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=0x01, ISPACKED=0x02 and ISBROKEN=0x04 are public interfaces */
   8 #define REF_KNOWS_PEELED 0x10
   9
  10 struct ref_entry {
  11         unsigned char flag; /* ISSYMREF? ISPACKED? */
  12         unsigned char sha1[20];
  13         unsigned char peeled[20];
  14         /* The full name of the reference (e.g., "refs/heads/master"): */
  15         char name[FLEX_ARRAY];
  16 };
  17
  18 struct ref_array {
  19         int nr, alloc;
  20         struct ref_entry **refs;
  21 };
  22
  23 /*
  24  * Parse one line from a packed-refs file.  Write the SHA1 to sha1.
  25  * Return a pointer to the refname within the line (null-terminated),
  26  * or NULL if there was a problem.
  27  */
  28 static const char *parse_ref_line(char *line, unsigned char *sha1)
  29 {
  30         /*
  31          * 42: the answer to everything.
  32          *
  33          * In this case, it happens to be the answer to
  34          *  40 (length of sha1 hex representation)
  35          *  +1 (space in between hex and name)
  36          *  +1 (newline at the end of the line)
  37          */
  38         int len = strlen(line) - 42;
  39
  40         if (len <= 0)
  41                 return NULL;
  42         if (get_sha1_hex(line, sha1) < 0)
  43                 return NULL;
  44         if (!isspace(line[40]))
  45                 return NULL;
  46         line += 41;
  47         if (isspace(*line))
  48                 return NULL;
  49         if (line[len] != '\n')
  50                 return NULL;
  51         line[len] = 0;
  52
  53         return line;
  54 }
  55
  56 static void add_ref(const char *refname, const unsigned char *sha1,
  57                     int flag, int check_name, struct ref_array *refs,
  58                     struct ref_entry **new_entry)
  59 {
  60         int len;
  61         struct ref_entry *entry;
  62
  63         /* Allocate it and add it in.. */
  64         len = strlen(refname) + 1;
  65         entry = xmalloc(sizeof(struct ref_entry) + len);
  66         hashcpy(entry->sha1, sha1);
  67         hashclr(entry->peeled);
  68         if (check_name &&
  69             check_refname_format(refname, REFNAME_ALLOW_ONELEVEL|REFNAME_DOT_COMPONENT))
  70                 die("Reference has invalid format: '%s'", refname);
  71         memcpy(entry->name, refname, len);
  72         entry->flag = flag;
  73         if (new_entry)
  74                 *new_entry = entry;
  75         ALLOC_GROW(refs->refs, refs->nr + 1, refs->alloc);
  76         refs->refs[refs->nr++] = entry;
  77 }
  78
  79 static int ref_entry_cmp(const void *a, const void *b)
  80 {
  81         struct ref_entry *one = *(struct ref_entry **)a;
  82         struct ref_entry *two = *(struct ref_entry **)b;
  83         return strcmp(one->name, two->name);
  84 }
  85
  86 static void sort_ref_array(struct ref_array *array)
  87 {
  88         int i = 0, j = 1;
  89
  90         /* Nothing to sort unless there are at least two entries */
  91         if (array->nr < 2)
  92                 return;
  93
  94         qsort(array->refs, array->nr, sizeof(*array->refs), ref_entry_cmp);
  95
  96         /* Remove any duplicates from the ref_array */
  97         for (; j < array->nr; j++) {
  98                 struct ref_entry *a = array->refs[i];
  99                 struct ref_entry *b = array->refs[j];
 100                 if (!strcmp(a->name, b->name)) {
 101                         if (hashcmp(a->sha1, b->sha1))
 102                                 die("Duplicated ref, and SHA1s don't match: %s",
 103                                     a->name);
 104                         warning("Duplicated ref: %s", a->name);
 105                         free(b);
 106                         continue;
 107                 }
 108                 i++;
 109                 array->refs[i] = array->refs[j];
 110         }
 111         array->nr = i + 1;
 112 }
 113
 114 static struct ref_entry *search_ref_array(struct ref_array *array, const char *refname)
 115 {
 116         struct ref_entry *e, **r;
 117         int len;
 118
 119         if (refname == NULL)
 120                 return NULL;
 121
 122         if (!array->nr)
 123                 return NULL;
 124
 125         len = strlen(refname) + 1;
 126         e = xmalloc(sizeof(struct ref_entry) + len);
 127         memcpy(e->name, refname, len);
 128
 129         r = bsearch(&e, array->refs, array->nr, sizeof(*array->refs), ref_entry_cmp);
 130
 131         free(e);
 132
 133         if (r == NULL)
 134                 return NULL;
 135
 136         return *r;
 137 }
 138
 139 /*
 140  * Future: need to be in "struct repository"
 141  * when doing a full libification.
 142  */
 143 static struct ref_cache {
 144         struct ref_cache *next;
 145         char did_loose;
 146         char did_packed;
 147         struct ref_array loose;
 148         struct ref_array packed;
 149         /* The submodule name, or "" for the main repo. */
 150         char name[FLEX_ARRAY];
 151 } *ref_cache;
 152
 153 static struct ref_entry *current_ref;
 154
 155 static struct ref_array extra_refs;
 156
 157 static void clear_ref_array(struct ref_array *array)
 158 {
 159         int i;
 160         for (i = 0; i < array->nr; i++)
 161                 free(array->refs[i]);
 162         free(array->refs);
 163         array->nr = array->alloc = 0;
 164         array->refs = NULL;
 165 }
 166
 167 static void clear_packed_ref_cache(struct ref_cache *refs)
 168 {
 169         if (refs->did_packed)
 170                 clear_ref_array(&refs->packed);
 171         refs->did_packed = 0;
 172 }
 173
 174 static void clear_loose_ref_cache(struct ref_cache *refs)
 175 {
 176         if (refs->did_loose)
 177                 clear_ref_array(&refs->loose);
 178         refs->did_loose = 0;
 179 }
 180
 181 static struct ref_cache *create_ref_cache(const char *submodule)
 182 {
 183         int len;
 184         struct ref_cache *refs;
 185         if (!submodule)
 186                 submodule = "";
 187         len = strlen(submodule) + 1;
 188         refs = xcalloc(1, sizeof(struct ref_cache) + len);
 189         memcpy(refs->name, submodule, len);
 190         return refs;
 191 }
 192
 193 /*
 194  * Return a pointer to a ref_cache for the specified submodule. For
 195  * the main repository, use submodule==NULL. The returned structure
 196  * will be allocated and initialized but not necessarily populated; it
 197  * should not be freed.
 198  */
 199 static struct ref_cache *get_ref_cache(const char *submodule)
 200 {
 201         struct ref_cache *refs = ref_cache;
 202         if (!submodule)
 203                 submodule = "";
 204         while (refs) {
 205                 if (!strcmp(submodule, refs->name))
 206                         return refs;
 207                 refs = refs->next;
 208         }
 209
 210         refs = create_ref_cache(submodule);
 211         refs->next = ref_cache;
 212         ref_cache = refs;
 213         return refs;
 214 }
 215
 216 void invalidate_ref_cache(const char *submodule)
 217 {
 218         struct ref_cache *refs = get_ref_cache(submodule);
 219         clear_packed_ref_cache(refs);
 220         clear_loose_ref_cache(refs);
 221 }
 222
 223 static void read_packed_refs(FILE *f, struct ref_array *array)
 224 {
 225         struct ref_entry *last = NULL;
 226         char refline[PATH_MAX];
 227         int flag = REF_ISPACKED;
 228
 229         while (fgets(refline, sizeof(refline), f)) {
 230                 unsigned char sha1[20];
 231                 const char *refname;
 232                 static const char header[] = "# pack-refs with:";
 233
 234                 if (!strncmp(refline, header, sizeof(header)-1)) {
 235                         const char *traits = refline + sizeof(header) - 1;
 236                         if (strstr(traits, " peeled "))
 237                                 flag |= REF_KNOWS_PEELED;
 238                         /* perhaps other traits later as well */
 239                         continue;
 240                 }
 241
 242                 refname = parse_ref_line(refline, sha1);
 243                 if (refname) {
 244                         add_ref(refname, sha1, flag, 1, array, &last);
 245                         continue;
 246                 }
 247                 if (last &&
 248                     refline[0] == '^' &&
 249                     strlen(refline) == 42 &&
 250                     refline[41] == '\n' &&
 251                     !get_sha1_hex(refline + 1, sha1))
 252                         hashcpy(last->peeled, sha1);
 253         }
 254         sort_ref_array(array);
 255 }
 256
 257 void add_extra_ref(const char *refname, const unsigned char *sha1, int flag)
 258 {
 259         add_ref(refname, sha1, flag, 0, &extra_refs, NULL);
 260 }
 261
 262 void clear_extra_refs(void)
 263 {
 264         clear_ref_array(&extra_refs);
 265 }
 266
 267 static struct ref_array *get_packed_refs(const char *submodule)
 268 {
 269         struct ref_cache *refs = get_ref_cache(submodule);
 270
 271         if (!refs->did_packed) {
 272                 const char *packed_refs_file;
 273                 FILE *f;
 274
 275                 if (submodule)
 276                         packed_refs_file = git_path_submodule(submodule, "packed-refs");
 277                 else
 278                         packed_refs_file = git_path("packed-refs");
 279                 f = fopen(packed_refs_file, "r");
 280                 if (f) {
 281                         read_packed_refs(f, &refs->packed);
 282                         fclose(f);
 283                 }
 284                 refs->did_packed = 1;
 285         }
 286         return &refs->packed;
 287 }
 288
 289 static void get_ref_dir(const char *submodule, const char *base,
 290                         struct ref_array *array)
 291 {
 292         DIR *dir;
 293         const char *path;
 294
 295         if (submodule)
 296                 path = git_path_submodule(submodule, "%s", base);
 297         else
 298                 path = git_path("%s", base);
 299
 300
 301         dir = opendir(path);
 302
 303         if (dir) {
 304                 struct dirent *de;
 305                 int baselen = strlen(base);
 306                 char *refname = xmalloc(baselen + 257);
 307
 308                 memcpy(refname, base, baselen);
 309                 if (baselen && base[baselen-1] != '/')
 310                         refname[baselen++] = '/';
 311
 312                 while ((de = readdir(dir)) != NULL) {
 313                         unsigned char sha1[20];
 314                         struct stat st;
 315                         int flag;
 316                         int namelen;
 317                         const char *refdir;
 318
 319                         if (de->d_name[0] == '.')
