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         const char **p, *r;
 396         int refs_found = 0;
 397
 398         *ref = NULL;
 399         for (p = ref_rev_parse_rules; *p; p++) {
 400                 char fullref[PATH_MAX];
 401                 unsigned char sha1_from_ref[20];
 402                 unsigned char *this_result;
 403                 int flag;
 404
 405                 this_result = refs_found ? sha1_from_ref : sha1;
 406                 mksnpath(fullref, sizeof(fullref), *p, len, str);
 407                 r = resolve_ref_unsafe(fullref, RESOLVE_REF_READING,
 408                                        this_result, &flag);
 409                 if (r) {
 410                         if (!refs_found++)
 411                                 *ref = xstrdup(r);
 412                         if (!warn_ambiguous_refs)
 413                                 break;
 414                 } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD")) {
 415                         warning("ignoring dangling symref %s.", fullref);
 416                 } else if ((flag & REF_ISBROKEN) && strchr(fullref, '/')) {
 417                         warning("ignoring broken ref %s.", fullref);
 418                 }
 419         }
 420         free(last_branch);
 421         return refs_found;
 422 }
 423
 424 int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
 425 {
 426         char *last_branch = substitute_branch_name(&str, &len);
 427         const char **p;
 428         int logs_found = 0;
 429
 430         *log = NULL;
 431         for (p = ref_rev_parse_rules; *p; p++) {
 432                 unsigned char hash[20];
 433                 char path[PATH_MAX];
 434                 const char *ref, *it;
 435
 436                 mksnpath(path, sizeof(path), *p, len, str);
 437                 ref = resolve_ref_unsafe(path, RESOLVE_REF_READING,
 438                                          hash, NULL);
 439                 if (!ref)
 440                         continue;
 441                 if (reflog_exists(path))
 442                         it = path;
 443                 else if (strcmp(ref, path) && reflog_exists(ref))
 444                         it = ref;
 445                 else
 446                         continue;
 447                 if (!logs_found++) {
 448                         *log = xstrdup(it);
 449                         hashcpy(sha1, hash);
 450                 }
 451                 if (!warn_ambiguous_refs)
 452                         break;
 453         }
 454         free(last_branch);
 455         return logs_found;
 456 }
 457
 458 static int is_per_worktree_ref(const char *refname)
 459 {
 460         return !strcmp(refname, "HEAD") ||
 461                 starts_with(refname, "refs/bisect/");
 462 }
 463
 464 static int is_pseudoref_syntax(const char *refname)
 465 {
 466         const char *c;
 467
 468         for (c = refname; *c; c++) {
 469                 if (!isupper(*c) && *c != '-' && *c != '_')
 470                         return 0;
 471         }
 472
 473         return 1;
 474 }
 475
 476 enum ref_type ref_type(const char *refname)
 477 {
 478         if (is_per_worktree_ref(refname))
 479                 return REF_TYPE_PER_WORKTREE;
 480         if (is_pseudoref_syntax(refname))
 481                 return REF_TYPE_PSEUDOREF;
 482        return REF_TYPE_NORMAL;
 483 }
 484
 485 static int write_pseudoref(const char *pseudoref, const unsigned char *sha1,
 486                            const unsigned char *old_sha1, struct strbuf *err)
 487 {
 488         const char *filename;
 489         int fd;
 490         static struct lock_file lock;
 491         struct strbuf buf = STRBUF_INIT;
 492         int ret = -1;
 493
 494         strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
 495
 496         filename = git_path("%s", pseudoref);
 497         fd = hold_lock_file_for_update(&lock, filename, LOCK_DIE_ON_ERROR);
 498         if (fd < 0) {
 499                 strbuf_addf(err, "Could not open '%s' for writing: %s",
 500                             filename, strerror(errno));
 501                 return -1;
 502         }
 503
 504         if (old_sha1) {
 505                 unsigned char actual_old_sha1[20];
 506
 507                 if (read_ref(pseudoref, actual_old_sha1))
 508                         die("could not read ref '%s'", pseudoref);
 509                 if (hashcmp(actual_old_sha1, old_sha1)) {
 510                         strbuf_addf(err, "Unexpected sha1 when writing %s", pseudoref);
 511                         rollback_lock_file(&lock);
 512                         goto done;
 513                 }
 514         }
 515
 516         if (write_in_full(fd, buf.buf, buf.len) != buf.len) {
 517                 strbuf_addf(err, "Could not write to '%s'", filename);
 518                 rollback_lock_file(&lock);
 519                 goto done;
