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         struct cached_refs *next;
 157         char did_loose;
 158         char did_packed;
 159         struct ref_list *loose;
 160         struct ref_list *packed;
 161         /* The submodule name, or "" for the main repo. */
 162         char name[FLEX_ARRAY];
 163 } *cached_refs;
 164
 165 static struct ref_list *current_ref;
 166
 167 static struct ref_list *extra_refs;
 168
 169 static void free_ref_list(struct ref_list *list)
 170 {
 171         struct ref_list *next;
 172         for ( ; list; list = next) {
 173                 next = list->next;
 174                 free(list);
 175         }
 176 }
 177
 178 static void clear_cached_refs(struct cached_refs *ca)
 179 {
 180         if (ca->did_loose && ca->loose)
 181                 free_ref_list(ca->loose);
 182         if (ca->did_packed && ca->packed)
 183                 free_ref_list(ca->packed);
 184         ca->loose = ca->packed = NULL;
 185         ca->did_loose = ca->did_packed = 0;
 186 }
 187
 188 static struct cached_refs *create_cached_refs(const char *submodule)
 189 {
 190         int len;
 191         struct cached_refs *refs;
 192         if (!submodule)
 193                 submodule = "";
 194         len = strlen(submodule) + 1;
 195         refs = xmalloc(sizeof(struct cached_refs) + len);
 196         refs->next = NULL;
 197         refs->did_loose = refs->did_packed = 0;
 198         refs->loose = refs->packed = NULL;
 199         memcpy(refs->name, submodule, len);
 200         return refs;
 201 }
 202
 203 /*
 204  * Return a pointer to a cached_refs for the specified submodule. For
 205  * the main repository, use submodule==NULL. The returned structure
 206  * will be allocated and initialized but not necessarily populated; it
 207  * should not be freed.
 208  */
 209 static struct cached_refs *get_cached_refs(const char *submodule)
 210 {
 211         struct cached_refs *refs = cached_refs;
 212         if (!submodule)
 213                 submodule = "";
 214         while (refs) {
 215                 if (!strcmp(submodule, refs->name))
 216                         return refs;
 217                 refs = refs->next;
 218         }
 219
 220         refs = create_cached_refs(submodule);
 221         refs->next = cached_refs;
 222         cached_refs = refs;
 223         return refs;
 224 }
 225
 226 static void invalidate_cached_refs(void)
 227 {
 228         struct cached_refs *refs = cached_refs;
 229         while (refs) {
 230                 clear_cached_refs(refs);
 231                 refs = refs->next;
 232         }
 233 }
 234
 235 static struct ref_list *read_packed_refs(FILE *f)
 236 {
 237         struct ref_list *list = NULL;
 238         struct ref_list *last = NULL;
 239         char refline[PATH_MAX];
 240         int flag = REF_ISPACKED;
 241
 242         while (fgets(refline, sizeof(refline), f)) {
 243                 unsigned char sha1[20];
 244                 const char *name;
 245                 static const char header[] = "# pack-refs with:";
 246
 247                 if (!strncmp(refline, header, sizeof(header)-1)) {
 248                         const char *traits = refline + sizeof(header) - 1;
 249                         if (strstr(traits, " peeled "))
 250                                 flag |= REF_KNOWS_PEELED;
 251                         /* perhaps other traits later as well */
 252                         continue;
 253                 }
 254
 255                 name = parse_ref_line(refline, sha1);
 256                 if (name) {
 257                         list = add_ref(name, sha1, flag, list, &last);
 258                         continue;
 259                 }
 260                 if (last &&
 261                     refline[0] == '^' &&
 262                     strlen(refline) == 42 &&
 263                     refline[41] == '\n' &&
 264                     !get_sha1_hex(refline + 1, sha1))
 265                         hashcpy(last->peeled, sha1);
 266         }
 267         return sort_ref_list(list);
 268 }
 269
 270 void add_extra_ref(const char *name, const unsigned char *sha1, int flag)
 271 {
 272         extra_refs = add_ref(name, sha1, flag, extra_refs, NULL);
 273 }
 274
 275 void clear_extra_refs(void)
 276 {
 277         free_ref_list(extra_refs);
 278         extra_refs = NULL;
 279 }
 280
 281 static struct ref_list *get_packed_refs(const char *submodule)
 282 {
 283         struct cached_refs *refs = get_cached_refs(submodule);
 284
 285         if (!refs->did_packed) {
 286                 const char *packed_refs_file;
 287                 FILE *f;
 288
 289                 if (submodule)
 290                         packed_refs_file = git_path_submodule(submodule, "packed-refs");
 291                 else
 292                         packed_refs_file = git_path("packed-refs");
 293                 f = fopen(packed_refs_file, "r");
 294                 refs->packed = NULL;
 295                 if (f) {
 296                         refs->packed = read_packed_refs(f);
 297                         fclose(f);
 298                 }
 299                 refs->did_packed = 1;
 300         }
 301         return refs->packed;
 302 }
 303
 304 static struct ref_list *get_ref_dir(const char *submodule, const char *base,
 305                                     struct ref_list *list)
 306 {
 307         DIR *dir;
 308         const char *path;
 309
 310         if (submodule)
 311                 path = git_path_submodule(submodule, "%s", base);
 312         else
 313                 path = git_path("%s", base);
 314
 315
 316         dir = opendir(path);
 317
 318         if (dir) {
 319                 struct dirent *de;
 320                 int baselen = strlen(base);
 321                 char *ref = xmalloc(baselen + 257);
 322
 323                 memcpy(ref, base, baselen);
 324                 if (baselen && base[baselen-1] != '/')
 325                         ref[baselen++] = '/';
 326
 327                 while ((de = readdir(dir)) != NULL) {
 328                         unsigned char sha1[20];
 329                         struct stat st;
 330                         int flag;
 331                         int namelen;
 332                         const char *refdir;
 333
 334                         if (de->d_name[0] == '.')