 320                                 continue;
 321                         namelen = strlen(de->d_name);
 322                         if (namelen > 255)
 323                                 continue;
 324                         if (has_extension(de->d_name, ".lock"))
 325                                 continue;
 326                         memcpy(refname + baselen, de->d_name, namelen+1);
 327                         refdir = submodule
 328                                 ? git_path_submodule(submodule, "%s", refname)
 329                                 : git_path("%s", refname);
 330                         if (stat(refdir, &st) < 0)
 331                                 continue;
 332                         if (S_ISDIR(st.st_mode)) {
 333                                 get_ref_dir(submodule, refname, array);
 334                                 continue;
 335                         }
 336                         if (submodule) {
 337                                 hashclr(sha1);
 338                                 flag = 0;
 339                                 if (resolve_gitlink_ref(submodule, refname, sha1) < 0) {
 340                                         hashclr(sha1);
 341                                         flag |= REF_ISBROKEN;
 342                                 }
 343                         } else if (read_ref_full(refname, sha1, 1, &flag)) {
 344                                 hashclr(sha1);
 345                                 flag |= REF_ISBROKEN;
 346                         }
 347                         add_ref(refname, sha1, flag, 1, array, NULL);
 348                 }
 349                 free(refname);
 350                 closedir(dir);
 351         }
 352 }
 353
 354 struct warn_if_dangling_data {
 355         FILE *fp;
 356         const char *refname;
 357         const char *msg_fmt;
 358 };
 359
 360 static int warn_if_dangling_symref(const char *refname, const unsigned char *sha1,
 361                                    int flags, void *cb_data)
 362 {
 363         struct warn_if_dangling_data *d = cb_data;
 364         const char *resolves_to;
 365         unsigned char junk[20];
 366
 367         if (!(flags & REF_ISSYMREF))
 368                 return 0;
 369
 370         resolves_to = resolve_ref(refname, junk, 0, NULL);
 371         if (!resolves_to || strcmp(resolves_to, d->refname))
 372                 return 0;
 373
 374         fprintf(d->fp, d->msg_fmt, refname);
 375         return 0;
 376 }
 377
 378 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 379 {
 380         struct warn_if_dangling_data data;
 381
 382         data.fp = fp;
 383         data.refname = refname;
 384         data.msg_fmt = msg_fmt;
 385         for_each_rawref(warn_if_dangling_symref, &data);
 386 }
 387
 388 static struct ref_array *get_loose_refs(const char *submodule)
 389 {
 390         struct ref_cache *refs = get_ref_cache(submodule);
 391
 392         if (!refs->did_loose) {
 393                 get_ref_dir(submodule, "refs", &refs->loose);
 394                 sort_ref_array(&refs->loose);
 395                 refs->did_loose = 1;
 396         }
 397         return &refs->loose;
 398 }
 399
 400 /* We allow "recursive" symbolic refs. Only within reason, though */
 401 #define MAXDEPTH 5
 402 #define MAXREFLEN (1024)
 403
 404 /*
 405  * Called by resolve_gitlink_ref_recursive() after it failed to read
 406  * from "name", which is "module/.git/<refname>". Find <refname> in
 407  * the packed-refs file for the submodule.
 408  */
 409 static int resolve_gitlink_packed_ref(char *name, int pathlen,
 410                                       const char *refname, unsigned char *sha1)
 411 {
 412         int retval = -1;
 413         struct ref_entry *ref;
 414         struct ref_array *array;
 415
 416         /* being defensive: resolve_gitlink_ref() did this for us */
 417         if (pathlen < 6 || memcmp(name + pathlen - 6, "/.git/", 6))
 418                 die("Oops");
 419         name[pathlen - 6] = '\0'; /* make it path to the submodule */
 420         array = get_packed_refs(name);
 421         ref = search_ref_array(array, refname);
 422         if (ref != NULL) {
 423                 memcpy(sha1, ref->sha1, 20);
 424                 retval = 0;
 425         }
 426         return retval;
 427 }
 428
 429 static int resolve_gitlink_ref_recursive(char *name, int pathlen,
 430                                          const char *refname, unsigned char *sha1,
 431                                          int recursion)
 432 {
 433         int fd, len = strlen(refname);
 434         char buffer[128], *p;
 435
 436         if (recursion > MAXDEPTH || len > MAXREFLEN)
 437                 return -1;
 438         memcpy(name + pathlen, refname, len+1);
 439         fd = open(name, O_RDONLY);
 440         if (fd < 0)
 441                 return resolve_gitlink_packed_ref(name, pathlen, refname, sha1);
 442
 443         len = read(fd, buffer, sizeof(buffer)-1);
 444         close(fd);
 445         if (len < 0)
 446                 return -1;
 447         while (len && isspace(buffer[len-1]))
 448                 len--;
 449         buffer[len] = 0;
 450
 451         /* Was it a detached head or an old-fashioned symlink? */
 452         if (!get_sha1_hex(buffer, sha1))
 453                 return 0;
 454
 455         /* Symref? */
 456         if (strncmp(buffer, "ref:", 4))
 457                 return -1;
 458         p = buffer + 4;
 459         while (isspace(*p))
 460                 p++;
 461
 462         return resolve_gitlink_ref_recursive(name, pathlen, p, sha1, recursion+1);
 463 }
 464
 465 int resolve_gitlink_ref(const char *path, const char *refname, unsigned char *sha1)
 466 {
 467         int len = strlen(path), retval;
 468         char *gitdir;
 469         const char *tmp;
 470
 471         while (len && path[len-1] == '/')
 472                 len--;
 473         if (!len)
 474                 return -1;
 475         gitdir = xmalloc(len + MAXREFLEN + 8);
 476         memcpy(gitdir, path, len);
 477         memcpy(gitdir + len, "/.git", 6);
 478         len += 5;
 479
 480         tmp = read_gitfile(gitdir);
 481         if (tmp) {
 482                 free(gitdir);
 483                 len = strlen(tmp);
 484                 gitdir = xmalloc(len + MAXREFLEN + 3);
 485                 memcpy(gitdir, tmp, len);
 486         }
 487         gitdir[len] = '/';
 488         gitdir[++len] = '\0';
 489         retval = resolve_gitlink_ref_recursive(gitdir, len, refname, sha1, 0);
 490         free(gitdir);
 491         return retval;
 492 }
 493
 494 /*
 495  * Try to read ref from the packed references.  On success, set sha1
 496  * and return 0; otherwise, return -1.
 497  */
 498 static int get_packed_ref(const char *refname, unsigned char *sha1)
 499 {
 500         struct ref_array *packed = get_packed_refs(NULL);
 501         struct ref_entry *entry = search_ref_array(packed, refname);
 502         if (entry) {
 503                 hashcpy(sha1, entry->sha1);
 504                 return 0;
 505         }
 506         return -1;
 507 }
 508
 509 const char *resolve_ref(const char *refname, unsigned char *sha1, int reading, int *flag)
 510 {
 511         int depth = MAXDEPTH;
 512         ssize_t len;
 513         char buffer[256];
 514         static char refname_buffer[256];
 515
 516         if (flag)
 517                 *flag = 0;
 518
 519         if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
 520                 return NULL;
 521
 522         for (;;) {
 523                 char path[PATH_MAX];
 524                 struct stat st;
 525                 char *buf;
 526                 int fd;
 527
 528                 if (--depth < 0)
 529                         return NULL;
 530
 531                 git_snpath(path, sizeof(path), "%s", refname);
 532
 533                 if (lstat(path, &st) < 0) {
 534                         if (errno != ENOENT)
 535                                 return NULL;
 536                         /*
 537                          * The loose reference file does not exist;
 538                          * check for a packed reference.
 539                          */
 540                         if (!get_packed_ref(refname, sha1)) {
 541                                 if (flag)
 542                                         *flag |= REF_ISPACKED;
 543                                 return refname;
 544                         }
 545                         /* The reference is not a packed reference, either. */
 546                         if (reading) {
 547                                 return NULL;
 548                         } else {
 549                                 hashclr(sha1);
 550                                 return refname;
 551                         }
 552                 }
 553
 554                 /* Follow "normalized" - ie "refs/.." symlinks by hand */
 555                 if (S_ISLNK(st.st_mode)) {
 556                         len = readlink(path, buffer, sizeof(buffer)-1);
 557                         if (len < 0)
 558                                 return NULL;
 559                         buffer[len] = 0;
 560                         if (!prefixcmp(buffer, "refs/") &&
 561                                         !check_refname_format(buffer, 0)) {
 562                                 strcpy(refname_buffer, buffer);
 563                                 refname = refname_buffer;
 564                                 if (flag)
 565                                         *flag |= REF_ISSYMREF;
 566                                 continue;
 567                         }
 568                 }
 569
 570                 /* Is it a directory? */
 571                 if (S_ISDIR(st.st_mode)) {
 572                         errno = EISDIR;
 573                         return NULL;
 574                 }
 575
 576                 /*
 577                  * Anything else, just open it and try to use it as
 578                  * a ref
 579                  */
 580                 fd = open(path, O_RDONLY);
 581                 if (fd < 0)
 582                         return NULL;
 583                 len = read_in_full(fd, buffer, sizeof(buffer)-1);
 584                 close(fd);
 585                 if (len < 0)
 586                         return NULL;
 587                 while (len && isspace(buffer[len-1]))
 588                         len--;
 589                 buffer[len] = '\0';
 590
 591                 /*
 592                  * Is it a symbolic ref?
