gitdir + len, "/.git/", 7);
 293
 294         retval = resolve_gitlink_ref_recursive(gitdir, len+6, refname, result, 0);
 295         free(gitdir);
 296         return retval;
 297 }
 298
 299 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 300 {
 301         int depth = MAXDEPTH, len;
 302         char buffer[256];
 303         static char ref_buffer[256];
 304
 305         if (flag)
 306                 *flag = 0;
 307
 308         for (;;) {
 309                 const char *path = git_path("%s", ref);
 310                 struct stat st;
 311                 char *buf;
 312                 int fd;
 313
 314                 if (--depth < 0)
 315                         return NULL;
 316
 317                 /* Special case: non-existing file.
 318                  * Not having the refs/heads/new-branch is OK
 319                  * if we are writing into it, so is .git/HEAD
 320                  * that points at refs/heads/master still to be
 321                  * born.  It is NOT OK if we are resolving for
 322                  * reading.
 323                  */
 324                 if (lstat(path, &st) < 0) {
 325                         struct ref_list *list = get_packed_refs();
 326                         while (list) {
 327                                 if (!strcmp(ref, list->name)) {
 328                                         hashcpy(sha1, list->sha1);
 329                                         if (flag)
 330                                                 *flag |= REF_ISPACKED;
 331                                         return ref;
 332                                 }
 333                                 list = list->next;
 334                         }
 335                         if (reading || errno != ENOENT)
 336                                 return NULL;
 337                         hashclr(sha1);
 338                         return ref;
 339                 }
 340
 341                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 342                 if (S_ISLNK(st.st_mode)) {
 343                         len = readlink(path, buffer, sizeof(buffer)-1);
 344                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 345                                 buffer[len] = 0;
 346                                 strcpy(ref_buffer, buffer);
 347                                 ref = ref_buffer;
 348                                 if (flag)
 349                                         *flag |= REF_ISSYMREF;
 350                                 continue;
 351                         }
 352                 }
 353
 354                 /* Is it a directory? */
 355                 if (S_ISDIR(st.st_mode)) {
 356                         errno = EISDIR;
 357                         return NULL;
 358                 }
 359
 360                 /*
 361                  * Anything else, just open it and try to use it as
 362                  * a ref
 363                  */
 364                 fd = open(path, O_RDONLY);
 365                 if (fd < 0)
 366                         return NULL;
 367                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
 368                 close(fd);
 369
 370                 /*
 371                  * Is it a symbolic ref?
 372                  */
 373                 if (len < 4 || memcmp("ref:", buffer, 4))
 374                         break;
 375                 buf = buffer + 4;
 376                 len -= 4;
 377                 while (len && isspace(*buf))
 378                         buf++, len--;
 379                 while (len && isspace(buf[len-1]))
 380                         len--;
 381                 buf[len] = 0;
 382                 memcpy(ref_buffer, buf, len + 1);
 383                 ref = ref_buffer;
 384                 if (flag)
 385                         *flag |= REF_ISSYMREF;
 386         }
 387         if (len < 40 || get_sha1_hex(buffer, sha1))
 388                 return NULL;
 389         return ref;
 390 }
 391
 392 int read_ref(const char *ref, unsigned char *sha1)
 393 {
 394         if (resolve_ref(ref, sha1, 1, NULL))
 395                 return 0;
 396         return -1;
 397 }
 398
 399 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
 400                       void *cb_data, struct ref_list *entry)
 401 {
 402         if (strncmp(base, entry->name, trim))
 403                 return 0;
 404         if (is_null_sha1(entry->sha1))
 405                 return 0;
 406         if (!has_sha1_file(entry->sha1)) {
 407                 error("%s does not point to a valid object!", entry->name);
 408                 return 0;
 409         }
 410         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 411 }
 412
 413 int peel_ref(const char *ref, unsigned char *sha1)
 414 {
 415         int flag;
 416         unsigned char base[20];
 417         struct object *o;
 418
 419         if (!resolve_ref(ref, base, 1, &flag))
 420                 return -1;
 421
 422         if ((flag & REF_ISPACKED)) {
 423                 struct ref_list *list = get_packed_refs();
 424
