refs.c

   1 #include "cache.h"
   2 #include "refs.h"
   3 #include "object.h"
   4 #include "tag.h"
   5 #include "dir.h"
   6
   7 /* ISSYMREF=01 and ISPACKED=02 are public interfaces */
   8 #define REF_KNOWS_PEELED 04
   9 #define REF_BROKEN 010
  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 *entry;
  53
  54         /* Allocate it and add it in.. */
  55         len = strlen(name) + 1;
  56         entry = xmalloc(sizeof(struct ref_list) + len);
  57         hashcpy(entry->sha1, sha1);
  58         hashclr(entry->peeled);
  59         memcpy(entry->name, name, len);
  60         entry->flag = flag;
  61         entry->next = list;
  62         if (new_entry)
  63                 *new_entry = entry;
  64         return entry;
  65 }
  66
  67 /* merge sort the ref list */
  68 static struct ref_list *sort_ref_list(struct ref_list *list)
  69 {
  70         int psize, qsize, last_merge_count, cmp;
  71         struct ref_list *p, *q, *l, *e;
  72         struct ref_list *new_list = list;
  73         int k = 1;
  74         int merge_count = 0;
  75
  76         if (!list)
  77                 return list;
  78
  79         do {
  80                 last_merge_count = merge_count;
  81                 merge_count = 0;
  82
  83                 psize = 0;
  84
  85                 p = new_list;
  86                 q = new_list;
  87                 new_list = NULL;
  88                 l = NULL;
  89
  90                 while (p) {
  91                         merge_count++;
  92
  93                         while (psize < k && q->next) {
  94                                 q = q->next;
  95                                 psize++;
  96                         }
  97                         qsize = k;
  98
  99                         while ((psize > 0) || (qsize > 0 && q)) {
 100                                 if (qsize == 0 || !q) {
 101                                         e = p;
 102                                         p = p->next;
 103                                         psize--;
 104                                 } else if (psize == 0) {
 105                                         e = q;
 106                                         q = q->next;
 107                                         qsize--;
 108                                 } else {
 109                                         cmp = strcmp(q->name, p->name);
 110                                         if (cmp < 0) {
 111                                                 e = q;
 112                                                 q = q->next;
 113                                                 qsize--;
 114                                         } else if (cmp > 0) {
 115                                                 e = p;
 116                                                 p = p->next;
 117                                                 psize--;
 118                                         } else {
 119                                                 if (hashcmp(q->sha1, p->sha1))
 120                                                         die("Duplicated ref, and SHA1s don't match: %s",
 121                                                             q->name);
 122                                                 warning("Duplicated ref: %s", q->name);
 123                                                 e = q;
 124                                                 q = q->next;
 125                                                 qsize--;
 126                                                 free(e);
 127                                                 e = p;
 128                                                 p = p->next;
 129                                                 psize--;
 130                                         }
 131                                 }
 132
 133                                 e->next = NULL;
 134
 135                                 if (l)
 136                                         l->next = e;
 137                                 if (!new_list)
 138                                         new_list = e;
 139                                 l = e;
 140                         }
 141
 142                         p = q;
 143                 };
 144
 145                 k = k * 2;
 146         } while ((last_merge_count != merge_count) || (last_merge_count != 1));
 147
 148         return new_list;
 149 }
 150
 151 /*
 152  * Future: need to be in "struct repository"
 153  * when doing a full libification.
 154  */
 155 static struct cached_refs {
 156         char did_loose;
 157         char did_packed;
 158         struct ref_list *loose;
 159         struct ref_list *packed;
 160 } cached_refs;
 161 static struct ref_list *current_ref;
 162
 163 static struct ref_list *extra_refs;
 164
 165 static void free_ref_list(struct ref_list *list)
 166 {
 167         struct ref_list *next;
 168         for ( ; list; list = next) {
 169                 next = list->next;
 170                 free(list);
 171         }
 172 }
 173
 174 static void invalidate_cached_refs(void)
 175 {
 176         struct cached_refs *ca = &cached_refs;
 177
 178         if (ca->did_loose && ca->loose)
 179                 free_ref_list(ca->loose);
 180         if (ca->did_packed && ca->packed)
 181                 free_ref_list(ca->packed);
 182         ca->loose = ca->packed = NULL;
 183         ca->did_loose = ca->did_packed = 0;
 184 }
 185
 186 static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
 187 {
 188         struct ref_list *list = NULL;
 189         struct ref_list *last = NULL;
 190         char refline[PATH_MAX];
 191         int flag = REF_ISPACKED;
 192
 193         while (fgets(refline, sizeof(refline), f)) {
 194                 unsigned char sha1[20];
 195                 const char *name;
 196                 static const char header[] = "# pack-refs with:";
 197
 198                 if (!strncmp(refline, header, sizeof(header)-1)) {
 199                         const char *traits = refline + sizeof(header) - 1;
 200                         if (strstr(traits, " peeled "))
 201                                 flag |= REF_KNOWS_PEELED;
 202                         /* perhaps other traits later as well */
 203                         continue;
 204                 }
 205
 206                 name = parse_ref_line(refline, sha1);
 207                 if (name) {
 208                         list = add_ref(name, sha1, flag, list, &last);
 209                         continue;
 210                 }
 211                 if (last &&
 212                     refline[0] == '^' &&
 213                     strlen(refline) == 42 &&
 214                     refline[41] == '\n' &&
 215                     !get_sha1_hex(refline + 1, sha1))
 216                         hashcpy(last->peeled, sha1);
 217         }
 218         cached_refs->packed = sort_ref_list(list);
 219 }
 220
 221 void add_extra_ref(const char *name, const unsigned char *sha1, int flag)
 222 {
 223         extra_refs = add_ref(name, sha1, flag, extra_refs, NULL);
 224 }
 225
 226 void clear_extra_refs(void)
 227 {
 228         free_ref_list(extra_refs);
 229         extra_refs = NULL;
 230 }
 231
 232 static struct ref_list *get_packed_refs(void)
 233 {
 234         if (!cached_refs.did_packed) {
 235                 FILE *f = fopen(git_path("packed-refs"), "r");
 236                 cached_refs.packed = NULL;
 237                 if (f) {
 238                         read_packed_refs(f, &cached_refs);
 239                         fclose(f);
 240                 }
 241                 cached_refs.did_packed = 1;
 242         }
 243         return cached_refs.packed;
 244 }
 245
 246 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
 247 {
 248         DIR *dir = opendir(git_path("%s", base));
 249
 250         if (dir) {
 251                 struct dirent *de;
 252                 int baselen = strlen(base);
 253                 char *ref = xmalloc(baselen + 257);
 254
 255                 memcpy(ref, base, baselen);
 256                 if (baselen && base[baselen-1] != '/')
 257                         ref[baselen++] = '/';
 258
 259                 while ((de = readdir(dir)) != NULL) {
 260                         unsigned char sha1[20];
 261                         struct stat st;
 262                         int flag;
 263                         int namelen;
 264
 265                         if (de->d_name[0] == '.')