 593                  */
 594                 if (prefixcmp(buffer, "ref:"))
 595                         break;
 596                 if (flag)
 597                         *flag |= REF_ISSYMREF;
 598                 buf = buffer + 4;
 599                 while (isspace(*buf))
 600                         buf++;
 601                 if (check_refname_format(buf, REFNAME_ALLOW_ONELEVEL)) {
 602                         if (flag)
 603                                 *flag |= REF_ISBROKEN;
 604                         return NULL;
 605                 }
 606                 refname = strcpy(refname_buffer, buf);
 607         }
 608         /* Please note that FETCH_HEAD has a second line containing other data. */
 609         if (get_sha1_hex(buffer, sha1) || (buffer[40] != '\0' && !isspace(buffer[40]))) {
 610                 if (flag)
 611                         *flag |= REF_ISBROKEN;
 612                 return NULL;
 613         }
 614         return refname;
 615 }
 616
 617 /* The argument to filter_refs */
 618 struct ref_filter {
 619         const char *pattern;
 620         each_ref_fn *fn;
 621         void *cb_data;
 622 };
 623
 624 int read_ref_full(const char *refname, unsigned char *sha1, int reading, int *flags)
 625 {
 626         if (resolve_ref(refname, sha1, reading, flags))
 627                 return 0;
 628         return -1;
 629 }
 630
 631 int read_ref(const char *refname, unsigned char *sha1)
 632 {
 633         return read_ref_full(refname, sha1, 1, NULL);
 634 }
 635
 636 #define DO_FOR_EACH_INCLUDE_BROKEN 01
 637 static int do_one_ref(const char *base, each_ref_fn fn, int trim,
 638                       int flags, void *cb_data, struct ref_entry *entry)
 639 {
 640         if (prefixcmp(entry->name, base))
 641                 return 0;
 642
 643         if (!(flags & DO_FOR_EACH_INCLUDE_BROKEN)) {
 644                 if (entry->flag & REF_ISBROKEN)
 645                         return 0; /* ignore broken refs e.g. dangling symref */
 646                 if (!has_sha1_file(entry->sha1)) {
 647                         error("%s does not point to a valid object!", entry->name);
 648                         return 0;
 649                 }
 650         }
 651         current_ref = entry;
 652         return fn(entry->name + trim, entry->sha1, entry->flag, cb_data);
 653 }
 654
 655 static int filter_refs(const char *refname, const unsigned char *sha1, int flags,
 656                        void *data)
 657 {
 658         struct ref_filter *filter = (struct ref_filter *)data;
 659         if (fnmatch(filter->pattern, refname, 0))
 660                 return 0;
 661         return filter->fn(refname, sha1, flags, filter->cb_data);
 662 }
 663
 664 int peel_ref(const char *refname, unsigned char *sha1)
 665 {
 666         int flag;
 667         unsigned char base[20];
 668         struct object *o;
 669
 670         if (current_ref && (current_ref->name == refname
 671                 || !strcmp(current_ref->name, refname))) {
 672                 if (current_ref->flag & REF_KNOWS_PEELED) {
 673                         hashcpy(sha1, current_ref->peeled);
 674                         return 0;
 675                 }
 676                 hashcpy(base, current_ref->sha1);
 677                 goto fallback;
 678         }
 679
 680         if (read_ref_full(refname, base, 1, &flag))
 681                 return -1;
 682
 683         if ((flag & REF_ISPACKED)) {
 684                 struct ref_array *array = get_packed_refs(NULL);
 685                 struct ref_entry *r = search_ref_array(array, refname);
 686
 687                 if (r != NULL && r->flag & REF_KNOWS_PEELED) {
 688                         hashcpy(sha1, r->peeled);
 689                         return 0;
 690                 }
 691         }
 692
 693 fallback:
 694         o = parse_object(base);
 695         if (o && o->type == OBJ_TAG) {
 696                 o = deref_tag(o, refname, 0);
 697                 if (o) {
 698                         hashcpy(sha1, o->sha1);
 699                         return 0;
 700                 }
 701         }
 702         return -1;
 703 }
 704
 705 static int do_for_each_ref(const char *submodule, const char *base, each_ref_fn fn,
 706                            int trim, int flags, void *cb_data)
 707 {
 708         int retval = 0, i, p = 0, l = 0;
 709         struct ref_array *packed = get_packed_refs(submodule);
 710         struct ref_array *loose = get_loose_refs(submodule);
 711
 712         struct ref_array *extra = &extra_refs;
 713
 714         for (i = 0; i < extra->nr; i++)
 715                 retval = do_one_ref(base, fn, trim, flags, cb_data, extra->refs[i]);
 716
 717         while (p < packed->nr && l < loose->nr) {
 718                 struct ref_entry *entry;
 719                 int cmp = strcmp(packed->refs[p]->name, loose->refs[l]->name);
 720                 if (!cmp) {
 721                         p++;
 722                         continue;
 723                 }
 724                 if (cmp > 0) {
 725                         entry = loose->refs[l++];
 726                 } else {
 727                         entry = packed->refs[p++];
 728                 }
 729                 retval = do_one_ref(base, fn, trim, flags, cb_data, entry);
 730                 if (retval)
 731                         goto end_each;
 732         }
 733
 734         if (l < loose->nr) {
 735                 p = l;
 736                 packed = loose;
 737         }
 738
 739         for (; p < packed->nr; p++) {
 740                 retval = do_one_ref(base, fn, trim, flags, cb_data, packed->refs[p]);
 741                 if (retval)
 742                         goto end_each;
 743         }
 744
 745 end_each:
 746         current_ref = NULL;
 747         return retval;
 748 }
 749
 750
 751 static int do_head_ref(const char *submodule, each_ref_fn fn, void *cb_data)
 752 {
 753         unsigned char sha1[20];
 754         int flag;
 755
 756         if (submodule) {
 757                 if (resolve_gitlink_ref(submodule, "HEAD", sha1) == 0)
 758                         return fn("HEAD", sha1, 0, cb_data);
 759
 760                 return 0;
 761         }
 762
 763         if (!read_ref_full("HEAD", sha1, 1, &flag))
 764                 return fn("HEAD", sha1, flag, cb_data);
 765
 766         return 0;
 767 }
 768
 769 int head_ref(each_ref_fn fn, void *cb_data)
 770 {
 771         return do_head_ref(NULL, fn, cb_data);
 772 }
 773
 774 int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 775 {
 776         return do_head_ref(submodule, fn, cb_data);
 777 }
 778
 779 int for_each_ref(each_ref_fn fn, void *cb_data)
 780 {
 781         return do_for_each_ref(NULL, "", fn, 0, 0, cb_data);
 782 }
 783
 784 int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 785 {
 786         return do_for_each_ref(submodule, "", fn, 0, 0, cb_data);
 787 }
 788
 789 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
 790 {
 791         return do_for_each_ref(NULL, prefix, fn, strlen(prefix), 0, cb_data);
 792 }
 793
 794 int for_each_ref_in_submodule(const char *submodule, const char *prefix,
 795                 each_ref_fn fn, void *cb_data)
 796 {
 797         return do_for_each_ref(submodule, prefix, fn, strlen(prefix), 0, cb_data);
 798 }
 799
 800 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 801 {
 802         return for_each_ref_in("refs/tags/", fn, cb_data);
 803 }
 804
 805 int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 806 {
 807         return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
 808 }
 809
 810 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 811 {
 812         return for_each_ref_in("refs/heads/", fn, cb_data);
 813 }
 814
 815 int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 816 {
 817         return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
 818 }
 819
 820 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 821 {
 822         return for_each_ref_in("refs/remotes/", fn, cb_data);
 823 }
 824
 825 int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 826 {
 827         return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
 828 }
 829
 830 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
 831 {
 832         return do_for_each_ref(NULL, "refs/replace/", fn, 13, 0, cb_data);
 833 }
 834
 835 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
 836 {
 837         struct strbuf buf = STRBUF_INIT;
 838         int ret = 0;
 839         unsigned char sha1[20];
 840         int flag;
 841
 842         strbuf_addf(&buf, "%sHEAD", get_git_namespace());
 843         if (!read_ref_full(buf.buf, sha1, 1, &flag))
 844                 ret = fn(buf.buf, sha1, flag, cb_data);
 845         strbuf_release(&buf);
 846
 847         return ret;
 848 }
 849
 850 int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
 851 {
 852         struct strbuf buf = STRBUF_INIT;
 853         int ret;
 854         strbuf_addf(&buf, "%srefs/", get_git_namespace());
 855         ret = do_for_each_ref(NULL, buf.buf, fn, 0, 0, cb_data);
 856         strbuf_release(&buf);
 857         return ret;
 858 }
 859
 860 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 861         const char *prefix, void *cb_data)
 862 {
 863         struct strbuf real_pattern = STRBUF_INIT;
 864         struct ref_filter filter;
 865         int ret;
 866
 867         if (!prefix && prefixcmp(pattern, "refs/"))
 868                 strbuf_addstr(&real_pattern, "refs/");
 869         else if (prefix)
 870                 strbuf_addstr(&real_pattern, prefix);
 871         strbuf_addstr(&real_pattern, pattern);
 872
 873         if (!has_glob_specials(pattern)) {
 874                 /* Append implied '/' '*' if not present. */
 875                 if (real_pattern.buf[real_pattern.len - 1] != '/')
 876                         strbuf_addch(&real_pattern, '/');
 877                 /* No need to check for '*', there is none. */
 878                 strbuf_addch(&real_pattern, '*');
 879         }
 880
 881         filter.pattern = real_pattern.buf;
 882         filter.fn = fn;
 883         filter.cb_data = cb_data;
 884         ret = for_each_ref(filter_refs, &filter);
 885
 886         strbuf_release(&real_pattern);
 887         return ret;
 888 }
 889
 890 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 891 {
 892         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
 893 }
 894
 895 int for_each_rawref(each_ref_fn fn, void *cb_data)
 896 {
 897         return do_for_each_ref(NULL, "", fn, 0,
 898                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
 899 }
 900
 901 /*
 902  * Make sure "ref" is something reasonable to have under ".git/refs/";
 903  * We do not like it if:
 904  *
 905  * - any path component of it begins with ".", or
 906  * - it has double dots "..", or
 907  * - it has ASCII control character, "~", "^", ":" or SP, anywhere, or
 908  * - it ends with a "/".