 425                 while (list) {
 426                         if (!strcmp(list->name, ref)) {
 427                                 if (list->flag & REF_KNOWS_PEELED) {
 428                                         hashcpy(sha1, list->peeled);
 429                                         return 0;
 430                                 }
 431                                 /* older pack-refs did not leave peeled ones */
 432                                 break;
 433                         }
 434                         list = list->next;
 435                 }
 436         }
 437
 438         /* fallback - callers should not call this for unpacked refs */
 439         o = parse_object(base);
 440         if (o->type == OBJ_TAG) {
 441                 o = deref_tag(o, ref, 0);
 442                 if (o) {
 443                         hashcpy(sha1, o->sha1);
 444                         return 0;
 445                 }
 446         }
 447         return -1;
 448 }
 449
 450 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
 451                            void *cb_data)
 452 {
 453         int retval;
 454         struct ref_list *packed = get_packed_refs();
 455         struct ref_list *loose = get_loose_refs();
 456
 457         while (packed && loose) {
 458                 struct ref_list *entry;
 459                 int cmp = strcmp(packed->name, loose->name);
 460                 if (!cmp) {
 461                         packed = packed->next;
 462                         continue;
 463                 }
 464                 if (cmp > 0) {
 465                         entry = loose;
 466                         loose = loose->next;
 467                 } else {
 468                         entry = packed;
 469                         packed = packed->next;
 470                 }
 471                 retval = do_one_ref(base, fn, trim, cb_data, entry);
 472                 if (retval)
 473                         return retval;
 474         }
 475
 476         for (packed = packed ? packed : loose; packed; packed = packed->next) {
 477                 retval = do_one_ref(base, fn, trim, cb_data, packed);
 478                 if (retval)
 479                         return retval;
 480         }
 481         return 0;
 482 }
 483
 484 int head_ref(each_ref_fn fn, void *cb_data)
 485 {
 486         unsigned char sha1[20];
 487         int flag;
 488
 489         if (resolve_ref("HEAD", sha1, 1, &flag))
 490                 return fn("HEAD", sha1, flag, cb_data);
 491         return 0;
 492 }
 493
 494 int for_each_ref(each_ref_fn fn, void *cb_data)
 495 {
 496         return do_for_each_ref("refs/", fn, 0, cb_data);
 497 }
 498
 499 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 500 {
 501         return do_for_each_ref("refs/tags/", fn, 10, cb_data);
 502 }
 503
 504 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 505 {
 506         return do_for_each_ref("refs/heads/", fn, 11, cb_data);
 507 }
 508
 509 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 510 {
 511         return do_for_each_ref("refs/remotes/", fn, 13, cb_data);
 512 }
 513
 514 /* NEEDSWORK: This is only used by ssh-upload and it should go; the
 515  * caller should do resolve_ref or read_ref like everybody else.  Or
 516  * maybe everybody else should use get_ref_sha1() instead of doing
 517  * read_ref().
 518  */
 519 int get_ref_sha1(const char *ref, unsigned char *sha1)
 520 {
 521         if (check_ref_format(ref))
 522                 return -1;
 523         return read_ref(mkpath("refs/%s", ref), sha1);
 524 }
 525
 526 /*
 527  * Make sure "ref" is something reasonable to have under ".git/refs/";
 528  * We do not like it if:
 529  *
 530  * - any path component of it begins with ".", or
 531  * - it has double dots "..", or
 532  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 533  * - it ends with a "/".
 534  */
 535
 536 static inline int bad_ref_char(int ch)
 537 {
 538         return (((unsigned) ch) <= ' ' ||
 539                 ch == '~' || ch == '^' || ch == ':' ||
 540                 /* 2.13 Pattern Matching Notation */
 541                 ch == '?' || ch == '*' || ch == '[');
 542 }
 543
 544 int check_ref_format(const char *ref)
 545 {
 546         int ch, level;
 547         const char *cp = ref;
 548
 549         level = 0;
 550         while (1) {
 551                 while ((ch = *cp++) == '/')
 552                         ; /* tolerate duplicated slashes */
 553                 if (!ch)
 554                         return -1; /* should not end with slashes */
 555
 556                 /* we are at the beginning of the path component */
 557                 if (ch == '.' || bad_ref_char(ch))
 558                         return -1;
 559
 560                 /* scan the rest of the path component */
 561                 while ((ch = *cp++) != 0) {
 562                         if (bad_ref_char(ch))
 563                                 return -1;
 564                         if (ch == '/')
 565                                 break;
 566                         if (ch == '.' && *cp == '.')
