git.oblomov.eu Git - git/blob - refs.c

   1 /*
   2  * The backend-independent part of the reference module.
   3  */
   4
   5 #include "cache.h"
   6 #include "lockfile.h"
   7 #include "refs.h"
   8 #include "refs/refs-internal.h"
   9 #include "object.h"
  10 #include "tag.h"
  11
  12 /*
  13  * How to handle various characters in refnames:
  14  * 0: An acceptable character for refs
  15  * 1: End-of-component
  16  * 2: ., look for a preceding . to reject .. in refs
  17  * 3: {, look for a preceding @ to reject @{ in refs
  18  * 4: A bad character: ASCII control characters, and
  19  *    ":", "?", "[", "\", "^", "~", SP, or TAB
  20  * 5: *, reject unless REFNAME_REFSPEC_PATTERN is set
  21  */
  22 static unsigned char refname_disposition[256] = {
  23         1, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
  24         4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
  25         4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5, 0, 0, 0, 2, 1,
  26         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 4,
  27         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  28         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 0, 4, 0,
  29         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  30         0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 4, 4
  31 };
  32
  33 /*
  34  * Try to read one refname component from the front of refname.
  35  * Return the length of the component found, or -1 if the component is
  36  * not legal.  It is legal if it is something reasonable to have under
  37  * ".git/refs/"; We do not like it if:
  38  *
  39  * - any path component of it begins with ".", or
  40  * - it has double dots "..", or
  41  * - it has ASCII control characters, or
  42  * - it has ":", "?", "[", "\", "^", "~", SP, or TAB anywhere, or
  43  * - it has "*" anywhere unless REFNAME_REFSPEC_PATTERN is set, or
  44  * - it ends with a "/", or
  45  * - it ends with ".lock", or
  46  * - it contains a "@{" portion
  47  */
  48 static int check_refname_component(const char *refname, int *flags)
  49 {
  50         const char *cp;
  51         char last = '\0';
  52
  53         for (cp = refname; ; cp++) {
  54                 int ch = *cp & 255;
  55                 unsigned char disp = refname_disposition[ch];
  56                 switch (disp) {
  57                 case 1:
  58                         goto out;
  59                 case 2:
  60                         if (last == '.')
  61                                 return -1; /* Refname contains "..". */
  62                         break;
  63                 case 3:
  64                         if (last == '@')
  65                                 return -1; /* Refname contains "@{". */
  66                         break;
  67                 case 4:
  68                         return -1;
  69                 case 5:
  70                         if (!(*flags & REFNAME_REFSPEC_PATTERN))
  71                                 return -1; /* refspec can't be a pattern */
  72
  73                         /*
  74                          * Unset the pattern flag so that we only accept
  75                          * a single asterisk for one side of refspec.
  76                          */
  77                         *flags &= ~ REFNAME_REFSPEC_PATTERN;
  78                         break;
  79                 }
  80                 last = ch;
  81         }
  82 out:
  83         if (cp == refname)
  84                 return 0; /* Component has zero length. */
  85         if (refname[0] == '.')
  86                 return -1; /* Component starts with '.'. */
  87         if (cp - refname >= LOCK_SUFFIX_LEN &&
  88             !memcmp(cp - LOCK_SUFFIX_LEN, LOCK_SUFFIX, LOCK_SUFFIX_LEN))
  89                 return -1; /* Refname ends with ".lock". */
  90         return cp - refname;
  91 }
  92
  93 int check_refname_format(const char *refname, int flags)
  94 {
  95         int component_len, component_count = 0;
  96
  97         if (!strcmp(refname, "@"))
  98                 /* Refname is a single character '@'. */
  99                 return -1;
 100
 101         while (1) {
 102                 /* We are at the start of a path component. */
 103                 component_len = check_refname_component(refname, &flags);
 104                 if (component_len <= 0)
 105                         return -1;
 106
 107                 component_count++;
 108                 if (refname[component_len] == '\0')
 109                         break;
 110                 /* Skip to next component. */
 111                 refname += component_len + 1;
 112         }
 113
 114         if (refname[component_len - 1] == '.')
 115                 return -1; /* Refname ends with '.'. */
 116         if (!(flags & REFNAME_ALLOW_ONELEVEL) && component_count < 2)
 117                 return -1; /* Refname has only one component. */
 118         return 0;
 119 }
 120
 121 int refname_is_safe(const char *refname)
 122 {
 123         if (starts_with(refname, "refs/")) {
 124                 char *buf;
 125                 int result;
 126
 127                 buf = xmalloc(strlen(refname) + 1);
 128                 /*
 129                  * Does the refname try to escape refs/?
 130                  * For example: refs/foo/../bar is safe but refs/foo/../../bar
 131                  * is not.