 909  * - it ends with ".lock"
 910  * - it contains a "\" (backslash)
 911  */
 912
 913 /* Return true iff ch is not allowed in reference names. */
 914 static inline int bad_ref_char(int ch)
 915 {
 916         if (((unsigned) ch) <= ' ' || ch == 0x7f ||
 917             ch == '~' || ch == '^' || ch == ':' || ch == '\\')
 918                 return 1;
 919         /* 2.13 Pattern Matching Notation */
 920         if (ch == '*' || ch == '?' || ch == '[') /* Unsupported */
 921                 return 1;
 922         return 0;
 923 }
 924
 925 /*
 926  * Try to read one refname component from the front of refname.  Return
 927  * the length of the component found, or -1 if the component is not
 928  * legal.
 929  */
 930 static int check_refname_component(const char *refname, int flags)
 931 {
 932         const char *cp;
 933         char last = '\0';
 934
 935         for (cp = refname; ; cp++) {
 936                 char ch = *cp;
 937                 if (ch == '\0' || ch == '/')
 938                         break;
 939                 if (bad_ref_char(ch))
 940                         return -1; /* Illegal character in refname. */
 941                 if (last == '.' && ch == '.')
 942                         return -1; /* Refname contains "..". */
 943                 if (last == '@' && ch == '{')
 944                         return -1; /* Refname contains "@{". */
 945                 last = ch;
 946         }
 947         if (cp == refname)
 948                 return -1; /* Component has zero length. */
 949         if (refname[0] == '.') {
 950                 if (!(flags & REFNAME_DOT_COMPONENT))
 951                         return -1; /* Component starts with '.'. */
 952                 /*
 953                  * Even if leading dots are allowed, don't allow "."
 954                  * as a component (".." is prevented by a rule above).
 955                  */
 956                 if (refname[1] == '\0')
 957                         return -1; /* Component equals ".". */
 958         }
 959         if (cp - refname >= 5 && !memcmp(cp - 5, ".lock", 5))
 960                 return -1; /* Refname ends with ".lock". */
 961         return cp - refname;
 962 }
 963
 964 int check_refname_format(const char *refname, int flags)
 965 {
 966         int component_len, component_count = 0;
 967
 968         while (1) {
 969                 /* We are at the start of a path component. */
 970                 component_len = check_refname_component(refname, flags);
 971                 if (component_len < 0) {
 972                         if ((flags & REFNAME_REFSPEC_PATTERN) &&
 973                                         refname[0] == '*' &&
 974                                         (refname[1] == '\0' || refname[1] == '/')) {
 975                                 /* Accept one wildcard as a full refname component. */
 976                                 flags &= ~REFNAME_REFSPEC_PATTERN;
 977                                 component_len = 1;
 978                         } else {
 979                                 return -1;
 980                         }
 981                 }
 982                 component_count++;
 983                 if (refname[component_len] == '\0')
 984                         break;
 985                 /* Skip to next component. */
 986                 refname += component_len + 1;
 987         }
 988
 989         if (refname[component_len - 1] == '.')
 990                 return -1; /* Refname ends with '.'. */
 991         if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
 992                 return -1; /* Refname has only one component. */
 993         return 0;
 994 }
 995
 996 const char *prettify_refname(const char *name)
 997 {
 998         return name + (
 999                 !prefixcmp(name, "refs/heads/") ? 11 :
1000                 !prefixcmp(name, "refs/tags/") ? 10 :
1001                 !prefixcmp(name, "refs/remotes/") ? 13 :
1002                 0);
1003 }
1004
1005 const char *ref_rev_parse_rules[] = {
1006         "%.*s",
1007         "refs/%.*s",
1008         "refs/tags/%.*s",
1009         "refs/heads/%.*s",
1010         "refs/remotes/%.*s",
1011         "refs/remotes/%.*s/HEAD",
1012         NULL
1013 };
1014
1015 int refname_match(const char *abbrev_name, const char *full_name, const char **rules)
1016 {
1017         const char **p;
1018         const int abbrev_name_len = strlen(abbrev_name);
1019
1020         for (p = rules; *p; p++) {
1021                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
1022                         return 1;
1023                 }
1024         }
1025
1026         return 0;
1027 }
1028
1029 static struct ref_lock *verify_lock(struct ref_lock *lock,
1030         const unsigned char *old_sha1, int mustexist)
1031 {
1032         if (read_ref_full(lock->ref_name, lock->old_sha1, mustexist, NULL)) {
1033                 error("Can't verify ref %s", lock->ref_name);
1034                 unlock_ref(lock);
1035                 return NULL;
1036         }
1037         if (hashcmp(lock->old_sha1, old_sha1)) {
1038                 error("Ref %s is at %s but expected %s", lock->ref_name,
1039                         sha1_to_hex(lock->old_sha1), sha1_to_hex(old_sha1));
1040                 unlock_ref(lock);
1041                 return NULL;
1042         }
1043         return lock;
1044 }
1045
1046 static int remove_empty_directories(const char *file)
1047 {
1048         /* we want to create a file but there is a directory there;
1049          * if that is an empty directory (or a directory that contains
1050          * only empty directories), remove them.
1051          */
1052         struct strbuf path;
1053         int result;
1054
1055         strbuf_init(&path, 20);
1056         strbuf_addstr(&path, file);
1057
1058         result = remove_dir_recursively(&path, REMOVE_DIR_EMPTY_ONLY);
1059
1060         strbuf_release(&path);
1061
1062         return result;
1063 }
1064
1065 /*
1066  * Return true iff a reference named refname could be created without
1067  * conflicting with the name of an existing reference.  If oldrefname
1068  * is non-NULL, ignore potential conflicts with oldrefname (e.g.,
1069  * because oldrefname is scheduled for deletion in the same
1070  * operation).
1071  */
1072 static int is_refname_available(const char *refname, const char *oldrefname,
1073                                 struct ref_array *array)
1074 {
1075         int i, namlen = strlen(refname); /* e.g. 'foo/bar' */
1076         for (i = 0; i < array->nr; i++ ) {
1077                 struct ref_entry *entry = array->refs[i];
1078                 /* entry->name could be 'foo' or 'foo/bar/baz' */
1079                 if (!oldrefname || strcmp(oldrefname, entry->name)) {
1080                         int len = strlen(entry->name);
1081                         int cmplen = (namlen < len) ? namlen : len;
1082                         const char *lead = (namlen < len) ? entry->name : refname;
1083                         if (!strncmp(refname, entry->name, cmplen) &&
1084                             lead[cmplen] == '/') {
1085                                 error("'%s' exists; cannot create '%s'",
1086                                       entry->name, refname);
1087                                 return 0;
1088                         }
1089                 }
1090         }
1091         return 1;
1092 }
1093
1094 /*
1095  * *string and *len will only be substituted, and *string returned (for
1096  * later free()ing) if the string passed in is a magic short-hand form
1097  * to name a branch.
