refs.c

   1 #include "cache.h"
   2 #include "refs.h"
   3 #include "object.h"
   4 #include "tag.h"
   5 #include "dir.h"
   6
   7 /* ISSYMREF=01 and ISPACKED=02 are public interfaces */
   8 #define REF_KNOWS_PEELED 04
   9
  10 struct ref_list {
  11         struct ref_list *next;
  12         unsigned char flag; /* ISSYMREF? ISPACKED? */
  13         unsigned char sha1[20];
  14         unsigned char peeled[20];
  15         char name[FLEX_ARRAY];
  16 };
  17
  18 static const char *parse_ref_line(char *line, unsigned char *sha1)
  19 {
  20         /*
  21          * 42: the answer to everything.
  22          *
  23          * In this case, it happens to be the answer to
  24          *  40 (length of sha1 hex representation)
  25          *  +1 (space in between hex and name)
  26          *  +1 (newline at the end of the line)
  27          */
  28         int len = strlen(line) - 42;
  29
  30         if (len <= 0)
  31                 return NULL;
  32         if (get_sha1_hex(line, sha1) < 0)
  33                 return NULL;
  34         if (!isspace(line[40]))
  35                 return NULL;
  36         line += 41;
  37         if (isspace(*line))
  38                 return NULL;
  39         if (line[len] != '\n')
  40                 return NULL;
  41         line[len] = 0;
  42
  43         return line;
  44 }
  45
  46 static struct ref_list *add_ref(const char *name, const unsigned char *sha1,
  47                                 int flag, struct ref_list *list,
  48                                 struct ref_list **new_entry)
  49 {
  50         int len;
  51         struct ref_list *entry;
  52
  53         /* Allocate it and add it in.. */
  54         len = strlen(name) + 1;
  55         entry = xmalloc(sizeof(struct ref_list) + len);
  56         hashcpy(entry->sha1, sha1);
  57         hashclr(entry->peeled);
  58         memcpy(entry->name, name, len);
  59         entry->flag = flag;
  60         entry->next = list;
  61         if (new_entry)
  62                 *new_entry = entry;
  63         return entry;
  64 }
  65
  66 /* merge sort the ref list */
  67 static struct ref_list *sort_ref_list(struct ref_list *list)
  68 {
  69         int psize, qsize, last_merge_count, cmp;
  70         struct ref_list *p, *q, *l, *e;
  71         struct ref_list *new_list = list;
  72         int k = 1;
  73         int merge_count = 0;
  74
  75         if (!list)
  76                 return list;
  77
  78         do {
  79                 last_merge_count = merge_count;
  80                 merge_count = 0;
  81
  82                 psize = 0;
  83
  84                 p = new_list;
  85                 q = new_list;
  86                 new_list = NULL;
  87                 l = NULL;
  88
  89                 while (p) {
  90                         merge_count++;
  91
  92                         while (psize < k && q->next) {
  93                                 q = q->next;
  94                                 psize++;
  95                         }
  96                         qsize = k;
  97
  98                         while ((psize > 0) || (qsize > 0 && q)) {
  99                                 if (qsize == 0 || !q) {
 100                                         e = p;
 101                                         p = p->next;
 102                                         psize--;
 103                                 } else if (psize == 0) {
 104                                         e = q;
 105                                         q = q->next;
 106                                         qsize--;
 107                                 } else {
 108                                         cmp = strcmp(q->name, p->name);
 109                                         if (cmp < 0) {
 110                                                 e = q;
 111                                                 q = q->next;
 112                                                 qsize--;
 113                                         } else if (cmp > 0) {
 114                                                 e = p;
 115                                                 p = p->next;
 116                                                 psize--;
 117                                         } else {
 118                                                 if (hashcmp(q->sha1, p->sha1))
 119                                                         die("Duplicated ref, and SHA1s don't match: %s",
 120                                                             q->name);
 121                                                 warning("Duplicated ref: %s", q->name);
 122                                                 e = q;
 123                                                 q = q->next;
 124                                                 qsize--;
 125                                                 free(e);
 126                                                 e = p;
 127                                                 p = p->next;
 128                                                 psize--;
 129                                         }
 130                                 }
 131
 132                                 e->next = NULL;
 133
 134                                 if (l)
 135                                         l->next = e;
 136                                 if (!new_list)
 137                                         new_list = e;
 138                                 l = e;
 139                         }
 140
 141                         p = q;
 142                 };
 143
 144                 k = k * 2;
 145         } while ((last_merge_count != merge_count) || (last_merge_count != 1));
 146
 147         return new_list;
 148 }
 149
 150 /*
 151  * Future: need to be in "struct repository"
 152  * when doing a full libification.
 153  */
 154 static struct cached_refs {
 155         char did_loose;
 156         char did_packed;
 157         struct ref_list *loose;
 158         struct ref_list *packed;
 159 } cached_refs;
 160 static struct ref_list *current_ref;
 161
 162 static struct ref_list *extra_refs;
 163
 164 static void free_ref_list(struct ref_list *list)
 165 {
 166         struct ref_list *next;
 167         for ( ; list; list = next) {
 168                 next = list->next;
 169                 free(list);
 170         }
 171 }
 172
 173 static void invalidate_cached_refs(void)
 174 {
 175         struct cached_refs *ca = &cached_refs;
 176
 177         if (ca->did_loose && ca->loose)
 178                 free_ref_list(ca->loose);
 179         if (ca->did_packed && ca->packed)
 180                 free_ref_list(ca->packed);
 181         ca->loose = ca->packed = NULL;
 182         ca->did_loose = ca->did_packed = 0;
 183 }
 184
 185 static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
 186 {
 187         struct ref_list *list = NULL;
 188         struct ref_list *last = NULL;
 189         char refline[PATH_MAX];
 190         int flag = REF_ISPACKED;
 191
 192         while (fgets(refline, sizeof(refline), f)) {
 193                 unsigned char sha1[20];
 194                 const char *name;
 195                 static const char header[] = "# pack-refs with:";
 196
 197                 if (!strncmp(refline, header, sizeof(header)-1)) {
 198                         const char *traits = refline + sizeof(header) - 1;
 199                         if (strstr(traits, " peeled "))
 200                                 flag |= REF_KNOWS_PEELED;
 201                         /* perhaps other traits later as well */
 202                         continue;
 203                 }
 204
 205                 name = parse_ref_line(refline, sha1);
 206                 if (name) {
 207                         list = add_ref(name, sha1, flag, list, &last);
 208                         continue;
 209                 }
 210                 if (last &&
 211                     refline[0] == '^' &&
 212                     strlen(refline) == 42 &&
 213                     refline[41] == '\n' &&
 214                     !get_sha1_hex(refline + 1, sha1))
 215                         hashcpy(last->peeled, sha1);
 216         }
 217         cached_refs->packed = sort_ref_list(list);
 218 }
 219
 220 void add_extra_ref(const char *name, const unsigned char *sha1, int flag)
 221 {
 222         extra_refs = add_ref(name, sha1, flag, extra_refs, NULL);
 223 }
 224
 225 void clear_extra_refs(void)
 226 {
 227         free_ref_list(extra_refs);
 228         extra_refs = NULL;
 229 }
 230
 231 static struct ref_list *get_packed_refs(void)
 232 {
 233         if (!cached_refs.did_packed) {
 234                 FILE *f = fopen(git_path("packed-refs"), "r");
 235                 cached_refs.packed = NULL;
 236                 if (f) {
 237                         read_packed_refs(f, &cached_refs);
 238                         fclose(f);
 239                 }
 240                 cached_refs.did_packed = 1;
 241         }
 242         return cached_refs.packed;
 243 }
 244
 245 static struct ref_list *get_ref_dir(const char *base, struct ref_list *list)
 246 {
 247         DIR *dir = opendir(git_path("%s", base));
 248
 249         if (dir) {
 250                 struct dirent *de;
 251                 int baselen = strlen(base);
 252                 char *ref = xmalloc(baselen + 257);
 253
 254                 memcpy(ref, base, baselen);
 255                 if (baselen && base[baselen-1] != '/')
 256                         ref[baselen++] = '/';
 257
 258                 while ((de = readdir(dir)) != NULL) {
 259                         unsigned char sha1[20];
 260                         struct stat st;
 261                         int flag;
 262                         int namelen;
 263
 264                         if (de->d_name[0] == '.')