 335                                 continue;
 336                         namelen = strlen(de->d_name);
 337                         if (namelen > 255)
 338                                 continue;
 339                         if (has_extension(de->d_name, ".lock"))
 340                                 continue;
 341                         memcpy(ref + baselen, de->d_name, namelen+1);
 342                         refdir = submodule
 343                                 ? git_path_submodule(submodule, "%s", ref)
 344                                 : git_path("%s", ref);
 345                         if (stat(refdir, &st) < 0)
 346                                 continue;
 347                         if (S_ISDIR(st.st_mode)) {
 348                                 list = get_ref_dir(submodule, ref, list);
 349                                 continue;
 350                         }
 351                         if (submodule) {
 352                                 hashclr(sha1);
 353                                 flag = 0;
 354                                 if (resolve_gitlink_ref(submodule, ref, sha1) < 0) {
 355                                         hashclr(sha1);
 356                                         flag |= REF_BROKEN;
 357                                 }
 358                         } else
 359                                 if (!resolve_ref(ref, sha1, 1, &flag)) {
 360                                         hashclr(sha1);
 361                                         flag |= REF_BROKEN;
 362                                 }
 363                         list = add_ref(ref, sha1, flag, list, NULL);
 364                 }
 365                 free(ref);
 366                 closedir(dir);
 367         }
 368         return sort_ref_list(list);
 369 }
 370
 371 struct warn_if_dangling_data {
 372         FILE *fp;
 373         const char *refname;
 374         const char *msg_fmt;
 375 };
 376
 377 static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
 378                                    int flags, void *cb_data)
 379 {
 380         struct warn_if_dangling_data *d = cb_data;
 381         const char *resolves_to;
 382         unsigned char junk[20];
 383
 384         if (!(flags & REF_ISSYMREF))
 385                 return 0;
 386
 387         resolves_to = resolve_ref(refname, junk, 0, NULL);
 388         if (!resolves_to || strcmp(resolves_to, d->refname))
 389                 return 0;
 390
 391         fprintf(d->fp, d->msg_fmt, refname);
 392         return 0;
 393 }
 394
 395 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 396 {
 397         struct warn_if_dangling_data data;
 398
 399         data.fp = fp;
 400         data.refname = refname;
 401         data.msg_fmt = msg_fmt;
 402         for_each_rawref(warn_if_dangling_symref, &data);
 403 }
 404
 405 static struct ref_list *get_loose_refs(const char *submodule)
 406 {
 407         struct cached_refs *refs = get_cached_refs(submodule);
 408
 409         if (!refs->did_loose) {
 410                 refs->loose = get_ref_dir(submodule, "refs", NULL);
 411                 refs->did_loose = 1;
 412         }
 413         return refs->loose;
 414 }
 415
 416 /* We allow "recursive" symbolic refs. Only within reason, though */
 417 #define MAXDEPTH 5
 418 #define MAXREFLEN (1024)
 419
 420 static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
 421 {
 422         FILE *f;
 423         struct ref_list *packed_refs;
 424         struct ref_list *ref;
 425         int retval;
 426
 427         strcpy(name + pathlen, "packed-refs");
 428         f = fopen(name, "r");
 429         if (!f)
 430                 return -1;
 431         packed_refs = read_packed_refs(f);
 432         fclose(f);
 433         ref = packed_refs;
 434         retval = -1;
 435         while (ref) {
 436                 if (!strcmp(ref->name, refname)) {
 437                         retval = 0;
 438                         memcpy(result, ref->sha1, 20);
 439                         break;
 440                 }
 441                 ref = ref->next;
 442         }
 443         free_ref_list(packed_refs);
 444         return retval;
 445 }
 446
 447 static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
 448 {
 449         int fd, len = strlen(refname);
 450         char buffer[128], *p;
 451
 452         if (recursion > MAXDEPTH || len > MAXREFLEN)
 453                 return -1;
 454         memcpy(name + pathlen, refname, len+1);
 455         fd = open(name, O_RDONLY);
 456         if (fd < 0)
 457                 return resolve_gitlink_packed_ref(name, pathlen, refname, result);
 458
 459         len = read(fd, buffer, sizeof(buffer)-1);
 460         close(fd);
 461         if (len < 0)
 462                 return -1;
 463         while (len && isspace(buffer[len-1]))
 464                 len--;
 465         buffer[len] = 0;
 466
 467         /* Was it a detached head or an old-fashioned symlink? */
 468         if (!get_sha1_hex(buffer, result))
 469                 return 0;
 470
 471         /* Symref? */
 472         if (strncmp(buffer, "ref:", 4))
 473                 return -1;
 474         p = buffer + 4;
 475         while (isspace(*p))
 476                 p++;
 477
 478         return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
 479 }
 480
 481 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
 482 {
 483         int len = strlen(path), retval;
 484         char *gitdir;
 485         const char *tmp;
 486
 487         while (len && path[len-1] == '/')
 488                 len--;
 489         if (!len)
 490                 return -1;
 491         gitdir = xmalloc(len + MAXREFLEN + 8);
 492         memcpy(gitdir, path, len);
 493         memcpy(gitdir + len, "/.git", 6);
 494         len += 5;
 495
 496         tmp = read_gitfile(gitdir);
 497         if (tmp) {
 498                 free(gitdir);
 499                 len = strlen(tmp);
 500                 gitdir = xmalloc(len + MAXREFLEN + 3);
 501                 memcpy(gitdir, tmp, len);
 502         }
 503         gitdir[len] = '/';
 504         gitdir[++len] = '\0';
 505         retval = resolve_gitlink_ref_recursive(gitdir, len, refname, result, 0);
 506         free(gitdir);
 507         return retval;
 508 }
 509
 510 /*
 511  * If the "reading" argument is set, this function finds out what _object_
 512  * the ref points at by "reading" the ref.  The ref, if it is not symbolic,
 513  * has to exist, and if it is symbolic, it has to point at an existing ref,
 514  * because the "read" goes through the symref to the ref it points at.
 515  *
 516  * The access that is not "reading" may often be "writing", but does not
 517  * have to; it can be merely checking _where it leads to_. If it is a
 518  * prelude to "writing" to the ref, a write to a symref that points at
 519  * yet-to-be-born ref will create the real ref pointed by the symref.
 520  * reading=0 allows the caller to check where such a symref leads to.
 521  */
 522 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 523 {
 524         int depth = MAXDEPTH;
 525         ssize_t len;
 526         char buffer[256];
 527         static char ref_buffer[256];
 528
 529         if (flag)
 530                 *flag = 0;
 531
 532         for (;;) {
 533                 char path[PATH_MAX];
 534                 struct stat st;
 535                 char *buf;
 536                 int fd;
 537
 538                 if (--depth < 0)
 539                         return NULL;
 540
 541                 git_snpath(path, sizeof(path), "%s", ref);
 542                 /* Special case: non-existing file. */
 543                 if (lstat(path, &st) < 0) {
 544                         struct ref_list *list = get_packed_refs(NULL);
 545                         while (list) {
 546                                 if (!strcmp(ref, list->name)) {
 547                                         hashcpy(sha1, list->sha1);
 548                                         if (flag)
 549                                                 *flag |= REF_ISPACKED;
 550                                         return ref;
 551                                 }
 552                                 list = list->next;
 553                         }
 554                         if (reading || errno != ENOENT)
 555                                 return NULL;
 556                         hashclr(sha1);
 557                         return ref;
 558                 }
 559
 560                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 561                 if (S_ISLNK(st.st_mode)) {
 562                         len = readlink(path, buffer, sizeof(buffer)-1);
 563                         if (len >= 5 && !memcmp("refs/", buffer, 5)) {
 564                                 buffer[len] = 0;
 565                                 strcpy(ref_buffer, buffer);
 566                                 ref = ref_buffer;
 567                                 if (flag)
 568                                         *flag |= REF_ISSYMREF;
 569                                 continue;
 570                         }
 571                 }
 572
 573                 /* Is it a directory? */
 574                 if (S_ISDIR(st.st_mode)) {
 575                         errno = EISDIR;
 576                         return NULL;
 577                 }
 578
 579                 /*
 580                  * Anything else, just open it and try to use it as
 581                  * a ref
 582                  */
 583                 fd = open(path, O_RDONLY);
 584                 if (fd < 0)
 585                         return NULL;
 586                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
 587                 close(fd);
 588
 589                 /*
 590                  * Is it a symbolic ref?
