Pileus Git - ~andy/git/blob - refs.c

   1 #include "cache.h"
   2 #include "refs.h"
   3 #include "object.h"
   4 #include "tag.h"
   5 #include "dir.h"
   6
   7 /* ISSYMREF=01 and ISPACKED=02 are public interfaces */
   8 #define REF_KNOWS_PEELED 04
   9 #define REF_BROKEN 010
  10
  11 struct ref_list {
  12         struct ref_list *next;
  13         unsigned char flag; /* ISSYMREF? ISPACKED? */
  14         unsigned char sha1[20];
  15         unsigned char peeled[20];
  16         char name[FLEX_ARRAY];
  17 };
  18
  19 static const char *parse_ref_line(char *line, unsigned char *sha1)
  20 {
  21         /*
  22          * 42: the answer to everything.
  23          *
  24          * In this case, it happens to be the answer to
  25          *  40 (length of sha1 hex representation)
  26          *  +1 (space in between hex and name)
  27          *  +1 (newline at the end of the line)
  28          */
  29         int len = strlen(line) - 42;
  30
  31         if (len <= 0)
  32                 return NULL;
  33         if (get_sha1_hex(line, sha1) < 0)
  34                 return NULL;
  35         if (!isspace(line[40]))
  36                 return NULL;
  37         line += 41;
  38         if (isspace(*line))
  39                 return NULL;
  40         if (line[len] != '\n')
  41                 return NULL;
  42         line[len] = 0;
  43
  44         return line;
  45 }
  46
  47 static struct ref_list *add_ref(const char *name, const unsigned char *sha1,
  48                                 int flag, struct ref_list *list,
  49                                 struct ref_list **new_entry)
  50 {
  51         int len;
  52         struct ref_list *entry;
  53
  54         /* Allocate it and add it in.. */
  55         len = strlen(name) + 1;
  56         entry = xmalloc(sizeof(struct ref_list) + len);
  57         hashcpy(entry->sha1, sha1);
  58         hashclr(entry->peeled);
  59         memcpy(entry->name, name, len);
  60         entry->flag = flag;
  61         entry->next = list;
  62         if (new_entry)
  63                 *new_entry = entry;
  64         return entry;
  65 }
  66
  67 /* merge sort the ref list */
  68 static struct ref_list *sort_ref_list(struct ref_list *list)
  69 {
  70         int psize, qsize, last_merge_count, cmp;
  71         struct ref_list *p, *q, *l, *e;
  72         struct ref_list *new_list = list;
  73         int k = 1;
  74         int merge_count = 0;
  75
  76         if (!list)
  77                 return list;
  78
  79         do {
  80                 last_merge_count = merge_count;
  81                 merge_count = 0;
  82
  83                 psize = 0;
  84
  85                 p = new_list;
  86                 q = new_list;
  87                 new_list = NULL;
  88                 l = NULL;
  89
  90                 while (p) {
  91                         merge_count++;
  92
  93                         while (psize < k && q->next) {
  94                                 q = q->next;
  95                                 psize++;
  96                         }
  97                         qsize = k;
  98
  99                         while ((psize > 0) || (qsize > 0 && q)) {
 100                                 if (qsize == 0 || !q) {
 101                                         e = p;
 102                                         p = p->next;
 103                                         psize--;
 104                                 } else if (psize == 0) {
 105                                         e = q;
 106                                         q = q->next;
 107                                         qsize--;
 108                                 } else {
 109                                         cmp = strcmp(q->name, p->name);
 110                                         if (cmp < 0) {
 111                                                 e = q;
 112                                                 q = q->next;
 113                                                 qsize--;
 114                                         } else if (cmp > 0) {
 115                                                 e = p;
 116                                                 p = p->next;
 117                                                 psize--;
 118                                         } else {
 119                                                 if (hashcmp(q->sha1, p->sha1))
 120                                                         die("Duplicated ref, and SHA1s don't match: %s",
 121                                                             q->name);
 122                                                 warning("Duplicated ref: %s", q->name);
 123                                                 e = q;
 124                                                 q = q->next;
 125                                                 qsize--;
 126                                                 free(e);
 127                                                 e = p;
 128                                                 p = p->next;
 129                                                 psize--;
 130                                         }
 131                                 }
 132
 133                                 e->next = NULL;
 134
 135                                 if (l)
 136                                         l->next = e;
 137                                 if (!new_list)
 138                                         new_list = e;
 139                                 l = e;
 140                         }
 141
 142                         p = q;
 143                 };
 144
 145                 k = k * 2;
 146         } while ((last_merge_count != merge_count) || (last_merge_count != 1));
 147
 148         return new_list;
 149 }
 150
 151 /*
 152  * Future: need to be in "struct repository"
 153  * when doing a full libification.
 154  */
 155 static struct cached_refs {
 156         char did_loose;
 157         char did_packed;
 158         struct ref_list *loose;
 159         struct ref_list *packed;
 160 } cached_refs, submodule_refs;
 161 static struct ref_list *current_ref;
 162
 163 static struct ref_list *extra_refs;
 164
 165 static void free_ref_list(struct ref_list *list)
 166 {
 167         struct ref_list *next;
 168         for ( ; list; list = next) {
 169                 next = list->next;
 170                 free(list);
 171         }
 172 }
 173
 174 static void invalidate_cached_refs(void)
 175 {
 176         struct cached_refs *ca = &cached_refs;
 177
 178         if (ca->did_loose && ca->loose)
 179                 free_ref_list(ca->loose);
 180         if (ca->did_packed && ca->packed)
 181                 free_ref_list(ca->packed);
 182         ca->loose = ca->packed = NULL;
 183         ca->did_loose = ca->did_packed = 0;
 184 }
 185
 186 static void read_packed_refs(FILE *f, struct cached_refs *cached_refs)
 187 {
 188         struct ref_list *list = NULL;
 189         struct ref_list *last = NULL;
 190         char refline[PATH_MAX];
 191         int flag = REF_ISPACKED;
 192
 193         while (fgets(refline, sizeof(refline), f)) {
 194                 unsigned char sha1[20];
 195                 const char *name;
 196                 static const char header[] = "# pack-refs with:";
 197
 198                 if (!strncmp(refline, header, sizeof(header)-1)) {
 199                         const char *traits = refline + sizeof(header) - 1;
 200                         if (strstr(traits, " peeled "))
 201                                 flag |= REF_KNOWS_PEELED;
 202                         /* perhaps other traits later as well */
 203                         continue;
 204                 }
 205
 206                 name = parse_ref_line(refline, sha1);
 207                 if (name) {
 208                         list = add_ref(name, sha1, flag, list, &last);
 209                         continue;
 210                 }
 211                 if (last &&
 212                     refline[0] == '^' &&
 213                     strlen(refline) == 42 &&
 214                     refline[41] == '\n' &&
 215                     !get_sha1_hex(refline + 1, sha1))
 216                         hashcpy(last->peeled, sha1);
 217         }
 218         cached_refs->packed = sort_ref_list(list);
 219 }
 220
 221 void add_extra_ref(const char *name, const unsigned char *sha1, int flag)
 222 {
 223         extra_refs = add_ref(name, sha1, flag, extra_refs, NULL);
 224 }
 225
 226 void clear_extra_refs(void)
 227 {
 228         free_ref_list(extra_refs);
 229         extra_refs = NULL;
 230 }
 231
 232 static struct ref_list *get_packed_refs(const char *submodule)
 233 {
 234         const char *packed_refs_file;
 235         struct cached_refs *refs;
 236
 237         if (submodule) {
 238                 packed_refs_file = git_path_submodule(submodule, "packed-refs");
 239                 refs = &submodule_refs;
 240                 free_ref_list(refs->packed);
 241         } else {
 242                 packed_refs_file = git_path("packed-refs");
 243                 refs = &cached_refs;
 244         }
 245
 246         if (!refs->did_packed || submodule) {
 247                 FILE *f = fopen(packed_refs_file, "r");
 248                 refs->packed = NULL;
 249                 if (f) {
 250                         read_packed_refs(f, refs);
 251                         fclose(f);
 252                 }
 253                 refs->did_packed = 1;
 254         }
 255         return refs->packed;
 256 }
 257
 258 static struct ref_list *get_ref_dir(const char *submodule, const char *base,
 259                                     struct ref_list *list)
 260 {
 261         DIR *dir;
 262         const char *path;
 263
 264         if (submodule)
 265                 path = git_path_submodule(submodule, "%s", base);
 266         else
 267                 path = git_path("%s", base);
 268
 269
 270         dir = opendir(path);
 271
 272         if (dir) {
 273                 struct dirent *de;
 274                 int baselen = strlen(base);
 275                 char *ref = xmalloc(baselen + 257);
 276
 277                 memcpy(ref, base, baselen);
 278                 if (baselen && base[baselen-1] != '/')
 279                         ref[baselen++] = '/';
 280
 281                 while ((de = readdir(dir)) != NULL) {
 282                         unsigned char sha1[20];
 283                         struct stat st;
 284                         int flag;
 285                         int namelen;
 286                         const char *refdir;
 287
 288                         if (de->d_name[0] == '.')