 265                                 continue;
 266                         namelen = strlen(de->d_name);
 267                         if (namelen > 255)
 268                                 continue;
 269                         if (has_extension(de->d_name, ".lock"))
 270                                 continue;
 271                         memcpy(ref + baselen, de->d_name, namelen+1);
 272                         if (stat(git_path("%s", ref), &st) < 0)
 273                                 continue;
 274                         if (S_ISDIR(st.st_mode)) {
 275                                 list = get_ref_dir(ref, list);
 276                                 continue;
 277                         }
 278                         if (!resolve_ref(ref, sha1, 1, &flag))
 279                                 hashclr(sha1);
 280                         list = add_ref(ref, sha1, flag, list, NULL);
 281                 }
 282                 free(ref);
 283                 closedir(dir);
 284         }
 285         return sort_ref_list(list);
 286 }
 287
 288 struct warn_if_dangling_data {
 289         const char *refname;
 290         const char *msg_fmt;
 291 };
 292
 293 static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
 294                                    int flags, void *cb_data)
 295 {
 296         struct warn_if_dangling_data *d = cb_data;
 297         const char *resolves_to;
 298         unsigned char junk[20];
 299
 300         if (!(flags & REF_ISSYMREF))
 301                 return 0;
 302
 303         resolves_to = resolve_ref(refname, junk, 0, NULL);
 304         if (!resolves_to || strcmp(resolves_to, d->refname))
 305                 return 0;
 306
 307         printf(d->msg_fmt, refname);
 308         return 0;
 309 }
 310
 311 void warn_dangling_symref(const char *msg_fmt, const char *refname)
 312 {
 313         struct warn_if_dangling_data data = { refname, msg_fmt };
 314         for_each_rawref(warn_if_dangling_symref, &data);
 315 }
 316
 317 static struct ref_list *get_loose_refs(void)
 318 {
 319         if (!cached_refs.did_loose) {
 320                 cached_refs.loose = get_ref_dir("refs", NULL);
 321                 cached_refs.did_loose = 1;
 322         }
 323         return cached_refs.loose;
 324 }
 325
 326 /* We allow "recursive" symbolic refs. Only within reason, though */
 327 #define MAXDEPTH 5
 328 #define MAXREFLEN (1024)
 329
 330 static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
 331 {
 332         FILE *f;
 333         struct cached_refs refs;
 334         struct ref_list *ref;
 335         int retval;
 336
 337         strcpy(name + pathlen, "packed-refs");
 338         f = fopen(name, "r");
 339         if (!f)
 340                 return -1;
 341         read_packed_refs(f, &refs);
 342         fclose(f);
 343         ref = refs.packed;
 344         retval = -1;
 345         while (ref) {
 346                 if (!strcmp(ref->name, refname)) {
 347                         retval = 0;
 348                         memcpy(result, ref->sha1, 20);
 349                         break;
 350                 }
 351                 ref = ref->next;
 352         }
 353         free_ref_list(refs.packed);
 354         return retval;
 355 }
 356
 357 static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
 358 {
 359         int fd, len = strlen(refname);
 360         char buffer[128], *p;
 361
 362         if (recursion > MAXDEPTH || len > MAXREFLEN)
 363                 return -1;
 364         memcpy(name + pathlen, refname, len+1);
 365         fd = open(name, O_RDONLY);
 366         if (fd < 0)
 367                 return resolve_gitlink_packed_ref(name, pathlen, refname, result);
 368
 369         len = read(fd, buffer, sizeof(buffer)-1);
 370         close(fd);
 371         if (len < 0)
 372                 return -1;
 373         while (len && isspace(buffer[len-1]))
 374                 len--;
 375         buffer[len] = 0;
 376
 377         /* Was it a detached head or an old-fashioned symlink? */
 378         if (!get_sha1_hex(buffer, result))
 379                 return 0;
 380
 381         /* Symref? */
 382         if (strncmp(buffer, "ref:", 4))
 383                 return -1;
 384         p = buffer + 4;
 385         while (isspace(*p))
 386                 p++;
 387
 388         return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
 389 }
 390
 391 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
 392 {
 393         int len = strlen(path), retval;
 394         char *gitdir;
 395         const char *tmp;
 396
 397         while (len && path[len-1] == '/')
 398                 len--;
 399         if (!len)
 400                 return -1;
 401         gitdir = xmalloc(len + MAXREFLEN + 8);
 402         memcpy(gitdir, path, len);
 403         memcpy(gitdir + len, "/.git", 6);
 404         len += 5;
 405
 406         tmp = read_gitfile_gently(gitdir);
 407         if (tmp) {
 408                 free(gitdir);
 409                 len = strlen(tmp);
 410                 gitdir = xmalloc(len + MAXREFLEN + 3);
 411                 memcpy(gitdir, tmp, len);
 412         }
 413         gitdir[len] = '/';
 414         gitdir[++len] = '\0';
 415         retval = resolve_gitlink_ref_recursive(gitdir, len, refname, result, 0);
 416         free(gitdir);
 417         return retval;
 418 }
 419
 420 /*
 421  * If the "reading" argument is set, this function finds out what _object_
 422  * the ref points at by "reading" the ref.  The ref, if it is not symbolic,
 423  * has to exist, and if it is symbolic, it has to point at an existing ref,
 424  * because the "read" goes through the symref to the ref it points at.
 425  *
 426  * The access that is not "reading" may often be "writing", but does not
 427  * have to; it can be merely checking _where it leads to_. If it is a
 428  * prelude to "writing" to the ref, a write to a symref that points at
 429  * yet-to-be-born ref will create the real ref pointed by the symref.
 430  * reading=0 allows the caller to check where such a symref leads to.