1098  */
1099 static char *substitute_branch_name(const char **string, int *len)
1100 {
1101         struct strbuf buf = STRBUF_INIT;
1102         int ret = interpret_branch_name(*string, &buf);
1103
1104         if (ret == *len) {
1105                 size_t size;
1106                 *string = strbuf_detach(&buf, &size);
1107                 *len = size;
1108                 return (char *)*string;
1109         }
1110
1111         return NULL;
1112 }
1113
1114 int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
1115 {
1116         char *last_branch = substitute_branch_name(&str, &len);
1117         const char **p, *r;
1118         int refs_found = 0;
1119
1120         *ref = NULL;
1121         for (p = ref_rev_parse_rules; *p; p++) {
1122                 char fullref[PATH_MAX];
1123                 unsigned char sha1_from_ref[20];
1124                 unsigned char *this_result;
1125                 int flag;
1126
1127                 this_result = refs_found ? sha1_from_ref : sha1;
1128                 mksnpath(fullref, sizeof(fullref), *p, len, str);
1129                 r = resolve_ref(fullref, this_result, 1, &flag);
1130                 if (r) {
1131                         if (!refs_found++)
1132                                 *ref = xstrdup(r);
1133                         if (!warn_ambiguous_refs)
1134                                 break;
1135                 } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD")) {
1136                         warning("ignoring dangling symref %s.", fullref);
1137                 } else if ((flag & REF_ISBROKEN) && strchr(fullref, '/')) {
1138                         warning("ignoring broken ref %s.", fullref);
1139                 }
1140         }
1141         free(last_branch);
1142         return refs_found;
1143 }
1144
1145 int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
1146 {
1147         char *last_branch = substitute_branch_name(&str, &len);
1148         const char **p;
1149         int logs_found = 0;
1150
1151         *log = NULL;
1152         for (p = ref_rev_parse_rules; *p; p++) {
1153                 struct stat st;
1154                 unsigned char hash[20];
1155                 char path[PATH_MAX];
1156                 const char *ref, *it;
1157
1158                 mksnpath(path, sizeof(path), *p, len, str);
1159                 ref = resolve_ref(path, hash, 1, NULL);
1160                 if (!ref)
1161                         continue;
1162                 if (!stat(git_path("logs/%s", path), &st) &&
1163                     S_ISREG(st.st_mode))
1164                         it = path;
1165                 else if (strcmp(ref, path) &&
1166                          !stat(git_path("logs/%s", ref), &st) &&
1167                          S_ISREG(st.st_mode))
1168                         it = ref;
1169                 else
1170                         continue;
1171                 if (!logs_found++) {
1172                         *log = xstrdup(it);
1173                         hashcpy(sha1, hash);
1174                 }
1175                 if (!warn_ambiguous_refs)
1176                         break;
1177         }
1178         free(last_branch);
1179         return logs_found;
1180 }
1181
1182 static struct ref_lock *lock_ref_sha1_basic(const char *refname,
1183                                             const unsigned char *old_sha1,
1184                                             int flags, int *type_p)
1185 {
1186         char *ref_file;
1187         const char *orig_refname = refname;
1188         struct ref_lock *lock;
1189         int last_errno = 0;
1190         int type, lflags;
1191         int mustexist = (old_sha1 && !is_null_sha1(old_sha1));
1192         int missing = 0;
1193
1194         lock = xcalloc(1, sizeof(struct ref_lock));
1195         lock->lock_fd = -1;
1196
1197         refname = resolve_ref(refname, lock->old_sha1, mustexist, &type);
1198         if (!refname && errno == EISDIR) {
1199                 /* we are trying to lock foo but we used to
1200                  * have foo/bar which now does not exist;
1201                  * it is normal for the empty directory 'foo'
1202                  * to remain.
1203                  */
1204                 ref_file = git_path("%s", orig_refname);
1205                 if (remove_empty_directories(ref_file)) {
1206                         last_errno = errno;
1207                         error("there are still refs under '%s'", orig_refname);
1208                         goto error_return;
1209                 }
1210                 refname = resolve_ref(orig_refname, lock->old_sha1, mustexist, &type);
1211         }
1212         if (type_p)
1213             *type_p = type;
1214         if (!refname) {
1215                 last_errno = errno;
1216                 error("unable to resolve reference %s: %s",
1217                         orig_refname, strerror(errno));
1218                 goto error_return;
1219         }
1220         missing = is_null_sha1(lock->old_sha1);
1221         /* When the ref did not exist and we are creating it,
1222          * make sure there is no existing ref that is packed
1223          * whose name begins with our refname, nor a ref whose
1224          * name is a proper prefix of our refname.
1225          */
1226         if (missing &&
1227              !is_refname_available(refname, NULL, get_packed_refs(NULL))) {
1228                 last_errno = ENOTDIR;
1229                 goto error_return;
1230         }
1231
1232         lock->lk = xcalloc(1, sizeof(struct lock_file));
1233
1234         lflags = LOCK_DIE_ON_ERROR;
1235         if (flags & REF_NODEREF) {
1236                 refname = orig_refname;
1237                 lflags |= LOCK_NODEREF;
1238         }
1239         lock->ref_name = xstrdup(refname);
1240         lock->orig_ref_name = xstrdup(orig_refname);
1241         ref_file = git_path("%s", refname);
1242         if (missing)
1243                 lock->force_write = 1;
1244         if ((flags & REF_NODEREF) && (type & REF_ISSYMREF))
1245                 lock->force_write = 1;
1246
1247         if (safe_create_leading_directories(ref_file)) {
1248                 last_errno = errno;
1249                 error("unable to create directory for %s", ref_file);
1250                 goto error_return;
1251         }
1252
1253         lock->lock_fd = hold_lock_file_for_update(lock->lk, ref_file, lflags);
1254         return old_sha1 ? verify_lock(lock, old_sha1, mustexist) : lock;
1255
1256  error_return:
1257         unlock_ref(lock);
1258         errno = last_errno;
1259         return NULL;
1260 }
1261
1262 struct ref_lock *lock_ref_sha1(const char *refname, const unsigned char *old_sha1)
1263 {
1264         char refpath[PATH_MAX];
1265         if (check_refname_format(refname, 0))
1266                 return NULL;
1267         strcpy(refpath, mkpath("refs/%s", refname));
1268         return lock_ref_sha1_basic(refpath, old_sha1, 0, NULL);
1269 }
1270
1271 struct ref_lock *lock_any_ref_for_update(const char *refname,
1272                                          const unsigned char *old_sha1, int flags)
1273 {
1274         if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL))
1275                 return NULL;
1276         return lock_ref_sha1_basic(refname, old_sha1, flags, NULL);
1277 }
1278
1279 static struct lock_file packlock;
1280
1281 static int repack_without_ref(const char *refname)
1282 {
1283         struct ref_array *packed;
1284         struct ref_entry *ref;
1285         int fd, i;
1286
1287         packed = get_packed_refs(NULL);
1288         ref = search_ref_array(packed, refname);
1289         if (ref == NULL)
1290                 return 0;
1291         fd = hold_lock_file_for_update(&packlock, git_path("packed-refs"), 0);
1292         if (fd < 0) {
1293                 unable_to_lock_error(git_path("packed-refs"), errno);
1294                 return error("cannot delete '%s' from packed refs", refname);
1295         }
1296
1297         for (i = 0; i < packed->nr; i++) {
1298                 char line[PATH_MAX + 100];
1299                 int len;
1300
1301                 ref = packed->refs[i];
1302
1303                 if (!strcmp(refname, ref->name))
1304                         continue;
1305                 len = snprintf(line, sizeof(line), "%s %s\n",
1306                                sha1_to_hex(ref->sha1), ref->name);
1307                 /* this should not happen but just being defensive */
1308                 if (len > sizeof(line))
1309                         die("too long a refname '%s'", ref->name);
1310                 write_or_die(fd, line, len);
1311         }
1312         return commit_lock_file(&packlock);
1313 }
1314
1315 int delete_ref(const char *refname, const unsigned char *sha1, int delopt)
1316 {
1317         struct ref_lock *lock;
1318         int err, i = 0, ret = 0, flag = 0;
1319
1320         lock = lock_ref_sha1_basic(refname, sha1, 0, &flag);
1321         if (!lock)
1322                 return 1;
1323         if (!(flag & REF_ISPACKED) || flag & REF_ISSYMREF) {
1324                 /* loose */
1325                 const char *path;
1326
1327                 if (!(delopt & REF_NODEREF)) {
1328                         i = strlen(lock->lk->filename) - 5; /* .lock */
1329                         lock->lk->filename[i] = 0;
1330                         path = lock->lk->filename;
1331                 } else {
1332                         path = git_path("%s", refname);
1333                 }
1334                 err = unlink_or_warn(path);
1335                 if (err && errno != ENOENT)
1336                         ret = 1;
1337
1338                 if (!(delopt & REF_NODEREF))
1339                         lock->lk->filename[i] = '.';
1340         }
1341         /* removing the loose one could have resurrected an earlier
1342          * packed one.  Also, if it was not loose we need to repack
1343          * without it.
1344          */
1345         ret |= repack_without_ref(refname);
1346
1347         unlink_or_warn(git_path("logs/%s", lock->ref_name));
1348         invalidate_ref_cache(NULL);
1349         unlock_ref(lock);
1350         return ret;
1351 }
1352
1353 /*
1354  * People using contrib's git-new-workdir have .git/logs/refs ->
1355  * /some/other/path/.git/logs/refs, and that may live on another device.
1356  *
1357  * IOW, to avoid cross device rename errors, the temporary renamed log must
1358  * live into logs/refs.