 591                  */
 592                 if (len < 4 || memcmp("ref:", buffer, 4))
 593                         break;
 594                 buf = buffer + 4;
 595                 len -= 4;
 596                 while (len && isspace(*buf))
 597                         buf++, len--;
 598                 while (len && isspace(buf[len-1]))
 599                         len--;
 600                 buf[len] = 0;
 601                 memcpy(ref_buffer, buf, len + 1);
 602                 ref = ref_buffer;
 603                 if (flag)
 604                         *flag |= REF_ISSYMREF;
 605         }
 606         if (len < 40 || get_sha1_hex(buffer, sha1))
 607                 return NULL;
 608         return ref;
 609 }
 610
 611 /* The argument to filter_refs */
 612 struct ref_filter {
 613         const char *pattern;
 614         each_ref_fn *fn;
 615         void *cb_data;
 616 };
 617
 618 int read_ref(const char *ref, unsigned char *sha1)
 619 {
 620         if (resolve_ref(ref, sha1, 1, NULL))
 621                 return 0;
 622         return -1;
 623 }
 624
 625 #define DO_FOR_EACH_INCLUDE_BROKEN 01
 626 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
 627                       int flags, void *cb_data, struct ref_list *entry)
 628 {
 629         if (prefixcmp(entry->name, base))
 630                 return 0;
 631
 632         if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
 633                 if (entry->flag & REF_BROKEN)
 634                         return 0; /* ignore dangling symref */
 635                 if (!has_sha1_file(entry->sha1)) {
 636                         error("%s does not point to a valid object!", entry->name);
 637                         return 0;
 638                 }
 639         }
 640         current_ref = entry;
 641         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 642 }
 643
 644 static int filter_refs(const char *ref, const unsigned char *sha, int flags,
 645         void *data)
 646 {
 647         struct ref_filter *filter = (struct ref_filter *)data;
 648         if (fnmatch(filter->pattern, ref, 0))
 649                 return 0;
 650         return filter->fn(ref, sha, flags, filter->cb_data);
 651 }
 652
 653 int peel_ref(const char *ref, unsigned char *sha1)
 654 {
 655         int flag;
 656         unsigned char base[20];
 657         struct object *o;
 658
 659         if (current_ref && (current_ref->name == ref
 660                 || !strcmp(current_ref->name, ref))) {
 661                 if (current_ref->flag & REF_KNOWS_PEELED) {
 662                         hashcpy(sha1, current_ref->peeled);
 663                         return 0;
 664                 }
 665                 hashcpy(base, current_ref->sha1);
 666                 goto fallback;
 667         }
 668
 669         if (!resolve_ref(ref, base, 1, &flag))
 670                 return -1;
 671
 672         if ((flag & REF_ISPACKED)) {
 673                 struct ref_list *list = get_packed_refs(NULL);
 674
 675                 while (list) {
 676                         if (!strcmp(list->name, ref)) {
 677                                 if (list->flag & REF_KNOWS_PEELED) {
 678                                         hashcpy(sha1, list->peeled);
 679                                         return 0;
 680                                 }
 681                                 /* older pack-refs did not leave peeled ones */
 682                                 break;
 683                         }
 684                         list = list->next;
 685                 }
 686         }
 687
 688 fallback:
 689         o = parse_object(base);
 690         if (o && o->type == OBJ_TAG) {
 691                 o = deref_tag(o, ref, 0);
 692                 if (o) {
 693                         hashcpy(sha1, o->sha1);
 694                         return 0;
 695                 }
 696         }
 697         return -1;
 698 }
 699
 700 static int do_for_each_ref(const char *submodule, const char *base, each_ref_fn fn,
 701                            int trim, int flags, void *cb_data)
 702 {
 703         int retval = 0;
 704         struct ref_list *packed = get_packed_refs(submodule);
 705         struct ref_list *loose = get_loose_refs(submodule);
 706
 707         struct ref_list *extra;
 708
 709         for (extra = extra_refs; extra; extra = extra->next)
 710                 retval = do_one_ref(base, fn, trim, flags, cb_data, extra);
 711
 712         while (packed && loose) {
 713                 struct ref_list *entry;
 714                 int cmp = strcmp(packed->name, loose->name);
 715                 if (!cmp) {
 716                         packed = packed->next;
 717                         continue;
 718                 }
 719                 if (cmp > 0) {
 720                         entry = loose;
 721                         loose = loose->next;
 722                 } else {
 723                         entry = packed;
 724                         packed = packed->next;
 725                 }
 726                 retval = do_one_ref(base, fn, trim, flags, cb_data, entry);
 727                 if (retval)
 728                         goto end_each;
 729         }
 730
 731         for (packed = packed ? packed : loose; packed; packed = packed->next) {
 732                 retval = do_one_ref(base, fn, trim, flags, cb_data, packed);
 733                 if (retval)
 734                         goto end_each;
 735         }
 736
 737 end_each:
 738         current_ref = NULL;
 739         return retval;
 740 }
 741
 742
 743 static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
 744 {
 745         unsigned char sha1[20];
 746         int flag;
 747
 748         if (submodule) {
 749                 if (resolve_gitlink_ref(submodule, "HEAD", sha1) == 0)
 750                         return fn("HEAD", sha1, 0, cb_data);
 751
 752                 return 0;
 753         }
 754
 755         if (resolve_ref("HEAD", sha1, 1, &flag))
 756                 return fn("HEAD", sha1, flag, cb_data);
 757
 758         return 0;
 759 }
 760
 761 int head_ref(each_ref_fn fn, void *cb_data)
 762 {
 763         return do_head_ref(NULL, fn, cb_data);
 764 }
 765
 766 int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 767 {
 768         return do_head_ref(submodule, fn, cb_data);
 769 }
 770
 771 int for_each_ref(each_ref_fn fn, void *cb_data)
 772 {
 773         return do_for_each_ref(NULL, "", fn, 0, 0, cb_data);
 774 }
 775
 776 int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 777 {
 778         return do_for_each_ref(submodule, "", fn, 0, 0, cb_data);
 779 }
 780
 781 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
 782 {
 783         return do_for_each_ref(NULL, prefix, fn, strlen(prefix), 0, cb_data);
 784 }
 785
 786 int for_each_ref_in_submodule(const char *submodule, const char *prefix,
 787                 each_ref_fn fn, void *cb_data)
 788 {
 789         return do_for_each_ref(submodule, prefix, fn, strlen(prefix), 0, cb_data);
 790 }
 791
 792 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 793 {
 794         return for_each_ref_in("refs/tags/", fn, cb_data);
 795 }
 796
 797 int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 798 {
 799         return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
 800 }
 801
 802 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 803 {
 804         return for_each_ref_in("refs/heads/", fn, cb_data);
 805 }
 806
 807 int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 808 {
 809         return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
 810 }
 811
 812 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 813 {
 814         return for_each_ref_in("refs/remotes/", fn, cb_data);
 815 }
 816
 817 int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 818 {
 819         return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
 820 }
 821
 822 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
 823 {
 824         return do_for_each_ref(NULL, "refs/replace/", fn, 13, 0, cb_data);
 825 }
 826
 827 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
 828 {
 829         struct strbuf buf = STRBUF_INIT;
 830         int ret = 0;
 831         unsigned char sha1[20];
 832         int flag;
 833
 834         strbuf_addf(&buf, "%sHEAD", get_git_namespace());
 835         if (resolve_ref(buf.buf, sha1, 1, &flag))
 836                 ret = fn(buf.buf, sha1, flag, cb_data);
 837         strbuf_release(&buf);
 838
 839         return ret;
 840 }
 841
 842 int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
 843 {
 844         struct strbuf buf = STRBUF_INIT;
 845         int ret;
 846         strbuf_addf(&buf, "%srefs/", get_git_namespace());
 847         ret = do_for_each_ref(NULL, buf.buf, fn, 0, 0, cb_data);
 848         strbuf_release(&buf);
 849         return ret;
 850 }
 851
 852 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 853         const char *prefix, void *cb_data)
 854 {
 855         struct strbuf real_pattern = STRBUF_INIT;
 856         struct ref_filter filter;
 857         int ret;
 858
 859         if (!prefix && prefixcmp(pattern, "refs/"))
 860                 strbuf_addstr(&real_pattern, "refs/");
 861         else if (prefix)
 862                 strbuf_addstr(&real_pattern, prefix);
 863         strbuf_addstr(&real_pattern, pattern);
 864
 865         if (!has_glob_specials(pattern)) {
 866                 /* Append implied '/' '*' if not present. */
 867                 if (real_pattern.buf[real_pattern.len - 1] != '/')
 868                         strbuf_addch(&real_pattern, '/');
 869                 /* No need to check for '*', there is none. */
 870                 strbuf_addch(&real_pattern, '*');
 871         }
 872
 873         filter.pattern = real_pattern.buf;
 874         filter.fn = fn;
 875         filter.cb_data = cb_data;
 876         ret = for_each_ref(filter_refs, &filter);
 877
 878         strbuf_release(&real_pattern);
 879         return ret;
 880 }
 881
 882 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 883 {
 884         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
 885 }
 886
 887 int for_each_rawref(each_ref_fn fn, void *cb_data)
 888 {
 889         return do_for_each_ref(NULL, "", fn, 0,
 890                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
 891 }
 892
 893 /*
 894  * Make sure "ref" is something reasonable to have under ".git/refs/";
 895  * We do not like it if:
 896  *
 897  * - any path component of it begins with ".", or
 898  * - it has double dots "..", or
 899  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 900  * - it ends with a "/".