 132                  */
 133                 result = !normalize_path_copy(buf, refname + strlen("refs/"));
 134                 free(buf);
 135                 return result;
 136         }
 137         while (*refname) {
 138                 if (!isupper(*refname) && *refname != '_')
 139                         return 0;
 140                 refname++;
 141         }
 142         return 1;
 143 }
 144
 145 char *resolve_refdup(const char *refname, int resolve_flags,
 146                      unsigned char *sha1, int *flags)
 147 {
 148         return xstrdup_or_null(resolve_ref_unsafe(refname, resolve_flags,
 149                                                   sha1, flags));
 150 }
 151
 152 /* The argument to filter_refs */
 153 struct ref_filter {
 154         const char *pattern;
 155         each_ref_fn *fn;
 156         void *cb_data;
 157 };
 158
 159 int read_ref_full(const char *refname, int resolve_flags, unsigned char *sha1, int *flags)
 160 {
 161         if (resolve_ref_unsafe(refname, resolve_flags, sha1, flags))
 162                 return 0;
 163         return -1;
 164 }
 165
 166 int read_ref(const char *refname, unsigned char *sha1)
 167 {
 168         return read_ref_full(refname, RESOLVE_REF_READING, sha1, NULL);
 169 }
 170
 171 int ref_exists(const char *refname)
 172 {
 173         unsigned char sha1[20];
 174         return !!resolve_ref_unsafe(refname, RESOLVE_REF_READING, sha1, NULL);
 175 }
 176
 177 static int filter_refs(const char *refname, const struct object_id *oid,
 178                            int flags, void *data)
 179 {
 180         struct ref_filter *filter = (struct ref_filter *)data;
 181
 182         if (wildmatch(filter->pattern, refname, 0, NULL))
 183                 return 0;
 184         return filter->fn(refname, oid, flags, filter->cb_data);
 185 }
 186
 187 enum peel_status peel_object(const unsigned char *name, unsigned char *sha1)
 188 {
 189         struct object *o = lookup_unknown_object(name);
 190
 191         if (o->type == OBJ_NONE) {
 192                 int type = sha1_object_info(name, NULL);
 193                 if (type < 0 || !object_as_type(o, type, 0))
 194                         return PEEL_INVALID;
 195         }
 196
 197         if (o->type != OBJ_TAG)
 198                 return PEEL_NON_TAG;
 199
 200         o = deref_tag_noverify(o);
 201         if (!o)
 202                 return PEEL_INVALID;
 203
 204         hashcpy(sha1, o->oid.hash);
 205         return PEEL_PEELED;
 206 }
 207
 208 struct warn_if_dangling_data {
 209         FILE *fp;
 210         const char *refname;
 211         const struct string_list *refnames;
 212         const char *msg_fmt;
 213 };
 214
 215 static int warn_if_dangling_symref(const char *refname, const struct object_id *oid,
 216                                    int flags, void *cb_data)
 217 {
 218         struct warn_if_dangling_data *d = cb_data;
 219         const char *resolves_to;
 220         struct object_id junk;
 221
 222         if (!(flags & REF_ISSYMREF))
 223                 return 0;
 224
 225         resolves_to = resolve_ref_unsafe(refname, 0, junk.hash, NULL);
 226         if (!resolves_to
 227             || (d->refname
 228                 ? strcmp(resolves_to, d->refname)
 229                 : !string_list_has_string(d->refnames, resolves_to))) {
 230                 return 0;
 231         }
 232
 233         fprintf(d->fp, d->msg_fmt, refname);
 234         fputc('\n', d->fp);
 235         return 0;
 236 }
 237
 238 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 239 {
 240         struct warn_if_dangling_data data;
 241
 242         data.fp = fp;
 243         data.refname = refname;
 244         data.refnames = NULL;
 245         data.msg_fmt = msg_fmt;
 246         for_each_rawref(warn_if_dangling_symref, &data);
 247 }
 248
 249 void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames)
 250 {
 251         struct warn_if_dangling_data data;
 252
 253         data.fp = fp;
 254         data.refname = NULL;
 255         data.refnames = refnames;
 256         data.msg_fmt = msg_fmt;
 257         for_each_rawref(warn_if_dangling_symref, &data);
 258 }
 259
 260 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 261 {
 262         return for_each_ref_in("refs/tags/", fn, cb_data);
 263 }
 264
 265 int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 266 {
 267         return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
 268 }
 269
 270 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 271 {
 272         return for_each_ref_in("refs/heads/", fn, cb_data);
 273 }
 274