 567                                 return -1;
 568                 }
 569                 level++;
 570                 if (!ch) {
 571                         if (level < 2)
 572                                 return -2; /* at least of form "heads/blah" */
 573                         return 0;
 574                 }
 575         }
 576 }
 577
 578 static struct ref_lock *verify_lock(struct ref_lock *lock,
 579         const unsigned char *old_sha1, int mustexist)
 580 {
 581         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
 582                 error("Can't verify ref %s", lock->ref_name);
 583                 unlock_ref(lock);
 584                 return NULL;
 585         }
 586         if (hashcmp(lock->old_sha1, old_sha1)) {
 587                 error("Ref %s is at %s but expected %s", lock->ref_name,
 588                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 589                 unlock_ref(lock);
 590                 return NULL;
 591         }
 592         return lock;
 593 }
 594
 595 static int remove_empty_dir_recursive(char *path, int len)
 596 {
 597         DIR *dir = opendir(path);
 598         struct dirent *e;
 599         int ret = 0;
 600
 601         if (!dir)
 602                 return -1;
 603         if (path[len-1] != '/')
 604                 path[len++] = '/';
 605         while ((e = readdir(dir)) != NULL) {
 606                 struct stat st;
 607                 int namlen;
 608                 if ((e->d_name[0] == '.') &&
 609                     ((e->d_name[1] == 0) ||
 610                      ((e->d_name[1] == '.') && e->d_name[2] == 0)))
 611                         continue; /* "." and ".." */
 612
 613                 namlen = strlen(e->d_name);
 614                 if ((len + namlen < PATH_MAX) &&
 615                     strcpy(path + len, e->d_name) &&
 616                     !lstat(path, &st) &&
 617                     S_ISDIR(st.st_mode) &&
 618                     !remove_empty_dir_recursive(path, len + namlen))
 619                         continue; /* happy */
 620
 621                 /* path too long, stat fails, or non-directory still exists */
 622                 ret = -1;
 623                 break;
 624         }
 625         closedir(dir);
 626         if (!ret) {
 627                 path[len] = 0;
 628                 ret = rmdir(path);
 629         }
 630         return ret;
 631 }
 632
 633 static int remove_empty_directories(char *file)
 634 {
 635         /* we want to create a file but there is a directory there;
 636          * if that is an empty directory (or a directory that contains
 637          * only empty directories), remove them.
 638          */
 639         char path[PATH_MAX];
 640         int len = strlen(file);
 641
 642         if (len >= PATH_MAX) /* path too long ;-) */
 643                 return -1;
 644         strcpy(path, file);
 645         return remove_empty_dir_recursive(path, len);
 646 }
 647
 648 static int is_refname_available(const char *ref, const char *oldref,
 649                                 struct ref_list *list, int quiet)
 650 {
 651         int namlen = strlen(ref); /* e.g. 'foo/bar' */
 652         while (list) {
 653                 /* list->name could be 'foo' or 'foo/bar/baz' */
 654                 if (!oldref || strcmp(oldref, list->name)) {
 655                         int len = strlen(list->name);
 656                         int cmplen = (namlen < len) ? namlen : len;
 657                         const char *lead = (namlen < len) ? list->name : ref;
 658                         if (!strncmp(ref, list->name, cmplen) &&
 659                             lead[cmplen] == '/') {
 660                                 if (!quiet)
 661                                         error("'%s' exists; cannot create '%s'",
 662                                               list->name, ref);
 663                                 return 0;
 664                         }
 665                 }
 666                 list = list->next;
 667         }
 668         return 1;
 669 }
 670
 671 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int *flag)
 672 {
 673         char *ref_file;
 674         const char *orig_ref = ref;
 675         struct ref_lock *lock;
 676         struct stat st;
 677         int last_errno = 0;
 678         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 679
 680         lock = xcalloc(1, sizeof(struct ref_lock));
 681         lock->lock_fd = -1;
 682
 683         ref = resolve_ref(ref, lock->old_sha1, mustexist, flag);
 684         if (!ref && errno == EISDIR) {
 685                 /* we are trying to lock foo but we used to
 686                  * have foo/bar which now does not exist;
 687                  * it is normal for the empty directory 'foo'
 688                  * to remain.
 689                  */
 690                 ref_file = git_path("%s", orig_ref);
 691                 if (remove_empty_directories(ref_file)) {
 692                         last_errno = errno;
 693                         error("there are still refs under '%s'", orig_ref);
 694                         goto error_return;
 695                 }
 696                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, flag);
 697         }
 698         if (!ref) {
 699                 last_errno = errno;
 700                 error("unable to resolve reference %s: %s",
 701                         orig_ref, strerror(errno));
 702                 goto error_return;
 703         }
 704         /* When the ref did not exist and we are creating it,
 705          * make sure there is no existing ref that is packed
 706          * whose name begins with our refname, nor a ref whose
 707          * name is a proper prefix of our refname.