 266                                 continue;
 267                         namelen = strlen(de->d_name);
 268                         if (namelen > 255)
 269                                 continue;
 270                         if (has_extension(de->d_name, ".lock"))
 271                                 continue;
 272                         memcpy(ref + baselen, de->d_name, namelen+1);
 273                         if (stat(git_path("%s", ref), &st) < 0)
 274                                 continue;
 275                         if (S_ISDIR(st.st_mode)) {
 276                                 list = get_ref_dir(ref, list);
 277                                 continue;
 278                         }
 279                         if (!resolve_ref(ref, sha1, 1, &flag)) {
 280                                 hashclr(sha1);
 281                                 flag |= REF_BROKEN;
 282                         }
 283                         list = add_ref(ref, sha1, flag, list, NULL);
 284                 }
 285                 free(ref);
 286                 closedir(dir);
 287         }
 288         return sort_ref_list(list);
 289 }
 290
 291 struct warn_if_dangling_data {
 292         FILE *fp;
 293         const char *refname;
 294         const char *msg_fmt;
 295 };
 296
 297 static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
 298                                    int flags, void *cb_data)
 299 {
 300         struct warn_if_dangling_data *d = cb_data;
 301         const char *resolves_to;
 302         unsigned char junk[20];
 303
 304         if (!(flags & REF_ISSYMREF))
 305                 return 0;
 306
 307         resolves_to = resolve_ref(refname, junk, 0, NULL);
 308         if (!resolves_to || strcmp(resolves_to, d->refname))
 309                 return 0;
 310
 311         fprintf(d->fp, d->msg_fmt, refname);
 312         return 0;
 313 }
 314
 315 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 316 {
 317         struct warn_if_dangling_data data = { fp, refname, msg_fmt };
 318         for_each_rawref(warn_if_dangling_symref, &data);
 319 }
 320
 321 static struct ref_list *get_loose_refs(void)
 322 {
 323         if (!cached_refs.did_loose) {
 324                 cached_refs.loose = get_ref_dir("refs", NULL);
 325                 cached_refs.did_loose = 1;
 326         }
 327         return cached_refs.loose;
 328 }
 329
 330 /* We allow "recursive" symbolic refs. Only within reason, though */
 331 #define MAXDEPTH 5
 332 #define MAXREFLEN (1024)
 333
 334 static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
 335 {
 336         FILE *f;
 337         struct cached_refs refs;
 338         struct ref_list *ref;
 339         int retval;
 340
 341         strcpy(name + pathlen, "packed-refs");
 342         f = fopen(name, "r");
 343         if (!f)
 344                 return -1;
 345         read_packed_refs(f, &refs);
 346         fclose(f);
 347         ref = refs.packed;
 348         retval = -1;
 349         while (ref) {
 350                 if (!strcmp(ref->name, refname)) {
 351                         retval = 0;
 352                         memcpy(result, ref->sha1, 20);
 353                         break;
 354                 }
 355                 ref = ref->next;
 356         }
 357         free_ref_list(refs.packed);
 358         return retval;
 359 }
 360
 361 static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
 362 {
 363         int fd, len = strlen(refname);
 364         char buffer[128], *p;
 365
 366         if (recursion > MAXDEPTH || len > MAXREFLEN)
 367                 return -1;
 368         memcpy(name + pathlen, refname, len+1);
 369         fd = open(name, O_RDONLY);
 370         if (fd < 0)
 371                 return resolve_gitlink_packed_ref(name, pathlen, refname, result);
 372
 373         len = read(fd, buffer, sizeof(buffer)-1);
 374         close(fd);
 375         if (len < 0)
 376                 return -1;
 377         while (len && isspace(buffer[len-1]))
 378                 len--;
 379         buffer[len] = 0;
 380
 381         /* Was it a detached head or an old-fashioned symlink? */
 382         if (!get_sha1_hex(buffer, result))
 383                 return 0;
 384
 385         /* Symref? */
 386         if (strncmp(buffer, "ref:", 4))
 387                 return -1;
 388         p = buffer + 4;
 389         while (isspace(*p))
 390                 p++;
 391
 392         return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
 393 }
 394
 395 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
 396 {
 397         int len = strlen(path), retval;
 398         char *gitdir;
 399         const char *tmp;
 400
 401         while (len && path[len-1] == '/')
 402                 len--;
 403         if (!len)
 404                 return -1;
 405         gitdir = xmalloc(len + MAXREFLEN + 8);
 406         memcpy(gitdir, path, len);
 407         memcpy(gitdir + len, "/.git", 6);
 408         len += 5;
 409
 410         tmp = read_gitfile_gently(gitdir);
 411         if (tmp) {
 412                 free(gitdir);
 413                 len = strlen(tmp);
 414                 gitdir = xmalloc(len + MAXREFLEN + 3);
 415                 memcpy(gitdir, tmp, len);
 416         }
 417         gitdir[len] = '/';
 418         gitdir[++len] = '\0';
 419         retval = resolve_gitlink_ref_recursive(gitdir, len, refname, result, 0);
 420         free(gitdir);
 421         return retval;
 422 }
 423
 424 /*
 425  * If the "reading" argument is set, this function finds out what _object_
 426  * the ref points at by "reading" the ref.  The ref, if it is not symbolic,
 427  * has to exist, and if it is symbolic, it has to point at an existing ref,
 428  * because the "read" goes through the symref to the ref it points at.
 429  *
 430  * The access that is not "reading" may often be "writing", but does not
 431  * have to; it can be merely checking _where it leads to_. If it is a
 432  * prelude to "writing" to the ref, a write to a symref that points at
 433  * yet-to-be-born ref will create the real ref pointed by the symref.
 434  * reading=0 allows the caller to check where such a symref leads to.
 435  */
 436 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 437 {
 438         int depth = MAXDEPTH;
 439         ssize_t len;
 440         char buffer[256];
 441         static char ref_buffer[256];
 442
 443         if (flag)
 444                 *flag = 0;
 445
 446         for (;;) {
 447                 char path[PATH_MAX];
 448                 struct stat st;
 449                 char *buf;
 450                 int fd;
 451
 452                 if (--depth < 0)
 453                         return NULL;
 454
 455                 git_snpath(path, sizeof(path), "%s", ref);
 456                 /* Special case: non-existing file. */
 457                 if (lstat(path, &st) < 0) {
 458                         struct ref_list *list = get_packed_refs();
 459                         while (list) {
 460                                 if (!strcmp(ref, list->name)) {
 461                                         hashcpy(sha1, list->sha1);
 462                                         if (flag)
 463                                                 *flag |= REF_ISPACKED;
 464                                         return ref;
 465                                 }
 466                                 list = list->next;
 467                         }
 468                         if (reading || errno != ENOENT)
 469                                 return NULL;
 470                         hashclr(sha1);
 471                         return ref;
 472                 }
 473
 474                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 475                 if (S_ISLNK(st.st_mode)) {
 476                         len = readlink(path, buffer, sizeof(buffer)-1);
 477                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 478                                 buffer[len] = 0;
 479                                 strcpy(ref_buffer, buffer);
 480                                 ref = ref_buffer;
 481                                 if (flag)
 482                                         *flag |= REF_ISSYMREF;
 483                                 continue;
 484                         }
 485                 }
 486
 487                 /* Is it a directory? */
 488                 if (S_ISDIR(st.st_mode)) {
 489                         errno = EISDIR;
 490                         return NULL;
 491                 }
 492
 493                 /*
 494                  * Anything else, just open it and try to use it as
 495                  * a ref
 496                  */
 497                 fd = open(path, O_RDONLY);
 498                 if (fd < 0)
 499                         return NULL;
 500                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
 501                 close(fd);
 502
 503                 /*
 504                  * Is it a symbolic ref?