 275 int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 276 {
 277         return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
 278 }
 279
 280 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 281 {
 282         return for_each_ref_in("refs/remotes/", fn, cb_data);
 283 }
 284
 285 int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 286 {
 287         return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
 288 }
 289
 290 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
 291 {
 292         struct strbuf buf = STRBUF_INIT;
 293         int ret = 0;
 294         struct object_id oid;
 295         int flag;
 296
 297         strbuf_addf(&buf, "%sHEAD", get_git_namespace());
 298         if (!read_ref_full(buf.buf, RESOLVE_REF_READING, oid.hash, &flag))
 299                 ret = fn(buf.buf, &oid, flag, cb_data);
 300         strbuf_release(&buf);
 301
 302         return ret;
 303 }
 304
 305 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 306         const char *prefix, void *cb_data)
 307 {
 308         struct strbuf real_pattern = STRBUF_INIT;
 309         struct ref_filter filter;
 310         int ret;
 311
 312         if (!prefix && !starts_with(pattern, "refs/"))
 313                 strbuf_addstr(&real_pattern, "refs/");
 314         else if (prefix)
 315                 strbuf_addstr(&real_pattern, prefix);
 316         strbuf_addstr(&real_pattern, pattern);
 317
 318         if (!has_glob_specials(pattern)) {
 319                 /* Append implied '/' '*' if not present. */
 320                 strbuf_complete(&real_pattern, '/');
 321                 /* No need to check for '*', there is none. */
 322                 strbuf_addch(&real_pattern, '*');
 323         }
 324
 325         filter.pattern = real_pattern.buf;
 326         filter.fn = fn;
 327         filter.cb_data = cb_data;
 328         ret = for_each_ref(filter_refs, &filter);
 329
 330         strbuf_release(&real_pattern);
 331         return ret;
 332 }
 333
 334 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 335 {
 336         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
 337 }
 338
 339 const char *prettify_refname(const char *name)
 340 {
 341         return name + (
 342                 starts_with(name, "refs/heads/") ? 11 :
 343                 starts_with(name, "refs/tags/") ? 10 :
 344                 starts_with(name, "refs/remotes/") ? 13 :
 345                 0);
 346 }
 347
 348 static const char *ref_rev_parse_rules[] = {
 349         "%.*s",
 350         "refs/%.*s",
 351         "refs/tags/%.*s",
 352         "refs/heads/%.*s",
 353         "refs/remotes/%.*s",
 354         "refs/remotes/%.*s/HEAD",
 355         NULL
 356 };
 357
 358 int refname_match(const char *abbrev_name, const char *full_name)
 359 {
 360         const char **p;
 361         const int abbrev_name_len = strlen(abbrev_name);
 362
 363         for (p = ref_rev_parse_rules; *p; p++) {
 364                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
 365                         return 1;
 366                 }
 367         }
 368
 369         return 0;
 370 }
 371
 372 /*
 373  * *string and *len will only be substituted, and *string returned (for
 374  * later free()ing) if the string passed in is a magic short-hand form
 375  * to name a branch.
 376  */
 377 static char *substitute_branch_name(const char **string, int *len)
 378 {
 379         struct strbuf buf = STRBUF_INIT;
 380         int ret = interpret_branch_name(*string, *len, &buf);
 381
 382         if (ret == *len) {
 383                 size_t size;
 384                 *string = strbuf_detach(&buf, &size);
 385                 *len = size;
 386                 return (char *)*string;
 387         }
 388
 389         return NULL;
 390 }
 391
 392 int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
 393 {
 394         char *last_branch = substitute_branch_name(&str, &len);
 395         int   refs_found  = expand_ref(str, len, sha1, ref);
 396         free(last_branch);
 397         return refs_found;
 398 }
 399
 400 int expand_ref(const char *str, int len, unsigned char *sha1, char **ref)
 401 {
 402         const char **p, *r;
 403         int refs_found = 0;
 404
 405         *ref = NULL;
 406         for (p = ref_rev_parse_rules; *p; p++) {
 407                 char fullref[PATH_MAX];
 408                 unsigned char sha1_from_ref[20];
 409                 unsigned char *this_result;
 410                 int flag;
 411
 412                 this_result = refs_found ? sha1_from_ref : sha1;
 413                 mksnpath(fullref, sizeof(fullref), *p, len, str);