 901  * - it ends with ".lock"
 902  * - it contains a "\" (backslash)
 903  */
 904
 905 static inline int bad_ref_char(int ch)
 906 {
 907         if (((unsigned) ch) <= ' ' || ch == 0x7f ||
 908             ch == '~' || ch == '^' || ch == ':' || ch == '\\')
 909                 return 1;
 910         /* 2.13 Pattern Matching Notation */
 911         if (ch == '?' || ch == '[') /* Unsupported */
 912                 return 1;
 913         if (ch == '*') /* Supported at the end */
 914                 return 2;
 915         return 0;
 916 }
 917
 918 int check_ref_format(const char *ref)
 919 {
 920         int ch, level, bad_type, last;
 921         int ret = CHECK_REF_FORMAT_OK;
 922         const char *cp = ref;
 923
 924         level = 0;
 925         while (1) {
 926                 while ((ch = *cp++) == '/')
 927                         ; /* tolerate duplicated slashes */
 928                 if (!ch)
 929                         /* should not end with slashes */
 930                         return CHECK_REF_FORMAT_ERROR;
 931
 932                 /* we are at the beginning of the path component */
 933                 if (ch == '.')
 934                         return CHECK_REF_FORMAT_ERROR;
 935                 bad_type = bad_ref_char(ch);
 936                 if (bad_type) {
 937                         if (bad_type == 2 && (!*cp || *cp == '/') &&
 938                             ret == CHECK_REF_FORMAT_OK)
 939                                 ret = CHECK_REF_FORMAT_WILDCARD;
 940                         else
 941                                 return CHECK_REF_FORMAT_ERROR;
 942                 }
 943
 944                 last = ch;
 945                 /* scan the rest of the path component */
 946                 while ((ch = *cp++) != 0) {
 947                         bad_type = bad_ref_char(ch);
 948                         if (bad_type)
 949                                 return CHECK_REF_FORMAT_ERROR;
 950                         if (ch == '/')
 951                                 break;
 952                         if (last == '.' && ch == '.')
 953                                 return CHECK_REF_FORMAT_ERROR;
 954                         if (last == '@' && ch == '{')
 955                                 return CHECK_REF_FORMAT_ERROR;
 956                         last = ch;
 957                 }
 958                 level++;
 959                 if (!ch) {
 960                         if (ref <= cp - 2 && cp[-2] == '.')
 961                                 return CHECK_REF_FORMAT_ERROR;
 962                         if (level < 2)
 963                                 return CHECK_REF_FORMAT_ONELEVEL;
 964                         if (has_extension(ref, ".lock"))
 965                                 return CHECK_REF_FORMAT_ERROR;
 966                         return ret;
 967                 }
 968         }
 969 }
 970
 971 const char *prettify_refname(const char *name)
 972 {
 973         return name + (
 974                 !prefixcmp(name, "refs/heads/") ? 11 :
 975                 !prefixcmp(name, "refs/tags/") ? 10 :
 976                 !prefixcmp(name, "refs/remotes/") ? 13 :
 977                 0);
 978 }
 979
 980 const char *ref_rev_parse_rules[] = {
 981         "%.*s",
 982         "refs/%.*s",
 983         "refs/tags/%.*s",
 984         "refs/heads/%.*s",
 985         "refs/remotes/%.*s",
 986         "refs/remotes/%.*s/HEAD",
 987         NULL
 988 };
 989
 990 const char *ref_fetch_rules[] = {
 991         "%.*s",
 992         "refs/%.*s",
 993         "refs/heads/%.*s",
 994         NULL
 995 };
 996
 997 int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
 998 {
 999         const char **p;
1000         const int abbrev_name_len = strlen(abbrev_name);
1001
1002         for (p = rules; *p; p++) {
1003                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
1004                         return 1;
1005                 }
1006         }
1007
1008         return 0;
1009 }
1010
1011 static struct ref_lock *verify_lock(struct ref_lock *lock,
1012         const unsigned char *old_sha1, int mustexist)
1013 {
1014         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
1015                 error("Can't verify ref %s", lock->ref_name);
1016                 unlock_ref(lock);
1017                 return NULL;
1018         }
1019         if (hashcmp(lock->old_sha1, old_sha1)) {
1020                 error("Ref %s is at %s but expected %s", lock->ref_name,
1021                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
1022                 unlock_ref(lock);
1023                 return NULL;
1024         }
1025         return lock;
1026 }
1027
1028 static int remove_empty_directories(const char *file)
1029 {
1030         /* we want to create a file but there is a directory there;
1031          * if that is an empty directory (or a directory that contains
1032          * only empty directories), remove them.
1033          */
1034         struct strbuf path;
1035         int result;
1036
1037         strbuf_init(&path, 20);
1038         strbuf_addstr(&path, file);
1039
1040         result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
1041
1042         strbuf_release(&path);
1043
1044         return result;
1045 }
1046
1047 static int is_refname_available(const char *ref, const char *oldref,
1048                                 struct ref_list *list, int quiet)
1049 {
1050         int namlen = strlen(ref); /* e.g. 'foo/bar' */
1051         while (list) {
1052                 /* list->name could be 'foo' or 'foo/bar/baz' */
1053                 if (!oldref || strcmp(oldref, list->name)) {
1054                         int len = strlen(list->name);
1055                         int cmplen = (namlen < len) ? namlen : len;
1056                         const char *lead = (namlen < len) ? list->name : ref;
1057                         if (!strncmp(ref, list->name, cmplen) &&
1058                             lead[cmplen] == '/') {
1059                                 if (!quiet)
1060                                         error("'%s' exists; cannot create '%s'",
1061                                               list->name, ref);
1062                                 return 0;
1063                         }
1064                 }
1065                 list = list->next;
1066         }
1067         return 1;
1068 }
1069
1070 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
1071 {
1072         char *ref_file;
1073         const char *orig_ref = ref;
1074         struct ref_lock *lock;
1075         int last_errno = 0;
1076         int type, lflags;
1077         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
1078         int missing = 0;
1079
1080         lock = xcalloc(1, sizeof(struct ref_lock));
1081         lock->lock_fd = -1;
1082
1083         ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
1084         if (!ref && errno == EISDIR) {
1085                 /* we are trying to lock foo but we used to
1086                  * have foo/bar which now does not exist;
1087                  * it is normal for the empty directory 'foo'
1088                  * to remain.
1089                  */
1090                 ref_file = git_path("%s", orig_ref);
1091                 if (remove_empty_directories(ref_file)) {
1092                         last_errno = errno;
1093                         error("there are still refs under '%s'", orig_ref);
1094                         goto error_return;
1095                 }
1096                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
1097         }
1098         if (type_p)
1099             *type_p = type;
1100         if (!ref) {
1101                 last_errno = errno;
1102                 error("unable to resolve reference %s: %s",
1103                         orig_ref, strerror(errno));
1104                 goto error_return;
1105         }
1106         missing = is_null_sha1(lock->old_sha1);
1107         /* When the ref did not exist and we are creating it,
1108          * make sure there is no existing ref that is packed
1109          * whose name begins with our refname, nor a ref whose
1110          * name is a proper prefix of our refname.