 505                  */
 506                 if (len < 4 || memcmp("ref:", buffer, 4))
 507                         break;
 508                 buf = buffer + 4;
 509                 len -= 4;
 510                 while (len && isspace(*buf))
 511                         buf++, len--;
 512                 while (len && isspace(buf[len-1]))
 513                         len--;
 514                 buf[len] = 0;
 515                 memcpy(ref_buffer, buf, len + 1);
 516                 ref = ref_buffer;
 517                 if (flag)
 518                         *flag |= REF_ISSYMREF;
 519         }
 520         if (len < 40 || get_sha1_hex(buffer, sha1))
 521                 return NULL;
 522         return ref;
 523 }
 524
 525 /* The argument to filter_refs */
 526 struct ref_filter {
 527         const char *pattern;
 528         each_ref_fn *fn;
 529         void *cb_data;
 530 };
 531
 532 int read_ref(const char *ref, unsigned char *sha1)
 533 {
 534         if (resolve_ref(ref, sha1, 1, NULL))
 535                 return 0;
 536         return -1;
 537 }
 538
 539 #define DO_FOR_EACH_INCLUDE_BROKEN 01
 540 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
 541                       int flags, void *cb_data, struct ref_list *entry)
 542 {
 543         if (strncmp(base, entry->name, trim))
 544                 return 0;
 545
 546         if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
 547                 if (entry->flag & REF_BROKEN)
 548                         return 0; /* ignore dangling symref */
 549                 if (!has_sha1_file(entry->sha1)) {
 550                         error("%s does not point to a valid object!", entry->name);
 551                         return 0;
 552                 }
 553         }
 554         current_ref = entry;
 555         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 556 }
 557
 558 static int filter_refs(const char *ref, const unsigned char *sha, int flags,
 559         void *data)
 560 {
 561         struct ref_filter *filter = (struct ref_filter *)data;
 562         if (fnmatch(filter->pattern, ref, 0))
 563                 return 0;
 564         return filter->fn(ref, sha, flags, filter->cb_data);
 565 }
 566
 567 int peel_ref(const char *ref, unsigned char *sha1)
 568 {
 569         int flag;
 570         unsigned char base[20];
 571         struct object *o;
 572
 573         if (current_ref && (current_ref->name == ref
 574                 || !strcmp(current_ref->name, ref))) {
 575                 if (current_ref->flag & REF_KNOWS_PEELED) {
 576                         hashcpy(sha1, current_ref->peeled);
 577                         return 0;
 578                 }
 579                 hashcpy(base, current_ref->sha1);
 580                 goto fallback;
 581         }
 582
 583         if (!resolve_ref(ref, base, 1, &flag))
 584                 return -1;
 585
 586         if ((flag & REF_ISPACKED)) {
 587                 struct ref_list *list = get_packed_refs();
 588
 589                 while (list) {
 590                         if (!strcmp(list->name, ref)) {
 591                                 if (list->flag & REF_KNOWS_PEELED) {
 592                                         hashcpy(sha1, list->peeled);
 593                                         return 0;
 594                                 }
 595                                 /* older pack-refs did not leave peeled ones */
 596                                 break;
 597                         }
 598                         list = list->next;
 599                 }
 600         }
 601
 602 fallback:
 603         o = parse_object(base);
 604         if (o && o->type == OBJ_TAG) {
 605                 o = deref_tag(o, ref, 0);
 606                 if (o) {
 607                         hashcpy(sha1, o->sha1);
 608                         return 0;
 609                 }
 610         }
 611         return -1;
 612 }
 613
 614 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
 615                            int flags, void *cb_data)
 616 {
 617         int retval = 0;
 618         struct ref_list *packed = get_packed_refs();
 619         struct ref_list *loose = get_loose_refs();
 620
 621         struct ref_list *extra;
 622
 623         for (extra = extra_refs; extra; extra = extra->next)
 624                 retval = do_one_ref(base, fn, trim, flags, cb_data, extra);
 625
 626         while (packed && loose) {
 627                 struct ref_list *entry;
 628                 int cmp = strcmp(packed->name, loose->name);
 629                 if (!cmp) {
 630                         packed = packed->next;
 631                         continue;
 632                 }
 633                 if (cmp > 0) {
 634                         entry = loose;
 635                         loose = loose->next;
 636                 } else {
 637                         entry = packed;
 638                         packed = packed->next;
 639                 }
 640                 retval = do_one_ref(base, fn, trim, flags, cb_data, entry);
 641                 if (retval)
 642                         goto end_each;
 643         }
 644
 645         for (packed = packed ? packed : loose; packed; packed = packed->next) {
 646                 retval = do_one_ref(base, fn, trim, flags, cb_data, packed);
 647                 if (retval)
 648                         goto end_each;
 649         }
 650
 651 end_each:
 652         current_ref = NULL;
 653         return retval;
 654 }
 655
 656 int head_ref(each_ref_fn fn, void *cb_data)
 657 {
 658         unsigned char sha1[20];
 659         int flag;
 660
 661         if (resolve_ref("HEAD", sha1, 1, &flag))
 662                 return fn("HEAD", sha1, flag, cb_data);
 663         return 0;
 664 }
 665
 666 int for_each_ref(each_ref_fn fn, void *cb_data)
 667 {
 668         return do_for_each_ref("refs/", fn, 0, 0, cb_data);
 669 }
 670
 671 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
 672 {
 673         return do_for_each_ref(prefix, fn, strlen(prefix), 0, cb_data);
 674 }
 675
 676 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 677 {
 678         return for_each_ref_in("refs/tags/", fn, cb_data);
 679 }
 680
 681 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 682 {
 683         return for_each_ref_in("refs/heads/", fn, cb_data);
 684 }
 685
 686 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 687 {
 688         return for_each_ref_in("refs/remotes/", fn, cb_data);
 689 }
 690
 691 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
 692 {
 693         return do_for_each_ref("refs/replace/", fn, 13, 0, cb_data);
 694 }
 695
 696 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 697         const char *prefix, void *cb_data)
 698 {
 699         struct strbuf real_pattern = STRBUF_INIT;
 700         struct ref_filter filter;
 701         int ret;
 702
 703         if (!prefix && prefixcmp(pattern, "refs/"))
 704                 strbuf_addstr(&real_pattern, "refs/");
 705         else if (prefix)
 706                 strbuf_addstr(&real_pattern, prefix);
 707         strbuf_addstr(&real_pattern, pattern);
 708
 709         if (!has_glob_specials(pattern)) {
 710                 /* Append implied '/' '*' if not present. */
 711                 if (real_pattern.buf[real_pattern.len - 1] != '/')
 712                         strbuf_addch(&real_pattern, '/');
 713                 /* No need to check for '*', there is none. */
 714                 strbuf_addch(&real_pattern, '*');
 715         }
 716
 717         filter.pattern = real_pattern.buf;
 718         filter.fn = fn;
 719         filter.cb_data = cb_data;
 720         ret = for_each_ref(filter_refs, &filter);
 721
 722         strbuf_release(&real_pattern);
 723         return ret;
 724 }
 725
 726 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 727 {
 728         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
 729 }
 730
 731 int for_each_rawref(each_ref_fn fn, void *cb_data)
 732 {
 733         return do_for_each_ref("refs/", fn, 0,
 734                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
 735 }
 736
 737 /*
 738  * Make sure "ref" is something reasonable to have under ".git/refs/";
 739  * We do not like it if:
 740  *
 741  * - any path component of it begins with ".", or
 742  * - it has double dots "..", or
 743  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 744  * - it ends with a "/".