 414                 r = resolve_ref_unsafe(fullref, RESOLVE_REF_READING,
 415                                        this_result, &flag);
 416                 if (r) {
 417                         if (!refs_found++)
 418                                 *ref = xstrdup(r);
 419                         if (!warn_ambiguous_refs)
 420                                 break;
 421                 } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD")) {
 422                         warning("ignoring dangling symref %s.", fullref);
 423                 } else if ((flag & REF_ISBROKEN) && strchr(fullref, '/')) {
 424                         warning("ignoring broken ref %s.", fullref);
 425                 }
 426         }
 427         return refs_found;
 428 }
 429
 430 int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
 431 {
 432         char *last_branch = substitute_branch_name(&str, &len);
 433         const char **p;
 434         int logs_found = 0;
 435
 436         *log = NULL;
 437         for (p = ref_rev_parse_rules; *p; p++) {
 438                 unsigned char hash[20];
 439                 char path[PATH_MAX];
 440                 const char *ref, *it;
 441
 442                 mksnpath(path, sizeof(path), *p, len, str);
 443                 ref = resolve_ref_unsafe(path, RESOLVE_REF_READING,
 444                                          hash, NULL);
 445                 if (!ref)
 446                         continue;
 447                 if (reflog_exists(path))
 448                         it = path;
 449                 else if (strcmp(ref, path) && reflog_exists(ref))
 450                         it = ref;
 451                 else
 452                         continue;
 453                 if (!logs_found++) {
 454                         *log = xstrdup(it);
 455                         hashcpy(sha1, hash);
 456                 }
 457                 if (!warn_ambiguous_refs)
 458                         break;
 459         }
 460         free(last_branch);
 461         return logs_found;
 462 }
 463
 464 static int is_per_worktree_ref(const char *refname)
 465 {
 466         return !strcmp(refname, "HEAD") ||
 467                 starts_with(refname, "refs/bisect/");
 468 }
 469
 470 static int is_pseudoref_syntax(const char *refname)
 471 {
 472         const char *c;
 473
 474         for (c = refname; *c; c++) {
 475                 if (!isupper(*c) && *c != '-' && *c != '_')
 476                         return 0;
 477         }
 478
 479         return 1;
 480 }
 481
 482 enum ref_type ref_type(const char *refname)
 483 {
 484         if (is_per_worktree_ref(refname))
 485                 return REF_TYPE_PER_WORKTREE;
 486         if (is_pseudoref_syntax(refname))
 487                 return REF_TYPE_PSEUDOREF;
 488        return REF_TYPE_NORMAL;
 489 }
 490
 491 static int write_pseudoref(const char *pseudoref, const unsigned char *sha1,
 492                            const unsigned char *old_sha1, struct strbuf *err)
 493 {
 494         const char *filename;
 495         int fd;
 496         static struct lock_file lock;
 497         struct strbuf buf = STRBUF_INIT;
 498         int ret = -1;
 499
 500         strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
 501
 502         filename = git_path("%s", pseudoref);
 503         fd = hold_lock_file_for_update(&lock, filename, LOCK_DIE_ON_ERROR);
 504         if (fd < 0) {
 505                 strbuf_addf(err, "Could not open '%s' for writing: %s",
 506                             filename, strerror(errno));
 507                 return -1;
 508         }
 509
 510         if (old_sha1) {
 511                 unsigned char actual_old_sha1[20];
 512
 513                 if (read_ref(pseudoref, actual_old_sha1))
 514                         die("could not read ref '%s'", pseudoref);
 515                 if (hashcmp(actual_old_sha1, old_sha1)) {
 516                         strbuf_addf(err, "Unexpected sha1 when writing %s", pseudoref);
 517                         rollback_lock_file(&lock);
 518                         goto done;
 519                 }
 520         }
 521
 522         if (write_in_full(fd, buf.buf, buf.len) != buf.len) {
 523                 strbuf_addf(err, "Could not write to '%s'", filename);
 524                 rollback_lock_file(&lock);
 525                 goto done;
 526         }
 527
 528         commit_lock_file(&lock);
 529         ret = 0;
 530 done:
 531         strbuf_release(&buf);
 532         return ret;
 533 }
 534
 535 static int delete_pseudoref(const char *pseudoref, const unsigned char *old_sha1)
 536 {
 537         static struct lock_file lock;