 708          */
 709         if (is_null_sha1(lock->old_sha1) &&
 710             !is_refname_available(ref, NULL, get_packed_refs(), 0))
 711                 goto error_return;
 712
 713         lock->lk = xcalloc(1, sizeof(struct lock_file));
 714
 715         lock->ref_name = xstrdup(ref);
 716         lock->orig_ref_name = xstrdup(orig_ref);
 717         ref_file = git_path("%s", ref);
 718         lock->force_write = lstat(ref_file, &st) && errno == ENOENT;
 719
 720         if (safe_create_leading_directories(ref_file)) {
 721                 last_errno = errno;
 722                 error("unable to create directory for %s", ref_file);
 723                 goto error_return;
 724         }
 725         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, 1);
 726
 727         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 728
 729  error_return:
 730         unlock_ref(lock);
 731         errno = last_errno;
 732         return NULL;
 733 }
 734
 735 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 736 {
 737         char refpath[PATH_MAX];
 738         if (check_ref_format(ref))
 739                 return NULL;
 740         strcpy(refpath, mkpath("refs/%s", ref));
 741         return lock_ref_sha1_basic(refpath, old_sha1, NULL);
 742 }
 743
 744 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1)
 745 {
 746         if (check_ref_format(ref) == -1)
 747                 return NULL;
 748         return lock_ref_sha1_basic(ref, old_sha1, NULL);
 749 }
 750
 751 static struct lock_file packlock;
 752
 753 static int repack_without_ref(const char *refname)
 754 {
 755         struct ref_list *list, *packed_ref_list;
 756         int fd;
 757         int found = 0;
 758
 759         packed_ref_list = get_packed_refs();
 760         for (list = packed_ref_list; list; list = list->next) {
 761                 if (!strcmp(refname, list->name)) {
 762                         found = 1;
 763                         break;
 764                 }
 765         }
 766         if (!found)
 767                 return 0;
 768         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
 769         if (fd < 0)
 770                 return error("cannot delete '%s' from packed refs", refname);
 771
 772         for (list = packed_ref_list; list; list = list->next) {
 773                 char line[PATH_MAX + 100];
 774                 int len;
 775
 776                 if (!strcmp(refname, list->name))
 777                         continue;
 778                 len = snprintf(line, sizeof(line), "%s %s\n",
 779                                sha1_to_hex(list->sha1), list->name);
 780                 /* this should not happen but just being defensive */
 781                 if (len > sizeof(line))
 782                         die("too long a refname '%s'", list->name);
 783                 write_or_die(fd, line, len);
 784         }
 785         return commit_lock_file(&packlock);
 786 }
 787
 788 int delete_ref(const char *refname, unsigned char *sha1)
 789 {
 790         struct ref_lock *lock;
 791         int err, i, ret = 0, flag = 0;
 792
 793         lock = lock_ref_sha1_basic(refname, sha1, &flag);
 794         if (!lock)
 795                 return 1;
 796         if (!(flag & REF_ISPACKED)) {
 797                 /* loose */
 798                 i = strlen(lock->lk->filename) - 5; /* .lock */
 799                 lock->lk->filename[i] = 0;
 800                 err = unlink(lock->lk->filename);
 801                 if (err) {
 802                         ret = 1;
 803                         error("unlink(%s) failed: %s",
 804                               lock->lk->filename, strerror(errno));
 805                 }
 806                 lock->lk->filename[i] = '.';
 807         }
 808         /* removing the loose one could have resurrected an earlier
 809          * packed one.  Also, if it was not loose we need to repack
 810          * without it.