1111          */
1112         if (missing &&
1113              !is_refname_available(ref, NULL, get_packed_refs(NULL), 0)) {
1114                 last_errno = ENOTDIR;
1115                 goto error_return;
1116         }
1117
1118         lock->lk = xcalloc(1, sizeof(struct lock_file));
1119
1120         lflags = LOCK_DIE_ON_ERROR;
1121         if (flags & REF_NODEREF) {
1122                 ref = orig_ref;
1123                 lflags |= LOCK_NODEREF;
1124         }
1125         lock->ref_name = xstrdup(ref);
1126         lock->orig_ref_name = xstrdup(orig_ref);
1127         ref_file = git_path("%s", ref);
1128         if (missing)
1129                 lock->force_write = 1;
1130         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
1131                 lock->force_write = 1;
1132
1133         if (safe_create_leading_directories(ref_file)) {
1134                 last_errno = errno;
1135                 error("unable to create directory for %s", ref_file);
1136                 goto error_return;
1137         }
1138
1139         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
1140         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
1141
1142  error_return:
1143         unlock_ref(lock);
1144         errno = last_errno;
1145         return NULL;
1146 }
1147
1148 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
1149 {
1150         char refpath[PATH_MAX];
1151         if (check_ref_format(ref))
1152                 return NULL;
1153         strcpy(refpath, mkpath("refs/%s", ref));
1154         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
1155 }
1156
1157 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
1158 {
1159         switch (check_ref_format(ref)) {
1160         default:
1161                 return NULL;
1162         case 0:
1163         case CHECK_REF_FORMAT_ONELEVEL:
1164                 return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
1165         }
1166 }
1167
1168 static struct lock_file packlock;
1169
1170 static int repack_without_ref(const char *refname)
1171 {
1172         struct ref_list *list, *packed_ref_list;
1173         int fd;
1174         int found = 0;
1175
1176         packed_ref_list = get_packed_refs(NULL);
1177         for (list = packed_ref_list; list; list = list->next) {
1178                 if (!strcmp(refname, list->name)) {
1179                         found = 1;
1180                         break;
1181                 }
1182         }
1183         if (!found)
1184                 return 0;
1185         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
1186         if (fd < 0) {
1187                 unable_to_lock_error(git_path("packed-refs"), errno);
1188                 return error("cannot delete '%s' from packed refs", refname);
1189         }
1190
1191         for (list = packed_ref_list; list; list = list->next) {
1192                 char line[PATH_MAX + 100];
1193                 int len;
1194
1195                 if (!strcmp(refname, list->name))
1196                         continue;
1197                 len = snprintf(line, sizeof(line), "%s %s\n",
1198                                sha1_to_hex(list->sha1), list->name);
1199                 /* this should not happen but just being defensive */
1200                 if (len > sizeof(line))
1201                         die("too long a refname '%s'", list->name);
1202                 write_or_die(fd, line, len);
1203         }
1204         return commit_lock_file(&packlock);
1205 }
1206
1207 int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
1208 {
1209         struct ref_lock *lock;
1210         int err, i = 0, ret = 0, flag = 0;
1211
1212         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
1213         if (!lock)
1214                 return 1;
1215         if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
1216                 /* loose */
1217                 const char *path;
1218
1219                 if (!(delopt & REF_NODEREF)) {
1220                         i = strlen(lock->lk->filename) - 5; /* .lock */
1221                         lock->lk->filename[i] = 0;
1222                         path = lock->lk->filename;
1223                 } else {
1224                         path = git_path("%s", refname);
1225                 }
1226                 err = unlink_or_warn(path);
1227                 if (err && errno != ENOENT)
1228                         ret = 1;
1229
1230                 if (!(delopt & REF_NODEREF))
1231                         lock->lk->filename[i] = '.';
1232         }
1233         /* removing the loose one could have resurrected an earlier
1234          * packed one.  Also, if it was not loose we need to repack
1235          * without it.
1236          */
1237         ret |= repack_without_ref(refname);
1238
1239         unlink_or_warn(git_path("logs/%s", lock->ref_name));
1240         invalidate_cached_refs();
1241         unlock_ref(lock);
1242         return ret;
1243 }
1244
1245 /*
1246  * People using contrib's git-new-workdir have .git/logs/refs ->
1247  * /some/other/path/.git/logs/refs, and that may live on another device.
1248  *
1249  * IOW, to avoid cross device rename errors, the temporary renamed log must
1250  * live into logs/refs.
1251  */
1252 #define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
1253
1254 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
1255 {
1256         static const char renamed_ref[] = "RENAMED-REF";
1257         unsigned char sha1[20], orig_sha1[20];
1258         int flag = 0, logmoved = 0;
1259         struct ref_lock *lock;
1260         struct stat loginfo;
1261         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
1262         const char *symref = NULL;
1263
1264         if (log && S_ISLNK(loginfo.st_mode))
1265                 return error("reflog for %s is a symlink", oldref);
1266
1267         symref = resolve_ref(oldref, orig_sha1, 1, &flag);
1268         if (flag & REF_ISSYMREF)
1269                 return error("refname %s is a symbolic ref, renaming it is not supported",
1270                         oldref);
1271         if (!symref)
1272                 return error("refname %s not found", oldref);
1273
1274         if (!is_refname_available(newref, oldref, get_packed_refs(NULL), 0))
1275                 return 1;
1276
1277         if (!is_refname_available(newref, oldref, get_loose_refs(NULL), 0))
1278                 return 1;
1279
1280         lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
1281         if (!lock)
1282                 return error("unable to lock %s", renamed_ref);
1283         lock->force_write = 1;
1284         if (write_ref_sha1(lock, orig_sha1, logmsg))
1285                 return error("unable to save current sha1 in %s", renamed_ref);
1286
1287         if (log && rename(git_path("logs/%s", oldref), git_path(TMP_RENAMED_LOG)))
1288                 return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
1289                         oldref, strerror(errno));
1290
1291         if (delete_ref(oldref, orig_sha1, REF_NODEREF)) {
1292                 error("unable to delete old %s", oldref);
1293                 goto rollback;
1294         }
1295
1296         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1, REF_NODEREF)) {
1297                 if (errno==EISDIR) {
1298                         if (remove_empty_directories(git_path("%s", newref))) {
1299                                 error("Directory not empty: %s", newref);
1300                                 goto rollback;
1301                         }
1302                 } else {
1303                         error("unable to delete existing %s", newref);
1304                         goto rollback;
1305                 }
1306         }
1307
1308         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
1309                 error("unable to create directory for %s", newref);
1310                 goto rollback;
1311         }
1312
1313  retry:
1314         if (log && rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newref))) {
1315                 if (errno==EISDIR || errno==ENOTDIR) {
1316                         /*
1317                          * rename(a, b) when b is an existing
1318                          * directory ought to result in ISDIR, but
1319                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
1320                          */
1321                         if (remove_empty_directories(git_path("logs/%s", newref))) {
1322                                 error("Directory not empty: logs/%s", newref);
1323                                 goto rollback;
1324                         }
1325                         goto retry;
1326                 } else {
1327                         error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
1328                                 newref, strerror(errno));
1329                         goto rollback;
1330                 }
1331         }
1332         logmoved = log;
1333
1334         lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
1335         if (!lock) {
1336                 error("unable to lock %s for update", newref);
1337                 goto rollback;
1338         }
1339         lock->force_write = 1;
1340         hashcpy(lock->old_sha1, orig_sha1);
1341         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
1342                 error("unable to write current sha1 into %s", newref);
1343                 goto rollback;
1344         }
1345
1346         return 0;
1347
1348  rollback:
1349         lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
1350         if (!lock) {
1351                 error("unable to lock %s for rollback", oldref);
1352                 goto rollbacklog;
1353         }
1354
1355         lock->force_write = 1;
1356         flag = log_all_ref_updates;
1357         log_all_ref_updates = 0;
1358         if (write_ref_sha1(lock, orig_sha1, NULL))
1359                 error("unable to write current sha1 into %s", oldref);
1360         log_all_ref_updates = flag;
1361
1362  rollbacklog:
1363         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
1364                 error("unable to restore logfile %s from %s: %s",
1365                         oldref, newref, strerror(errno));
1366         if (!logmoved && log &&
1367             rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldref)))
1368                 error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
1369                         oldref, strerror(errno));
1370
1371         return 1;
1372 }
1373
1374 int close_ref(struct ref_lock *lock)
1375 {
1376         if (close_lock_file(lock->lk))
1377                 return -1;
1378         lock->lock_fd = -1;
1379         return 0;
1380 }
1381
1382 int commit_ref(struct ref_lock *lock)
1383 {
1384         if (commit_lock_file(lock->lk))
1385                 return -1;
1386         lock->lock_fd = -1;
1387         return 0;
1388 }
1389
1390 void unlock_ref(struct ref_lock *lock)
1391 {
1392         /* Do not free lock->lk -- atexit() still looks at them */
1393         if (lock->lk)
1394                 rollback_lock_file(lock->lk);
1395         free(lock->ref_name);
1396         free(lock->orig_ref_name);
1397         free(lock);
1398 }
1399
1400 /*
1401  * copy the reflog message msg to buf, which has been allocated sufficiently
1402  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1403  * because reflog file is one line per entry.