 289                                 continue;
 290                         namelen = strlen(de->d_name);
 291                         if (namelen > 255)
 292                                 continue;
 293                         if (has_extension(de->d_name, ".lock"))
 294                                 continue;
 295                         memcpy(ref + baselen, de->d_name, namelen+1);
 296                         refdir = submodule
 297                                 ? git_path_submodule(submodule, "%s", ref)
 298                                 : git_path("%s", ref);
 299                         if (stat(refdir, &st) < 0)
 300                                 continue;
 301                         if (S_ISDIR(st.st_mode)) {
 302                                 list = get_ref_dir(submodule, ref, list);
 303                                 continue;
 304                         }
 305                         if (submodule) {
 306                                 hashclr(sha1);
 307                                 flag = 0;
 308                                 if (resolve_gitlink_ref(submodule, ref, sha1) < 0) {
 309                                         hashclr(sha1);
 310                                         flag |= REF_BROKEN;
 311                                 }
 312                         } else
 313                                 if (!resolve_ref(ref, sha1, 1, &flag)) {
 314                                         hashclr(sha1);
 315                                         flag |= REF_BROKEN;
 316                                 }
 317                         list = add_ref(ref, sha1, flag, list, NULL);
 318                 }
 319                 free(ref);
 320                 closedir(dir);
 321         }
 322         return sort_ref_list(list);
 323 }
 324
 325 struct warn_if_dangling_data {
 326         FILE *fp;
 327         const char *refname;
 328         const char *msg_fmt;
 329 };
 330
 331 static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
 332                                    int flags, void *cb_data)
 333 {
 334         struct warn_if_dangling_data *d = cb_data;
 335         const char *resolves_to;
 336         unsigned char junk[20];
 337
 338         if (!(flags & REF_ISSYMREF))
 339                 return 0;
 340
 341         resolves_to = resolve_ref(refname, junk, 0, NULL);
 342         if (!resolves_to || strcmp(resolves_to, d->refname))
 343                 return 0;
 344
 345         fprintf(d->fp, d->msg_fmt, refname);
 346         return 0;
 347 }
 348
 349 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 350 {
 351         struct warn_if_dangling_data data;
 352
 353         data.fp = fp;
 354         data.refname = refname;
 355         data.msg_fmt = msg_fmt;
 356         for_each_rawref(warn_if_dangling_symref, &data);
 357 }
 358
 359 static struct ref_list *get_loose_refs(const char *submodule)
 360 {
 361         if (submodule) {
 362                 free_ref_list(submodule_refs.loose);
 363                 submodule_refs.loose = get_ref_dir(submodule, "refs", NULL);
 364                 return submodule_refs.loose;
 365         }
 366
 367         if (!cached_refs.did_loose) {
 368                 cached_refs.loose = get_ref_dir(NULL, "refs", NULL);
 369                 cached_refs.did_loose = 1;
 370         }
 371         return cached_refs.loose;
 372 }
 373
 374 /* We allow "recursive" symbolic refs. Only within reason, though */
 375 #define MAXDEPTH 5
 376 #define MAXREFLEN (1024)
 377
 378 static int resolve_gitlink_packed_ref(char *name, int pathlen, const char *refname, unsigned char *result)
 379 {
 380         FILE *f;
 381         struct cached_refs refs;
 382         struct ref_list *ref;
 383         int retval;
 384
 385         strcpy(name + pathlen, "packed-refs");
 386         f = fopen(name, "r");
 387         if (!f)
 388                 return -1;
 389         read_packed_refs(f, &refs);
 390         fclose(f);
 391         ref = refs.packed;
 392         retval = -1;
 393         while (ref) {
 394                 if (!strcmp(ref->name, refname)) {
 395                         retval = 0;
 396                         memcpy(result, ref->sha1, 20);
 397                         break;
 398                 }
 399                 ref = ref->next;
 400         }
 401         free_ref_list(refs.packed);
 402         return retval;
 403 }
 404
 405 static int resolve_gitlink_ref_recursive(char *name, int pathlen, const char *refname, unsigned char *result, int recursion)
 406 {
 407         int fd, len = strlen(refname);
 408         char buffer[128], *p;
 409
 410         if (recursion > MAXDEPTH || len > MAXREFLEN)
 411                 return -1;
 412         memcpy(name + pathlen, refname, len+1);
 413         fd = open(name, O_RDONLY);
 414         if (fd < 0)
 415                 return resolve_gitlink_packed_ref(name, pathlen, refname, result);
 416
 417         len = read(fd, buffer, sizeof(buffer)-1);
 418         close(fd);
 419         if (len < 0)
 420                 return -1;
 421         while (len && isspace(buffer[len-1]))
 422                 len--;
 423         buffer[len] = 0;
 424
 425         /* Was it a detached head or an old-fashioned symlink? */
 426         if (!get_sha1_hex(buffer, result))
 427                 return 0;
 428
 429         /* Symref? */
 430         if (strncmp(buffer, "ref:", 4))
 431                 return -1;
 432         p = buffer + 4;
 433         while (isspace(*p))
 434                 p++;
 435
 436         return resolve_gitlink_ref_recursive(name, pathlen, p, result, recursion+1);
 437 }
 438
 439 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *result)
 440 {
 441         int len = strlen(path), retval;
 442         char *gitdir;
 443         const char *tmp;
 444
 445         while (len && path[len-1] == '/')
 446                 len--;
 447         if (!len)
 448                 return -1;
 449         gitdir = xmalloc(len + MAXREFLEN + 8);
 450         memcpy(gitdir, path, len);
 451         memcpy(gitdir + len, "/.git", 6);
 452         len += 5;
 453
 454         tmp = read_gitfile(gitdir);
 455         if (tmp) {
 456                 free(gitdir);
 457                 len = strlen(tmp);
 458                 gitdir = xmalloc(len + MAXREFLEN + 3);
 459                 memcpy(gitdir, tmp, len);
 460         }
 461         gitdir[len] = '/';
 462         gitdir[++len] = '\0';
 463         retval = resolve_gitlink_ref_recursive(gitdir, len, refname, result, 0);
 464         free(gitdir);
 465         return retval;
 466 }
 467
 468 /*
 469  * Try to read ref from the packed references.  On success, set sha1
 470  * and return 0; otherwise, return -1.
 471  */
 472 static int get_packed_ref(const char *ref, unsigned char *sha1)
 473 {
 474         struct ref_list *list = get_packed_refs(NULL);
 475         while (list) {
 476                 if (!strcmp(ref, list->name)) {
 477                         hashcpy(sha1, list->sha1);
 478                         return 0;
 479                 }
 480                 list = list->next;
 481         }
 482         return -1;
 483 }
 484
 485 /*
 486  * If the "reading" argument is set, this function finds out what _object_
 487  * the ref points at by "reading" the ref.  The ref, if it is not symbolic,
 488  * has to exist, and if it is symbolic, it has to point at an existing ref,
 489  * because the "read" goes through the symref to the ref it points at.
 490  *
 491  * The access that is not "reading" may often be "writing", but does not
 492  * have to; it can be merely checking _where it leads to_. If it is a
 493  * prelude to "writing" to the ref, a write to a symref that points at
 494  * yet-to-be-born ref will create the real ref pointed by the symref.
 495  * reading=0 allows the caller to check where such a symref leads to.
 496  */
 497 const char *resolve_ref(const char *ref, unsigned char *sha1, int reading, int *flag)
 498 {
 499         int depth = MAXDEPTH;
 500         ssize_t len;
 501         char buffer[256];
 502         static char ref_buffer[256];
 503
 504         if (flag)
 505                 *flag = 0;
 506
 507         if (check_refname_format(ref, REFNAME_ALLOW_ONELEVEL))
 508                 return NULL;
 509
 510         for (;;) {
 511                 char path[PATH_MAX];
 512                 struct stat st;
 513                 char *buf;
 514                 int fd;
 515
 516                 if (--depth < 0)
 517                         return NULL;
 518
 519                 git_snpath(path, sizeof(path), "%s", ref);
 520
 521                 if (lstat(path, &st) < 0) {
 522                         if (errno != ENOENT)
 523                                 return NULL;
 524                         /*
 525                          * The loose reference file does not exist;
 526                          * check for a packed reference.