 431  */
 432 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 433 {
 434         int depth = MAXDEPTH;
 435         ssize_t len;
 436         char buffer[256];
 437         static char ref_buffer[256];
 438
 439         if (flag)
 440                 *flag = 0;
 441
 442         for (;;) {
 443                 char path[PATH_MAX];
 444                 struct stat st;
 445                 char *buf;
 446                 int fd;
 447
 448                 if (--depth < 0)
 449                         return NULL;
 450
 451                 git_snpath(path, sizeof(path), "%s", ref);
 452                 /* Special case: non-existing file. */
 453                 if (lstat(path, &st) < 0) {
 454                         struct ref_list *list = get_packed_refs();
 455                         while (list) {
 456                                 if (!strcmp(ref, list->name)) {
 457                                         hashcpy(sha1, list->sha1);
 458                                         if (flag)
 459                                                 *flag |= REF_ISPACKED;
 460                                         return ref;
 461                                 }
 462                                 list = list->next;
 463                         }
 464                         if (reading || errno != ENOENT)
 465                                 return NULL;
 466                         hashclr(sha1);
 467                         return ref;
 468                 }
 469
 470                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 471                 if (S_ISLNK(st.st_mode)) {
 472                         len = readlink(path, buffer, sizeof(buffer)-1);
 473                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 474                                 buffer[len] = 0;
 475                                 strcpy(ref_buffer, buffer);
 476                                 ref = ref_buffer;
 477                                 if (flag)
 478                                         *flag |= REF_ISSYMREF;
 479                                 continue;
 480                         }
 481                 }
 482
 483                 /* Is it a directory? */
 484                 if (S_ISDIR(st.st_mode)) {
 485                         errno = EISDIR;
 486                         return NULL;
 487                 }
 488
 489                 /*
 490                  * Anything else, just open it and try to use it as
 491                  * a ref
 492                  */
 493                 fd = open(path, O_RDONLY);
 494                 if (fd < 0)
 495                         return NULL;
 496                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
 497                 close(fd);
 498
 499                 /*
 500                  * Is it a symbolic ref?
 501                  */
 502                 if (len < 4 || memcmp("ref:", buffer, 4))
 503                         break;
 504                 buf = buffer + 4;
 505                 len -= 4;
 506                 while (len && isspace(*buf))
 507                         buf++, len--;
 508                 while (len && isspace(buf[len-1]))
 509                         len--;
 510                 buf[len] = 0;
 511                 memcpy(ref_buffer, buf, len + 1);
 512                 ref = ref_buffer;
 513                 if (flag)
 514                         *flag |= REF_ISSYMREF;
 515         }
 516         if (len < 40 || get_sha1_hex(buffer, sha1))
 517                 return NULL;
 518         return ref;
 519 }
 520
 521 int read_ref(const char *ref, unsigned char *sha1)
 522 {
 523         if (resolve_ref(ref, sha1, 1, NULL))
 524                 return 0;
 525         return -1;
 526 }
 527
 528 #define DO_FOR_EACH_INCLUDE_BROKEN 01
 529 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
 530                       int flags, void *cb_data, struct ref_list *entry)
 531 {
 532         if (strncmp(base, entry->name, trim))
 533                 return 0;
 534         /* Is this a "negative ref" that represents a deleted ref? */
 535         if (is_null_sha1(entry->sha1))
 536                 return 0;
 537         if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
 538                 if (!has_sha1_file(entry->sha1)) {
 539                         error("%s does not point to a valid object!", entry->name);
 540                         return 0;
 541                 }
 542         }
 543         current_ref = entry;
 544         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 545 }
 546
 547 int peel_ref(const char *ref, unsigned char *sha1)
 548 {
 549         int flag;
 550         unsigned char base[20];
 551         struct object *o;
 552
 553         if (current_ref && (current_ref->name == ref
 554                 || !strcmp(current_ref->name, ref))) {
 555                 if (current_ref->flag & REF_KNOWS_PEELED) {
 556                         hashcpy(sha1, current_ref->peeled);
 557                         return 0;
 558                 }
 559                 hashcpy(base, current_ref->sha1);
 560                 goto fallback;
 561         }
 562
 563         if (!resolve_ref(ref, base, 1, &flag))
 564                 return -1;
 565
 566         if ((flag & REF_ISPACKED)) {
 567                 struct ref_list *list = get_packed_refs();
 568
 569                 while (list) {
 570                         if (!strcmp(list->name, ref)) {
 571                                 if (list->flag & REF_KNOWS_PEELED) {
 572                                         hashcpy(sha1, list->peeled);
 573                                         return 0;
 574                                 }
 575                                 /* older pack-refs did not leave peeled ones */
 576                                 break;
 577                         }
 578                         list = list->next;
 579                 }
 580         }
 581
 582 fallback:
 583         o = parse_object(base);
 584         if (o && o->type == OBJ_TAG) {
 585                 o = deref_tag(o, ref, 0);
 586                 if (o) {
 587                         hashcpy(sha1, o->sha1);
 588                         return 0;
 589                 }
 590         }
 591         return -1;
 592 }
 593
 594 static int do_for_each_ref(const char *base, each_ref_fn fn, int trim,
 595                            int flags, void *cb_data)
 596 {
 597         int retval = 0;
 598         struct ref_list *packed = get_packed_refs();
 599         struct ref_list *loose = get_loose_refs();
 600
 601         struct ref_list *extra;
 602
 603         for (extra = extra_refs; extra; extra = extra->next)
 604                 retval = do_one_ref(base, fn, trim, flags, cb_data, extra);
 605
 606         while (packed && loose) {
 607                 struct ref_list *entry;
 608                 int cmp = strcmp(packed->name, loose->name);
 609                 if (!cmp) {
 610                         packed = packed->next;
 611                         continue;
 612                 }
 613                 if (cmp > 0) {
 614                         entry = loose;
 615                         loose = loose->next;
 616                 } else {
 617                         entry = packed;
 618                         packed = packed->next;
 619                 }
 620                 retval = do_one_ref(base, fn, trim, flags, cb_data, entry);
 621                 if (retval)
 622                         goto end_each;
 623         }
 624
 625         for (packed = packed ? packed : loose; packed; packed = packed->next) {
 626                 retval = do_one_ref(base, fn, trim, flags, cb_data, packed);
 627                 if (retval)
 628                         goto end_each;
 629         }
 630
 631 end_each:
 632         current_ref = NULL;
 633         return retval;
 634 }
 635
 636 int head_ref(each_ref_fn fn, void *cb_data)
 637 {
 638         unsigned char sha1[20];
 639         int flag;
 640
 641         if (resolve_ref("HEAD", sha1, 1, &flag))
 642                 return fn("HEAD", sha1, flag, cb_data);
 643         return 0;
 644 }
 645
 646 int for_each_ref(each_ref_fn fn, void *cb_data)
 647 {
 648         return do_for_each_ref("refs/", fn, 0, 0, cb_data);
 649 }
 650
 651 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
 652 {
 653         return do_for_each_ref(prefix, fn, strlen(prefix), 0, cb_data);
 654 }
 655
 656 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 657 {
 658         return for_each_ref_in("refs/tags/", fn, cb_data);
 659 }
 660
 661 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 662 {
 663         return for_each_ref_in("refs/heads/", fn, cb_data);
 664 }
 665
 666 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 667 {
 668         return for_each_ref_in("refs/remotes/", fn, cb_data);
 669 }
 670
 671 int for_each_rawref(each_ref_fn fn, void *cb_data)
 672 {
 673         return do_for_each_ref("refs/", fn, 0,
 674                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
 675 }
 676
 677 /*
 678  * Make sure "ref" is something reasonable to have under ".git/refs/";
 679  * We do not like it if:
 680  *
 681  * - any path component of it begins with ".", or
 682  * - it has double dots "..", or
 683  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 684  * - it ends with a "/".