 811          */
 812         ret |= repack_without_ref(refname);
 813
 814         err = unlink(git_path("logs/%s", lock->ref_name));
 815         if (err && errno != ENOENT)
 816                 fprintf(stderr, "warning: unlink(%s) failed: %s",
 817                         git_path("logs/%s", lock->ref_name), strerror(errno));
 818         invalidate_cached_refs();
 819         unlock_ref(lock);
 820         return ret;
 821 }
 822
 823 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
 824 {
 825         static const char renamed_ref[] = "RENAMED-REF";
 826         unsigned char sha1[20], orig_sha1[20];
 827         int flag = 0, logmoved = 0;
 828         struct ref_lock *lock;
 829         struct stat loginfo;
 830         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
 831
 832         if (S_ISLNK(loginfo.st_mode))
 833                 return error("reflog for %s is a symlink", oldref);
 834
 835         if (!resolve_ref(oldref, orig_sha1, 1, &flag))
 836                 return error("refname %s not found", oldref);
 837
 838         if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
 839                 return 1;
 840
 841         if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
 842                 return 1;
 843
 844         lock = lock_ref_sha1_basic(renamed_ref, NULL, NULL);
 845         if (!lock)
 846                 return error("unable to lock %s", renamed_ref);
 847         lock->force_write = 1;
 848         if (write_ref_sha1(lock, orig_sha1, logmsg))
 849                 return error("unable to save current sha1 in %s", renamed_ref);
 850
 851         if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
 852                 return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
 853                         oldref, strerror(errno));
 854
 855         if (delete_ref(oldref, orig_sha1)) {
 856                 error("unable to delete old %s", oldref);
 857                 goto rollback;
 858         }
 859
 860         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1)) {
 861                 if (errno==EISDIR) {
 862                         if (remove_empty_directories(git_path("%s", newref))) {
 863                                 error("Directory not empty: %s", newref);
 864                                 goto rollback;
 865                         }
 866                 } else {
 867                         error("unable to delete existing %s", newref);
 868                         goto rollback;
 869                 }
 870         }
 871
 872         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
 873                 error("unable to create directory for %s", newref);
 874                 goto rollback;
 875         }
 876
 877  retry:
 878         if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
 879                 if (errno==EISDIR || errno==ENOTDIR) {
 880                         /*
 881                          * rename(a, b) when b is an existing
 882                          * directory ought to result in ISDIR, but
 883                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
 884                          */
 885                         if (remove_empty_directories(git_path("logs/%s", newref))) {
 886                                 error("Directory not empty: logs/%s", newref);
 887                                 goto rollback;
 888                         }
 889                         goto retry;
 890                 } else {
 891                         error("unable to move logfile tmp-renamed-log to logs/%s: %s",
 892                                 newref, strerror(errno));
 893                         goto rollback;
 894                 }
 895         }
 896         logmoved = log;
 897
 898         lock = lock_ref_sha1_basic(newref, NULL, NULL);
 899         if (!lock) {
 900                 error("unable to lock %s for update", newref);
 901                 goto rollback;
 902         }
 903
 904         lock->force_write = 1;
 905         hashcpy(lock->old_sha1, orig_sha1);
 906         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
 907                 error("unable to write current sha1 into %s", newref);
 908                 goto rollback;
 909         }
 910
 911         return 0;
 912
 913  rollback:
 914         lock = lock_ref_sha1_basic(oldref, NULL, NULL);
 915         if (!lock) {
 916                 error("unable to lock %s for rollback", oldref);
 917                 goto rollbacklog;
 918         }
 919
 920         lock->force_write = 1;
 921         flag = log_all_ref_updates;
 922         log_all_ref_updates = 0;
 923         if (write_ref_sha1(lock, orig_sha1, NULL))
 924                 error("unable to write current sha1 into %s", oldref);
 925         log_all_ref_updates = flag;
 926
 927  rollbacklog:
 928         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
 929                 error("unable to restore logfile %s from %s: %s",
 930                         oldref, newref, strerror(errno));
 931         if (!logmoved && log &&
 932             rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
 933                 error("unable to restore logfile %s from tmp-renamed-log: %s",
 934                         oldref, strerror(errno));
 935
 936         return 1;
 937 }
 938
 939 void unlock_ref(struct ref_lock *lock)
 940 {
 941         if (lock->lock_fd >= 0) {
 942                 close(lock->lock_fd);
 943                 /* Do not free lock->lk -- atexit() still looks at them */
 944                 if (lock->lk)
 945                         rollback_lock_file(lock->lk);
 946         }
 947         free(lock->ref_name);
 948         free(lock->orig_ref_name);
 949         free(lock);
 950 }
 951