 527                          */
 528                         if (!get_packed_ref(ref, sha1)) {
 529                                 if (flag)
 530                                         *flag |= REF_ISPACKED;
 531                                 return ref;
 532                         }
 533                         /* The reference is not a packed reference, either. */
 534                         if (reading) {
 535                                 return NULL;
 536                         } else {
 537                                 hashclr(sha1);
 538                                 return ref;
 539                         }
 540                 }
 541
 542                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 543                 if (S_ISLNK(st.st_mode)) {
 544                         len = readlink(path, buffer, sizeof(buffer)-1);
 545                         if (len < 0)
 546                                 return NULL;
 547                         buffer[len] = 0;
 548                         if (!prefixcmp(buffer, "refs/") &&
 549                                         !check_refname_format(buffer, 0)) {
 550                                 strcpy(ref_buffer, buffer);
 551                                 ref = ref_buffer;
 552                                 if (flag)
 553                                         *flag |= REF_ISSYMREF;
 554                                 continue;
 555                         }
 556                 }
 557
 558                 /* Is it a directory? */
 559                 if (S_ISDIR(st.st_mode)) {
 560                         errno = EISDIR;
 561                         return NULL;
 562                 }
 563
 564                 /*
 565                  * Anything else, just open it and try to use it as
 566                  * a ref
 567                  */
 568                 fd = open(path, O_RDONLY);
 569                 if (fd < 0)
 570                         return NULL;
 571                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
 572                 close(fd);
 573                 if (len < 0)
 574                         return NULL;
 575                 while (len && isspace(buffer[len-1]))
 576                         len--;
 577                 buffer[len] = '\0';
 578
 579                 /*
 580                  * Is it a symbolic ref?
 581                  */
 582                 if (prefixcmp(buffer, "ref:"))
 583                         break;
 584                 buf = buffer + 4;
 585                 while (isspace(*buf))
 586                         buf++;
 587                 if (check_refname_format(buf, REFNAME_ALLOW_ONELEVEL)) {
 588                         warning("symbolic reference in %s is formatted incorrectly",
 589                                 path);
 590                         return NULL;
 591                 }
 592                 ref = strcpy(ref_buffer, buf);
 593                 if (flag)
 594                         *flag |= REF_ISSYMREF;
 595         }
 596         if (get_sha1_hex(buffer, sha1))
 597                 return NULL;
 598         return ref;
 599 }
 600
 601 /* The argument to filter_refs */
 602 struct ref_filter {
 603         const char *pattern;
 604         each_ref_fn *fn;
 605         void *cb_data;
 606 };
 607
 608 int read_ref(const char *ref, unsigned char *sha1)
 609 {
 610         if (resolve_ref(ref, sha1, 1, NULL))
 611                 return 0;
 612         return -1;
 613 }
 614
 615 #define DO_FOR_EACH_INCLUDE_BROKEN 01
 616 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
 617                       int flags, void *cb_data, struct ref_list *entry)
 618 {
 619         if (prefixcmp(entry->name, base))
 620                 return 0;
 621
 622         if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
 623                 if (entry->flag & REF_BROKEN)
 624                         return 0; /* ignore dangling symref */
 625                 if (!has_sha1_file(entry->sha1)) {
 626                         error("%s does not point to a valid object!", entry->name);
 627                         return 0;
 628                 }
 629         }
 630         current_ref = entry;
 631         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 632 }
 633
 634 static int filter_refs(const char *ref, const unsigned char *sha, int flags,
 635         void *data)
 636 {
 637         struct ref_filter *filter = (struct ref_filter *)data;
 638         if (fnmatch(filter->pattern, ref, 0))
 639                 return 0;
 640         return filter->fn(ref, sha, flags, filter->cb_data);
 641 }
 642
 643 int peel_ref(const char *ref, unsigned char *sha1)
 644 {
 645         int flag;
 646         unsigned char base[20];
 647         struct object *o;
 648
 649         if (current_ref && (current_ref->name == ref
 650                 || !strcmp(current_ref->name, ref))) {
 651                 if (current_ref->flag & REF_KNOWS_PEELED) {
 652                         hashcpy(sha1, current_ref->peeled);
 653                         return 0;
 654                 }
 655                 hashcpy(base, current_ref->sha1);
 656                 goto fallback;
 657         }
 658
 659         if (!resolve_ref(ref, base, 1, &flag))
 660                 return -1;
 661
 662         if ((flag & REF_ISPACKED)) {
 663                 struct ref_list *list = get_packed_refs(NULL);
 664
 665                 while (list) {
 666                         if (!strcmp(list->name, ref)) {
 667                                 if (list->flag & REF_KNOWS_PEELED) {
 668                                         hashcpy(sha1, list->peeled);
 669                                         return 0;
 670                                 }
 671                                 /* older pack-refs did not leave peeled ones */
 672                                 break;
 673                         }
 674                         list = list->next;
 675                 }
 676         }
 677
 678 fallback:
 679         o = parse_object(base);
 680         if (o && o->type == OBJ_TAG) {
 681                 o = deref_tag(o, ref, 0);
 682                 if (o) {
 683                         hashcpy(sha1, o->sha1);
 684                         return 0;
 685                 }
 686         }
 687         return -1;
 688 }
 689
 690 static int do_for_each_ref(const char *submodule, const char *base, each_ref_fn fn,
 691                            int trim, int flags, void *cb_data)
 692 {
 693         int retval = 0;
 694         struct ref_list *packed = get_packed_refs(submodule);
 695         struct ref_list *loose = get_loose_refs(submodule);
 696
 697         struct ref_list *extra;
 698
 699         for (extra = extra_refs; extra; extra = extra->next)
 700                 retval = do_one_ref(base, fn, trim, flags, cb_data, extra);
 701
 702         while (packed && loose) {
 703                 struct ref_list *entry;
 704                 int cmp = strcmp(packed->name, loose->name);
 705                 if (!cmp) {
 706                         packed = packed->next;
 707                         continue;
 708                 }
 709                 if (cmp > 0) {
 710                         entry = loose;
 711                         loose = loose->next;
 712                 } else {
 713                         entry = packed;
 714                         packed = packed->next;
 715                 }
 716                 retval = do_one_ref(base, fn, trim, flags, cb_data, entry);
 717                 if (retval)
 718                         goto end_each;
 719         }
 720
 721         for (packed = packed ? packed : loose; packed; packed = packed->next) {
 722                 retval = do_one_ref(base, fn, trim, flags, cb_data, packed);
 723                 if (retval)
 724                         goto end_each;
 725         }
 726
 727 end_each:
 728         current_ref = NULL;
 729         return retval;
 730 }
 731
 732
 733 static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
 734 {
 735         unsigned char sha1[20];
 736         int flag;
 737
 738         if (submodule) {
 739                 if (resolve_gitlink_ref(submodule, "HEAD", sha1) == 0)
 740                         return fn("HEAD", sha1, 0, cb_data);
 741
 742                 return 0;
 743         }
 744
 745         if (resolve_ref("HEAD", sha1, 1, &flag))
 746                 return fn("HEAD", sha1, flag, cb_data);
 747
 748         return 0;
 749 }
 750
 751 int head_ref(each_ref_fn fn, void *cb_data)
 752 {
 753         return do_head_ref(NULL, fn, cb_data);
 754 }
 755
 756 int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 757 {
 758         return do_head_ref(submodule, fn, cb_data);
 759 }
 760
 761 int for_each_ref(each_ref_fn fn, void *cb_data)
 762 {
 763         return do_for_each_ref(NULL, "", fn, 0, 0, cb_data);
 764 }
 765
 766 int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 767 {
 768         return do_for_each_ref(submodule, "", fn, 0, 0, cb_data);
 769 }
 770
 771 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
 772 {
 773         return do_for_each_ref(NULL, prefix, fn, strlen(prefix), 0, cb_data);