1359  */
1360 #define TMP_RENAMED_LOG  "logs/refs/.tmp-renamed-log"
1361
1362 int rename_ref(const char *oldrefname, const char *newrefname, const char *logmsg)
1363 {
1364         unsigned char sha1[20], orig_sha1[20];
1365         int flag = 0, logmoved = 0;
1366         struct ref_lock *lock;
1367         struct stat loginfo;
1368         int log = !lstat(git_path("logs/%s", oldrefname), &loginfo);
1369         const char *symref = NULL;
1370
1371         if (log && S_ISLNK(loginfo.st_mode))
1372                 return error("reflog for %s is a symlink", oldrefname);
1373
1374         symref = resolve_ref(oldrefname, orig_sha1, 1, &flag);
1375         if (flag & REF_ISSYMREF)
1376                 return error("refname %s is a symbolic ref, renaming it is not supported",
1377                         oldrefname);
1378         if (!symref)
1379                 return error("refname %s not found", oldrefname);
1380
1381         if (!is_refname_available(newrefname, oldrefname, get_packed_refs(NULL)))
1382                 return 1;
1383
1384         if (!is_refname_available(newrefname, oldrefname, get_loose_refs(NULL)))
1385                 return 1;
1386
1387         if (log && rename(git_path("logs/%s", oldrefname), git_path(TMP_RENAMED_LOG)))
1388                 return error("unable to move logfile logs/%s to "TMP_RENAMED_LOG": %s",
1389                         oldrefname, strerror(errno));
1390
1391         if (delete_ref(oldrefname, orig_sha1, REF_NODEREF)) {
1392                 error("unable to delete old %s", oldrefname);
1393                 goto rollback;
1394         }
1395
1396         if (!read_ref_full(newrefname, sha1, 1, &flag) &&
1397             delete_ref(newrefname, sha1, REF_NODEREF)) {
1398                 if (errno==EISDIR) {
1399                         if (remove_empty_directories(git_path("%s", newrefname))) {
1400                                 error("Directory not empty: %s", newrefname);
1401                                 goto rollback;
1402                         }
1403                 } else {
1404                         error("unable to delete existing %s", newrefname);
1405                         goto rollback;
1406                 }
1407         }
1408
1409         if (log && safe_create_leading_directories(git_path("logs/%s", newrefname))) {
1410                 error("unable to create directory for %s", newrefname);
1411                 goto rollback;
1412         }
1413
1414  retry:
1415         if (log && rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", newrefname))) {
1416                 if (errno==EISDIR || errno==ENOTDIR) {
1417                         /*
1418                          * rename(a, b) when b is an existing
1419                          * directory ought to result in ISDIR, but
1420                          * Solaris 5.8 gives ENOTDIR.  Sheesh.
1421                          */
1422                         if (remove_empty_directories(git_path("logs/%s", newrefname))) {
1423                                 error("Directory not empty: logs/%s", newrefname);
1424                                 goto rollback;
1425                         }
1426                         goto retry;
1427                 } else {
1428                         error("unable to move logfile "TMP_RENAMED_LOG" to logs/%s: %s",
1429                                 newrefname, strerror(errno));
1430                         goto rollback;
1431                 }
1432         }
1433         logmoved = log;
1434
1435         lock = lock_ref_sha1_basic(newrefname, NULL, 0, NULL);
1436         if (!lock) {
1437                 error("unable to lock %s for update", newrefname);
1438                 goto rollback;
1439         }
1440         lock->force_write = 1;
1441         hashcpy(lock->old_sha1, orig_sha1);
1442         if (write_ref_sha1(lock, orig_sha1, logmsg)) {
1443                 error("unable to write current sha1 into %s", newrefname);
1444                 goto rollback;
1445         }
1446
1447         return 0;
1448
1449  rollback:
1450         lock = lock_ref_sha1_basic(oldrefname, NULL, 0, NULL);
1451         if (!lock) {
1452                 error("unable to lock %s for rollback", oldrefname);
1453                 goto rollbacklog;
1454         }
1455
1456         lock->force_write = 1;
1457         flag = log_all_ref_updates;
1458         log_all_ref_updates = 0;
1459         if (write_ref_sha1(lock, orig_sha1, NULL))
1460                 error("unable to write current sha1 into %s", oldrefname);
1461         log_all_ref_updates = flag;
1462
1463  rollbacklog:
1464         if (logmoved && rename(git_path("logs/%s", newrefname), git_path("logs/%s", oldrefname)))
1465                 error("unable to restore logfile %s from %s: %s",
1466                         oldrefname, newrefname, strerror(errno));
1467         if (!logmoved && log &&
1468             rename(git_path(TMP_RENAMED_LOG), git_path("logs/%s", oldrefname)))
1469                 error("unable to restore logfile %s from "TMP_RENAMED_LOG": %s",
1470                         oldrefname, strerror(errno));
1471
1472         return 1;
1473 }
1474
1475 int close_ref(struct ref_lock *lock)
1476 {
1477         if (close_lock_file(lock->lk))
1478                 return -1;
1479         lock->lock_fd = -1;
1480         return 0;
1481 }
1482
1483 int commit_ref(struct ref_lock *lock)
1484 {
1485         if (commit_lock_file(lock->lk))
1486                 return -1;
1487         lock->lock_fd = -1;
1488         return 0;
1489 }
1490
1491 void unlock_ref(struct ref_lock *lock)
1492 {
1493         /* Do not free lock->lk -- atexit() still looks at them */
1494         if (lock->lk)
1495                 rollback_lock_file(lock->lk);
1496         free(lock->ref_name);
1497         free(lock->orig_ref_name);
1498         free(lock);
1499 }
1500
1501 /*
1502  * copy the reflog message msg to buf, which has been allocated sufficiently
1503  * large, while cleaning up the whitespaces.  Especially, convert LF to space,
1504  * because reflog file is one line per entry.
1505  */
1506 static int copy_msg(char *buf, const char *msg)
1507 {
1508         char *cp = buf;
1509         char c;
1510         int wasspace = 1;
1511
1512         *cp++ = '\t';
1513         while ((c = *msg++)) {
1514                 if (wasspace && isspace(c))
1515                         continue;
1516                 wasspace = isspace(c);
1517                 if (wasspace)
1518                         c = ' ';
1519                 *cp++ = c;
1520         }
1521         while (buf < cp && isspace(cp[-1]))
1522                 cp--;
1523         *cp++ = '\n';
1524         return cp - buf;
1525 }
1526
1527 int log_ref_setup(const char *refname, char *logfile, int bufsize)
1528 {
1529         int logfd, oflags = O_APPEND | O_WRONLY;
1530
1531         git_snpath(logfile, bufsize, "logs/%s", refname);
1532         if (log_all_ref_updates &&
1533             (!prefixcmp(refname, "refs/heads/") ||
1534              !prefixcmp(refname, "refs/remotes/") ||
1535              !prefixcmp(refname, "refs/notes/") ||
1536              !strcmp(refname, "HEAD"))) {
1537                 if (safe_create_leading_directories(logfile) < 0)
1538                         return error("unable to create directory for %s",
1539                                      logfile);
1540                 oflags |= O_CREAT;
1541         }
1542
1543         logfd = open(logfile, oflags, 0666);
1544         if (logfd < 0) {
1545                 if (!(oflags & O_CREAT) && errno == ENOENT)
1546                         return 0;
1547
1548                 if ((oflags & O_CREAT) && errno == EISDIR) {
1549                         if (remove_empty_directories(logfile)) {
1550                                 return error("There are still logs under '%s'",
1551                                              logfile);
1552                         }
1553                         logfd = open(logfile, oflags, 0666);
1554                 }
1555
1556                 if (logfd < 0)
1557                         return error("Unable to append to %s: %s",
1558                                      logfile, strerror(errno));
1559         }
1560
1561         adjust_shared_perm(logfile);
1562         close(logfd);
1563         return 0;
1564 }
1565
1566 static int log_ref_write(const char *refname, const unsigned char *old_sha1,
1567                          const unsigned char *new_sha1, const char *msg)
1568 {
1569         int logfd, result, written, oflags = O_APPEND | O_WRONLY;
1570         unsigned maxlen, len;
1571         int msglen;
1572         char log_file[PATH_MAX];
1573         char *logrec;
1574         const char *committer;
1575
1576         if (log_all_ref_updates < 0)
1577                 log_all_ref_updates = !is_bare_repository();
1578
1579         result = log_ref_setup(refname, log_file, sizeof(log_file));
1580         if (result)
1581                 return result;
1582
1583         logfd = open(log_file, oflags);
1584         if (logfd < 0)
1585                 return 0;
1586         msglen = msg ? strlen(msg) : 0;
1587         committer = git_committer_info(0);
1588         maxlen = strlen(committer) + msglen + 100;
1589         logrec = xmalloc(maxlen);
1590         len = sprintf(logrec, "%s %s %s\n",
1591                       sha1_to_hex(old_sha1),
1592                       sha1_to_hex(new_sha1),
1593                       committer);
1594         if (msglen)
1595                 len += copy_msg(logrec + len - 1, msg) - 1;
1596         written = len <= maxlen ? write_in_full(logfd, logrec, len) : -1;
1597         free(logrec);
1598         if (close(logfd) != 0 || written != len)
1599                 return error("Unable to append to %s", log_file);
1600         return 0;
1601 }
1602
1603 static int is_branch(const char *refname)
1604 {
1605         return !strcmp(refname, "HEAD") || !prefixcmp(refname, "refs/heads/");
1606 }
1607
1608 int write_ref_sha1(struct ref_lock *lock,
1609         const unsigned char *sha1, const char *logmsg)
1610 {
1611         static char term = '\n';
1612         struct object *o;
1613
1614         if (!lock)
1615                 return -1;
1616         if (!lock->force_write && !hashcmp(lock->old_sha1, sha1)) {
1617                 unlock_ref(lock);
1618                 return 0;
1619         }
1620         o = parse_object(sha1);
1621         if (!o) {
1622                 error("Trying to write ref %s with nonexistent object %s",
1623                         lock->ref_name, sha1_to_hex(sha1));
1624                 unlock_ref(lock);
1625                 return -1;
1626         }
1627         if (o->type != OBJ_COMMIT && is_branch(lock->ref_name)) {
1628                 error("Trying to write non-commit object %s to branch %s",
1629                         sha1_to_hex(sha1), lock->ref_name);
1630                 unlock_ref(lock);
1631                 return -1;
1632         }
1633         if (write_in_full(lock->lock_fd, sha1_to_hex(sha1), 40) != 40 ||
1634             write_in_full(lock->lock_fd, &term, 1) != 1
1635                 || close_ref(lock) < 0) {
1636                 error("Couldn't write %s", lock->lk->filename);
1637                 unlock_ref(lock);
1638                 return -1;
1639         }
1640         clear_loose_ref_cache(get_ref_cache(NULL));
1641         if (log_ref_write(lock->ref_name, lock->old_sha1, sha1, logmsg) < 0 ||
1642             (strcmp(lock->ref_name, lock->orig_ref_name) &&
1643              log_ref_write(lock->orig_ref_name, lock->old_sha1, sha1, logmsg) < 0)) {
1644                 unlock_ref(lock);
1645                 return -1;
1646         }
1647         if (strcmp(lock->orig_ref_name, "HEAD") != 0) {
1648                 /*
1649                  * Special hack: If a branch is updated directly and HEAD
1650                  * points to it (may happen on the remote side of a push
1651                  * for example) then logically the HEAD reflog should be
1652                  * updated too.