 745  * - it ends with ".lock"
 746  * - it contains a "\" (backslash)
 747  */
 748
 749 static inline int bad_ref_char(int ch)
 750 {
 751         if (((unsigned) ch) <= ' ' ||
 752             ch == '~' || ch == '^' || ch == ':' || ch == '\\')
 753                 return 1;
 754         /* 2.13 Pattern Matching Notation */
 755         if (ch == '?' || ch == '[') /* Unsupported */
 756                 return 1;
 757         if (ch == '*') /* Supported at the end */
 758                 return 2;
 759         return 0;
 760 }
 761
 762 int check_ref_format(const char *ref)
 763 {
 764         int ch, level, bad_type, last;
 765         int ret = CHECK_REF_FORMAT_OK;
 766         const char *cp = ref;
 767
 768         level = 0;
 769         while (1) {
 770                 while ((ch = *cp++) == '/')
 771                         ; /* tolerate duplicated slashes */
 772                 if (!ch)
 773                         /* should not end with slashes */
 774                         return CHECK_REF_FORMAT_ERROR;
 775
 776                 /* we are at the beginning of the path component */
 777                 if (ch == '.')
 778                         return CHECK_REF_FORMAT_ERROR;
 779                 bad_type = bad_ref_char(ch);
 780                 if (bad_type) {
 781                         if (bad_type == 2 && (!*cp || *cp == '/') &&
 782                             ret == CHECK_REF_FORMAT_OK)
 783                                 ret = CHECK_REF_FORMAT_WILDCARD;
 784                         else
 785                                 return CHECK_REF_FORMAT_ERROR;
 786                 }
 787
 788                 last = ch;
 789                 /* scan the rest of the path component */
 790                 while ((ch = *cp++) != 0) {
 791                         bad_type = bad_ref_char(ch);
 792                         if (bad_type)
 793                                 return CHECK_REF_FORMAT_ERROR;
 794                         if (ch == '/')
 795                                 break;
 796                         if (last == '.' && ch == '.')
 797                                 return CHECK_REF_FORMAT_ERROR;
 798                         if (last == '@' && ch == '{')
 799                                 return CHECK_REF_FORMAT_ERROR;
 800                         last = ch;
 801                 }
 802                 level++;
 803                 if (!ch) {
 804                         if (ref <= cp - 2 && cp[-2] == '.')
 805                                 return CHECK_REF_FORMAT_ERROR;
 806                         if (level < 2)
 807                                 return CHECK_REF_FORMAT_ONELEVEL;
 808                         if (has_extension(ref, ".lock"))
 809                                 return CHECK_REF_FORMAT_ERROR;
 810                         return ret;
 811                 }
 812         }
 813 }
 814
 815 const char *prettify_refname(const char *name)
 816 {
 817         return name + (
 818                 !prefixcmp(name, "refs/heads/") ? 11 :
 819                 !prefixcmp(name, "refs/tags/") ? 10 :
 820                 !prefixcmp(name, "refs/remotes/") ? 13 :
 821                 0);
 822 }
 823
 824 const char *ref_rev_parse_rules[] = {
 825         "%.*s",
 826         "refs/%.*s",
 827         "refs/tags/%.*s",
 828         "refs/heads/%.*s",
 829         "refs/remotes/%.*s",
 830         "refs/remotes/%.*s/HEAD",
 831         NULL
 832 };
 833
 834 const char *ref_fetch_rules[] = {
 835         "%.*s",
 836         "refs/%.*s",
 837         "refs/heads/%.*s",
 838         NULL
 839 };
 840
 841 int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
 842 {
 843         const char **p;
 844         const int abbrev_name_len = strlen(abbrev_name);
 845
 846         for (p = rules; *p; p++) {
 847                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
 848                         return 1;
 849                 }
 850         }
 851
 852         return 0;
 853 }
 854
 855 static struct ref_lock *verify_lock(struct ref_lock *lock,
 856         const unsigned char *old_sha1, int mustexist)
 857 {
 858         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
 859                 error("Can't verify ref %s", lock->ref_name);
 860                 unlock_ref(lock);
 861                 return NULL;
 862         }
 863         if (hashcmp(lock->old_sha1, old_sha1)) {
 864                 error("Ref %s is at %s but expected %s", lock->ref_name,
 865                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 866                 unlock_ref(lock);
 867                 return NULL;
 868         }
 869         return lock;
 870 }
 871
 872 static int remove_empty_directories(const char *file)
 873 {
 874         /* we want to create a file but there is a directory there;
 875          * if that is an empty directory (or a directory that contains
 876          * only empty directories), remove them.
 877          */
 878         struct strbuf path;
 879         int result;
 880
 881         strbuf_init(&path, 20);
 882         strbuf_addstr(&path, file);
 883
 884         result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
 885
 886         strbuf_release(&path);
 887
 888         return result;
 889 }
 890
 891 static int is_refname_available(const char *ref, const char *oldref,
 892                                 struct ref_list *list, int quiet)
 893 {
 894         int namlen = strlen(ref); /* e.g. 'foo/bar' */
 895         while (list) {
 896                 /* list->name could be 'foo' or 'foo/bar/baz' */
 897                 if (!oldref || strcmp(oldref, list->name)) {
 898                         int len = strlen(list->name);
 899                         int cmplen = (namlen < len) ? namlen : len;
 900                         const char *lead = (namlen < len) ? list->name : ref;
 901                         if (!strncmp(ref, list->name, cmplen) &&
 902                             lead[cmplen] == '/') {
 903                                 if (!quiet)
 904                                         error("'%s' exists; cannot create '%s'",
 905                                               list->name, ref);
 906                                 return 0;
 907                         }
 908                 }
 909                 list = list->next;
 910         }
 911         return 1;
 912 }
 913
 914 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
 915 {
 916         char *ref_file;
 917         const char *orig_ref = ref;
 918         struct ref_lock *lock;
 919         int last_errno = 0;
 920         int type, lflags;
 921         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 922         int missing = 0;
 923
 924         lock = xcalloc(1, sizeof(struct ref_lock));
 925         lock->lock_fd = -1;
 926
 927         ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
 928         if (!ref && errno == EISDIR) {
 929                 /* we are trying to lock foo but we used to
 930                  * have foo/bar which now does not exist;
 931                  * it is normal for the empty directory 'foo'
 932                  * to remain.
 933                  */
 934                 ref_file = git_path("%s", orig_ref);
 935                 if (remove_empty_directories(ref_file)) {
 936                         last_errno = errno;
 937                         error("there are still refs under '%s'", orig_ref);
 938                         goto error_return;
 939                 }
 940                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
 941         }
 942         if (type_p)
 943             *type_p = type;
 944         if (!ref) {
 945                 last_errno = errno;
 946                 error("unable to resolve reference %s: %s",
 947                         orig_ref, strerror(errno));
 948                 goto error_return;
 949         }
 950         missing = is_null_sha1(lock->old_sha1);
 951         /* When the ref did not exist and we are creating it,
 952          * make sure there is no existing ref that is packed
 953          * whose name begins with our refname, nor a ref whose
 954          * name is a proper prefix of our refname.