1404  */
1405 static int copy_msg(char *buf, const char *msg)
1406 {
1407         char *cp = buf;
1408         char c;
1409         int wasspace = 1;
1410
1411         *cp++ = '\t';
1412         while ((c = *msg++)) {
1413                 if (wasspace && isspace(c))
1414                         continue;
1415                 wasspace = isspace(c);
1416                 if (wasspace)
1417                         c = ' ';
1418                 *cp++ = c;
1419         }
1420         while (buf < cp && isspace(cp[-1]))
1421                 cp--;
1422         *cp++ = '\n';
1423         return cp - buf;
1424 }
1425
1426 int log_ref_setup(const char *ref_name, char *logfile, int bufsize)
1427 {
1428         int logfd, oflags = O_APPEND | O_WRONLY;
1429
1430         git_snpath(logfile, bufsize, "logs/%s", ref_name);
1431         if (log_all_ref_updates &&
1432             (!prefixcmp(ref_name, "refs/heads/") ||
1433              !prefixcmp(ref_name, "refs/remotes/") ||
1434              !prefixcmp(ref_name, "refs/notes/") ||
1435              !strcmp(ref_name, "HEAD"))) {
1436                 if (safe_create_leading_directories(logfile) < 0)
1437                         return error("unable to create directory for %s",
1438                                      logfile);
1439                 oflags |= O_CREAT;
1440         }
1441
1442         logfd = open(logfile, oflags, 0666);
1443         if (logfd < 0) {
1444                 if (!(oflags & O_CREAT) && errno == ENOENT)
1445                         return 0;
1446
1447                 if ((oflags & O_CREAT) && errno == EISDIR) {
1448                         if (remove_empty_directories(logfile)) {
1449                                 return error("There are still logs under '%s'",
1450                                              logfile);
1451                         }
1452                         logfd = open(logfile, oflags, 0666);
1453                 }
1454
1455                 if (logfd < 0)
1456                         return error("Unable to append to %s: %s",
1457                                      logfile, strerror(errno));
1458         }
1459
1460         adjust_shared_perm(logfile);
1461         close(logfd);
1462         return 0;
1463 }
1464
1465 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1466                          const unsigned char *new_sha1, const char *msg)
1467 {
1468         int logfd, result, written, oflags = O_APPEND | O_WRONLY;
1469         unsigned maxlen, len;
1470         int msglen;
1471         char log_file[PATH_MAX];
1472         char *logrec;
1473         const char *committer;
1474
1475         if (log_all_ref_updates < 0)
1476                 log_all_ref_updates = !is_bare_repository();
1477
1478         result = log_ref_setup(ref_name, log_file, sizeof(log_file));
1479         if (result)
1480                 return result;
1481
1482         logfd = open(log_file, oflags);
1483         if (logfd < 0)
1484                 return 0;
1485         msglen = msg ? strlen(msg) : 0;
1486         committer = git_committer_info(0);
1487         maxlen = strlen(committer) + msglen + 100;
1488         logrec = xmalloc(maxlen);
1489         len = sprintf(logrec, "%s %s %s\n",
1490                       sha1_to_hex(old_sha1),
1491                       sha1_to_hex(new_sha1),
1492                       committer);
1493         if (msglen)
1494                 len += copy_msg(logrec + len - 1, msg) - 1;
1495         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1496         free(logrec);
1497         if (close(logfd) != 0 || written != len)
1498                 return error("Unable to append to %s", log_file);
1499         return 0;
1500 }
1501
1502 static int is_branch(const char *refname)
1503 {
1504         return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
1505 }
1506
1507 int write_ref_sha1(struct ref_lock *lock,
1508         const unsigned char *sha1, const char *logmsg)
1509 {
1510         static char term = '\n';
1511         struct object *o;
1512
1513         if (!lock)
1514                 return -1;
1515         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1516                 unlock_ref(lock);
1517                 return 0;
1518         }
1519         o = parse_object(sha1);
1520         if (!o) {
1521                 error("Trying to write ref %s with nonexistent object %s",
1522                         lock->ref_name, sha1_to_hex(sha1));
1523                 unlock_ref(lock);
1524                 return -1;
1525         }
1526         if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1527                 error("Trying to write non-commit object %s to branch %s",
1528                         sha1_to_hex(sha1), lock->ref_name);
1529                 unlock_ref(lock);
1530                 return -1;
1531         }
1532         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1533             write_in_full(lock->lock_fd, &term, 1) != 1
1534                 || close_ref(lock) < 0) {
1535                 error("Couldn't write %s", lock->lk->filename);
1536                 unlock_ref(lock);
1537                 return -1;
1538         }
1539         invalidate_cached_refs();
1540         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1541             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1542              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1543                 unlock_ref(lock);
1544                 return -1;
1545         }
1546         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1547                 /*
1548                  * Special hack: If a branch is updated directly and HEAD
1549                  * points to it (may happen on the remote side of a push
1550                  * for example) then logically the HEAD reflog should be
1551                  * updated too.
1552                  * A generic solution implies reverse symref information,
1553                  * but finding all symrefs pointing to the given branch
1554                  * would be rather costly for this rare event (the direct
1555                  * update of a branch) to be worth it.  So let's cheat and
1556                  * check with HEAD only which should cover 99% of all usage
1557                  * scenarios (even 100% of the default ones).