1653                  * A generic solution implies reverse symref information,
1654                  * but finding all symrefs pointing to the given branch
1655                  * would be rather costly for this rare event (the direct
1656                  * update of a branch) to be worth it.  So let's cheat and
1657                  * check with HEAD only which should cover 99% of all usage
1658                  * scenarios (even 100% of the default ones).
1659                  */
1660                 unsigned char head_sha1[20];
1661                 int head_flag;
1662                 const char *head_ref;
1663                 head_ref = resolve_ref("HEAD", head_sha1, 1, &head_flag);
1664                 if (head_ref && (head_flag & REF_ISSYMREF) &&
1665                     !strcmp(head_ref, lock->ref_name))
1666                         log_ref_write("HEAD", lock->old_sha1, sha1, logmsg);
1667         }
1668         if (commit_ref(lock)) {
1669                 error("Couldn't set %s", lock->ref_name);
1670                 unlock_ref(lock);
1671                 return -1;
1672         }
1673         unlock_ref(lock);
1674         return 0;
1675 }
1676
1677 int create_symref(const char *ref_target, const char *refs_heads_master,
1678                   const char *logmsg)
1679 {
1680         const char *lockpath;
1681         char ref[1000];
1682         int fd, len, written;
1683         char *git_HEAD = git_pathdup("%s", ref_target);
1684         unsigned char old_sha1[20], new_sha1[20];
1685
1686         if (logmsg && read_ref(ref_target, old_sha1))
1687                 hashclr(old_sha1);
1688
1689         if (safe_create_leading_directories(git_HEAD) < 0)
1690                 return error("unable to create directory for %s", git_HEAD);
1691
1692 #ifndef NO_SYMLINK_HEAD
1693         if (prefer_symlink_refs) {
1694                 unlink(git_HEAD);
1695                 if (!symlink(refs_heads_master, git_HEAD))
1696                         goto done;
1697                 fprintf(stderr, "no symlink - falling back to symbolic ref\n");
1698         }
1699 #endif
1700
1701         len = snprintf(ref, sizeof(ref), "ref: %s\n", refs_heads_master);
1702         if (sizeof(ref) <= len) {
1703                 error("refname too long: %s", refs_heads_master);
1704                 goto error_free_return;
1705         }
1706         lockpath = mkpath("%s.lock", git_HEAD);
1707         fd = open(lockpath, O_CREAT | O_EXCL | O_WRONLY, 0666);
1708         if (fd < 0) {
1709                 error("Unable to open %s for writing", lockpath);
1710                 goto error_free_return;
1711         }
1712         written = write_in_full(fd, ref, len);
1713         if (close(fd) != 0 || written != len) {
1714                 error("Unable to write to %s", lockpath);
1715                 goto error_unlink_return;
1716         }
1717         if (rename(lockpath, git_HEAD) < 0) {
1718                 error("Unable to create %s", git_HEAD);
1719                 goto error_unlink_return;
1720         }
1721         if (adjust_shared_perm(git_HEAD)) {
1722                 error("Unable to fix permissions on %s", lockpath);
1723         error_unlink_return:
1724                 unlink_or_warn(lockpath);
1725         error_free_return:
1726                 free(git_HEAD);
1727                 return -1;
1728         }
1729
1730 #ifndef NO_SYMLINK_HEAD
1731         done:
1732 #endif
1733         if (logmsg && !read_ref(refs_heads_master, new_sha1))
1734                 log_ref_write(ref_target, old_sha1, new_sha1, logmsg);
1735
1736         free(git_HEAD);
1737         return 0;
1738 }
1739
1740 static char *ref_msg(const char *line, const char *endp)
1741 {
1742         const char *ep;
1743         line += 82;
1744         ep = memchr(line, '\n', endp - line);
1745         if (!ep)
1746                 ep = endp;
1747         return xmemdupz(line, ep - line);
1748 }
1749
1750 int read_ref_at(const char *refname, unsigned long at_time, int cnt,
1751                 unsigned char *sha1, char **msg,
1752                 unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
1753 {
1754         const char *logfile, *logdata, *logend, *rec, *lastgt, *lastrec;
1755         char *tz_c;
1756         int logfd, tz, reccnt = 0;
1757         struct stat st;
1758         unsigned long date;
1759         unsigned char logged_sha1[20];
1760         void *log_mapped;
1761         size_t mapsz;
1762
1763         logfile = git_path("logs/%s", refname);
1764         logfd = open(logfile, O_RDONLY, 0);
1765         if (logfd < 0)
1766                 die_errno("Unable to read log '%s'", logfile);
1767         fstat(logfd, &st);
1768         if (!st.st_size)
1769                 die("Log %s is empty.", logfile);
1770         mapsz = xsize_t(st.st_size);
1771         log_mapped = xmmap(NULL, mapsz, PROT_READ, MAP_PRIVATE, logfd, 0);
1772         logdata = log_mapped;
1773         close(logfd);
1774
1775         lastrec = NULL;
1776         rec = logend = logdata + st.st_size;
1777         while (logdata < rec) {
1778                 reccnt++;
1779                 if (logdata < rec && *(rec-1) == '\n')
1780                         rec--;
1781                 lastgt = NULL;
1782                 while (logdata < rec && *(rec-1) != '\n') {
1783                         rec--;
1784                         if (*rec == '>')
1785                                 lastgt = rec;
1786                 }
1787                 if (!lastgt)
1788                         die("Log %s is corrupt.", logfile);
1789                 date = strtoul(lastgt + 1, &tz_c, 10);
1790                 if (date <= at_time || cnt == 0) {
1791                         tz = strtoul(tz_c, NULL, 10);
1792                         if (msg)
1793                                 *msg = ref_msg(rec, logend);
1794                         if (cutoff_time)
1795                                 *cutoff_time = date;
1796                         if (cutoff_tz)
1797                                 *cutoff_tz = tz;
1798                         if (cutoff_cnt)
1799                                 *cutoff_cnt = reccnt - 1;
1800                         if (lastrec) {
1801                                 if (get_sha1_hex(lastrec, logged_sha1))
1802                                         die("Log %s is corrupt.", logfile);
1803                                 if (get_sha1_hex(rec + 41, sha1))
1804                                         die("Log %s is corrupt.", logfile);
1805                                 if (hashcmp(logged_sha1, sha1)) {
1806                                         warning("Log %s has gap after %s.",
1807                                                 logfile, show_date(date, tz, DATE_RFC2822));
1808                                 }
1809                         }
1810                         else if (date == at_time) {
1811                                 if (get_sha1_hex(rec + 41, sha1))
1812                                         die("Log %s is corrupt.", logfile);
1813                         }
1814                         else {
1815                                 if (get_sha1_hex(rec + 41, logged_sha1))
1816                                         die("Log %s is corrupt.", logfile);
1817                                 if (hashcmp(logged_sha1, sha1)) {
1818                                         warning("Log %s unexpectedly ended on %s.",
1819                                                 logfile, show_date(date, tz, DATE_RFC2822));
1820                                 }
1821                         }
1822                         munmap(log_mapped, mapsz);
1823                         return 0;
1824                 }
1825                 lastrec = rec;
1826                 if (cnt > 0)
1827                         cnt--;
1828         }
1829
1830         rec = logdata;
1831         while (rec < logend && *rec != '>' && *rec != '\n')
1832                 rec++;
1833         if (rec == logend || *rec == '\n')
1834                 die("Log %s is corrupt.", logfile);
1835         date = strtoul(rec + 1, &tz_c, 10);
1836         tz = strtoul(tz_c, NULL, 10);
1837         if (get_sha1_hex(logdata, sha1))
1838                 die("Log %s is corrupt.", logfile);
1839         if (is_null_sha1(sha1)) {
1840                 if (get_sha1_hex(logdata + 41, sha1))
1841                         die("Log %s is corrupt.", logfile);
1842         }
1843         if (msg)
1844                 *msg = ref_msg(logdata, logend);
1845         munmap(log_mapped, mapsz);
1846
1847         if (cutoff_time)
1848                 *cutoff_time = date;
1849         if (cutoff_tz)
1850                 *cutoff_tz = tz;
1851         if (cutoff_cnt)
1852                 *cutoff_cnt = reccnt;
1853         return 1;
1854 }
1855
1856 int for_each_recent_reflog_ent(const char *refname, each_reflog_ent_fn fn, long ofs, void *cb_data)
1857 {
1858         const char *logfile;
1859         FILE *logfp;
1860         struct strbuf sb = STRBUF_INIT;
1861         int ret = 0;
1862
1863         logfile = git_path("logs/%s", refname);
1864         logfp = fopen(logfile, "r");
1865         if (!logfp)
1866                 return -1;
1867
1868         if (ofs) {
1869                 struct stat statbuf;
1870                 if (fstat(fileno(logfp), &statbuf) ||
1871                     statbuf.st_size < ofs ||
1872                     fseek(logfp, -ofs, SEEK_END) ||
1873                     strbuf_getwholeline(&sb, logfp, '\n')) {
1874                         fclose(logfp);
1875                         strbuf_release(&sb);
1876                         return -1;
1877                 }
1878         }
1879
1880         while (!strbuf_getwholeline(&sb, logfp, '\n')) {
1881                 unsigned char osha1[20], nsha1[20];