 685  * - it ends with ".lock"
 686  * - it contains a "\" (backslash)
 687  */
 688
 689 static inline int bad_ref_char(int ch)
 690 {
 691         if (((unsigned) ch) <= ' ' ||
 692             ch == '~' || ch == '^' || ch == ':' || ch == '\\')
 693                 return 1;
 694         /* 2.13 Pattern Matching Notation */
 695         if (ch == '?' || ch == '[') /* Unsupported */
 696                 return 1;
 697         if (ch == '*') /* Supported at the end */
 698                 return 2;
 699         return 0;
 700 }
 701
 702 int check_ref_format(const char *ref)
 703 {
 704         int ch, level, bad_type, last;
 705         int ret = CHECK_REF_FORMAT_OK;
 706         const char *cp = ref;
 707
 708         level = 0;
 709         while (1) {
 710                 while ((ch = *cp++) == '/')
 711                         ; /* tolerate duplicated slashes */
 712                 if (!ch)
 713                         /* should not end with slashes */
 714                         return CHECK_REF_FORMAT_ERROR;
 715
 716                 /* we are at the beginning of the path component */
 717                 if (ch == '.')
 718                         return CHECK_REF_FORMAT_ERROR;
 719                 bad_type = bad_ref_char(ch);
 720                 if (bad_type) {
 721                         if (bad_type == 2 && (!*cp || *cp == '/') &&
 722                             ret == CHECK_REF_FORMAT_OK)
 723                                 ret = CHECK_REF_FORMAT_WILDCARD;
 724                         else
 725                                 return CHECK_REF_FORMAT_ERROR;
 726                 }
 727
 728                 last = ch;
 729                 /* scan the rest of the path component */
 730                 while ((ch = *cp++) != 0) {
 731                         bad_type = bad_ref_char(ch);
 732                         if (bad_type)
 733                                 return CHECK_REF_FORMAT_ERROR;
 734                         if (ch == '/')
 735                                 break;
 736                         if (last == '.' && ch == '.')
 737                                 return CHECK_REF_FORMAT_ERROR;
 738                         if (last == '@' && ch == '{')
 739                                 return CHECK_REF_FORMAT_ERROR;
 740                         last = ch;
 741                 }
 742                 level++;
 743                 if (!ch) {
 744                         if (ref <= cp - 2 && cp[-2] == '.')
 745                                 return CHECK_REF_FORMAT_ERROR;
 746                         if (level < 2)
 747                                 return CHECK_REF_FORMAT_ONELEVEL;
 748                         if (has_extension(ref, ".lock"))
 749                                 return CHECK_REF_FORMAT_ERROR;
 750                         return ret;
 751                 }
 752         }
 753 }
 754
 755 const char *prettify_refname(const char *name)
 756 {
 757         return name + (
 758                 !prefixcmp(name, "refs/heads/") ? 11 :
 759                 !prefixcmp(name, "refs/tags/") ? 10 :
 760                 !prefixcmp(name, "refs/remotes/") ? 13 :
 761                 0);
 762 }
 763
 764 const char *ref_rev_parse_rules[] = {
 765         "%.*s",
 766         "refs/%.*s",
 767         "refs/tags/%.*s",
 768         "refs/heads/%.*s",
 769         "refs/remotes/%.*s",
 770         "refs/remotes/%.*s/HEAD",
 771         NULL
 772 };
 773
 774 const char *ref_fetch_rules[] = {
 775         "%.*s",
 776         "refs/%.*s",
 777         "refs/heads/%.*s",
 778         NULL
 779 };
 780
 781 int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
 782 {
 783         const char **p;
 784         const int abbrev_name_len = strlen(abbrev_name);
 785
 786         for (p = rules; *p; p++) {
 787                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
 788                         return 1;
 789                 }
 790         }
 791
 792         return 0;
 793 }
 794
 795 static struct ref_lock *verify_lock(struct ref_lock *lock,
 796         const unsigned char *old_sha1, int mustexist)
 797 {
 798         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
 799                 error("Can't verify ref %s", lock->ref_name);
 800                 unlock_ref(lock);
 801                 return NULL;
 802         }
 803         if (hashcmp(lock->old_sha1, old_sha1)) {
 804                 error("Ref %s is at %s but expected %s", lock->ref_name,
 805                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
 806                 unlock_ref(lock);
 807                 return NULL;
 808         }
 809         return lock;
 810 }
 811
 812 static int remove_empty_directories(const char *file)
 813 {
 814         /* we want to create a file but there is a directory there;
 815          * if that is an empty directory (or a directory that contains
 816          * only empty directories), remove them.
 817          */
 818         struct strbuf path;
 819         int result;
 820
 821         strbuf_init(&path, 20);
 822         strbuf_addstr(&path, file);
 823
 824         result = remove_dir_recursively(&path, 1);
 825
 826         strbuf_release(&path);
 827
 828         return result;
 829 }
 830
 831 static int is_refname_available(const char *ref, const char *oldref,
 832                                 struct ref_list *list, int quiet)
 833 {
 834         int namlen = strlen(ref); /* e.g. 'foo/bar' */
 835         while (list) {
 836                 /* list->name could be 'foo' or 'foo/bar/baz' */
 837                 if (!oldref || strcmp(oldref, list->name)) {
 838                         int len = strlen(list->name);
 839                         int cmplen = (namlen < len) ? namlen : len;
 840                         const char *lead = (namlen < len) ? list->name : ref;
 841                         if (!strncmp(ref, list->name, cmplen) &&
 842                             lead[cmplen] == '/') {
 843                                 if (!quiet)
 844                                         error("'%s' exists; cannot create '%s'",
 845                                               list->name, ref);
 846                                 return 0;
 847                         }
 848                 }
 849                 list = list->next;
 850         }
 851         return 1;
 852 }
 853
 854 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
 855 {
 856         char *ref_file;
 857         const char *orig_ref = ref;
 858         struct ref_lock *lock;
 859         int last_errno = 0;
 860         int type, lflags;
 861         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
 862         int missing = 0;
 863
 864         lock = xcalloc(1, sizeof(struct ref_lock));
 865         lock->lock_fd = -1;
 866
 867         ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
 868         if (!ref && errno == EISDIR) {
 869                 /* we are trying to lock foo but we used to
 870                  * have foo/bar which now does not exist;
 871                  * it is normal for the empty directory 'foo'
 872                  * to remain.
 873                  */
 874                 ref_file = git_path("%s", orig_ref);
 875                 if (remove_empty_directories(ref_file)) {
 876                         last_errno = errno;
 877                         error("there are still refs under '%s'", orig_ref);
 878                         goto error_return;
 879                 }
 880                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
 881         }
 882         if (type_p)
 883             *type_p = type;
 884         if (!ref) {
 885                 last_errno = errno;
 886                 error("unable to resolve reference %s: %s",
 887                         orig_ref, strerror(errno));
 888                 goto error_return;
 889         }
 890         missing = is_null_sha1(lock->old_sha1);
 891         /* When the ref did not exist and we are creating it,
 892          * make sure there is no existing ref that is packed
 893          * whose name begins with our refname, nor a ref whose
 894          * name is a proper prefix of our refname.