 955          */
 956         if (missing &&
 957              !is_refname_available(ref, NULL, get_packed_refs(), 0)) {
 958                 last_errno = ENOTDIR;
 959                 goto error_return;
 960         }
 961
 962         lock->lk = xcalloc(1, sizeof(struct lock_file));
 963
 964         lflags = LOCK_DIE_ON_ERROR;
 965         if (flags & REF_NODEREF) {
 966                 ref = orig_ref;
 967                 lflags |= LOCK_NODEREF;
 968         }
 969         lock->ref_name = xstrdup(ref);
 970         lock->orig_ref_name = xstrdup(orig_ref);
 971         ref_file = git_path("%s", ref);
 972         if (missing)
 973                 lock->force_write = 1;
 974         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
 975                 lock->force_write = 1;
 976
 977         if (safe_create_leading_directories(ref_file)) {
 978                 last_errno = errno;
 979                 error("unable to create directory for %s", ref_file);
 980                 goto error_return;
 981         }
 982
 983         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
 984         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 985
 986  error_return:
 987         unlock_ref(lock);
 988         errno = last_errno;
 989         return NULL;
 990 }
 991
 992 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 993 {
 994         char refpath[PATH_MAX];
 995         if (check_ref_format(ref))
 996                 return NULL;
 997         strcpy(refpath, mkpath("refs/%s", ref));
 998         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
 999 }
1000
1001 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
1002 {
1003         switch (check_ref_format(ref)) {
1004         default:
1005                 return NULL;
1006         case 0:
1007         case CHECK_REF_FORMAT_ONELEVEL:
1008                 return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
1009         }
1010 }
1011
1012 static struct lock_file packlock;
1013
1014 static int repack_without_ref(const char *refname)
1015 {
1016         struct ref_list *list, *packed_ref_list;
1017         int fd;
1018         int found = 0;
1019
1020         packed_ref_list = get_packed_refs();
1021         for (list = packed_ref_list; list; list = list->next) {
1022                 if (!strcmp(refname, list->name)) {
1023                         found = 1;
1024                         break;
1025                 }
1026         }
1027         if (!found)
1028                 return 0;
1029         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
1030         if (fd < 0) {
1031                 unable_to_lock_error(git_path("packed-refs"), errno);
1032                 return error("cannot delete '%s' from packed refs", refname);
1033         }
1034
1035         for (list = packed_ref_list; list; list = list->next) {
1036                 char line[PATH_MAX + 100];
1037                 int len;
1038
1039                 if (!strcmp(refname, list->name))
1040                         continue;
1041                 len = snprintf(line, sizeof(line), "%s %s\n",
1042                                sha1_to_hex(list->sha1), list->name);
1043                 /* this should not happen but just being defensive */
1044                 if (len > sizeof(line))
1045                         die("too long a refname '%s'", list->name);
1046                 write_or_die(fd, line, len);
1047         }
1048         return commit_lock_file(&packlock);
1049 }
1050
1051 int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
1052 {
1053         struct ref_lock *lock;
1054         int err, i = 0, ret = 0, flag = 0;
1055
1056         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
1057         if (!lock)
1058                 return 1;
1059         if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
1060                 /* loose */
1061                 const char *path;
1062
1063                 if (!(delopt & REF_NODEREF)) {
1064                         i = strlen(lock->lk->filename) - 5; /* .lock */
1065                         lock->lk->filename[i] = 0;
1066                         path = lock->lk->filename;
1067                 } else {
1068                         path = git_path("%s", refname);
1069                 }
1070                 err = unlink_or_warn(path);
1071                 if (err && errno != ENOENT)
1072                         ret = 1;
1073
1074                 if (!(delopt & REF_NODEREF))
1075                         lock->lk->filename[i] = '.';
1076         }
1077         /* removing the loose one could have resurrected an earlier
1078          * packed one.  Also, if it was not loose we need to repack
1079          * without it.
1080          */
1081         ret |= repack_without_ref(refname);
1082
1083         unlink_or_warn(git_path("logs/%s", lock->ref_name));
1084         invalidate_cached_refs();
1085         unlock_ref(lock);
1086         return ret;
1087 }
1088
1089 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
1090 {
1091         static const char renamed_ref[] = "RENAMED-REF";
1092         unsigned char sha1[20], orig_sha1[20];
1093         int flag = 0, logmoved = 0;
1094         struct ref_lock *lock;
1095         struct stat loginfo;
1096         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
1097         const char *symref = NULL;
1098
1099         if (log && S_ISLNK(loginfo.st_mode))
1100                 return error("reflog for %s is a symlink", oldref);
1101
1102         symref = resolve_ref(oldref, orig_sha1, 1, &flag);
1103         if (flag & REF_ISSYMREF)
1104                 return error("refname %s is a symbolic ref, renaming it is not supported",
1105                         oldref);
1106         if (!symref)
1107                 return error("refname %s not found", oldref);
1108
1109         if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
1110                 return 1;
1111
1112         if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
1113                 return 1;
1114
1115         lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
1116         if (!lock)
1117                 return error("unable to lock %s", renamed_ref);
1118         lock->force_write = 1;
1119         if (write_ref_sha1(lock, orig_sha1, logmsg))
1120                 return error("unable to save current sha1 in %s", renamed_ref);
1121
1122         if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
1123                 return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
1124                         oldref, strerror(errno));
1125
1126         if (delete_ref(oldref, orig_sha1, REF_NODEREF)) {
1127                 error("unable to delete old %s", oldref);
1128                 goto rollback;
1129         }
1130
1131         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1, REF_NODEREF)) {
1132                 if (errno==EISDIR) {
1133                         if (remove_empty_directories(git_path("%s", newref))) {
1134                                 error("Directory not empty: %s", newref);
1135                                 goto rollback;
1136                         }
1137                 } else {
1138                         error("unable to delete existing %s", newref);
1139                         goto rollback;
1140                 }
1141         }
1142
1143         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
1144                 error("unable to create directory for %s", newref);
1145                 goto rollback;
1146         }
1147
1148  retry:
1149         if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
1150                 if (errno==EISDIR || errno==ENOTDIR) {
1151                         /*
1152                          * rename(a, b) when b is an existing
1153                          * directory ought to result in ISDIR, but
1154                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
1155                          */
1156                         if (remove_empty_directories(git_path("logs/%s", newref))) {
1157                                 error("Directory not empty: logs/%s", newref);
1158                                 goto rollback;
1159                         }
1160                         goto retry;
1161                 } else {
1162                         error("unable to move logfile tmp-renamed-log to logs/%s: %s",
1163                                 newref, strerror(errno));
1164                         goto rollback;
1165                 }
1166         }
1167         logmoved = log;
1168
1169         lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
1170         if (!lock) {
1171                 error("unable to lock %s for update", newref);
1172                 goto rollback;
1173         }
1174         lock->force_write = 1;
1175         hashcpy(lock->old_sha1, orig_sha1);
1176         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
1177                 error("unable to write current sha1 into %s", newref);
1178                 goto rollback;
1179         }
1180
1181         return 0;
1182
1183  rollback:
1184         lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
1185         if (!lock) {
1186                 error("unable to lock %s for rollback", oldref);
1187                 goto rollbacklog;
1188         }
1189
1190         lock->force_write = 1;
1191         flag = log_all_ref_updates;
1192         log_all_ref_updates = 0;
1193         if (write_ref_sha1(lock, orig_sha1, NULL))
1194                 error("unable to write current sha1 into %s", oldref);
1195         log_all_ref_updates = flag;
1196
1197  rollbacklog:
1198         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
1199                 error("unable to restore logfile %s from %s: %s",
1200                         oldref, newref, strerror(errno));
1201         if (!logmoved && log &&
1202             rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
1203                 error("unable to restore logfile %s from tmp-renamed-log: %s",
1204                         oldref, strerror(errno));
1205
1206         return 1;
1207 }
1208
1209 int close_ref(struct ref_lock *lock)
1210 {
1211         if (close_lock_file(lock->lk))
1212                 return -1;
1213         lock->lock_fd = -1;
1214         return 0;
1215 }
1216
1217 int commit_ref(struct ref_lock *lock)
1218 {
1219         if (commit_lock_file(lock->lk))
1220                 return -1;
1221         lock->lock_fd = -1;
1222         return 0;
1223 }
1224
1225 void unlock_ref(struct ref_lock *lock)
1226 {
1227         /* Do not free lock->lk -- atexit() still looks at them */
1228         if (lock->lk)
1229                 rollback_lock_file(lock->lk);
1230         free(lock->ref_name);
1231         free(lock->orig_ref_name);
1232         free(lock);
1233 }
1234
1235 /*
1236  * copy the reflog message msg to buf, which has been allocated sufficiently
1237  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1238  * because reflog file is one line per entry.