1882                 char *email_end, *message;
1883                 unsigned long timestamp;
1884                 int tz;
1885
1886                 /* old SP new SP name <email> SP time TAB msg LF */
1887                 if (sb.len < 83 || sb.buf[sb.len - 1] != '\n' ||
1888                     get_sha1_hex(sb.buf, osha1) || sb.buf[40] != ' ' ||
1889                     get_sha1_hex(sb.buf + 41, nsha1) || sb.buf[81] != ' ' ||
1890                     !(email_end = strchr(sb.buf + 82, '>')) ||
1891                     email_end[1] != ' ' ||
1892                     !(timestamp = strtoul(email_end + 2, &message, 10)) ||
1893                     !message || message[0] != ' ' ||
1894                     (message[1] != '+' && message[1] != '-') ||
1895                     !isdigit(message[2]) || !isdigit(message[3]) ||
1896                     !isdigit(message[4]) || !isdigit(message[5]))
1897                         continue; /* corrupt? */
1898                 email_end[1] = '\0';
1899                 tz = strtol(message + 1, NULL, 10);
1900                 if (message[6] != '\t')
1901                         message += 6;
1902                 else
1903                         message += 7;
1904                 ret = fn(osha1, nsha1, sb.buf + 82, timestamp, tz, message,
1905                          cb_data);
1906                 if (ret)
1907                         break;
1908         }
1909         fclose(logfp);
1910         strbuf_release(&sb);
1911         return ret;
1912 }
1913
1914 int for_each_reflog_ent(const char *refname, each_reflog_ent_fn fn, void *cb_data)
1915 {
1916         return for_each_recent_reflog_ent(refname, fn, 0, cb_data);
1917 }
1918
1919 static int do_for_each_reflog(const char *base, each_ref_fn fn, void *cb_data)
1920 {
1921         DIR *dir = opendir(git_path("logs/%s", base));
1922         int retval = 0;
1923
1924         if (dir) {
1925                 struct dirent *de;
1926                 int baselen = strlen(base);
1927                 char *log = xmalloc(baselen + 257);
1928
1929                 memcpy(log, base, baselen);
1930                 if (baselen && base[baselen-1] != '/')
1931                         log[baselen++] = '/';
1932
1933                 while ((de = readdir(dir)) != NULL) {
1934                         struct stat st;
1935                         int namelen;
1936
1937                         if (de->d_name[0] == '.')
1938                                 continue;
1939                         namelen = strlen(de->d_name);
1940                         if (namelen > 255)
1941                                 continue;
1942                         if (has_extension(de->d_name, ".lock"))
1943                                 continue;
1944                         memcpy(log + baselen, de->d_name, namelen+1);
1945                         if (stat(git_path("logs/%s", log), &st) < 0)
1946                                 continue;
1947                         if (S_ISDIR(st.st_mode)) {
1948                                 retval = do_for_each_reflog(log, fn, cb_data);
1949                         } else {
1950                                 unsigned char sha1[20];
1951                                 if (read_ref_full(log, sha1, 0, NULL))
1952                                         retval = error("bad ref for %s", log);
1953                                 else
1954                                         retval = fn(log, sha1, 0, cb_data);
1955                         }
1956                         if (retval)
1957                                 break;
1958                 }
1959                 free(log);
1960                 closedir(dir);
1961         }
1962         else if (*base)
1963                 return errno;
1964         return retval;
1965 }
1966
1967 int for_each_reflog(each_ref_fn fn, void *cb_data)
1968 {
1969         return do_for_each_reflog("", fn, cb_data);
1970 }
1971
1972 int update_ref(const char *action, const char *refname,
1973                 const unsigned char *sha1, const unsigned char *oldval,
1974                 int flags, enum action_on_err onerr)
1975 {
1976         static struct ref_lock *lock;
1977         lock = lock_any_ref_for_update(refname, oldval, flags);
1978         if (!lock) {
1979                 const char *str = "Cannot lock the ref '%s'.";
1980                 switch (onerr) {
1981                 case MSG_ON_ERR: error(str, refname); break;
1982                 case DIE_ON_ERR: die(str, refname); break;
1983                 case QUIET_ON_ERR: break;
1984                 }
1985                 return 1;
1986         }
1987         if (write_ref_sha1(lock, sha1, action) < 0) {
1988                 const char *str = "Cannot update the ref '%s'.";
1989                 switch (onerr) {
1990                 case MSG_ON_ERR: error(str, refname); break;
1991                 case DIE_ON_ERR: die(str, refname); break;
1992                 case QUIET_ON_ERR: break;
1993                 }
1994                 return 1;
1995         }
1996         return 0;
1997 }
1998
1999 int ref_exists(const char *refname)
2000 {
2001         unsigned char sha1[20];
2002         return !!resolve_ref(refname, sha1, 1, NULL);
2003 }
2004
2005 struct ref *find_ref_by_name(const struct ref *list, const char *name)
2006 {
2007         for ( ; list; list = list->next)
2008                 if (!strcmp(list->name, name))
2009                         return (struct ref *)list;
2010         return NULL;
2011 }
2012
2013 /*
2014  * generate a format suitable for scanf from a ref_rev_parse_rules
2015  * rule, that is replace the "%.*s" spec with a "%s" spec
2016  */
2017 static void gen_scanf_fmt(char *scanf_fmt, const char *rule)
2018 {
2019         char *spec;
2020
2021         spec = strstr(rule, "%.*s");
2022         if (!spec || strstr(spec + 4, "%.*s"))
2023                 die("invalid rule in ref_rev_parse_rules: %s", rule);
2024
2025         /* copy all until spec */
2026         strncpy(scanf_fmt, rule, spec - rule);
2027         scanf_fmt[spec - rule] = '\0';
2028         /* copy new spec */
2029         strcat(scanf_fmt, "%s");
2030         /* copy remaining rule */
2031         strcat(scanf_fmt, spec + 4);
2032
2033         return;
2034 }
2035
2036 char *shorten_unambiguous_ref(const char *refname, int strict)
2037 {
2038         int i;
2039         static char **scanf_fmts;
2040         static int nr_rules;
2041         char *short_name;
2042
2043         /* pre generate scanf formats from ref_rev_parse_rules[] */
2044         if (!nr_rules) {
2045                 size_t total_len = 0;
2046
2047                 /* the rule list is NULL terminated, count them first */
2048                 for (; ref_rev_parse_rules[nr_rules]; nr_rules++)
2049                         /* no +1 because strlen("%s") < strlen("%.*s") */
2050                         total_len += strlen(ref_rev_parse_rules[nr_rules]);
2051
2052                 scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
2053
2054                 total_len = 0;
2055                 for (i = 0; i < nr_rules; i++) {
2056                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules]
2057                                         + total_len;
2058                         gen_scanf_fmt(scanf_fmts[i], ref_rev_parse_rules[i]);
2059                         total_len += strlen(ref_rev_parse_rules[i]);
2060                 }
2061         }
2062
2063         /* bail out if there are no rules */
2064         if (!nr_rules)
2065                 return xstrdup(refname);
2066
2067         /* buffer for scanf result, at most refname must fit */
2068         short_name = xstrdup(refname);
2069
2070         /* skip first rule, it will always match */
2071         for (i = nr_rules - 1; i > 0 ; --i) {
2072                 int j;
2073                 int rules_to_fail = i;
2074                 int short_name_len;
2075
2076                 if (1 != sscanf(refname, scanf_fmts[i], short_name))
2077                         continue;
2078
2079                 short_name_len = strlen(short_name);
2080
2081                 /*
2082                  * in strict mode, all (except the matched one) rules
2083                  * must fail to resolve to a valid non-ambiguous ref
2084                  */
2085                 if (strict)
2086                         rules_to_fail = nr_rules;
2087
2088                 /*
2089                  * check if the short name resolves to a valid ref,
2090                  * but use only rules prior to the matched one
2091                  */
2092                 for (j = 0; j < rules_to_fail; j++) {
2093                         const char *rule = ref_rev_parse_rules[j];
2094                         char refname[PATH_MAX];
2095
2096                         /* skip matched rule */
2097                         if (i == j)
2098                                 continue;
2099
2100                         /*
2101                          * the short name is ambiguous, if it resolves
2102                          * (with this previous rule) to a valid ref
2103                          * read_ref() returns 0 on success
2104                          */
2105                         mksnpath(refname, sizeof(refname),
2106                                  rule, short_name_len, short_name);
2107                         if (ref_exists(refname))
2108                                 break;
2109                 }
2110
2111                 /*
2112                  * short name is non-ambiguous if all previous rules
2113                  * haven't resolved to a valid ref
2114                  */
2115                 if (j == rules_to_fail)
2116                         return short_name;
2117         }
2118
2119         free(short_name);
2120         return xstrdup(refname);
2121 }