 774 }
 775
 776 int for_each_ref_in_submodule(const char *submodule, const char *prefix,
 777                 each_ref_fn fn, void *cb_data)
 778 {
 779         return do_for_each_ref(submodule, prefix, fn, strlen(prefix), 0, cb_data);
 780 }
 781
 782 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 783 {
 784         return for_each_ref_in("refs/tags/", fn, cb_data);
 785 }
 786
 787 int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 788 {
 789         return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
 790 }
 791
 792 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 793 {
 794         return for_each_ref_in("refs/heads/", fn, cb_data);
 795 }
 796
 797 int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 798 {
 799         return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
 800 }
 801
 802 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 803 {
 804         return for_each_ref_in("refs/remotes/", fn, cb_data);
 805 }
 806
 807 int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 808 {
 809         return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
 810 }
 811
 812 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
 813 {
 814         return do_for_each_ref(NULL, "refs/replace/", fn, 13, 0, cb_data);
 815 }
 816
 817 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
 818 {
 819         struct strbuf buf = STRBUF_INIT;
 820         int ret = 0;
 821         unsigned char sha1[20];
 822         int flag;
 823
 824         strbuf_addf(&buf, "%sHEAD", get_git_namespace());
 825         if (resolve_ref(buf.buf, sha1, 1, &flag))
 826                 ret = fn(buf.buf, sha1, flag, cb_data);
 827         strbuf_release(&buf);
 828
 829         return ret;
 830 }
 831
 832 int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
 833 {
 834         struct strbuf buf = STRBUF_INIT;
 835         int ret;
 836         strbuf_addf(&buf, "%srefs/", get_git_namespace());
 837         ret = do_for_each_ref(NULL, buf.buf, fn, 0, 0, cb_data);
 838         strbuf_release(&buf);
 839         return ret;
 840 }
 841
 842 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 843         const char *prefix, void *cb_data)
 844 {
 845         struct strbuf real_pattern = STRBUF_INIT;
 846         struct ref_filter filter;
 847         int ret;
 848
 849         if (!prefix && prefixcmp(pattern, "refs/"))
 850                 strbuf_addstr(&real_pattern, "refs/");
 851         else if (prefix)
 852                 strbuf_addstr(&real_pattern, prefix);
 853         strbuf_addstr(&real_pattern, pattern);
 854
 855         if (!has_glob_specials(pattern)) {
 856                 /* Append implied '/' '*' if not present. */
 857                 if (real_pattern.buf[real_pattern.len - 1] != '/')
 858                         strbuf_addch(&real_pattern, '/');
 859                 /* No need to check for '*', there is none. */
 860                 strbuf_addch(&real_pattern, '*');
 861         }
 862
 863         filter.pattern = real_pattern.buf;
 864         filter.fn = fn;
 865         filter.cb_data = cb_data;
 866         ret = for_each_ref(filter_refs, &filter);
 867
 868         strbuf_release(&real_pattern);
 869         return ret;
 870 }
 871
 872 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 873 {
 874         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
 875 }
 876
 877 int for_each_rawref(each_ref_fn fn, void *cb_data)
 878 {
 879         return do_for_each_ref(NULL, "", fn, 0,
 880                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
 881 }
 882
 883 /*
 884  * Make sure "ref" is something reasonable to have under ".git/refs/";
 885  * We do not like it if:
 886  *
 887  * - any path component of it begins with ".", or
 888  * - it has double dots "..", or
 889  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 890  * - it ends with a "/".
 891  * - it ends with ".lock"
 892  * - it contains a "\" (backslash)
 893  */
 894
 895 /* Return true iff ch is not allowed in reference names. */
 896 static inline int bad_ref_char(int ch)
 897 {
 898         if (((unsigned) ch) <= ' ' || ch == 0x7f ||
 899             ch == '~' || ch == '^' || ch == ':' || ch == '\\')
 900                 return 1;
 901         /* 2.13 Pattern Matching Notation */
 902         if (ch == '*' || ch == '?' || ch == '[') /* Unsupported */
 903                 return 1;
 904         return 0;
 905 }
 906
 907 /*
 908  * Try to read one refname component from the front of ref.  Return
 909  * the length of the component found, or -1 if the component is not
 910  * legal.
 911  */
 912 static int check_refname_component(const char *ref)
 913 {
 914         const char *cp;
 915         char last = '\0';
 916
 917         for (cp = ref; ; cp++) {
 918                 char ch = *cp;
 919                 if (ch == '\0' || ch == '/')
 920                         break;
 921                 if (bad_ref_char(ch))
 922                         return -1; /* Illegal character in refname. */
 923                 if (last == '.' && ch == '.')
 924                         return -1; /* Refname contains "..". */
 925                 if (last == '@' && ch == '{')
 926                         return -1; /* Refname contains "@{". */
 927                 last = ch;
 928         }
 929         if (cp == ref)
 930                 return -1; /* Component has zero length. */
 931         if (ref[0] == '.')
 932                 return -1; /* Component starts with '.'. */
 933         if (cp - ref >= 5 && !memcmp(cp - 5, ".lock", 5))
 934                 return -1; /* Refname ends with ".lock". */
 935         return cp - ref;
 936 }
 937
 938 int check_refname_format(const char *ref, int flags)
 939 {
 940         int component_len, component_count = 0;
 941
 942         while (1) {
 943                 /* We are at the start of a path component. */
 944                 component_len = check_refname_component(ref);
 945                 if (component_len < 0) {
 946                         if ((flags & REFNAME_REFSPEC_PATTERN) &&
 947                                         ref[0] == '*' &&
 948                                         (ref[1] == '\0' || ref[1] == '/')) {
 949                                 /* Accept one wildcard as a full refname component. */
 950                                 flags &= ~REFNAME_REFSPEC_PATTERN;
 951                                 component_len = 1;
 952                         } else {
 953                                 return -1;
 954                         }
 955                 }
 956                 component_count++;
 957                 if (ref[component_len] == '\0')
 958                         break;
 959                 /* Skip to next component. */
 960                 ref += component_len + 1;
 961         }
 962
 963         if (ref[component_len - 1] == '.')
 964                 return -1; /* Refname ends with '.'. */
 965         if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
 966                 return -1; /* Refname has only one component. */
 967         return 0;
 968 }
 969
 970 const char *prettify_refname(const char *name)
 971 {
 972         return name + (
 973                 !prefixcmp(name, "refs/heads/") ? 11 :
 974                 !prefixcmp(name, "refs/tags/") ? 10 :
 975                 !prefixcmp(name, "refs/remotes/") ? 13 :
 976                 0);
 977 }
 978
 979 const char *ref_rev_parse_rules[] = {
 980         "%.*s",
 981         "refs/%.*s",
 982         "refs/tags/%.*s",
 983         "refs/heads/%.*s",
 984         "refs/remotes/%.*s",
 985         "refs/remotes/%.*s/HEAD",
 986         NULL
 987 };
 988
 989 const char *ref_fetch_rules[] = {
 990         "%.*s",
 991         "refs/%.*s",
 992         "refs/heads/%.*s",
 993         NULL
 994 };
 995
 996 int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
 997 {
 998         const char **p;
 999         const int abbrev_name_len = strlen(abbrev_name);
1000
1001         for (p = rules; *p; p++) {
1002                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
1003                         return 1;
1004                 }
1005         }
1006
1007         return 0;
1008 }
1009
1010 static struct ref_lock *verify_lock(struct ref_lock *lock,
1011         const unsigned char *old_sha1, int mustexist)
1012 {
1013         if (!resolve_ref(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
1014                 error("Can't verify ref %s", lock->ref_name);
1015                 unlock_ref(lock);
1016                 return NULL;
1017         }
1018         if (hashcmp(lock->old_sha1, old_sha1)) {
1019                 error("Ref %s is at %s but expected %s", lock->ref_name,
1020                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
1021                 unlock_ref(lock);
1022                 return NULL;
1023         }
1024         return lock;
1025 }
1026
1027 static int remove_empty_directories(const char *file)
1028 {
1029         /* we want to create a file but there is a directory there;
1030          * if that is an empty directory (or a directory that contains
1031          * only empty directories), remove them.