1239  */
1240 static int copy_msg(char *buf, const char *msg)
1241 {
1242         char *cp = buf;
1243         char c;
1244         int wasspace = 1;
1245
1246         *cp++ = '\t';
1247         while ((c = *msg++)) {
1248                 if (wasspace && isspace(c))
1249                         continue;
1250                 wasspace = isspace(c);
1251                 if (wasspace)
1252                         c = ' ';
1253                 *cp++ = c;
1254         }
1255         while (buf < cp && isspace(cp[-1]))
1256                 cp--;
1257         *cp++ = '\n';
1258         return cp - buf;
1259 }
1260
1261 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1262                          const unsigned char *new_sha1, const char *msg)
1263 {
1264         int logfd, written, oflags = O_APPEND | O_WRONLY;
1265         unsigned maxlen, len;
1266         int msglen;
1267         char log_file[PATH_MAX];
1268         char *logrec;
1269         const char *committer;
1270
1271         if (log_all_ref_updates < 0)
1272                 log_all_ref_updates = !is_bare_repository();
1273
1274         git_snpath(log_file, sizeof(log_file), "logs/%s", ref_name);
1275
1276         if (log_all_ref_updates &&
1277             (!prefixcmp(ref_name, "refs/heads/") ||
1278              !prefixcmp(ref_name, "refs/remotes/") ||
1279              !prefixcmp(ref_name, "refs/notes/") ||
1280              !strcmp(ref_name, "HEAD"))) {
1281                 if (safe_create_leading_directories(log_file) < 0)
1282                         return error("unable to create directory for %s",
1283                                      log_file);
1284                 oflags |= O_CREAT;
1285         }
1286
1287         logfd = open(log_file, oflags, 0666);
1288         if (logfd < 0) {
1289                 if (!(oflags & O_CREAT) && errno == ENOENT)
1290                         return 0;
1291
1292                 if ((oflags & O_CREAT) && errno == EISDIR) {
1293                         if (remove_empty_directories(log_file)) {
1294                                 return error("There are still logs under '%s'",
1295                                              log_file);
1296                         }
1297                         logfd = open(log_file, oflags, 0666);
1298                 }
1299
1300                 if (logfd < 0)
1301                         return error("Unable to append to %s: %s",
1302                                      log_file, strerror(errno));
1303         }
1304
1305         adjust_shared_perm(log_file);
1306
1307         msglen = msg ? strlen(msg) : 0;
1308         committer = git_committer_info(0);
1309         maxlen = strlen(committer) + msglen + 100;
1310         logrec = xmalloc(maxlen);
1311         len = sprintf(logrec, "%s %s %s\n",
1312                       sha1_to_hex(old_sha1),
1313                       sha1_to_hex(new_sha1),
1314                       committer);
1315         if (msglen)
1316                 len += copy_msg(logrec + len - 1, msg) - 1;
1317         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1318         free(logrec);
1319         if (close(logfd) != 0 || written != len)
1320                 return error("Unable to append to %s", log_file);
1321         return 0;
1322 }
1323
1324 static int is_branch(const char *refname)
1325 {
1326         return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
1327 }
1328
1329 int write_ref_sha1(struct ref_lock *lock,
1330         const unsigned char *sha1, const char *logmsg)
1331 {
1332         static char term = '\n';
1333         struct object *o;
1334
1335         if (!lock)
1336                 return -1;
1337         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1338                 unlock_ref(lock);
1339                 return 0;
1340         }
1341         o = parse_object(sha1);
1342         if (!o) {
1343                 error("Trying to write ref %s with nonexistant object %s",
1344                         lock->ref_name, sha1_to_hex(sha1));
1345                 unlock_ref(lock);
1346                 return -1;
1347         }
1348         if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1349                 error("Trying to write non-commit object %s to branch %s",
1350                         sha1_to_hex(sha1), lock->ref_name);
1351                 unlock_ref(lock);
1352                 return -1;
1353         }
1354         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1355             write_in_full(lock->lock_fd, &term, 1) != 1
1356                 || close_ref(lock) < 0) {
1357                 error("Couldn't write %s", lock->lk->filename);
1358                 unlock_ref(lock);
1359                 return -1;
1360         }
1361         invalidate_cached_refs();
1362         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1363             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1364              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1365                 unlock_ref(lock);
1366                 return -1;
1367         }
1368         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1369                 /*
1370                  * Special hack: If a branch is updated directly and HEAD
1371                  * points to it (may happen on the remote side of a push
1372                  * for example) then logically the HEAD reflog should be
1373                  * updated too.
1374                  * A generic solution implies reverse symref information,
1375                  * but finding all symrefs pointing to the given branch
1376                  * would be rather costly for this rare event (the direct
1377                  * update of a branch) to be worth it.  So let's cheat and
1378                  * check with HEAD only which should cover 99% of all usage
1379                  * scenarios (even 100% of the default ones).