 895          */
 896         if (missing &&
 897              !is_refname_available(ref, NULL, get_packed_refs(), 0)) {
 898                 last_errno = ENOTDIR;
 899                 goto error_return;
 900         }
 901
 902         lock->lk = xcalloc(1, sizeof(struct lock_file));
 903
 904         lflags = LOCK_DIE_ON_ERROR;
 905         if (flags & REF_NODEREF) {
 906                 ref = orig_ref;
 907                 lflags |= LOCK_NODEREF;
 908         }
 909         lock->ref_name = xstrdup(ref);
 910         lock->orig_ref_name = xstrdup(orig_ref);
 911         ref_file = git_path("%s", ref);
 912         if (missing)
 913                 lock->force_write = 1;
 914         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
 915                 lock->force_write = 1;
 916
 917         if (safe_create_leading_directories(ref_file)) {
 918                 last_errno = errno;
 919                 error("unable to create directory for %s", ref_file);
 920                 goto error_return;
 921         }
 922
 923         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
 924         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
 925
 926  error_return:
 927         unlock_ref(lock);
 928         errno = last_errno;
 929         return NULL;
 930 }
 931
 932 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
 933 {
 934         char refpath[PATH_MAX];
 935         if (check_ref_format(ref))
 936                 return NULL;
 937         strcpy(refpath, mkpath("refs/%s", ref));
 938         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
 939 }
 940
 941 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
 942 {
 943         switch (check_ref_format(ref)) {
 944         default:
 945                 return NULL;
 946         case 0:
 947         case CHECK_REF_FORMAT_ONELEVEL:
 948                 return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
 949         }
 950 }
 951
 952 static struct lock_file packlock;
 953
 954 static int repack_without_ref(const char *refname)
 955 {
 956         struct ref_list *list, *packed_ref_list;
 957         int fd;
 958         int found = 0;
 959
 960         packed_ref_list = get_packed_refs();
 961         for (list = packed_ref_list; list; list = list->next) {
 962                 if (!strcmp(refname, list->name)) {
 963                         found = 1;
 964                         break;
 965                 }
 966         }
 967         if (!found)
 968                 return 0;
 969         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
 970         if (fd < 0)
 971                 return error("cannot delete '%s' from packed refs", refname);
 972
 973         for (list = packed_ref_list; list; list = list->next) {
 974                 char line[PATH_MAX + 100];
 975                 int len;
 976
 977                 if (!strcmp(refname, list->name))
 978                         continue;
 979                 len = snprintf(line, sizeof(line), "%s %s\n",
 980                                sha1_to_hex(list->sha1), list->name);
 981                 /* this should not happen but just being defensive */
 982                 if (len > sizeof(line))
 983                         die("too long a refname '%s'", list->name);
 984                 write_or_die(fd, line, len);
 985         }
 986         return commit_lock_file(&packlock);
 987 }
 988
 989 int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
 990 {
 991         struct ref_lock *lock;
 992         int err, i = 0, ret = 0, flag = 0;
 993
 994         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
 995         if (!lock)
 996                 return 1;
 997         if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
 998                 /* loose */
 999                 const char *path;
1000
1001                 if (!(delopt & REF_NODEREF)) {
1002                         i = strlen(lock->lk->filename) - 5; /* .lock */
1003                         lock->lk->filename[i] = 0;
1004                         path = lock->lk->filename;
1005                 } else {
1006                         path = git_path("%s", refname);
1007                 }
1008                 err = unlink_or_warn(path);
1009                 if (err && errno != ENOENT)
1010                         ret = 1;
1011
1012                 if (!(delopt & REF_NODEREF))
1013                         lock->lk->filename[i] = '.';
1014         }
1015         /* removing the loose one could have resurrected an earlier
1016          * packed one.  Also, if it was not loose we need to repack
1017          * without it.
1018          */
1019         ret |= repack_without_ref(refname);
1020
1021         unlink_or_warn(git_path("logs/%s", lock->ref_name));
1022         invalidate_cached_refs();
1023         unlock_ref(lock);
1024         return ret;
1025 }
1026
1027 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
1028 {
1029         static const char renamed_ref[] = "RENAMED-REF";
1030         unsigned char sha1[20], orig_sha1[20];
1031         int flag = 0, logmoved = 0;
1032         struct ref_lock *lock;
1033         struct stat loginfo;
1034         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
1035         const char *symref = NULL;
1036
1037         if (log && S_ISLNK(loginfo.st_mode))
1038                 return error("reflog for %s is a symlink", oldref);
1039
1040         symref = resolve_ref(oldref, orig_sha1, 1, &flag);
1041         if (flag & REF_ISSYMREF)
1042                 return error("refname %s is a symbolic ref, renaming it is not supported",
1043                         oldref);
1044         if (!symref)
1045                 return error("refname %s not found", oldref);
1046
1047         if (!is_refname_available(newref, oldref, get_packed_refs(), 0))
1048                 return 1;
1049
1050         if (!is_refname_available(newref, oldref, get_loose_refs(), 0))
1051                 return 1;
1052
1053         lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
1054         if (!lock)
1055                 return error("unable to lock %s", renamed_ref);
1056         lock->force_write = 1;
1057         if (write_ref_sha1(lock, orig_sha1, logmsg))
1058                 return error("unable to save current sha1 in %s", renamed_ref);
1059
1060         if (log && rename(git_path("logs/%s", oldref), git_path("tmp-renamed-log")))
1061                 return error("unable to move logfile logs/%s to tmp-renamed-log: %s",
1062                         oldref, strerror(errno));
1063
1064         if (delete_ref(oldref, orig_sha1, REF_NODEREF)) {
1065                 error("unable to delete old %s", oldref);
1066                 goto rollback;
1067         }
1068
1069         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1, REF_NODEREF)) {
1070                 if (errno==EISDIR) {
1071                         if (remove_empty_directories(git_path("%s", newref))) {
1072                                 error("Directory not empty: %s", newref);
1073                                 goto rollback;
1074                         }
1075                 } else {
1076                         error("unable to delete existing %s", newref);
1077                         goto rollback;
1078                 }
1079         }
1080
1081         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
1082                 error("unable to create directory for %s", newref);
1083                 goto rollback;
1084         }
1085
1086  retry:
1087         if (log && rename(git_path("tmp-renamed-log"), git_path("logs/%s", newref))) {
1088                 if (errno==EISDIR || errno==ENOTDIR) {
1089                         /*
1090                          * rename(a, b) when b is an existing
1091                          * directory ought to result in ISDIR, but
1092                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
1093                          */
1094                         if (remove_empty_directories(git_path("logs/%s", newref))) {
1095                                 error("Directory not empty: logs/%s", newref);
1096                                 goto rollback;
1097                         }
1098                         goto retry;
1099                 } else {
1100                         error("unable to move logfile tmp-renamed-log to logs/%s: %s",
1101                                 newref, strerror(errno));
1102                         goto rollback;
1103                 }
1104         }
1105         logmoved = log;
1106
1107         lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
1108         if (!lock) {
1109                 error("unable to lock %s for update", newref);
1110                 goto rollback;
1111         }
1112         lock->force_write = 1;
1113         hashcpy(lock->old_sha1, orig_sha1);
1114         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
1115                 error("unable to write current sha1 into %s", newref);
1116                 goto rollback;
1117         }
1118
1119         return 0;
1120
1121  rollback:
1122         lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
1123         if (!lock) {
1124                 error("unable to lock %s for rollback", oldref);
1125                 goto rollbacklog;
1126         }
1127
1128         lock->force_write = 1;
1129         flag = log_all_ref_updates;
1130         log_all_ref_updates = 0;
1131         if (write_ref_sha1(lock, orig_sha1, NULL))
1132                 error("unable to write current sha1 into %s", oldref);
1133         log_all_ref_updates = flag;
1134
1135  rollbacklog:
1136         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
1137                 error("unable to restore logfile %s from %s: %s",
1138                         oldref, newref, strerror(errno));
1139         if (!logmoved && log &&
1140             rename(git_path("tmp-renamed-log"), git_path("logs/%s", oldref)))
1141                 error("unable to restore logfile %s from tmp-renamed-log: %s",
1142                         oldref, strerror(errno));
1143
1144         return 1;
1145 }
1146
1147 int close_ref(struct ref_lock *lock)
1148 {
1149         if (close_lock_file(lock->lk))
1150                 return -1;
1151         lock->lock_fd = -1;
1152         return 0;
1153 }
1154
1155 int commit_ref(struct ref_lock *lock)
1156 {
1157         if (commit_lock_file(lock->lk))
1158                 return -1;
1159         lock->lock_fd = -1;
1160         return 0;
1161 }
1162
1163 void unlock_ref(struct ref_lock *lock)
1164 {
1165         /* Do not free lock->lk -- atexit() still looks at them */
1166         if (lock->lk)
1167                 rollback_lock_file(lock->lk);
1168         free(lock->ref_name);
1169         free(lock->orig_ref_name);
1170         free(lock);
1171 }
1172
1173 /*
1174  * copy the reflog message msg to buf, which has been allocated sufficiently
1175  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1176  * because reflog file is one line per entry.