1032          */
1033         struct strbuf path;
1034         int result;
1035
1036         strbuf_init(&path, 20);
1037         strbuf_addstr(&path, file);
1038
1039         result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
1040
1041         strbuf_release(&path);
1042
1043         return result;
1044 }
1045
1046 static int is_refname_available(const char *ref, const char *oldref,
1047                                 struct ref_list *list, int quiet)
1048 {
1049         int namlen = strlen(ref); /* e.g. 'foo/bar' */
1050         while (list) {
1051                 /* list->name could be 'foo' or 'foo/bar/baz' */
1052                 if (!oldref || strcmp(oldref, list->name)) {
1053                         int len = strlen(list->name);
1054                         int cmplen = (namlen < len) ? namlen : len;
1055                         const char *lead = (namlen < len) ? list->name : ref;
1056                         if (!strncmp(ref, list->name, cmplen) &&
1057                             lead[cmplen] == '/') {
1058                                 if (!quiet)
1059                                         error("'%s' exists; cannot create '%s'",
1060                                               list->name, ref);
1061                                 return 0;
1062                         }
1063                 }
1064                 list = list->next;
1065         }
1066         return 1;
1067 }
1068
1069 static struct ref_lock *lock_ref_sha1_basic(const char *ref, const unsigned char *old_sha1, int flags, int *type_p)
1070 {
1071         char *ref_file;
1072         const char *orig_ref = ref;
1073         struct ref_lock *lock;
1074         int last_errno = 0;
1075         int type, lflags;
1076         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
1077         int missing = 0;
1078
1079         lock = xcalloc(1, sizeof(struct ref_lock));
1080         lock->lock_fd = -1;
1081
1082         ref = resolve_ref(ref, lock->old_sha1, mustexist, &type);
1083         if (!ref && errno == EISDIR) {
1084                 /* we are trying to lock foo but we used to
1085                  * have foo/bar which now does not exist;
1086                  * it is normal for the empty directory 'foo'
1087                  * to remain.
1088                  */
1089                 ref_file = git_path("%s", orig_ref);
1090                 if (remove_empty_directories(ref_file)) {
1091                         last_errno = errno;
1092                         error("there are still refs under '%s'", orig_ref);
1093                         goto error_return;
1094                 }
1095                 ref = resolve_ref(orig_ref, lock->old_sha1, mustexist, &type);
1096         }
1097         if (type_p)
1098             *type_p = type;
1099         if (!ref) {
1100                 last_errno = errno;
1101                 error("unable to resolve reference %s: %s",
1102                         orig_ref, strerror(errno));
1103                 goto error_return;
1104         }
1105         missing = is_null_sha1(lock->old_sha1);
1106         /* When the ref did not exist and we are creating it,
1107          * make sure there is no existing ref that is packed
1108          * whose name begins with our refname, nor a ref whose
1109          * name is a proper prefix of our refname.
1110          */
1111         if (missing &&
1112              !is_refname_available(ref, NULL, get_packed_refs(NULL), 0)) {
1113                 last_errno = ENOTDIR;
1114                 goto error_return;
1115         }
1116
1117         lock->lk = xcalloc(1, sizeof(struct lock_file));
1118
1119         lflags = LOCK_DIE_ON_ERROR;
1120         if (flags & REF_NODEREF) {
1121                 ref = orig_ref;
1122                 lflags |= LOCK_NODEREF;
1123         }
1124         lock->ref_name = xstrdup(ref);
1125         lock->orig_ref_name = xstrdup(orig_ref);
1126         ref_file = git_path("%s", ref);
1127         if (missing)
1128                 lock->force_write = 1;
1129         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
1130                 lock->force_write = 1;
1131
1132         if (safe_create_leading_directories(ref_file)) {
1133                 last_errno = errno;
1134                 error("unable to create directory for %s", ref_file);
1135                 goto error_return;
1136         }
1137
1138         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
1139         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
1140
1141  error_return:
1142         unlock_ref(lock);
1143         errno = last_errno;
1144         return NULL;
1145 }
1146
1147 struct ref_lock *lock_ref_sha1(const char *ref, const unsigned char *old_sha1)
1148 {
1149         char refpath[PATH_MAX];
1150         if (check_refname_format(ref, 0))
1151                 return NULL;
1152         strcpy(refpath, mkpath("refs/%s", ref));
1153         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
1154 }
1155
1156 struct ref_lock *lock_any_ref_for_update(const char *ref, const unsigned char *old_sha1, int flags)
1157 {
1158         if (check_refname_format(ref, REFNAME_ALLOW_ONELEVEL))
1159                 return NULL;
1160         return lock_ref_sha1_basic(ref, old_sha1, flags, NULL);
1161 }
1162
1163 static struct lock_file packlock;
1164
1165 static int repack_without_ref(const char *refname)
1166 {
1167         struct ref_list *list, *packed_ref_list;
1168         int fd;
1169         int found = 0;
1170
1171         packed_ref_list = get_packed_refs(NULL);
1172         for (list = packed_ref_list; list; list = list->next) {
1173                 if (!strcmp(refname, list->name)) {
1174                         found = 1;
1175                         break;
1176                 }
1177         }
1178         if (!found)
1179                 return 0;
1180         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
1181         if (fd < 0) {
1182                 unable_to_lock_error(git_path("packed-refs"), errno);
1183                 return error("cannot delete '%s' from packed refs", refname);
1184         }
1185
1186         for (list = packed_ref_list; list; list = list->next) {
1187                 char line[PATH_MAX + 100];
1188                 int len;
1189
1190                 if (!strcmp(refname, list->name))
1191                         continue;
1192                 len = snprintf(line, sizeof(line), "%s %s\n",
1193                                sha1_to_hex(list->sha1), list->name);
1194                 /* this should not happen but just being defensive */
1195                 if (len > sizeof(line))
1196                         die("too long a refname '%s'", list->name);
1197                 write_or_die(fd, line, len);
1198         }
1199         return commit_lock_file(&packlock);
1200 }
1201
1202 int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
1203 {
1204         struct ref_lock *lock;
1205         int err, i = 0, ret = 0, flag = 0;
1206
1207         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
1208         if (!lock)
1209                 return 1;
1210         if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
1211                 /* loose */
1212                 const char *path;
1213
1214                 if (!(delopt & REF_NODEREF)) {
1215                         i = strlen(lock->lk->filename) - 5; /* .lock */
1216                         lock->lk->filename[i] = 0;
1217                         path = lock->lk->filename;
1218                 } else {
1219                         path = git_path("%s", refname);
1220                 }
1221                 err = unlink_or_warn(path);
1222                 if (err && errno != ENOENT)
1223                         ret = 1;
1224
1225                 if (!(delopt & REF_NODEREF))
1226                         lock->lk->filename[i] = '.';
1227         }
1228         /* removing the loose one could have resurrected an earlier
1229          * packed one.  Also, if it was not loose we need to repack
1230          * without it.
1231          */
1232         ret |= repack_without_ref(refname);
1233
1234         unlink_or_warn(git_path("logs/%s", lock->ref_name));
1235         invalidate_cached_refs();
1236         unlock_ref(lock);
1237         return ret;
1238 }
1239
1240 /*
1241  * People using contrib's git-new-workdir have .git/logs/refs ->
1242  * /some/other/path/.git/logs/refs, and that may live on another device.
1243  *
1244  * IOW, to avoid cross device rename errors, the temporary renamed log must
1245  * live into logs/refs.