 538         const char *filename;
 539
 540         filename = git_path("%s", pseudoref);
 541
 542         if (old_sha1 && !is_null_sha1(old_sha1)) {
 543                 int fd;
 544                 unsigned char actual_old_sha1[20];
 545
 546                 fd = hold_lock_file_for_update(&lock, filename,
 547                                                LOCK_DIE_ON_ERROR);
 548                 if (fd < 0)
 549                         die_errno(_("Could not open '%s' for writing"), filename);
 550                 if (read_ref(pseudoref, actual_old_sha1))
 551                         die("could not read ref '%s'", pseudoref);
 552                 if (hashcmp(actual_old_sha1, old_sha1)) {
 553                         warning("Unexpected sha1 when deleting %s", pseudoref);
 554                         rollback_lock_file(&lock);
 555                         return -1;
 556                 }
 557
 558                 unlink(filename);
 559                 rollback_lock_file(&lock);
 560         } else {
 561                 unlink(filename);
 562         }
 563
 564         return 0;
 565 }
 566
 567 int delete_ref(const char *refname, const unsigned char *old_sha1,
 568                unsigned int flags)
 569 {
 570         struct ref_transaction *transaction;
 571         struct strbuf err = STRBUF_INIT;
 572
 573         if (ref_type(refname) == REF_TYPE_PSEUDOREF)
 574                 return delete_pseudoref(refname, old_sha1);
 575
 576         transaction = ref_transaction_begin(&err);
 577         if (!transaction ||
 578             ref_transaction_delete(transaction, refname, old_sha1,
 579                                    flags, NULL, &err) ||
 580             ref_transaction_commit(transaction, &err)) {
 581                 error("%s", err.buf);
 582                 ref_transaction_free(transaction);
 583                 strbuf_release(&err);
 584                 return 1;
 585         }
 586         ref_transaction_free(transaction);
 587         strbuf_release(&err);
 588         return 0;
 589 }
 590
 591 int copy_reflog_msg(char *buf, const char *msg)
 592 {
 593         char *cp = buf;
 594         char c;
 595         int wasspace = 1;
 596
 597         *cp++ = '\t';
 598         while ((c = *msg++)) {
 599                 if (wasspace && isspace(c))
 600                         continue;
 601                 wasspace = isspace(c);
 602                 if (wasspace)
 603                         c = ' ';
 604                 *cp++ = c;
 605         }
 606         while (buf < cp && isspace(cp[-1]))
 607                 cp--;
 608         *cp++ = '\n';
 609         return cp - buf;
 610 }
 611
 612 int should_autocreate_reflog(const char *refname)
 613 {
 614         if (!log_all_ref_updates)
 615                 return 0;
 616         return starts_with(refname, "refs/heads/") ||
 617                 starts_with(refname, "refs/remotes/") ||
 618                 starts_with(refname, "refs/notes/") ||
 619                 !strcmp(refname, "HEAD");
 620 }
 621
 622 int is_branch(const char *refname)
 623 {
 624         return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
 625 }
 626
 627 struct read_ref_at_cb {
 628         const char *refname;
 629         unsigned long at_time;
 630         int cnt;
 631         int reccnt;
 632         unsigned char *sha1;
 633         int found_it;
 634
 635         unsigned char osha1[20];
 636         unsigned char nsha1[20];
 637         int tz;
 638         unsigned long date;
 639         char **msg;
 640         unsigned long *cutoff_time;
 641         int *cutoff_tz;
 642         int *cutoff_cnt;
 643 };
 644
 645 static int read_ref_at_ent(unsigned char *osha1, unsigned char *nsha1,
 646                 const char *email, unsigned long timestamp, int tz,
 647                 const char *message, void *cb_data)
 648 {
 649         struct read_ref_at_cb *cb = cb_data;
 650
 651         cb->reccnt++;
 652         cb->tz = tz;
 653         cb->date = timestamp;
 654
 655         if (timestamp <= cb->at_time || cb->cnt == 0) {
 656                 if (cb->msg)
 657                         *cb->msg = xstrdup(message);
 658                 if (cb->cutoff_time)
 659                         *cb->cutoff_time = timestamp;
 660                 if (cb->cutoff_tz)
 661                         *cb->cutoff_tz = tz;
 662                 if (cb->cutoff_cnt)
 663                         *cb->cutoff_cnt = cb->reccnt - 1;
 664                 /*
 665                  * we have not yet updated cb->[n|o]sha1 so they still
 666                  * hold the values for the previous record.