1558                  */
1559                 unsigned char head_sha1[20];
1560                 int head_flag;
1561                 const char *head_ref;
1562                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1563                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1564                     !strcmp(head_ref, lock->ref_name))
1565                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1566         }
1567         if (commit_ref(lock)) {
1568                 error("Couldn't set %s", lock->ref_name);
1569                 unlock_ref(lock);
1570                 return -1;
1571         }
1572         unlock_ref(lock);
1573         return 0;
1574 }
1575
1576 int create_symref(const char *ref_target, const char *refs_heads_master,
1577                   const char *logmsg)
1578 {
1579         const char *lockpath;
1580         char ref[1000];
1581         int fd, len, written;
1582         char *git_HEAD = git_pathdup("%s", ref_target);
1583         unsigned char old_sha1[20], new_sha1[20];
1584
1585         if (logmsg && read_ref(ref_target, old_sha1))
1586                 hashclr(old_sha1);
1587
1588         if (safe_create_leading_directories(git_HEAD) < 0)
1589                 return error("unable to create directory for %s", git_HEAD);
1590
1591 #ifndef NO_SYMLINK_HEAD
1592         if (prefer_symlink_refs) {
1593                 unlink(git_HEAD);
1594                 if (!symlink(refs_heads_master, git_HEAD))
1595                         goto done;
1596                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1597         }
1598 #endif
1599
1600         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1601         if (sizeof(ref) <= len) {
1602                 error("refname too long: %s", refs_heads_master);
1603                 goto error_free_return;
1604         }
1605         lockpath = mkpath("%s.lock", git_HEAD);
1606         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1607         if (fd < 0) {
1608                 error("Unable to open %s for writing", lockpath);
1609                 goto error_free_return;
1610         }
1611         written = write_in_full(fd, ref, len);
1612         if (close(fd) != 0 || written != len) {
1613                 error("Unable to write to %s", lockpath);
1614                 goto error_unlink_return;
1615         }
1616         if (rename(lockpath, git_HEAD) < 0) {
1617                 error("Unable to create %s", git_HEAD);
1618                 goto error_unlink_return;
1619         }
1620         if (adjust_shared_perm(git_HEAD)) {
1621                 error("Unable to fix permissions on %s", lockpath);
1622         error_unlink_return:
1623                 unlink_or_warn(lockpath);
1624         error_free_return:
1625                 free(git_HEAD);
1626                 return -1;
1627         }
1628
1629 #ifndef NO_SYMLINK_HEAD
1630         done:
1631 #endif
1632         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1633                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1634
1635         free(git_HEAD);
1636         return 0;
1637 }
1638
1639 static char *ref_msg(const char *line, const char *endp)
1640 {
1641         const char *ep;
1642         line += 82;
1643         ep = memchr(line, '\n', endp - line);
1644         if (!ep)
1645                 ep = endp;
1646         return xmemdupz(line, ep - line);
1647 }
1648
1649 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)
1650 {
1651         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1652         char *tz_c;
1653         int logfd, tz, reccnt = 0;
1654         struct stat st;
1655         unsigned long date;
1656         unsigned char logged_sha1[20];
1657         void *log_mapped;
1658         size_t mapsz;
1659
1660         logfile = git_path("logs/%s", ref);
1661         logfd = open(logfile, O_RDONLY, 0);
1662         if (logfd < 0)
1663                 die_errno("Unable to read log '%s'", logfile);
1664         fstat(logfd, &st);
1665         if (!st.st_size)
1666                 die("Log %s is empty.", logfile);
1667         mapsz = xsize_t(st.st_size);
1668         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1669         logdata = log_mapped;
1670         close(logfd);
1671
1672         lastrec = NULL;
1673         rec = logend = logdata + st.st_size;
1674         while (logdata < rec) {
1675                 reccnt++;
1676                 if (logdata < rec && *(rec-1) == '\n')
1677                         rec--;
1678                 lastgt = NULL;
1679                 while (logdata < rec && *(rec-1) != '\n') {
1680                         rec--;
1681                         if (*rec == '>')
1682                                 lastgt = rec;
1683                 }
1684                 if (!lastgt)
1685                         die("Log %s is corrupt.", logfile);
1686                 date = strtoul(lastgt + 1, &tz_c, 10);
1687                 if (date <= at_time || cnt == 0) {
1688                         tz = strtoul(tz_c, NULL, 10);
1689                         if (msg)
1690                                 *msg = ref_msg(rec, logend);
1691                         if (cutoff_time)
1692                                 *cutoff_time = date;
1693                         if (cutoff_tz)
1694                                 *cutoff_tz = tz;
1695                         if (cutoff_cnt)
1696                                 *cutoff_cnt = reccnt - 1;
1697                         if (lastrec) {
1698                                 if (get_sha1_hex(lastrec, logged_sha1))
1699                                         die("Log %s is corrupt.", logfile);
1700                                 if (get_sha1_hex(rec + 41, sha1))
1701                                         die("Log %s is corrupt.", logfile);
1702                                 if (hashcmp(logged_sha1, sha1)) {
1703                                         warning("Log %s has gap after %s.",
1704                                                 logfile, show_date(date, tz, DATE_RFC2822));
1705                                 }
1706                         }
1707                         else if (date == at_time) {
1708                                 if (get_sha1_hex(rec + 41, sha1))
1709                                         die("Log %s is corrupt.", logfile);
1710                         }
1711                         else {
1712                                 if (get_sha1_hex(rec + 41, logged_sha1))
1713                                         die("Log %s is corrupt.", logfile);
1714                                 if (hashcmp(logged_sha1, sha1)) {
1715                                         warning("Log %s unexpectedly ended on %s.",
1716                                                 logfile, show_date(date, tz, DATE_RFC2822));
1717                                 }
1718                         }
1719                         munmap(log_mapped, mapsz);
1720                         return 0;
1721                 }
1722                 lastrec = rec;
1723                 if (cnt > 0)
1724                         cnt--;
1725         }
1726
1727         rec = logdata;
1728         while (rec < logend && *rec != '>' && *rec != '\n')
1729                 rec++;
1730         if (rec == logend || *rec == '\n')
1731                 die("Log %s is corrupt.", logfile);
1732         date = strtoul(rec + 1, &tz_c, 10);
1733         tz = strtoul(tz_c, NULL, 10);
1734         if (get_sha1_hex(logdata, sha1))
1735                 die("Log %s is corrupt.", logfile);
1736         if (is_null_sha1(sha1)) {
1737                 if (get_sha1_hex(logdata + 41, sha1))
1738                         die("Log %s is corrupt.", logfile);
1739         }
1740         if (msg)
1741                 *msg = ref_msg(logdata, logend);
1742         munmap(log_mapped, mapsz);
1743
1744         if (cutoff_time)
1745                 *cutoff_time = date;
1746         if (cutoff_tz)
1747                 *cutoff_tz = tz;
1748         if (cutoff_cnt)
1749                 *cutoff_cnt = reccnt;
1750         return 1;
1751 }
1752
1753 int for_each_recent_reflog_ent(const char *ref, each_reflog_ent_fn fn, long ofs, void *cb_data)
1754 {
1755         const char *logfile;
1756         FILE *logfp;
1757         struct strbuf sb = STRBUF_INIT;
1758         int ret = 0;
1759
1760         logfile = git_path("logs/%s", ref);
1761         logfp = fopen(logfile, "r");
1762         if (!logfp)
1763                 return -1;
1764
1765         if (ofs) {
1766                 struct stat statbuf;
1767                 if (fstat(fileno(logfp), &statbuf) ||
1768                     statbuf.st_size < ofs ||
1769                     fseek(logfp, -ofs, SEEK_END) ||
1770                     strbuf_getwholeline(&sb, logfp, '\n')) {
1771                         fclose(logfp);
1772                         strbuf_release(&sb);
1773                         return -1;
1774                 }
1775         }
1776
1777         while (!strbuf_getwholeline(&sb, logfp, '\n')) {
1778                 unsigned char osha1[20], nsha1[20];
1779                 char *email_end, *message;
1780                 unsigned long timestamp;
1781                 int tz;
1782
1783                 /* old SP new SP name <email> SP time TAB msg LF */
1784                 if (sb.len < 83 || sb.buf[sb.len - 1] != '\n' ||
1785                     get_sha1_hex(sb.buf, osha1) || sb.buf[40] != ' ' ||
1786                     get_sha1_hex(sb.buf + 41, nsha1) || sb.buf[81] != ' ' ||
1787                     !(email_end = strchr(sb.buf + 82, '>')) ||
1788                     email_end[1] != ' ' ||
1789                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1790                     !message || message[0] != ' ' ||
1791                     (message[1] != '+' && message[1] != '-') ||
1792                     !isdigit(message[2]) || !isdigit(message[3]) ||
1793                     !isdigit(message[4]) || !isdigit(message[5]))
1794                         continue; /* corrupt? */
1795                 email_end[1] = '\0';
1796                 tz = strtol(message + 1, NULL, 10);
1797                 if (message[6] != '\t')
1798                         message += 6;
1799                 else
1800                         message += 7;
1801                 ret = fn(osha1, nsha1, sb.buf + 82, timestamp, tz, message,
1802                          cb_data);
1803                 if (ret)
1804                         break;
1805         }
1806         fclose(logfp);
1807         strbuf_release(&sb);
1808         return ret;
1809 }
1810
1811 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1812 {
1813         return for_each_recent_reflog_ent(ref, fn, 0, cb_data);
1814 }
1815
1816 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1817 {
1818         DIR *dir = opendir(git_path("logs/%s", base));
1819         int retval = 0;
1820
1821         if (dir) {
1822                 struct dirent *de;
1823                 int baselen = strlen(base);
1824                 char *log = xmalloc(baselen + 257);
1825
1826                 memcpy(log, base, baselen);
1827                 if (baselen && base[baselen-1] != '/')
1828                         log[baselen++] = '/';
1829
1830                 while ((de = readdir(dir)) != NULL) {
1831                         struct stat st;
1832                         int namelen;
1833
1834                         if (de->d_name[0] == '.')