1246  */
1247 #define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
1248
1249 int rename_ref(const char *oldref, const char *newref, const char *logmsg)
1250 {
1251         static const char renamed_ref[] = "RENAMED-REF";
1252         unsigned char sha1[20], orig_sha1[20];
1253         int flag = 0, logmoved = 0;
1254         struct ref_lock *lock;
1255         struct stat loginfo;
1256         int log = !lstat(git_path("logs/%s", oldref), &loginfo);
1257         const char *symref = NULL;
1258
1259         if (log && S_ISLNK(loginfo.st_mode))
1260                 return error("reflog for %s is a symlink", oldref);
1261
1262         symref = resolve_ref(oldref, orig_sha1, 1, &flag);
1263         if (flag & REF_ISSYMREF)
1264                 return error("refname %s is a symbolic ref, renaming it is not supported",
1265                         oldref);
1266         if (!symref)
1267                 return error("refname %s not found", oldref);
1268
1269         if (!is_refname_available(newref, oldref, get_packed_refs(NULL), 0))
1270                 return 1;
1271
1272         if (!is_refname_available(newref, oldref, get_loose_refs(NULL), 0))
1273                 return 1;
1274
1275         lock = lock_ref_sha1_basic(renamed_ref, NULL, 0, NULL);
1276         if (!lock)
1277                 return error("unable to lock %s", renamed_ref);
1278         lock->force_write = 1;
1279         if (write_ref_sha1(lock, orig_sha1, logmsg))
1280                 return error("unable to save current sha1 in %s", renamed_ref);
1281
1282         if (log && rename(git_path("logs/%s", oldref), git_path(TMP_RENAMED_LOG)))
1283                 return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
1284                         oldref, strerror(errno));
1285
1286         if (delete_ref(oldref, orig_sha1, REF_NODEREF)) {
1287                 error("unable to delete old %s", oldref);
1288                 goto rollback;
1289         }
1290
1291         if (resolve_ref(newref, sha1, 1, &flag) && delete_ref(newref, sha1, REF_NODEREF)) {
1292                 if (errno==EISDIR) {
1293                         if (remove_empty_directories(git_path("%s", newref))) {
1294                                 error("Directory not empty: %s", newref);
1295                                 goto rollback;
1296                         }
1297                 } else {
1298                         error("unable to delete existing %s", newref);
1299                         goto rollback;
1300                 }
1301         }
1302
1303         if (log && safe_create_leading_directories(git_path("logs/%s", newref))) {
1304                 error("unable to create directory for %s", newref);
1305                 goto rollback;
1306         }
1307
1308  retry:
1309         if (log && rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newref))) {
1310                 if (errno==EISDIR || errno==ENOTDIR) {
1311                         /*
1312                          * rename(a, b) when b is an existing
1313                          * directory ought to result in ISDIR, but
1314                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
1315                          */
1316                         if (remove_empty_directories(git_path("logs/%s", newref))) {
1317                                 error("Directory not empty: logs/%s", newref);
1318                                 goto rollback;
1319                         }
1320                         goto retry;
1321                 } else {
1322                         error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
1323                                 newref, strerror(errno));
1324                         goto rollback;
1325                 }
1326         }
1327         logmoved = log;
1328
1329         lock = lock_ref_sha1_basic(newref, NULL, 0, NULL);
1330         if (!lock) {
1331                 error("unable to lock %s for update", newref);
1332                 goto rollback;
1333         }
1334         lock->force_write = 1;
1335         hashcpy(lock->old_sha1, orig_sha1);
1336         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
1337                 error("unable to write current sha1 into %s", newref);
1338                 goto rollback;
1339         }
1340
1341         return 0;
1342
1343  rollback:
1344         lock = lock_ref_sha1_basic(oldref, NULL, 0, NULL);
1345         if (!lock) {
1346                 error("unable to lock %s for rollback", oldref);
1347                 goto rollbacklog;
1348         }
1349
1350         lock->force_write = 1;
1351         flag = log_all_ref_updates;
1352         log_all_ref_updates = 0;
1353         if (write_ref_sha1(lock, orig_sha1, NULL))
1354                 error("unable to write current sha1 into %s", oldref);
1355         log_all_ref_updates = flag;
1356
1357  rollbacklog:
1358         if (logmoved && rename(git_path("logs/%s", newref), git_path("logs/%s", oldref)))
1359                 error("unable to restore logfile %s from %s: %s",
1360                         oldref, newref, strerror(errno));
1361         if (!logmoved && log &&
1362             rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldref)))
1363                 error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
1364                         oldref, strerror(errno));
1365
1366         return 1;
1367 }
1368
1369 int close_ref(struct ref_lock *lock)
1370 {
1371         if (close_lock_file(lock->lk))
1372                 return -1;
1373         lock->lock_fd = -1;
1374         return 0;
1375 }
1376
1377 int commit_ref(struct ref_lock *lock)
1378 {
1379         if (commit_lock_file(lock->lk))
1380                 return -1;
1381         lock->lock_fd = -1;
1382         return 0;
1383 }
1384
1385 void unlock_ref(struct ref_lock *lock)
1386 {
1387         /* Do not free lock->lk -- atexit() still looks at them */
1388         if (lock->lk)
1389                 rollback_lock_file(lock->lk);
1390         free(lock->ref_name);
1391         free(lock->orig_ref_name);
1392         free(lock);
1393 }
1394
1395 /*
1396  * copy the reflog message msg to buf, which has been allocated sufficiently
1397  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1398  * because reflog file is one line per entry.
1399  */
1400 static int copy_msg(char *buf, const char *msg)
1401 {
1402         char *cp = buf;
1403         char c;
1404         int wasspace = 1;
1405
1406         *cp++ = '\t';
1407         while ((c = *msg++)) {
1408                 if (wasspace && isspace(c))
1409                         continue;
1410                 wasspace = isspace(c);
1411                 if (wasspace)
1412                         c = ' ';
1413                 *cp++ = c;
1414         }
1415         while (buf < cp && isspace(cp[-1]))
1416                 cp--;
1417         *cp++ = '\n';
1418         return cp - buf;
1419 }
1420
1421 int log_ref_setup(const char *ref_name, char *logfile, int bufsize)
1422 {
1423         int logfd, oflags = O_APPEND | O_WRONLY;
1424
1425         git_snpath(logfile, bufsize, "logs/%s", ref_name);
1426         if (log_all_ref_updates &&
1427             (!prefixcmp(ref_name, "refs/heads/") ||
1428              !prefixcmp(ref_name, "refs/remotes/") ||
1429              !prefixcmp(ref_name, "refs/notes/") ||
1430              !strcmp(ref_name, "HEAD"))) {
1431                 if (safe_create_leading_directories(logfile) < 0)
1432                         return error("unable to create directory for %s",
1433                                      logfile);
1434                 oflags |= O_CREAT;
1435         }
1436
1437         logfd = open(logfile, oflags, 0666);
1438         if (logfd < 0) {
1439                 if (!(oflags & O_CREAT) && errno == ENOENT)
1440                         return 0;
1441
1442                 if ((oflags & O_CREAT) && errno == EISDIR) {
1443                         if (remove_empty_directories(logfile)) {
1444                                 return error("There are still logs under '%s'",
1445                                              logfile);
1446                         }
1447                         logfd = open(logfile, oflags, 0666);
1448                 }
1449
1450                 if (logfd < 0)
1451                         return error("Unable to append to %s: %s",
1452                                      logfile, strerror(errno));
1453         }
1454
1455         adjust_shared_perm(logfile);
1456         close(logfd);
1457         return 0;
1458 }
1459
1460 static int log_ref_write(const char *ref_name, const unsigned char *old_sha1,
1461                          const unsigned char *new_sha1, const char *msg)
1462 {
1463         int logfd, result, written, oflags = O_APPEND | O_WRONLY;
1464         unsigned maxlen, len;
1465         int msglen;
1466         char log_file[PATH_MAX];
1467         char *logrec;
1468         const char *committer;
1469
1470         if (log_all_ref_updates < 0)
1471                 log_all_ref_updates = !is_bare_repository();
1472
1473         result = log_ref_setup(ref_name, log_file, sizeof(log_file));
1474         if (result)
1475                 return result;
1476
1477         logfd = open(log_file, oflags);
1478         if (logfd < 0)
1479                 return 0;
1480         msglen = msg ? strlen(msg) : 0;
1481         committer = git_committer_info(0);
1482         maxlen = strlen(committer) + msglen + 100;
1483         logrec = xmalloc(maxlen);
1484         len = sprintf(logrec, "%s %s %s\n",
1485                       sha1_to_hex(old_sha1),
1486                       sha1_to_hex(new_sha1),
1487                       committer);
1488         if (msglen)
1489                 len += copy_msg(logrec + len - 1, msg) - 1;
1490         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1491         free(logrec);
1492         if (close(logfd) != 0 || written != len)
1493                 return error("Unable to append to %s", log_file);
1494         return 0;
1495 }
1496
1497 static int is_branch(const char *refname)
1498 {
1499         return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
1500 }
1501
1502 int write_ref_sha1(struct ref_lock *lock,
1503         const unsigned char *sha1, const char *logmsg)
1504 {
1505         static char term = '\n';
1506         struct object *o;
1507
1508         if (!lock)
1509                 return -1;
1510         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1511                 unlock_ref(lock);
1512                 return 0;
1513         }
1514         o = parse_object(sha1);
1515         if (!o) {
1516                 error("Trying to write ref %s with nonexistent object %s",
1517                         lock->ref_name, sha1_to_hex(sha1));
1518                 unlock_ref(lock);
1519                 return -1;
1520         }
1521         if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1522                 error("Trying to write non-commit object %s to branch %s",
1523                         sha1_to_hex(sha1), lock->ref_name);
1524                 unlock_ref(lock);
1525                 return -1;
1526         }
1527         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1528             write_in_full(lock->lock_fd, &term, 1) != 1
1529                 || close_ref(lock) < 0) {
1530                 error("Couldn't write %s", lock->lk->filename);
1531                 unlock_ref(lock);
1532                 return -1;
1533         }
1534         invalidate_cached_refs();
1535         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1536             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1537              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1538                 unlock_ref(lock);
1539                 return -1;
1540         }
1541         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1542                 /*
1543                  * Special hack: If a branch is updated directly and HEAD
1544                  * points to it (may happen on the remote side of a push
1545                  * for example) then logically the HEAD reflog should be
1546                  * updated too.