1380                  */
1381                 unsigned char head_sha1[20];
1382                 int head_flag;
1383                 const char *head_ref;
1384                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1385                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1386                     !strcmp(head_ref, lock->ref_name))
1387                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1388         }
1389         if (commit_ref(lock)) {
1390                 error("Couldn't set %s", lock->ref_name);
1391                 unlock_ref(lock);
1392                 return -1;
1393         }
1394         unlock_ref(lock);
1395         return 0;
1396 }
1397
1398 int create_symref(const char *ref_target, const char *refs_heads_master,
1399                   const char *logmsg)
1400 {
1401         const char *lockpath;
1402         char ref[1000];
1403         int fd, len, written;
1404         char *git_HEAD = git_pathdup("%s", ref_target);
1405         unsigned char old_sha1[20], new_sha1[20];
1406
1407         if (logmsg && read_ref(ref_target, old_sha1))
1408                 hashclr(old_sha1);
1409
1410         if (safe_create_leading_directories(git_HEAD) < 0)
1411                 return error("unable to create directory for %s", git_HEAD);
1412
1413 #ifndef NO_SYMLINK_HEAD
1414         if (prefer_symlink_refs) {
1415                 unlink(git_HEAD);
1416                 if (!symlink(refs_heads_master, git_HEAD))
1417                         goto done;
1418                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1419         }
1420 #endif
1421
1422         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1423         if (sizeof(ref) <= len) {
1424                 error("refname too long: %s", refs_heads_master);
1425                 goto error_free_return;
1426         }
1427         lockpath = mkpath("%s.lock", git_HEAD);
1428         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1429         if (fd < 0) {
1430                 error("Unable to open %s for writing", lockpath);
1431                 goto error_free_return;
1432         }
1433         written = write_in_full(fd, ref, len);
1434         if (close(fd) != 0 || written != len) {
1435                 error("Unable to write to %s", lockpath);
1436                 goto error_unlink_return;
1437         }
1438         if (rename(lockpath, git_HEAD) < 0) {
1439                 error("Unable to create %s", git_HEAD);
1440                 goto error_unlink_return;
1441         }
1442         if (adjust_shared_perm(git_HEAD)) {
1443                 error("Unable to fix permissions on %s", lockpath);
1444         error_unlink_return:
1445                 unlink_or_warn(lockpath);
1446         error_free_return:
1447                 free(git_HEAD);
1448                 return -1;
1449         }
1450
1451 #ifndef NO_SYMLINK_HEAD
1452         done:
1453 #endif
1454         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1455                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1456
1457         free(git_HEAD);
1458         return 0;
1459 }
1460
1461 static char *ref_msg(const char *line, const char *endp)
1462 {
1463         const char *ep;
1464         line += 82;
1465         ep = memchr(line, '\n', endp - line);
1466         if (!ep)
1467                 ep = endp;
1468         return xmemdupz(line, ep - line);
1469 }
1470
1471 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)
1472 {
1473         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1474         char *tz_c;
1475         int logfd, tz, reccnt = 0;
1476         struct stat st;
1477         unsigned long date;
1478         unsigned char logged_sha1[20];
1479         void *log_mapped;
1480         size_t mapsz;
1481
1482         logfile = git_path("logs/%s", ref);
1483         logfd = open(logfile, O_RDONLY, 0);
1484         if (logfd < 0)
1485                 die_errno("Unable to read log '%s'", logfile);
1486         fstat(logfd, &st);
1487         if (!st.st_size)
1488                 die("Log %s is empty.", logfile);
1489         mapsz = xsize_t(st.st_size);
1490         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1491         logdata = log_mapped;
1492         close(logfd);
1493
1494         lastrec = NULL;
1495         rec = logend = logdata + st.st_size;
1496         while (logdata < rec) {
1497                 reccnt++;
1498                 if (logdata < rec && *(rec-1) == '\n')
1499                         rec--;
1500                 lastgt = NULL;
1501                 while (logdata < rec && *(rec-1) != '\n') {
1502                         rec--;
1503                         if (*rec == '>')
1504                                 lastgt = rec;
1505                 }
1506                 if (!lastgt)
1507                         die("Log %s is corrupt.", logfile);
1508                 date = strtoul(lastgt + 1, &tz_c, 10);
1509                 if (date <= at_time || cnt == 0) {
1510                         tz = strtoul(tz_c, NULL, 10);
1511                         if (msg)
1512                                 *msg = ref_msg(rec, logend);
1513                         if (cutoff_time)
1514                                 *cutoff_time = date;
1515                         if (cutoff_tz)
1516                                 *cutoff_tz = tz;
1517                         if (cutoff_cnt)
1518                                 *cutoff_cnt = reccnt - 1;
1519                         if (lastrec) {
1520                                 if (get_sha1_hex(lastrec, logged_sha1))
1521                                         die("Log %s is corrupt.", logfile);
1522                                 if (get_sha1_hex(rec + 41, sha1))
1523                                         die("Log %s is corrupt.", logfile);
1524                                 if (hashcmp(logged_sha1, sha1)) {
1525                                         warning("Log %s has gap after %s.",
1526                                                 logfile, show_date(date, tz, DATE_RFC2822));
1527                                 }
1528                         }
1529                         else if (date == at_time) {
1530                                 if (get_sha1_hex(rec + 41, sha1))
1531                                         die("Log %s is corrupt.", logfile);
1532                         }
1533                         else {
1534                                 if (get_sha1_hex(rec + 41, logged_sha1))
1535                                         die("Log %s is corrupt.", logfile);
1536                                 if (hashcmp(logged_sha1, sha1)) {
1537                                         warning("Log %s unexpectedly ended on %s.",
1538                                                 logfile, show_date(date, tz, DATE_RFC2822));
1539                                 }
1540                         }
1541                         munmap(log_mapped, mapsz);
1542                         return 0;
1543                 }
1544                 lastrec = rec;
1545                 if (cnt > 0)
1546                         cnt--;
1547         }
1548
1549         rec = logdata;
1550         while (rec < logend && *rec != '>' && *rec != '\n')
1551                 rec++;
1552         if (rec == logend || *rec == '\n')
1553                 die("Log %s is corrupt.", logfile);
1554         date = strtoul(rec + 1, &tz_c, 10);
1555         tz = strtoul(tz_c, NULL, 10);
1556         if (get_sha1_hex(logdata, sha1))
1557                 die("Log %s is corrupt.", logfile);
1558         if (is_null_sha1(sha1)) {
1559                 if (get_sha1_hex(logdata + 41, sha1))
1560                         die("Log %s is corrupt.", logfile);
1561         }
1562         if (msg)
1563                 *msg = ref_msg(logdata, logend);
1564         munmap(log_mapped, mapsz);
1565
1566         if (cutoff_time)
1567                 *cutoff_time = date;
1568         if (cutoff_tz)
1569                 *cutoff_tz = tz;
1570         if (cutoff_cnt)
1571                 *cutoff_cnt = reccnt;
1572         return 1;
1573 }
1574
1575 int for_each_recent_reflog_ent(const char *ref, each_reflog_ent_fn fn, long ofs, void *cb_data)
1576 {
1577         const char *logfile;
1578         FILE *logfp;
1579         struct strbuf sb = STRBUF_INIT;
1580         int ret = 0;
1581
1582         logfile = git_path("logs/%s", ref);
1583         logfp = fopen(logfile, "r");
1584         if (!logfp)
1585                 return -1;
1586
1587         if (ofs) {
1588                 struct stat statbuf;
1589                 if (fstat(fileno(logfp), &statbuf) ||
1590                     statbuf.st_size < ofs ||
1591                     fseek(logfp, -ofs, SEEK_END) ||
1592                     strbuf_getwholeline(&sb, logfp, '\n')) {
1593                         fclose(logfp);
1594                         strbuf_release(&sb);
1595                         return -1;
1596                 }
1597         }
1598
1599         while (!strbuf_getwholeline(&sb, logfp, '\n')) {
1600                 unsigned char osha1[20], nsha1[20];
1601                 char *email_end, *message;
1602                 unsigned long timestamp;
1603                 int tz;
1604
1605                 /* old SP new SP name <email> SP time TAB msg LF */
1606                 if (sb.len < 83 || sb.buf[sb.len - 1] != '\n' ||
1607                     get_sha1_hex(sb.buf, osha1) || sb.buf[40] != ' ' ||
1608                     get_sha1_hex(sb.buf + 41, nsha1) || sb.buf[81] != ' ' ||
1609                     !(email_end = strchr(sb.buf + 82, '>')) ||
1610                     email_end[1] != ' ' ||
1611                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1612                     !message || message[0] != ' ' ||
1613                     (message[1] != '+' && message[1] != '-') ||
1614                     !isdigit(message[2]) || !isdigit(message[3]) ||
1615                     !isdigit(message[4]) || !isdigit(message[5]))
1616                         continue; /* corrupt? */
1617                 email_end[1] = '\0';
1618                 tz = strtol(message + 1, NULL, 10);
1619                 if (message[6] != '\t')
1620                         message += 6;
1621                 else
1622                         message += 7;
1623                 ret = fn(osha1, nsha1, sb.buf + 82, timestamp, tz, message,
1624                          cb_data);
1625                 if (ret)
1626                         break;
1627         }
1628         fclose(logfp);
1629         strbuf_release(&sb);
1630         return ret;
1631 }
1632
1633 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1634 {
1635         return for_each_recent_reflog_ent(ref, fn, 0, cb_data);
1636 }
1637
1638 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1639 {
1640         DIR *dir = opendir(git_path("logs/%s", base));
1641         int retval = 0;
1642
1643         if (dir) {
1644                 struct dirent *de;
1645                 int baselen = strlen(base);
1646                 char *log = xmalloc(baselen + 257);
1647
1648                 memcpy(log, base, baselen);
1649                 if (baselen && base[baselen-1] != '/')
1650                         log[baselen++] = '/';
1651
1652                 while ((de = readdir(dir)) != NULL) {
1653                         struct stat st;
1654                         int namelen;
1655
1656                         if (de->d_name[0] == '.')