1177  */
1178 static int copy_msg(char *buf, const char *msg)
1179 {
1180         char *cp = buf;
1181         char c;
1182         int wasspace = 1;
1183
1184         *cp++ = '\t';
1185         while ((c = *msg++)) {
1186                 if (wasspace && isspace(c))
1187                         continue;
1188                 wasspace = isspace(c);
1189                 if (wasspace)
1190                         c = ' ';
1191                 *cp++ = c;
1192         }
1193         while (buf < cp && isspace(cp[-1]))
1194                 cp--;
1195         *cp++ = '\n';
1196         return cp - buf;
1197 }
1198
1199 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1200                          const unsigned char *new_sha1, const char *msg)
1201 {
1202         int logfd, written, oflags = O_APPEND | O_WRONLY;
1203         unsigned maxlen, len;
1204         int msglen;
1205         char log_file[PATH_MAX];
1206         char *logrec;
1207         const char *committer;
1208
1209         if (log_all_ref_updates < 0)
1210                 log_all_ref_updates = !is_bare_repository();
1211
1212         git_snpath(log_file, sizeof(log_file), "logs/%s", ref_name);
1213
1214         if (log_all_ref_updates &&
1215             (!prefixcmp(ref_name, "refs/heads/") ||
1216              !prefixcmp(ref_name, "refs/remotes/") ||
1217              !strcmp(ref_name, "HEAD"))) {
1218                 if (safe_create_leading_directories(log_file) < 0)
1219                         return error("unable to create directory for %s",
1220                                      log_file);
1221                 oflags |= O_CREAT;
1222         }
1223
1224         logfd = open(log_file, oflags, 0666);
1225         if (logfd < 0) {
1226                 if (!(oflags & O_CREAT) && errno == ENOENT)
1227                         return 0;
1228
1229                 if ((oflags & O_CREAT) && errno == EISDIR) {
1230                         if (remove_empty_directories(log_file)) {
1231                                 return error("There are still logs under '%s'",
1232                                              log_file);
1233                         }
1234                         logfd = open(log_file, oflags, 0666);
1235                 }
1236
1237                 if (logfd < 0)
1238                         return error("Unable to append to %s: %s",
1239                                      log_file, strerror(errno));
1240         }
1241
1242         adjust_shared_perm(log_file);
1243
1244         msglen = msg ? strlen(msg) : 0;
1245         committer = git_committer_info(0);
1246         maxlen = strlen(committer) + msglen + 100;
1247         logrec = xmalloc(maxlen);
1248         len = sprintf(logrec, "%s %s %s\n",
1249                       sha1_to_hex(old_sha1),
1250                       sha1_to_hex(new_sha1),
1251                       committer);
1252         if (msglen)
1253                 len += copy_msg(logrec + len - 1, msg) - 1;
1254         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1255         free(logrec);
1256         if (close(logfd) != 0 || written != len)
1257                 return error("Unable to append to %s", log_file);
1258         return 0;
1259 }
1260
1261 static int is_branch(const char *refname)
1262 {
1263         return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
1264 }
1265
1266 int write_ref_sha1(struct ref_lock *lock,
1267         const unsigned char *sha1, const char *logmsg)
1268 {
1269         static char term = '\n';
1270         struct object *o;
1271
1272         if (!lock)
1273                 return -1;
1274         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1275                 unlock_ref(lock);
1276                 return 0;
1277         }
1278         o = parse_object(sha1);
1279         if (!o) {
1280                 error("Trying to write ref %s with nonexistant object %s",
1281                         lock->ref_name, sha1_to_hex(sha1));
1282                 unlock_ref(lock);
1283                 return -1;
1284         }
1285         if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1286                 error("Trying to write non-commit object %s to branch %s",
1287                         sha1_to_hex(sha1), lock->ref_name);
1288                 unlock_ref(lock);
1289                 return -1;
1290         }
1291         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1292             write_in_full(lock->lock_fd, &term, 1) != 1
1293                 || close_ref(lock) < 0) {
1294                 error("Couldn't write %s", lock->lk->filename);
1295                 unlock_ref(lock);
1296                 return -1;
1297         }
1298         invalidate_cached_refs();
1299         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1300             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1301              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1302                 unlock_ref(lock);
1303                 return -1;
1304         }
1305         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1306                 /*
1307                  * Special hack: If a branch is updated directly and HEAD
1308                  * points to it (may happen on the remote side of a push
1309                  * for example) then logically the HEAD reflog should be
1310                  * updated too.
1311                  * A generic solution implies reverse symref information,
1312                  * but finding all symrefs pointing to the given branch
1313                  * would be rather costly for this rare event (the direct
1314                  * update of a branch) to be worth it.  So let's cheat and
1315                  * check with HEAD only which should cover 99% of all usage
1316                  * scenarios (even 100% of the default ones).