1547                  * A generic solution implies reverse symref information,
1548                  * but finding all symrefs pointing to the given branch
1549                  * would be rather costly for this rare event (the direct
1550                  * update of a branch) to be worth it.  So let's cheat and
1551                  * check with HEAD only which should cover 99% of all usage
1552                  * scenarios (even 100% of the default ones).
1553                  */
1554                 unsigned char head_sha1[20];
1555                 int head_flag;
1556                 const char *head_ref;
1557                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1558                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1559                     !strcmp(head_ref, lock->ref_name))
1560                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1561         }
1562         if (commit_ref(lock)) {
1563                 error("Couldn't set %s", lock->ref_name);
1564                 unlock_ref(lock);
1565                 return -1;
1566         }
1567         unlock_ref(lock);
1568         return 0;
1569 }
1570
1571 int create_symref(const char *ref_target, const char *refs_heads_master,
1572                   const char *logmsg)
1573 {
1574         const char *lockpath;
1575         char ref[1000];
1576         int fd, len, written;
1577         char *git_HEAD = git_pathdup("%s", ref_target);
1578         unsigned char old_sha1[20], new_sha1[20];
1579
1580         if (logmsg && read_ref(ref_target, old_sha1))
1581                 hashclr(old_sha1);
1582
1583         if (safe_create_leading_directories(git_HEAD) < 0)
1584                 return error("unable to create directory for %s", git_HEAD);
1585
1586 #ifndef NO_SYMLINK_HEAD
1587         if (prefer_symlink_refs) {
1588                 unlink(git_HEAD);
1589                 if (!symlink(refs_heads_master, git_HEAD))
1590                         goto done;
1591                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1592         }
1593 #endif
1594
1595         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1596         if (sizeof(ref) <= len) {
1597                 error("refname too long: %s", refs_heads_master);
1598                 goto error_free_return;
1599         }
1600         lockpath = mkpath("%s.lock", git_HEAD);
1601         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1602         if (fd < 0) {
1603                 error("Unable to open %s for writing", lockpath);
1604                 goto error_free_return;
1605         }
1606         written = write_in_full(fd, ref, len);
1607         if (close(fd) != 0 || written != len) {
1608                 error("Unable to write to %s", lockpath);
1609                 goto error_unlink_return;
1610         }
1611         if (rename(lockpath, git_HEAD) < 0) {
1612                 error("Unable to create %s", git_HEAD);
1613                 goto error_unlink_return;
1614         }
1615         if (adjust_shared_perm(git_HEAD)) {
1616                 error("Unable to fix permissions on %s", lockpath);
1617         error_unlink_return:
1618                 unlink_or_warn(lockpath);
1619         error_free_return:
1620                 free(git_HEAD);
1621                 return -1;
1622         }
1623
1624 #ifndef NO_SYMLINK_HEAD
1625         done:
1626 #endif
1627         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1628                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1629
1630         free(git_HEAD);
1631         return 0;
1632 }
1633
1634 static char *ref_msg(const char *line, const char *endp)
1635 {
1636         const char *ep;
1637         line += 82;
1638         ep = memchr(line, '\n', endp - line);
1639         if (!ep)
1640                 ep = endp;
1641         return xmemdupz(line, ep - line);
1642 }
1643
1644 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)
1645 {
1646         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1647         char *tz_c;
1648         int logfd, tz, reccnt = 0;
1649         struct stat st;
1650         unsigned long date;
1651         unsigned char logged_sha1[20];
1652         void *log_mapped;
1653         size_t mapsz;
1654
1655         logfile = git_path("logs/%s", ref);
1656         logfd = open(logfile, O_RDONLY, 0);
1657         if (logfd < 0)
1658                 die_errno("Unable to read log '%s'", logfile);
1659         fstat(logfd, &st);
1660         if (!st.st_size)
1661                 die("Log %s is empty.", logfile);
1662         mapsz = xsize_t(st.st_size);
1663         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1664         logdata = log_mapped;
1665         close(logfd);
1666
1667         lastrec = NULL;
1668         rec = logend = logdata + st.st_size;
1669         while (logdata < rec) {
1670                 reccnt++;
1671                 if (logdata < rec && *(rec-1) == '\n')
1672                         rec--;
1673                 lastgt = NULL;
1674                 while (logdata < rec && *(rec-1) != '\n') {
1675                         rec--;
1676                         if (*rec == '>')
1677                                 lastgt = rec;
1678                 }
1679                 if (!lastgt)
1680                         die("Log %s is corrupt.", logfile);
1681                 date = strtoul(lastgt + 1, &tz_c, 10);
1682                 if (date <= at_time || cnt == 0) {
1683                         tz = strtoul(tz_c, NULL, 10);
1684                         if (msg)
1685                                 *msg = ref_msg(rec, logend);
1686                         if (cutoff_time)
1687                                 *cutoff_time = date;
1688                         if (cutoff_tz)
1689                                 *cutoff_tz = tz;
1690                         if (cutoff_cnt)
1691                                 *cutoff_cnt = reccnt - 1;
1692                         if (lastrec) {
1693                                 if (get_sha1_hex(lastrec, logged_sha1))
1694                                         die("Log %s is corrupt.", logfile);
1695                                 if (get_sha1_hex(rec + 41, sha1))
1696                                         die("Log %s is corrupt.", logfile);
1697                                 if (hashcmp(logged_sha1, sha1)) {
1698                                         warning("Log %s has gap after %s.",
1699                                                 logfile, show_date(date, tz, DATE_RFC2822));
1700                                 }
1701                         }
1702                         else if (date == at_time) {
1703                                 if (get_sha1_hex(rec + 41, sha1))
1704                                         die("Log %s is corrupt.", logfile);
1705                         }
1706                         else {
1707                                 if (get_sha1_hex(rec + 41, logged_sha1))
1708                                         die("Log %s is corrupt.", logfile);
1709                                 if (hashcmp(logged_sha1, sha1)) {
1710                                         warning("Log %s unexpectedly ended on %s.",
1711                                                 logfile, show_date(date, tz, DATE_RFC2822));
1712                                 }
1713                         }
1714                         munmap(log_mapped, mapsz);
1715                         return 0;
1716                 }
1717                 lastrec = rec;
1718                 if (cnt > 0)
1719                         cnt--;
1720         }
1721
1722         rec = logdata;
1723         while (rec < logend && *rec != '>' && *rec != '\n')
1724                 rec++;
1725         if (rec == logend || *rec == '\n')
1726                 die("Log %s is corrupt.", logfile);
1727         date = strtoul(rec + 1, &tz_c, 10);
1728         tz = strtoul(tz_c, NULL, 10);
1729         if (get_sha1_hex(logdata, sha1))
1730                 die("Log %s is corrupt.", logfile);
1731         if (is_null_sha1(sha1)) {
1732                 if (get_sha1_hex(logdata + 41, sha1))
1733                         die("Log %s is corrupt.", logfile);
1734         }
1735         if (msg)
1736                 *msg = ref_msg(logdata, logend);
1737         munmap(log_mapped, mapsz);
1738
1739         if (cutoff_time)
1740                 *cutoff_time = date;
1741         if (cutoff_tz)
1742                 *cutoff_tz = tz;
1743         if (cutoff_cnt)
1744                 *cutoff_cnt = reccnt;
1745         return 1;
1746 }
1747
1748 int for_each_recent_reflog_ent(const char *ref, each_reflog_ent_fn fn, long ofs, void *cb_data)
1749 {
1750         const char *logfile;
1751         FILE *logfp;
1752         struct strbuf sb = STRBUF_INIT;
1753         int ret = 0;
1754
1755         logfile = git_path("logs/%s", ref);
1756         logfp = fopen(logfile, "r");
1757         if (!logfp)
1758                 return -1;
1759
1760         if (ofs) {
1761                 struct stat statbuf;
1762                 if (fstat(fileno(logfp), &statbuf) ||
1763                     statbuf.st_size < ofs ||
1764                     fseek(logfp, -ofs, SEEK_END) ||
1765                     strbuf_getwholeline(&sb, logfp, '\n')) {
1766                         fclose(logfp);
1767                         strbuf_release(&sb);
1768                         return -1;
1769                 }
1770         }
1771
1772         while (!strbuf_getwholeline(&sb, logfp, '\n')) {
1773                 unsigned char osha1[20], nsha1[20];
1774                 char *email_end, *message;
1775                 unsigned long timestamp;
1776                 int tz;
1777
1778                 /* old SP new SP name <email> SP time TAB msg LF */
1779                 if (sb.len < 83 || sb.buf[sb.len - 1] != '\n' ||
1780                     get_sha1_hex(sb.buf, osha1) || sb.buf[40] != ' ' ||
1781                     get_sha1_hex(sb.buf + 41, nsha1) || sb.buf[81] != ' ' ||
1782                     !(email_end = strchr(sb.buf + 82, '>')) ||
1783                     email_end[1] != ' ' ||
1784                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1785                     !message || message[0] != ' ' ||
1786                     (message[1] != '+' && message[1] != '-') ||
1787                     !isdigit(message[2]) || !isdigit(message[3]) ||
1788                     !isdigit(message[4]) || !isdigit(message[5]))
1789                         continue; /* corrupt? */
1790                 email_end[1] = '\0';
1791                 tz = strtol(message + 1, NULL, 10);
1792                 if (message[6] != '\t')
1793                         message += 6;
1794                 else
1795                         message += 7;
1796                 ret = fn(osha1, nsha1, sb.buf + 82, timestamp, tz, message,
1797                          cb_data);
1798                 if (ret)
1799                         break;
1800         }
1801         fclose(logfp);
1802         strbuf_release(&sb);
1803         return ret;
1804 }
1805
1806 int for_each_reflog_ent(const char *ref, each_reflog_ent_fn fn, void *cb_data)
1807 {
1808         return for_each_recent_reflog_ent(ref, fn, 0, cb_data);
1809 }
1810
1811 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1812 {
1813         DIR *dir = opendir(git_path("logs/%s", base));
1814         int retval = 0;
1815
1816         if (dir) {
1817                 struct dirent *de;
1818                 int baselen = strlen(base);
1819                 char *log = xmalloc(baselen + 257);
1820
1821                 memcpy(log, base, baselen);
1822                 if (baselen && base[baselen-1] != '/')
1823                         log[baselen++] = '/';
1824
1825                 while ((de = readdir(dir)) != NULL) {
1826                         struct stat st;
1827                         int namelen;
1828
1829                         if (de->d_name[0] == '.')