 667                  */
 668                 if (!is_null_sha1(cb->osha1)) {
 669                         hashcpy(cb->sha1, nsha1);
 670                         if (hashcmp(cb->osha1, nsha1))
 671                                 warning("Log for ref %s has gap after %s.",
 672                                         cb->refname, show_date(cb->date, cb->tz, DATE_MODE(RFC2822)));
 673                 }
 674                 else if (cb->date == cb->at_time)
 675                         hashcpy(cb->sha1, nsha1);
 676                 else if (hashcmp(nsha1, cb->sha1))
 677                         warning("Log for ref %s unexpectedly ended on %s.",
 678                                 cb->refname, show_date(cb->date, cb->tz,
 679                                                        DATE_MODE(RFC2822)));
 680                 hashcpy(cb->osha1, osha1);
 681                 hashcpy(cb->nsha1, nsha1);
 682                 cb->found_it = 1;
 683                 return 1;
 684         }
 685         hashcpy(cb->osha1, osha1);
 686         hashcpy(cb->nsha1, nsha1);
 687         if (cb->cnt > 0)
 688                 cb->cnt--;
 689         return 0;
 690 }
 691
 692 static int read_ref_at_ent_oldest(unsigned char *osha1, unsigned char *nsha1,
 693                                   const char *email, unsigned long timestamp,
 694                                   int tz, const char *message, void *cb_data)
 695 {
 696         struct read_ref_at_cb *cb = cb_data;
 697
 698         if (cb->msg)
 699                 *cb->msg = xstrdup(message);
 700         if (cb->cutoff_time)
 701                 *cb->cutoff_time = timestamp;
 702         if (cb->cutoff_tz)
 703                 *cb->cutoff_tz = tz;
 704         if (cb->cutoff_cnt)
 705                 *cb->cutoff_cnt = cb->reccnt;
 706         hashcpy(cb->sha1, osha1);
 707         if (is_null_sha1(cb->sha1))
 708                 hashcpy(cb->sha1, nsha1);
 709         /* We just want the first entry */
 710         return 1;
 711 }
 712
 713 int read_ref_at(const char *refname, unsigned int flags, unsigned long at_time, int cnt,
 714                 unsigned char *sha1, char **msg,
 715                 unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
 716 {
 717         struct read_ref_at_cb cb;
 718
 719         memset(&cb, 0, sizeof(cb));
 720         cb.refname = refname;
 721         cb.at_time = at_time;
 722         cb.cnt = cnt;
 723         cb.msg = msg;
 724         cb.cutoff_time = cutoff_time;
 725         cb.cutoff_tz = cutoff_tz;
 726         cb.cutoff_cnt = cutoff_cnt;
 727         cb.sha1 = sha1;
 728
 729         for_each_reflog_ent_reverse(refname, read_ref_at_ent, &cb);
 730
 731         if (!cb.reccnt) {
 732                 if (flags & GET_SHA1_QUIETLY)
 733                         exit(128);
 734                 else
 735                         die("Log for %s is empty.", refname);
 736         }
 737         if (cb.found_it)
 738                 return 0;
 739
 740         for_each_reflog_ent(refname, read_ref_at_ent_oldest, &cb);
 741
 742         return 1;
 743 }
 744
 745 struct ref_transaction *ref_transaction_begin(struct strbuf *err)
 746 {
 747         assert(err);
 748
 749         return xcalloc(1, sizeof(struct ref_transaction));
 750 }
 751
 752 void ref_transaction_free(struct ref_transaction *transaction)
 753 {
 754         int i;
 755
 756         if (!transaction)
 757                 return;
 758
 759         for (i = 0; i < transaction->nr; i++) {
 760                 free(transaction->updates[i]->msg);
 761                 free(transaction->updates[i]);
 762         }
 763         free(transaction->updates);
 764         free(transaction);
 765 }
 766
 767 static struct ref_update *add_update(struct ref_transaction *transaction,
 768                                      const char *refname)
 769 {
 770         size_t len = strlen(refname) + 1;
 771         struct ref_update *update = xcalloc(1, sizeof(*update) + len);
 772
 773         memcpy((char *)update->refname, refname, len); /* includes NUL */
 774         ALLOC_GROW(transaction->updates, transaction->nr + 1, transaction->alloc);
 775         transaction->updates[transaction->nr++] = update;
 776         return update;
 777 }
 778
 779 int ref_transaction_update(struct ref_transaction *transaction,
 780                            const char *refname,
 781                            const unsigned char *new_sha1,
 782                            const unsigned char *old_sha1,
 783                            unsigned int flags, const char *msg,
 784                            struct strbuf *err)
 785 {
 786         struct ref_update *update;
 787
 788         assert(err);
 789
 790         if (transaction->state != REF_TRANSACTION_OPEN)
 791                 die("BUG: update called for transaction that is not open");
 792
 793         if (new_sha1 && !is_null_sha1(new_sha1) &&
 794             check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
 795                 strbuf_addf(err, "refusing to update ref with bad name %s",
 796                             refname);
 797                 return -1;
 798         }
 799
 800         update = add_update(transaction, refname);
 801         if (new_sha1) {
 802                 hashcpy(update->new_sha1, new_sha1);
 803                 flags |= REF_HAVE_NEW;
 804         }
 805         if (old_sha1) {
 806                 hashcpy(update->old_sha1, old_sha1);
 807                 flags |= REF_HAVE_OLD;
 808         }
 809         update->flags = flags;
 810         if (msg)
 811                 update->msg = xstrdup(msg);
 812         return 0;
 813 }