1835                                 continue;
1836                         namelen = strlen(de->d_name);
1837                         if (namelen > 255)
1838                                 continue;
1839                         if (has_extension(de->d_name, ".lock"))
1840                                 continue;
1841                         memcpy(log + baselen, de->d_name, namelen+1);
1842                         if (stat(git_path("logs/%s", log), &st) < 0)
1843                                 continue;
1844                         if (S_ISDIR(st.st_mode)) {
1845                                 retval = do_for_each_reflog(log, fn, cb_data);
1846                         } else {
1847                                 unsigned char sha1[20];
1848                                 if (!resolve_ref(log, sha1, 0, NULL))
1849                                         retval = error("bad ref for %s", log);
1850                                 else
1851                                         retval = fn(log, sha1, 0, cb_data);
1852                         }
1853                         if (retval)
1854                                 break;
1855                 }
1856                 free(log);
1857                 closedir(dir);
1858         }
1859         else if (*base)
1860                 return errno;
1861         return retval;
1862 }
1863
1864 int for_each_reflog(each_ref_fn fn, void *cb_data)
1865 {
1866         return do_for_each_reflog("", fn, cb_data);
1867 }
1868
1869 int update_ref(const char *action, const char *refname,
1870                 const unsigned char *sha1, const unsigned char *oldval,
1871                 int flags, enum action_on_err onerr)
1872 {
1873         static struct ref_lock *lock;
1874         lock = lock_any_ref_for_update(refname, oldval, flags);
1875         if (!lock) {
1876                 const char *str = "Cannot lock the ref '%s'.";
1877                 switch (onerr) {
1878                 case MSG_ON_ERR: error(str, refname); break;
1879                 case DIE_ON_ERR: die(str, refname); break;
1880                 case QUIET_ON_ERR: break;
1881                 }
1882                 return 1;
1883         }
1884         if (write_ref_sha1(lock, sha1, action) < 0) {
1885                 const char *str = "Cannot update the ref '%s'.";
1886                 switch (onerr) {
1887                 case MSG_ON_ERR: error(str, refname); break;
1888                 case DIE_ON_ERR: die(str, refname); break;
1889                 case QUIET_ON_ERR: break;
1890                 }
1891                 return 1;
1892         }
1893         return 0;
1894 }
1895
1896 int ref_exists(char *refname)
1897 {
1898         unsigned char sha1[20];
1899         return !!resolve_ref(refname, sha1, 1, NULL);
1900 }
1901
1902 struct ref *find_ref_by_name(const struct ref *list, const char *name)
1903 {
1904         for ( ; list; list = list->next)
1905                 if (!strcmp(list->name, name))
1906                         return (struct ref *)list;
1907         return NULL;
1908 }
1909
1910 /*
1911  * generate a format suitable for scanf from a ref_rev_parse_rules
1912  * rule, that is replace the "%.*s" spec with a "%s" spec
1913  */
1914 static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
1915 {
1916         char *spec;
1917
1918         spec = strstr(rule, "%.*s");
1919         if (!spec || strstr(spec + 4, "%.*s"))
1920                 die("invalid rule in ref_rev_parse_rules: %s", rule);
1921
1922         /* copy all until spec */
1923         strncpy(scanf_fmt, rule, spec - rule);
1924         scanf_fmt[spec - rule] = '\0';
1925         /* copy new spec */
1926         strcat(scanf_fmt, "%s");
1927         /* copy remaining rule */
1928         strcat(scanf_fmt, spec + 4);
1929
1930         return;
1931 }
1932
1933 char *shorten_unambiguous_ref(const char *ref, int strict)
1934 {
1935         int i;
1936         static char **scanf_fmts;
1937         static int nr_rules;
1938         char *short_name;
1939
1940         /* pre generate scanf formats from ref_rev_parse_rules[] */
1941         if (!nr_rules) {
1942                 size_t total_len = 0;
1943
1944                 /* the rule list is NULL terminated, count them first */
1945                 for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
1946                         /* no +1 because strlen("%s") < strlen("%.*s") */
1947                         total_len += strlen(ref_rev_parse_rules[nr_rules]);
1948
1949                 scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
1950
1951                 total_len = 0;
1952                 for (i = 0; i < nr_rules; i++) {
1953                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
1954                                         + total_len;
1955                         gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
1956                         total_len += strlen(ref_rev_parse_rules[i]);
1957                 }
1958         }
1959
1960         /* bail out if there are no rules */
1961         if (!nr_rules)
1962                 return xstrdup(ref);
1963
1964         /* buffer for scanf result, at most ref must fit */
1965         short_name = xstrdup(ref);
1966
1967         /* skip first rule, it will always match */
1968         for (i = nr_rules - 1; i > 0 ; --i) {
1969                 int j;
1970                 int rules_to_fail = i;
1971                 int short_name_len;
1972
1973                 if (1 != sscanf(ref, scanf_fmts[i], short_name))
1974                         continue;
1975
1976                 short_name_len = strlen(short_name);
1977
1978                 /*
1979                  * in strict mode, all (except the matched one) rules
1980                  * must fail to resolve to a valid non-ambiguous ref
1981                  */
1982                 if (strict)
1983                         rules_to_fail = nr_rules;
1984
1985                 /*
1986                  * check if the short name resolves to a valid ref,
1987                  * but use only rules prior to the matched one
1988                  */
1989                 for (j = 0; j < rules_to_fail; j++) {
1990                         const char *rule = ref_rev_parse_rules[j];
1991                         unsigned char short_objectname[20];
1992                         char refname[PATH_MAX];
1993
1994                         /* skip matched rule */
1995                         if (i == j)
1996                                 continue;
1997
1998                         /*
1999                          * the short name is ambiguous, if it resolves
2000                          * (with this previous rule) to a valid ref
2001                          * read_ref() returns 0 on success
2002                          */
2003                         mksnpath(refname, sizeof(refname),
2004                                  rule, short_name_len, short_name);
2005                         if (!read_ref(refname, short_objectname))
2006                                 break;
2007                 }
2008
2009                 /*
2010                  * short name is non-ambiguous if all previous rules
2011                  * haven't resolved to a valid ref
2012                  */
2013                 if (j == rules_to_fail)
2014                         return short_name;
2015         }
2016
2017         free(short_name);
2018         return xstrdup(ref);
2019 }