1830                                 continue;
1831                         namelen = strlen(de->d_name);
1832                         if (namelen > 255)
1833                                 continue;
1834                         if (has_extension(de->d_name, ".lock"))
1835                                 continue;
1836                         memcpy(log + baselen, de->d_name, namelen+1);
1837                         if (stat(git_path("logs/%s", log), &st) < 0)
1838                                 continue;
1839                         if (S_ISDIR(st.st_mode)) {
1840                                 retval = do_for_each_reflog(log, fn, cb_data);
1841                         } else {
1842                                 unsigned char sha1[20];
1843                                 if (!resolve_ref(log, sha1, 0, NULL))
1844                                         retval = error("bad ref for %s", log);
1845                                 else
1846                                         retval = fn(log, sha1, 0, cb_data);
1847                         }
1848                         if (retval)
1849                                 break;
1850                 }
1851                 free(log);
1852                 closedir(dir);
1853         }
1854         else if (*base)
1855                 return errno;
1856         return retval;
1857 }
1858
1859 int for_each_reflog(each_ref_fn fn, void *cb_data)
1860 {
1861         return do_for_each_reflog("", fn, cb_data);
1862 }
1863
1864 int update_ref(const char *action, const char *refname,
1865                 const unsigned char *sha1, const unsigned char *oldval,
1866                 int flags, enum action_on_err onerr)
1867 {
1868         static struct ref_lock *lock;
1869         lock = lock_any_ref_for_update(refname, oldval, flags);
1870         if (!lock) {
1871                 const char *str = "Cannot lock the ref '%s'.";
1872                 switch (onerr) {
1873                 case MSG_ON_ERR: error(str, refname); break;
1874                 case DIE_ON_ERR: die(str, refname); break;
1875                 case QUIET_ON_ERR: break;
1876                 }
1877                 return 1;
1878         }
1879         if (write_ref_sha1(lock, sha1, action) < 0) {
1880                 const char *str = "Cannot update the ref '%s'.";
1881                 switch (onerr) {
1882                 case MSG_ON_ERR: error(str, refname); break;
1883                 case DIE_ON_ERR: die(str, refname); break;
1884                 case QUIET_ON_ERR: break;
1885                 }
1886                 return 1;
1887         }
1888         return 0;
1889 }
1890
1891 int ref_exists(char *refname)
1892 {
1893         unsigned char sha1[20];
1894         return !!resolve_ref(refname, sha1, 1, NULL);
1895 }
1896
1897 struct ref *find_ref_by_name(const struct ref *list, const char *name)
1898 {
1899         for ( ; list; list = list->next)
1900                 if (!strcmp(list->name, name))
1901                         return (struct ref *)list;
1902         return NULL;
1903 }
1904
1905 /*
1906  * generate a format suitable for scanf from a ref_rev_parse_rules
1907  * rule, that is replace the "%.*s" spec with a "%s" spec
1908  */
1909 static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
1910 {
1911         char *spec;
1912
1913         spec = strstr(rule, "%.*s");
1914         if (!spec || strstr(spec + 4, "%.*s"))
1915                 die("invalid rule in ref_rev_parse_rules: %s", rule);
1916
1917         /* copy all until spec */
1918         strncpy(scanf_fmt, rule, spec - rule);
1919         scanf_fmt[spec - rule] = '\0';
1920         /* copy new spec */
1921         strcat(scanf_fmt, "%s");
1922         /* copy remaining rule */
1923         strcat(scanf_fmt, spec + 4);
1924
1925         return;
1926 }
1927
1928 char *shorten_unambiguous_ref(const char *ref, int strict)
1929 {
1930         int i;
1931         static char **scanf_fmts;
1932         static int nr_rules;
1933         char *short_name;
1934
1935         /* pre generate scanf formats from ref_rev_parse_rules[] */
1936         if (!nr_rules) {
1937                 size_t total_len = 0;
1938
1939                 /* the rule list is NULL terminated, count them first */
1940                 for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
1941                         /* no +1 because strlen("%s") < strlen("%.*s") */
1942                         total_len += strlen(ref_rev_parse_rules[nr_rules]);
1943
1944                 scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
1945
1946                 total_len = 0;
1947                 for (i = 0; i < nr_rules; i++) {
1948                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
1949                                         + total_len;
1950                         gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
1951                         total_len += strlen(ref_rev_parse_rules[i]);
1952                 }
1953         }
1954
1955         /* bail out if there are no rules */
1956         if (!nr_rules)
1957                 return xstrdup(ref);
1958
1959         /* buffer for scanf result, at most ref must fit */
1960         short_name = xstrdup(ref);
1961
1962         /* skip first rule, it will always match */
1963         for (i = nr_rules - 1; i > 0 ; --i) {
1964                 int j;
1965                 int rules_to_fail = i;
1966                 int short_name_len;
1967
1968                 if (1 != sscanf(ref, scanf_fmts[i], short_name))
1969                         continue;
1970
1971                 short_name_len = strlen(short_name);
1972
1973                 /*
1974                  * in strict mode, all (except the matched one) rules
1975                  * must fail to resolve to a valid non-ambiguous ref
1976                  */
1977                 if (strict)
1978                         rules_to_fail = nr_rules;
1979
1980                 /*
1981                  * check if the short name resolves to a valid ref,
1982                  * but use only rules prior to the matched one
1983                  */
1984                 for (j = 0; j < rules_to_fail; j++) {
1985                         const char *rule = ref_rev_parse_rules[j];
1986                         unsigned char short_objectname[20];
1987                         char refname[PATH_MAX];
1988
1989                         /* skip matched rule */
1990                         if (i == j)
1991                                 continue;
1992
1993                         /*
1994                          * the short name is ambiguous, if it resolves
1995                          * (with this previous rule) to a valid ref
1996                          * read_ref() returns 0 on success
1997                          */
1998                         mksnpath(refname, sizeof(refname),
1999                                  rule, short_name_len, short_name);
2000                         if (!read_ref(refname, short_objectname))
2001                                 break;
2002                 }
2003
2004                 /*
2005                  * short name is non-ambiguous if all previous rules
2006                  * haven't resolved to a valid ref
2007                  */
2008                 if (j == rules_to_fail)
2009                         return short_name;
2010         }
2011
2012         free(short_name);
2013         return xstrdup(ref);
2014 }