 814
 815 int ref_transaction_create(struct ref_transaction *transaction,
 816                            const char *refname,
 817                            const unsigned char *new_sha1,
 818                            unsigned int flags, const char *msg,
 819                            struct strbuf *err)
 820 {
 821         if (!new_sha1 || is_null_sha1(new_sha1))
 822                 die("BUG: create called without valid new_sha1");
 823         return ref_transaction_update(transaction, refname, new_sha1,
 824                                       null_sha1, flags, msg, err);
 825 }
 826
 827 int ref_transaction_delete(struct ref_transaction *transaction,
 828                            const char *refname,
 829                            const unsigned char *old_sha1,
 830                            unsigned int flags, const char *msg,
 831                            struct strbuf *err)
 832 {
 833         if (old_sha1 && is_null_sha1(old_sha1))
 834                 die("BUG: delete called with old_sha1 set to zeros");
 835         return ref_transaction_update(transaction, refname,
 836                                       null_sha1, old_sha1,
 837                                       flags, msg, err);
 838 }
 839
 840 int ref_transaction_verify(struct ref_transaction *transaction,
 841                            const char *refname,
 842                            const unsigned char *old_sha1,
 843                            unsigned int flags,
 844                            struct strbuf *err)
 845 {
 846         if (!old_sha1)
 847                 die("BUG: verify called with old_sha1 set to NULL");
 848         return ref_transaction_update(transaction, refname,
 849                                       NULL, old_sha1,
 850                                       flags, NULL, err);
 851 }
 852
 853 int update_ref(const char *msg, const char *refname,
 854                const unsigned char *new_sha1, const unsigned char *old_sha1,
 855                unsigned int flags, enum action_on_err onerr)
 856 {
 857         struct ref_transaction *t = NULL;
 858         struct strbuf err = STRBUF_INIT;
 859         int ret = 0;
 860
 861         if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
 862                 ret = write_pseudoref(refname, new_sha1, old_sha1, &err);
 863         } else {
 864                 t = ref_transaction_begin(&err);
 865                 if (!t ||
 866                     ref_transaction_update(t, refname, new_sha1, old_sha1,
 867                                            flags, msg, &err) ||
 868                     ref_transaction_commit(t, &err)) {
 869                         ret = 1;
 870                         ref_transaction_free(t);
 871                 }
 872         }
 873         if (ret) {
 874                 const char *str = "update_ref failed for ref '%s': %s";
 875
 876                 switch (onerr) {
 877                 case UPDATE_REFS_MSG_ON_ERR:
 878                         error(str, refname, err.buf);
 879                         break;
 880                 case UPDATE_REFS_DIE_ON_ERR:
 881                         die(str, refname, err.buf);
 882                         break;
 883                 case UPDATE_REFS_QUIET_ON_ERR:
 884                         break;
 885                 }
 886                 strbuf_release(&err);
 887                 return 1;
 888         }
 889         strbuf_release(&err);
 890         if (t)
 891                 ref_transaction_free(t);
 892         return 0;
 893 }
 894
 895 char *shorten_unambiguous_ref(const char *refname, int strict)
 896 {
 897         int i;
 898         static char **scanf_fmts;
 899         static int nr_rules;
 900         char *short_name;
 901
 902         if (!nr_rules) {
 903                 /*
 904                  * Pre-generate scanf formats from ref_rev_parse_rules[].
 905                  * Generate a format suitable for scanf from a
 906                  * ref_rev_parse_rules rule by interpolating "%s" at the
 907                  * location of the "%.*s".
 908                  */
 909                 size_t total_len = 0;
 910                 size_t offset = 0;
 911
 912                 /* the rule list is NULL terminated, count them first */
 913                 for (nr_rules = 0; ref_rev_parse_rules[nr_rules]; nr_rules++)
 914                         /* -2 for strlen("%.*s") - strlen("%s"); +1 for NUL */
 915                         total_len += strlen(ref_rev_parse_rules[nr_rules]) - 2 + 1;
 916
 917                 scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
 918
 919                 offset = 0;
 920                 for (i = 0; i < nr_rules; i++) {
 921                         assert(offset < total_len);
 922                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules] + offset;
 923                         offset += snprintf(scanf_fmts[i], total_len - offset,
 924                                            ref_rev_parse_rules[i], 2, "%s") + 1;
 925                 }
 926         }
 927
 928         /* bail out if there are no rules */
 929         if (!nr_rules)
 930                 return xstrdup(refname);
 931
 932         /* buffer for scanf result, at most refname must fit */
 933         short_name = xstrdup(refname);
 934
 935         /* skip first rule, it will always match */
 936         for (i = nr_rules - 1; i > 0 ; --i) {
 937                 int j;
 938                 int rules_to_fail = i;
 939                 int short_name_len;
 940
 941                 if (1 != sscanf(refname, scanf_fmts[i], short_name))
 942                         continue;
 943