1317                  */
1318                 unsigned char head_sha1[20];
1319                 int head_flag;
1320                 const char *head_ref;
1321                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1322                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1323                     !strcmp(head_ref, lock->ref_name))
1324                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1325         }
1326         if (commit_ref(lock)) {
1327                 error("Couldn't set %s", lock->ref_name);
1328                 unlock_ref(lock);
1329                 return -1;
1330         }
1331         unlock_ref(lock);
1332         return 0;
1333 }
1334
1335 int create_symref(const char *ref_target, const char *refs_heads_master,
1336                   const char *logmsg)
1337 {
1338         const char *lockpath;
1339         char ref[1000];
1340         int fd, len, written;
1341         char *git_HEAD = git_pathdup("%s", ref_target);
1342         unsigned char old_sha1[20], new_sha1[20];
1343
1344         if (logmsg && read_ref(ref_target, old_sha1))
1345                 hashclr(old_sha1);
1346
1347         if (safe_create_leading_directories(git_HEAD) < 0)
1348                 return error("unable to create directory for %s", git_HEAD);
1349
1350 #ifndef NO_SYMLINK_HEAD
1351         if (prefer_symlink_refs) {
1352                 unlink(git_HEAD);
1353                 if (!symlink(refs_heads_master, git_HEAD))
1354                         goto done;
1355                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1356         }
1357 #endif
1358
1359         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1360         if (sizeof(ref) <= len) {
1361                 error("refname too long: %s", refs_heads_master);
1362                 goto error_free_return;
1363         }
1364         lockpath = mkpath("%s.lock", git_HEAD);
1365         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1366         if (fd < 0) {
1367                 error("Unable to open %s for writing", lockpath);
1368                 goto error_free_return;
1369         }
1370         written = write_in_full(fd, ref, len);
1371         if (close(fd) != 0 || written != len) {
1372                 error("Unable to write to %s", lockpath);
1373                 goto error_unlink_return;
1374         }
1375         if (rename(lockpath, git_HEAD) < 0) {
1376                 error("Unable to create %s", git_HEAD);
1377                 goto error_unlink_return;
1378         }
1379         if (adjust_shared_perm(git_HEAD)) {
1380                 error("Unable to fix permissions on %s", lockpath);
1381         error_unlink_return:
1382                 unlink_or_warn(lockpath);
1383         error_free_return:
1384                 free(git_HEAD);
1385                 return -1;
1386         }
1387
1388 #ifndef NO_SYMLINK_HEAD
1389         done:
1390 #endif
1391         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1392                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1393
1394         free(git_HEAD);
1395         return 0;
1396 }
1397
1398 static char *ref_msg(const char *line, const char *endp)
1399 {
1400         const char *ep;
1401         line += 82;
1402         ep = memchr(line, '\n', endp - line);
1403         if (!ep)
1404                 ep = endp;
1405         return xmemdupz(line, ep - line);
1406 }
1407
1408 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)
1409 {
1410         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1411         char *tz_c;
1412         int logfd, tz, reccnt = 0;
1413         struct stat st;
1414         unsigned long date;
1415         unsigned char logged_sha1[20];
1416         void *log_mapped;
1417         size_t mapsz;
1418
1419         logfile = git_path("logs/%s", ref);
1420         logfd = open(logfile, O_RDONLY, 0);
1421         if (logfd < 0)
1422                 die_errno("Unable to read log '%s'", logfile);
1423         fstat(logfd, &st);
1424         if (!st.st_size)
1425                 die("Log %s is empty.", logfile);
1426         mapsz = xsize_t(st.st_size);
1427         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1428         logdata = log_mapped;
1429         close(logfd);
1430
1431         lastrec = NULL;
1432         rec = logend = logdata + st.st_size;
1433         while (logdata < rec) {
1434                 reccnt++;
1435                 if (logdata < rec && *(rec-1) == '\n')
1436                         rec--;
1437                 lastgt = NULL;
1438                 while (logdata < rec && *(rec-1) != '\n') {
1439                         rec--;
1440                         if (*rec == '>')
1441                                 lastgt = rec;
1442                 }
1443                 if (!lastgt)
1444                         die("Log %s is corrupt.", logfile);
1445                 date = strtoul(lastgt + 1, &tz_c, 10);
1446                 if (date <= at_time || cnt == 0) {
1447                         tz = strtoul(tz_c, NULL, 10);
1448                         if (msg)
1449                                 *msg = ref_msg(rec, logend);
1450                         if (cutoff_time)
1451                                 *cutoff_time = date;
1452                         if (cutoff_tz)
1453                                 *cutoff_tz = tz;
1454                         if (cutoff_cnt)
1455                                 *cutoff_cnt = reccnt - 1;
1456                         if (lastrec) {
1457                                 if (get_sha1_hex(lastrec, logged_sha1))
1458                                         die("Log %s is corrupt.", logfile);
1459                                 if (get_sha1_hex(rec + 41, sha1))
1460                                         die("Log %s is corrupt.", logfile);
1461                                 if (hashcmp(logged_sha1, sha1)) {
1462                                         warning("Log %s has gap after %s.",
1463                                                 logfile, show_date(date, tz, DATE_RFC2822));
1464                                 }
1465                         }
1466                         else if (date == at_time) {
1467                                 if (get_sha1_hex(rec + 41, sha1))
1468                                         die("Log %s is corrupt.", logfile);
1469                         }
1470                         else {
1471                                 if (get_sha1_hex(rec + 41, logged_sha1))
1472                                         die("Log %s is corrupt.", logfile);
1473                                 if (hashcmp(logged_sha1, sha1)) {
1474                                         warning("Log %s unexpectedly ended on %s.",
1475                                                 logfile, show_date(date, tz, DATE_RFC2822));
1476                                 }
1477                         }
1478                         munmap(log_mapped, mapsz);
1479                         return 0;
1480                 }
1481                 lastrec = rec;
1482                 if (cnt > 0)
1483                         cnt--;
1484         }
1485
1486         rec = logdata;
1487         while (rec < logend && *rec != '>' && *rec != '\n')
1488                 rec++;
1489         if (rec == logend || *rec == '\n')
1490                 die("Log %s is corrupt.", logfile);
1491         date = strtoul(rec + 1, &tz_c, 10);
1492         tz = strtoul(tz_c, NULL, 10);
1493         if (get_sha1_hex(logdata, sha1))
1494                 die("Log %s is corrupt.", logfile);
1495         if (is_null_sha1(sha1)) {
1496                 if (get_sha1_hex(logdata + 41, sha1))
1497                         die("Log %s is corrupt.", logfile);
1498         }
1499         if (msg)
1500                 *msg = ref_msg(logdata, logend);
1501         munmap(log_mapped, mapsz);
1502
1503         if (cutoff_time)
1504                 *cutoff_time = date;
1505         if (cutoff_tz)
1506                 *cutoff_tz = tz;
1507         if (cutoff_cnt)
1508                 *cutoff_cnt = reccnt;
1509         return 1;
1510 }
1511
1512 int for_each_recent_reflog_ent(const char *ref, each_reflog_ent_fn fn, long ofs, void *cb_data)
1513 {
1514         const char *logfile;
1515         FILE *logfp;
1516         char buf[1024];
1517         int ret = 0;
1518
1519         logfile = git_path("logs/%s", ref);
1520         logfp = fopen(logfile, "r");
1521         if (!logfp)
1522                 return -1;
1523
1524         if (ofs) {
1525                 struct stat statbuf;
1526                 if (fstat(fileno(logfp), &statbuf) ||
1527                     statbuf.st_size < ofs ||
1528                     fseek(logfp, -ofs, SEEK_END) ||
1529                     fgets(buf, sizeof(buf), logfp)) {
1530                         fclose(logfp);
1531                         return -1;
1532                 }
1533         }
1534
1535         while (fgets(buf, sizeof(buf), logfp)) {
1536                 unsigned char osha1[20], nsha1[20];
1537                 char *email_end, *message;
1538                 unsigned long timestamp;
1539                 int len, tz;
1540
1541                 /* old SP new SP name <email> SP time TAB msg LF */
1542                 len = strlen(buf);
1543                 if (len < 83 || buf[len-1] != '\n' ||
1544                     get_sha1_hex(buf, osha1) || buf[40] != ' ' ||
1545                     get_sha1_hex(buf + 41, nsha1) || buf[81] != ' ' ||
1546                     !(email_end = strchr(buf + 82, '>')) ||
1547                     email_end[1] != ' ' ||
1548                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1549                     !message || message[0] != ' ' ||
1550                     (message[1] != '+' && message[1] != '-') ||
1551                     !isdigit(message[2]) || !isdigit(message[3]) ||
1552                     !isdigit(message[4]) || !isdigit(message[5]))
1553                         continue; /* corrupt? */
1554                 email_end[1] = '\0';
1555                 tz = strtol(message + 1, NULL, 10);
1556                 if (message[6] != '\t')
1557                         message += 6;
1558                 else
1559                         message += 7;
1560                 ret = fn(osha1, nsha1, buf+82, timestamp, tz, message, cb_data);
1561                 if (ret)
1562                         break;
1563         }
1564         fclose(logfp);
1565         return ret;
1566 }
1567
1568 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1569 {
1570         return for_each_recent_reflog_ent(ref, fn, 0, cb_data);
1571 }
1572
1573 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1574 {
1575         DIR *dir = opendir(git_path("logs/%s", base));
1576         int retval = 0;
1577
1578         if (dir) {
1579                 struct dirent *de;
1580                 int baselen = strlen(base);
1581                 char *log = xmalloc(baselen + 257);
1582
1583                 memcpy(log, base, baselen);
1584                 if (baselen && base[baselen-1] != '/')
1585                         log[baselen++] = '/';
1586
1587                 while ((de = readdir(dir)) != NULL) {
1588                         struct stat st;
1589                         int namelen;
1590
1591                         if (de->d_name[0] == '.')