 520         }
 521
 522         commit_lock_file(&lock);
 523         ret = 0;
 524 done:
 525         strbuf_release(&buf);
 526         return ret;
 527 }
 528
 529 static int delete_pseudoref(const char *pseudoref, const unsigned char *old_sha1)
 530 {
 531         static struct lock_file lock;
 532         const char *filename;
 533
 534         filename = git_path("%s", pseudoref);
 535
 536         if (old_sha1 && !is_null_sha1(old_sha1)) {
 537                 int fd;
 538                 unsigned char actual_old_sha1[20];
 539
 540                 fd = hold_lock_file_for_update(&lock, filename,
 541                                                LOCK_DIE_ON_ERROR);
 542                 if (fd < 0)
 543                         die_errno(_("Could not open '%s' for writing"), filename);
 544                 if (read_ref(pseudoref, actual_old_sha1))
 545                         die("could not read ref '%s'", pseudoref);
 546                 if (hashcmp(actual_old_sha1, old_sha1)) {
 547                         warning("Unexpected sha1 when deleting %s", pseudoref);
 548                         rollback_lock_file(&lock);
 549                         return -1;
 550                 }
 551
 552                 unlink(filename);
 553                 rollback_lock_file(&lock);
 554         } else {
 555                 unlink(filename);
 556         }
 557
 558         return 0;
 559 }
 560
 561 int delete_ref(const char *refname, const unsigned char *old_sha1,
 562                unsigned int flags)
 563 {
 564         struct ref_transaction *transaction;
 565         struct strbuf err = STRBUF_INIT;
 566
 567         if (ref_type(refname) == REF_TYPE_PSEUDOREF)
 568                 return delete_pseudoref(refname, old_sha1);
 569
 570         transaction = ref_transaction_begin(&err);
 571         if (!transaction ||
 572             ref_transaction_delete(transaction, refname, old_sha1,
 573                                    flags, NULL, &err) ||
 574             ref_transaction_commit(transaction, &err)) {
 575                 error("%s", err.buf);
 576                 ref_transaction_free(transaction);
 577                 strbuf_release(&err);
 578                 return 1;
 579         }
 580         ref_transaction_free(transaction);
 581         strbuf_release(&err);
 582         return 0;
 583 }
 584
 585 int copy_reflog_msg(char *buf, const char *msg)
 586 {
 587         char *cp = buf;
 588         char c;
 589         int wasspace = 1;
 590
 591         *cp++ = '\t';
 592         while ((c = *msg++)) {
 593                 if (wasspace && isspace(c))
 594                         continue;
 595                 wasspace = isspace(c);
 596                 if (wasspace)
 597                         c = ' ';
 598                 *cp++ = c;
 599         }
 600         while (buf < cp && isspace(cp[-1]))
 601                 cp--;
 602         *cp++ = '\n';
 603         return cp - buf;
 604 }
 605
 606 int should_autocreate_reflog(const char *refname)
 607 {
 608         if (!log_all_ref_updates)
 609                 return 0;
 610         return starts_with(refname, "refs/heads/") ||
 611                 starts_with(refname, "refs/remotes/") ||
 612                 starts_with(refname, "refs/notes/") ||
 613                 !strcmp(refname, "HEAD");
 614 }
 615
 616 int is_branch(const char *refname)
 617 {
 618         return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
 619 }
 620
 621 struct read_ref_at_cb {
 622         const char *refname;
 623         unsigned long at_time;
 624         int cnt;
 625         int reccnt;
 626         unsigned char *sha1;
 627         int found_it;
 628
 629         unsigned char osha1[20];
 630         unsigned char nsha1[20];
 631         int tz;
 632         unsigned long date;
 633         char **msg;
 634         unsigned long *cutoff_time;
 635         int *cutoff_tz;
 636         int *cutoff_cnt;
 637 };
 638
 639 static int read_ref_at_ent(unsigned char *osha1, unsigned char *nsha1,
 640                 const char *email, unsigned long timestamp, int tz,
 641                 const char *message, void *cb_data)
 642 {
 643         struct read_ref_at_cb *cb = cb_data;
 644
 645         cb->reccnt++;
 646         cb->tz = tz;
 647         cb->date = timestamp;
 648
 649         if (timestamp <= cb->at_time || cb->cnt == 0) {
 650                 if (cb->msg)
 651                         *cb->msg = xstrdup(message);
 652                 if (cb->cutoff_time)
 653                         *cb->cutoff_time = timestamp;
 654                 if (cb->cutoff_tz)
 655                         *cb->cutoff_tz = tz;
 656                 if (cb->cutoff_cnt)
 657                         *cb->cutoff_cnt = cb->reccnt - 1;
 658                 /*
 659                  * we have not yet updated cb->[n|o]sha1 so they still
 660                  * hold the values for the previous record.