 944                 short_name_len = strlen(short_name);
 945
 946                 /*
 947                  * in strict mode, all (except the matched one) rules
 948                  * must fail to resolve to a valid non-ambiguous ref
 949                  */
 950                 if (strict)
 951                         rules_to_fail = nr_rules;
 952
 953                 /*
 954                  * check if the short name resolves to a valid ref,
 955                  * but use only rules prior to the matched one
 956                  */
 957                 for (j = 0; j < rules_to_fail; j++) {
 958                         const char *rule = ref_rev_parse_rules[j];
 959                         char refname[PATH_MAX];
 960
 961                         /* skip matched rule */
 962                         if (i == j)
 963                                 continue;
 964
 965                         /*
 966                          * the short name is ambiguous, if it resolves
 967                          * (with this previous rule) to a valid ref
 968                          * read_ref() returns 0 on success
 969                          */
 970                         mksnpath(refname, sizeof(refname),
 971                                  rule, short_name_len, short_name);
 972                         if (ref_exists(refname))
 973                                 break;
 974                 }
 975
 976                 /*
 977                  * short name is non-ambiguous if all previous rules
 978                  * haven't resolved to a valid ref
 979                  */
 980                 if (j == rules_to_fail)
 981                         return short_name;
 982         }
 983
 984         free(short_name);
 985         return xstrdup(refname);
 986 }
 987
 988 static struct string_list *hide_refs;
 989
 990 int parse_hide_refs_config(const char *var, const char *value, const char *section)
 991 {
 992         if (!strcmp("transfer.hiderefs", var) ||
 993             /* NEEDSWORK: use parse_config_key() once both are merged */
 994             (starts_with(var, section) && var[strlen(section)] == '.' &&
 995              !strcmp(var + strlen(section), ".hiderefs"))) {
 996                 char *ref;
 997                 int len;
 998
 999                 if (!value)
1000                         return config_error_nonbool(var);
1001                 ref = xstrdup(value);
1002                 len = strlen(ref);
1003                 while (len && ref[len - 1] == '/')
1004                         ref[--len] = '\0';
1005                 if (!hide_refs) {
1006                         hide_refs = xcalloc(1, sizeof(*hide_refs));
1007                         hide_refs->strdup_strings = 1;
1008                 }
1009                 string_list_append(hide_refs, ref);
1010         }
1011         return 0;
1012 }
1013
1014 int ref_is_hidden(const char *refname, const char *refname_full)
1015 {
1016         int i;
1017
1018         if (!hide_refs)
1019                 return 0;
1020         for (i = hide_refs->nr - 1; i >= 0; i--) {
1021                 const char *match = hide_refs->items[i].string;
1022                 const char *subject;
1023                 int neg = 0;
1024                 int len;
1025
1026                 if (*match == '!') {
1027                         neg = 1;
1028                         match++;
1029                 }
1030
1031                 if (*match == '^') {
1032                         subject = refname_full;
1033                         match++;
1034                 } else {
1035                         subject = refname;
1036                 }
1037
1038                 /* refname can be NULL when namespaces are used. */
1039                 if (!subject || !starts_with(subject, match))
1040                         continue;
1041                 len = strlen(match);
1042                 if (!subject[len] || subject[len] == '/')
1043                         return !neg;
1044         }
1045         return 0;
1046 }
1047
1048 const char *find_descendant_ref(const char *dirname,
1049                                 const struct string_list *extras,
1050                                 const struct string_list *skip)
1051 {
1052         int pos;
1053
1054         if (!extras)
1055                 return NULL;
1056
1057         /*
1058          * Look at the place where dirname would be inserted into
1059          * extras. If there is an entry at that position that starts
1060          * with dirname (remember, dirname includes the trailing
1061          * slash) and is not in skip, then we have a conflict.
1062          */
1063         for (pos = string_list_find_insert_index(extras, dirname, 0);
1064              pos < extras->nr; pos++) {
1065                 const char *extra_refname = extras->items[pos].string;
1066
1067                 if (!starts_with(extra_refname, dirname))
1068                         break;
1069
1070                 if (!skip || !string_list_has_string(skip, extra_refname))
1071                         return extra_refname;
1072         }
1073         return NULL;
1074 }
1075
1076 int rename_ref_available(const char *oldname, const char *newname)
1077 {
1078         struct string_list skip = STRING_LIST_INIT_NODUP;
1079         struct strbuf err = STRBUF_INIT;
1080         int ret;
1081
1082         string_list_insert(&skip, oldname);
1083         ret = !verify_refname_available(newname, NULL, &skip, &err);
1084         if (!ret)
1085                 error("%s", err.buf);
1086
1087         string_list_clear(&skip, 0);
1088         strbuf_release(&err);
1089         return ret;
1090 }