1592                                 continue;
1593                         namelen = strlen(de->d_name);
1594                         if (namelen > 255)
1595                                 continue;
1596                         if (has_extension(de->d_name, ".lock"))
1597                                 continue;
1598                         memcpy(log + baselen, de->d_name, namelen+1);
1599                         if (stat(git_path("logs/%s", log), &st) < 0)
1600                                 continue;
1601                         if (S_ISDIR(st.st_mode)) {
1602                                 retval = do_for_each_reflog(log, fn, cb_data);
1603                         } else {
1604                                 unsigned char sha1[20];
1605                                 if (!resolve_ref(log, sha1, 0, NULL))
1606                                         retval = error("bad ref for %s", log);
1607                                 else
1608                                         retval = fn(log, sha1, 0, cb_data);
1609                         }
1610                         if (retval)
1611                                 break;
1612                 }
1613                 free(log);
1614                 closedir(dir);
1615         }
1616         else if (*base)
1617                 return errno;
1618         return retval;
1619 }
1620
1621 int for_each_reflog(each_ref_fn fn, void *cb_data)
1622 {
1623         return do_for_each_reflog("", fn, cb_data);
1624 }
1625
1626 int update_ref(const char *action, const char *refname,
1627                 const unsigned char *sha1, const unsigned char *oldval,
1628                 int flags, enum action_on_err onerr)
1629 {
1630         static struct ref_lock *lock;
1631         lock = lock_any_ref_for_update(refname, oldval, flags);
1632         if (!lock) {
1633                 const char *str = "Cannot lock the ref '%s'.";
1634                 switch (onerr) {
1635                 case MSG_ON_ERR: error(str, refname); break;
1636                 case DIE_ON_ERR: die(str, refname); break;
1637                 case QUIET_ON_ERR: break;
1638                 }
1639                 return 1;
1640         }
1641         if (write_ref_sha1(lock, sha1, action) < 0) {
1642                 const char *str = "Cannot update the ref '%s'.";
1643                 switch (onerr) {
1644                 case MSG_ON_ERR: error(str, refname); break;
1645                 case DIE_ON_ERR: die(str, refname); break;
1646                 case QUIET_ON_ERR: break;
1647                 }
1648                 return 1;
1649         }
1650         return 0;
1651 }
1652
1653 struct ref *find_ref_by_name(const struct ref *list, const char *name)
1654 {
1655         for ( ; list; list = list->next)
1656                 if (!strcmp(list->name, name))
1657                         return (struct ref *)list;
1658         return NULL;
1659 }
1660
1661 /*
1662  * generate a format suitable for scanf from a ref_rev_parse_rules
1663  * rule, that is replace the "%.*s" spec with a "%s" spec
1664  */
1665 static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
1666 {
1667         char *spec;
1668
1669         spec = strstr(rule, "%.*s");
1670         if (!spec || strstr(spec + 4, "%.*s"))
1671                 die("invalid rule in ref_rev_parse_rules: %s", rule);
1672
1673         /* copy all until spec */
1674         strncpy(scanf_fmt, rule, spec - rule);
1675         scanf_fmt[spec - rule] = '\0';
1676         /* copy new spec */
1677         strcat(scanf_fmt, "%s");
1678         /* copy remaining rule */
1679         strcat(scanf_fmt, spec + 4);
1680
1681         return;
1682 }
1683
1684 char *shorten_unambiguous_ref(const char *ref, int strict)
1685 {
1686         int i;
1687         static char **scanf_fmts;
1688         static int nr_rules;
1689         char *short_name;
1690
1691         /* pre generate scanf formats from ref_rev_parse_rules[] */
1692         if (!nr_rules) {
1693                 size_t total_len = 0;
1694
1695                 /* the rule list is NULL terminated, count them first */
1696                 for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
1697                         /* no +1 because strlen("%s") < strlen("%.*s") */
1698                         total_len += strlen(ref_rev_parse_rules[nr_rules]);
1699
1700                 scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
1701
1702                 total_len = 0;
1703                 for (i = 0; i < nr_rules; i++) {
1704                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
1705                                         + total_len;
1706                         gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
1707                         total_len += strlen(ref_rev_parse_rules[i]);
1708                 }
1709         }
1710
1711         /* bail out if there are no rules */
1712         if (!nr_rules)
1713                 return xstrdup(ref);
1714
1715         /* buffer for scanf result, at most ref must fit */
1716         short_name = xstrdup(ref);
1717
1718         /* skip first rule, it will always match */
1719         for (i = nr_rules - 1; i > 0 ; --i) {
1720                 int j;
1721                 int rules_to_fail = i;
1722                 int short_name_len;
1723
1724                 if (1 != sscanf(ref, scanf_fmts[i], short_name))
1725                         continue;
1726
1727                 short_name_len = strlen(short_name);
1728
1729                 /*
1730                  * in strict mode, all (except the matched one) rules
1731                  * must fail to resolve to a valid non-ambiguous ref
1732                  */
1733                 if (strict)
1734                         rules_to_fail = nr_rules;
1735
1736                 /*
1737                  * check if the short name resolves to a valid ref,
1738                  * but use only rules prior to the matched one
1739                  */
1740                 for (j = 0; j < rules_to_fail; j++) {
1741                         const char *rule = ref_rev_parse_rules[j];
1742                         unsigned char short_objectname[20];
1743                         char refname[PATH_MAX];
1744
1745                         /* skip matched rule */
1746                         if (i == j)
1747                                 continue;
1748
1749                         /*
1750                          * the short name is ambiguous, if it resolves
1751                          * (with this previous rule) to a valid ref
1752                          * read_ref() returns 0 on success
1753                          */
1754                         mksnpath(refname, sizeof(refname),
1755                                  rule, short_name_len, short_name);
1756                         if (!read_ref(refname, short_objectname))
1757                                 break;
1758                 }
1759
1760                 /*
1761                  * short name is non-ambiguous if all previous rules
1762                  * haven't resolved to a valid ref
1763                  */
1764                 if (j == rules_to_fail)
1765                         return short_name;
1766         }
1767
1768         free(short_name);
1769         return xstrdup(ref);
1770 }