 952 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
 953                          const unsigned char *new_sha1, const char *msg)
 954 {
 955         int logfd, written, oflags = O_APPEND | O_WRONLY;
 956         unsigned maxlen, len;
 957         int msglen;
 958         char *log_file, *logrec;
 959         const char *committer;
 960
 961         if (log_all_ref_updates < 0)
 962                 log_all_ref_updates = !is_bare_repository();
 963
 964         log_file = git_path("logs/%s", ref_name);
 965
 966         if (log_all_ref_updates &&
 967             (!prefixcmp(ref_name, "refs/heads/") ||
 968              !prefixcmp(ref_name, "refs/remotes/") ||
 969              !strcmp(ref_name, "HEAD"))) {
 970                 if (safe_create_leading_directories(log_file) < 0)
 971                         return error("unable to create directory for %s",
 972                                      log_file);
 973                 oflags |= O_CREAT;
 974         }
 975
 976         logfd = open(log_file, oflags, 0666);
 977         if (logfd < 0) {
 978                 if (!(oflags & O_CREAT) && errno == ENOENT)
 979                         return 0;
 980
 981                 if ((oflags & O_CREAT) && errno == EISDIR) {
 982                         if (remove_empty_directories(log_file)) {
 983                                 return error("There are still logs under '%s'",
 984                                              log_file);
 985                         }
 986                         logfd = open(log_file, oflags, 0666);
 987                 }
 988
 989                 if (logfd < 0)
 990                         return error("Unable to append to %s: %s",
 991                                      log_file, strerror(errno));
 992         }
 993
 994         adjust_shared_perm(log_file);
 995
 996         msglen = 0;
 997         if (msg) {
 998                 /* clean up the message and make sure it is a single line */
 999                 for ( ; *msg; msg++)
1000                         if (!isspace(*msg))
1001                                 break;
1002                 if (*msg) {
1003                         const char *ep = strchr(msg, '\n');
1004                         if (ep)
1005                                 msglen = ep - msg;
1006                         else
1007                                 msglen = strlen(msg);
1008                 }
1009         }
1010
1011         committer = git_committer_info(-1);
1012         maxlen = strlen(committer) + msglen + 100;
1013         logrec = xmalloc(maxlen);
1014         len = sprintf(logrec, "%s %s %s\n",
1015                       sha1_to_hex(old_sha1),
1016                       sha1_to_hex(new_sha1),
1017                       committer);
1018         if (msglen)
1019                 len += sprintf(logrec + len - 1, "\t%.*s\n", msglen, msg) - 1;
1020         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1021         free(logrec);
1022         close(logfd);
1023         if (written != len)
1024                 return error("Unable to append to %s", log_file);
1025         return 0;
1026 }
1027
1028 int write_ref_sha1(struct ref_lock *lock,
1029         const unsigned char *sha1, const char *logmsg)
1030 {
1031         static char term = '\n';
1032
1033         if (!lock)
1034                 return -1;
1035         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1036                 unlock_ref(lock);
1037                 return 0;
1038         }
1039         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1040             write_in_full(lock->lock_fd, &term, 1) != 1
1041                 || close(lock->lock_fd) < 0) {
1042                 error("Couldn't write %s", lock->lk->filename);
1043                 unlock_ref(lock);
1044                 return -1;
1045         }
1046         invalidate_cached_refs();
1047         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1048             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1049              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1050                 unlock_ref(lock);
1051                 return -1;
1052         }
1053         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1054                 /*
1055                  * Special hack: If a branch is updated directly and HEAD
1056                  * points to it (may happen on the remote side of a push
1057                  * for example) then logically the HEAD reflog should be
1058                  * updated too.
1059                  * A generic solution implies reverse symref information,
1060                  * but finding all symrefs pointing to the given branch
1061                  * would be rather costly for this rare event (the direct
1062                  * update of a branch) to be worth it.  So let's cheat and
1063                  * check with HEAD only which should cover 99% of all usage
1064                  * scenarios (even 100% of the default ones).
1065                  */
1066                 unsigned char head_sha1[20];
1067                 int head_flag;
1068                 const char *head_ref;
1069                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1070                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1071                     !strcmp(head_ref, lock->ref_name))
1072                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1073         }
1074         if (commit_lock_file(lock->lk)) {
1075                 error("Couldn't set %s", lock->ref_name);
1076                 unlock_ref(lock);
1077                 return -1;
1078         }
1079         lock->lock_fd = -1;
1080         unlock_ref(lock);
1081         return 0;
1082 }
1083
1084 int create_symref(const char *ref_target, const char *refs_heads_master,