1657                                 continue;
1658                         namelen = strlen(de->d_name);
1659                         if (namelen > 255)
1660                                 continue;
1661                         if (has_extension(de->d_name, ".lock"))
1662                                 continue;
1663                         memcpy(log + baselen, de->d_name, namelen+1);
1664                         if (stat(git_path("logs/%s", log), &st) < 0)
1665                                 continue;
1666                         if (S_ISDIR(st.st_mode)) {
1667                                 retval = do_for_each_reflog(log, fn, cb_data);
1668                         } else {
1669                                 unsigned char sha1[20];
1670                                 if (!resolve_ref(log, sha1, 0, NULL))
1671                                         retval = error("bad ref for %s", log);
1672                                 else
1673                                         retval = fn(log, sha1, 0, cb_data);
1674                         }
1675                         if (retval)
1676                                 break;
1677                 }
1678                 free(log);
1679                 closedir(dir);
1680         }
1681         else if (*base)
1682                 return errno;
1683         return retval;
1684 }
1685
1686 int for_each_reflog(each_ref_fn fn, void *cb_data)
1687 {
1688         return do_for_each_reflog("", fn, cb_data);
1689 }
1690
1691 int update_ref(const char *action, const char *refname,
1692                 const unsigned char *sha1, const unsigned char *oldval,
1693                 int flags, enum action_on_err onerr)
1694 {
1695         static struct ref_lock *lock;
1696         lock = lock_any_ref_for_update(refname, oldval, flags);
1697         if (!lock) {
1698                 const char *str = "Cannot lock the ref '%s'.";
1699                 switch (onerr) {
1700                 case MSG_ON_ERR: error(str, refname); break;
1701                 case DIE_ON_ERR: die(str, refname); break;
1702                 case QUIET_ON_ERR: break;
1703                 }
1704                 return 1;
1705         }
1706         if (write_ref_sha1(lock, sha1, action) < 0) {
1707                 const char *str = "Cannot update the ref '%s'.";
1708                 switch (onerr) {
1709                 case MSG_ON_ERR: error(str, refname); break;
1710                 case DIE_ON_ERR: die(str, refname); break;
1711                 case QUIET_ON_ERR: break;
1712                 }
1713                 return 1;
1714         }
1715         return 0;
1716 }
1717
1718 struct ref *find_ref_by_name(const struct ref *list, const char *name)
1719 {
1720         for ( ; list; list = list->next)
1721                 if (!strcmp(list->name, name))
1722                         return (struct ref *)list;
1723         return NULL;
1724 }
1725
1726 /*
1727  * generate a format suitable for scanf from a ref_rev_parse_rules
1728  * rule, that is replace the "%.*s" spec with a "%s" spec
1729  */
1730 static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
1731 {
1732         char *spec;
1733
1734         spec = strstr(rule, "%.*s");
1735         if (!spec || strstr(spec + 4, "%.*s"))
1736                 die("invalid rule in ref_rev_parse_rules: %s", rule);
1737
1738         /* copy all until spec */
1739         strncpy(scanf_fmt, rule, spec - rule);
1740         scanf_fmt[spec - rule] = '\0';
1741         /* copy new spec */
1742         strcat(scanf_fmt, "%s");
1743         /* copy remaining rule */
1744         strcat(scanf_fmt, spec + 4);
1745
1746         return;
1747 }
1748
1749 char *shorten_unambiguous_ref(const char *ref, int strict)
1750 {
1751         int i;
1752         static char **scanf_fmts;
1753         static int nr_rules;
1754         char *short_name;
1755
1756         /* pre generate scanf formats from ref_rev_parse_rules[] */
1757         if (!nr_rules) {
1758                 size_t total_len = 0;
1759
1760                 /* the rule list is NULL terminated, count them first */
1761                 for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
1762                         /* no +1 because strlen("%s") < strlen("%.*s") */
1763                         total_len += strlen(ref_rev_parse_rules[nr_rules]);
1764
1765                 scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
1766
1767                 total_len = 0;
1768                 for (i = 0; i < nr_rules; i++) {
1769                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
1770                                         + total_len;
1771                         gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
1772                         total_len += strlen(ref_rev_parse_rules[i]);
1773                 }
1774         }
1775
1776         /* bail out if there are no rules */
1777         if (!nr_rules)
1778                 return xstrdup(ref);
1779
1780         /* buffer for scanf result, at most ref must fit */
1781         short_name = xstrdup(ref);
1782
1783         /* skip first rule, it will always match */
1784         for (i = nr_rules - 1; i > 0 ; --i) {
1785                 int j;
1786                 int rules_to_fail = i;
1787                 int short_name_len;
1788
1789                 if (1 != sscanf(ref, scanf_fmts[i], short_name))
1790                         continue;
1791
1792                 short_name_len = strlen(short_name);
1793
1794                 /*
1795                  * in strict mode, all (except the matched one) rules
1796                  * must fail to resolve to a valid non-ambiguous ref
1797                  */
1798                 if (strict)
1799                         rules_to_fail = nr_rules;
1800
1801                 /*
1802                  * check if the short name resolves to a valid ref,
1803                  * but use only rules prior to the matched one
1804                  */
1805                 for (j = 0; j < rules_to_fail; j++) {
1806                         const char *rule = ref_rev_parse_rules[j];
1807                         unsigned char short_objectname[20];
1808                         char refname[PATH_MAX];
1809
1810                         /* skip matched rule */
1811                         if (i == j)
1812                                 continue;
1813
1814                         /*
1815                          * the short name is ambiguous, if it resolves
1816                          * (with this previous rule) to a valid ref
1817                          * read_ref() returns 0 on success
1818                          */
1819                         mksnpath(refname, sizeof(refname),
1820                                  rule, short_name_len, short_name);
1821                         if (!read_ref(refname, short_objectname))
1822                                 break;
1823                 }
1824
1825                 /*
1826                  * short name is non-ambiguous if all previous rules
1827                  * haven't resolved to a valid ref
1828                  */
1829                 if (j == rules_to_fail)
1830                         return short_name;
1831         }
1832
1833         free(short_name);
1834         return xstrdup(ref);
1835 }