1085                   const char *logmsg)
1086 {
1087         const char *lockpath;
1088         char ref[1000];
1089         int fd, len, written;
1090         char *git_HEAD = xstrdup(git_path("%s", ref_target));
1091         unsigned char old_sha1[20], new_sha1[20];
1092
1093         if (logmsg && read_ref(ref_target, old_sha1))
1094                 hashclr(old_sha1);
1095
1096         if (safe_create_leading_directories(git_HEAD) < 0)
1097                 return error("unable to create directory for %s", git_HEAD);
1098
1099 #ifndef NO_SYMLINK_HEAD
1100         if (prefer_symlink_refs) {
1101                 unlink(git_HEAD);
1102                 if (!symlink(refs_heads_master, git_HEAD))
1103                         goto done;
1104                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1105         }
1106 #endif
1107
1108         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1109         if (sizeof(ref) <= len) {
1110                 error("refname too long: %s", refs_heads_master);
1111                 goto error_free_return;
1112         }
1113         lockpath = mkpath("%s.lock", git_HEAD);
1114         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1115         if (fd < 0) {
1116                 error("Unable to open %s for writing", lockpath);
1117                 goto error_free_return;
1118         }
1119         written = write_in_full(fd, ref, len);
1120         close(fd);
1121         if (written != len) {
1122                 error("Unable to write to %s", lockpath);
1123                 goto error_unlink_return;
1124         }
1125         if (rename(lockpath, git_HEAD) < 0) {
1126                 error("Unable to create %s", git_HEAD);
1127                 goto error_unlink_return;
1128         }
1129         if (adjust_shared_perm(git_HEAD)) {
1130                 error("Unable to fix permissions on %s", lockpath);
1131         error_unlink_return:
1132                 unlink(lockpath);
1133         error_free_return:
1134                 free(git_HEAD);
1135                 return -1;
1136         }
1137
1138 #ifndef NO_SYMLINK_HEAD
1139         done:
1140 #endif
1141         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1142                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1143
1144         free(git_HEAD);
1145         return 0;
1146 }
1147
1148 static char *ref_msg(const char *line, const char *endp)
1149 {
1150         const char *ep;
1151         char *msg;
1152
1153         line += 82;
1154         for (ep = line; ep < endp && *ep != '\n'; ep++)
1155                 ;
1156         msg = xmalloc(ep - line + 1);
1157         memcpy(msg, line, ep - line);
1158         msg[ep - line] = 0;
1159         return msg;
1160 }
1161
1162 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)
1163 {
1164         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1165         char *tz_c;
1166         int logfd, tz, reccnt = 0;
1167         struct stat st;
1168         unsigned long date;
1169         unsigned char logged_sha1[20];
1170         void *log_mapped;
1171         size_t mapsz;
1172
1173         logfile = git_path("logs/%s", ref);
1174         logfd = open(logfile, O_RDONLY, 0);
1175         if (logfd < 0)
1176                 die("Unable to read log %s: %s", logfile, strerror(errno));
1177         fstat(logfd, &st);
1178         if (!st.st_size)
1179                 die("Log %s is empty.", logfile);
1180         mapsz = xsize_t(st.st_size);
1181         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1182         logdata = log_mapped;
1183         close(logfd);
1184
1185         lastrec = NULL;
1186         rec = logend = logdata + st.st_size;
1187         while (logdata < rec) {
1188                 reccnt++;
1189                 if (logdata < rec && *(rec-1) == '\n')
1190                         rec--;
1191                 lastgt = NULL;
1192                 while (logdata < rec && *(rec-1) != '\n') {
1193                         rec--;
1194                         if (*rec == '>')
1195                                 lastgt = rec;
1196                 }
1197                 if (!lastgt)
1198                         die("Log %s is corrupt.", logfile);
1199                 date = strtoul(lastgt + 1, &tz_c, 10);
1200                 if (date <= at_time || cnt == 0) {
1201                         tz = strtoul(tz_c, NULL, 10);
1202                         if (msg)
1203                                 *msg = ref_msg(rec, logend);
1204                         if (cutoff_time)
1205                                 *cutoff_time = date;
1206                         if (cutoff_tz)
1207                                 *cutoff_tz = tz;
1208                         if (cutoff_cnt)
1209                                 *cutoff_cnt = reccnt - 1;
1210                         if (lastrec) {
1211                                 if (get_sha1_hex(lastrec, logged_sha1))
1212                                         die("Log %s is corrupt.", logfile);
1213                                 if (get_sha1_hex(rec + 41, sha1))
1214                                         die("Log %s is corrupt.", logfile);
1215                                 if (hashcmp(logged_sha1, sha1)) {
1216                                         fprintf(stderr,
1217                                                 "warning: Log %s has gap after %s.\n",
1218                                                 logfile, show_rfc2822_date(date, tz));
1219                                 }
1220                         }
1221                         else if (date == at_time) {
1222                                 if (get_sha1_hex(rec + 41, sha1))
1223                                         die("Log %s is corrupt.", logfile);
1224                         }
1225                         else {
1226                                 if (get_sha1_hex(rec + 41, logged_sha1))
1227                                         die("Log %s is corrupt.", logfile);
1228                                 if (hashcmp(logged_sha1, sha1)) {
1229                                         fprintf(stderr,
1230                                                 "warning: Log %s unexpectedly ended on %s.\n",
1231                                                 logfile, show_rfc2822_date(date, tz));
1232                                 }
1233                         }
1234                         munmap(log_mapped, mapsz);
1235                         return 0;
1236                 }
1237                 lastrec = rec;
1238                 if (cnt > 0)
1239                         cnt--;
1240         }
1241
1242         rec = logdata;
1243         while (rec < logend && *rec != '>' && *rec != '\n')
1244                 rec++;
1245         if (rec == logend || *rec == '\n')
1246                 die("Log %s is corrupt.", logfile);
1247         date = strtoul(rec + 1, &tz_c, 10);
1248         tz = strtoul(tz_c, NULL, 10);
1249         if (get_sha1_hex(logdata, sha1))
1250                 die("Log %s is corrupt.", logfile);
1251         if (msg)
1252                 *msg = ref_msg(logdata, logend);
1253         munmap(log_mapped, mapsz);
1254
1255         if (cutoff_time)
1256                 *cutoff_time = date;
1257         if (cutoff_tz)
1258                 *cutoff_tz = tz;
1259         if (cutoff_cnt)
1260                 *cutoff_cnt = reccnt;
1261         return 1;
1262 }
1263
1264 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1265 {
1266         const char *logfile;
1267         FILE *logfp;
1268         char buf[1024];
1269         int ret = 0;
1270
1271         logfile = git_path("logs/%s", ref);
1272         logfp = fopen(logfile, "r");
1273         if (!logfp)
1274                 return -1;
1275         while (fgets(buf, sizeof(buf), logfp)) {
1276                 unsigned char osha1[20], nsha1[20];
1277                 char *email_end, *message;
1278                 unsigned long timestamp;
1279                 int len, tz;
1280
1281                 /* old SP new SP name <email> SP time TAB msg LF */
1282                 len = strlen(buf);
1283                 if (len < 83 || buf[len-1] != '\n' ||
1284                     get_sha1_hex(buf, osha1) || buf[40] != ' ' ||
1285                     get_sha1_hex(buf + 41, nsha1) || buf[81] != ' ' ||
1286                     !(email_end = strchr(buf + 82, '>')) ||
1287                     email_end[1] != ' ' ||
1288                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1289                     !message || message[0] != ' ' ||
1290                     (message[1] != '+' && message[1] != '-') ||
1291                     !isdigit(message[2]) || !isdigit(message[3]) ||
1292                     !isdigit(message[4]) || !isdigit(message[5]))
1293                         continue; /* corrupt? */
1294                 email_end[1] = '\0';
1295                 tz = strtol(message + 1, NULL, 10);
1296                 if (message[6] != '\t')
1297                         message += 6;
1298                 else
1299                         message += 7;
1300                 ret = fn(osha1, nsha1, buf+82, timestamp, tz, message, cb_data);
1301                 if (ret)
1302                         break;
1303         }
1304         fclose(logfp);
1305         return ret;
1306 }
1307
1308 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1309 {
1310         DIR *dir = opendir(git_path("logs/%s", base));
1311         int retval = 0;
1312
1313         if (dir) {
1314                 struct dirent *de;
1315                 int baselen = strlen(base);
1316                 char *log = xmalloc(baselen + 257);
1317
1318                 memcpy(log, base, baselen);
1319                 if (baselen && base[baselen-1] != '/')
1320                         log[baselen++] = '/';
1321
1322                 while ((de = readdir(dir)) != NULL) {
1323                         struct stat st;
1324                         int namelen;
1325
1326                         if (de->d_name[0] == '.')
1327                                 continue;
1328                         namelen = strlen(de->d_name);
1329                         if (namelen > 255)
1330                                 continue;
1331                         if (has_extension(de->d_name, ".lock"))
1332                                 continue;
1333                         memcpy(log + baselen, de->d_name, namelen+1);
1334                         if (stat(git_path("logs/%s", log), &st) < 0)
1335                                 continue;
1336                         if (S_ISDIR(st.st_mode)) {
1337                                 retval = do_for_each_reflog(log, fn, cb_data);
1338                         } else {
1339                                 unsigned char sha1[20];
1340                                 if (!resolve_ref(log, sha1, 0, NULL))
1341                                         retval = error("bad ref for %s", log);
1342                                 else
1343                                         retval = fn(log, sha1, 0, cb_data);
1344                         }
1345                         if (retval)
1346                                 break;
1347                 }
1348                 free(log);
1349                 closedir(dir);
1350         }
1351         else if (*base)
1352                 return errno;
1353         return retval;
1354 }
1355
1356 int for_each_reflog(each_ref_fn fn, void *cb_data)
1357 {
1358         return do_for_each_reflog("", fn, cb_data);
1359 }