 661                  */
 662                 if (!is_null_sha1(cb->osha1)) {
 663                         hashcpy(cb->sha1, nsha1);
 664                         if (hashcmp(cb->osha1, nsha1))
 665                                 warning("Log for ref %s has gap after %s.",
 666                                         cb->refname, show_date(cb->date, cb->tz, DATE_MODE(RFC2822)));
 667                 }
 668                 else if (cb->date == cb->at_time)
 669                         hashcpy(cb->sha1, nsha1);
 670                 else if (hashcmp(nsha1, cb->sha1))
 671                         warning("Log for ref %s unexpectedly ended on %s.",
 672                                 cb->refname, show_date(cb->date, cb->tz,
 673                                                        DATE_MODE(RFC2822)));
 674                 hashcpy(cb->osha1, osha1);
 675                 hashcpy(cb->nsha1, nsha1);
 676                 cb->found_it = 1;
 677                 return 1;
 678         }
 679         hashcpy(cb->osha1, osha1);
 680         hashcpy(cb->nsha1, nsha1);
 681         if (cb->cnt > 0)
 682                 cb->cnt--;
 683         return 0;
 684 }
 685
 686 static int read_ref_at_ent_oldest(unsigned char *osha1, unsigned char *nsha1,
 687                                   const char *email, unsigned long timestamp,
 688                                   int tz, const char *message, void *cb_data)
 689 {
 690         struct read_ref_at_cb *cb = cb_data;
 691
 692         if (cb->msg)
 693                 *cb->msg = xstrdup(message);
 694         if (cb->cutoff_time)
 695                 *cb->cutoff_time = timestamp;
 696         if (cb->cutoff_tz)
 697                 *cb->cutoff_tz = tz;
 698         if (cb->cutoff_cnt)
 699                 *cb->cutoff_cnt = cb->reccnt;
 700         hashcpy(cb->sha1, osha1);
 701         if (is_null_sha1(cb->sha1))
 702                 hashcpy(cb->sha1, nsha1);
 703         /* We just want the first entry */
 704         return 1;
 705 }
 706
 707 int read_ref_at(const char *refname, unsigned int flags, unsigned long at_time, int cnt,
 708                 unsigned char *sha1, char **msg,
 709                 unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
 710 {
 711         struct read_ref_at_cb cb;
 712
 713         memset(&cb, 0, sizeof(cb));
 714         cb.refname = refname;
 715         cb.at_time = at_time;
 716         cb.cnt = cnt;
 717         cb.msg = msg;
 718         cb.cutoff_time = cutoff_time;
 719         cb.cutoff_tz = cutoff_tz;
 720         cb.cutoff_cnt = cutoff_cnt;
 721         cb.sha1 = sha1;
 722
 723         for_each_reflog_ent_reverse(refname, read_ref_at_ent, &cb);
 724
 725         if (!cb.reccnt) {
 726                 if (flags & GET_SHA1_QUIETLY)
 727                         exit(128);
 728                 else
 729                         die("Log for %s is empty.", refname);
 730         }
 731         if (cb.found_it)
 732                 return 0;
 733
 734         for_each_reflog_ent(refname, read_ref_at_ent_oldest, &cb);
 735
 736         return 1;
 737 }
 738
 739 struct ref_transaction *ref_transaction_begin(struct strbuf *err)
 740 {
 741         assert(err);
 742
 743         return xcalloc(1, sizeof(struct ref_transaction));
 744 }
 745
 746 void ref_transaction_free(struct ref_transaction *transaction)
 747 {
 748         int i;
 749
 750         if (!transaction)
 751                 return;
 752
 753         for (i = 0; i < transaction->nr; i++) {
 754                 free(transaction->updates[i]->msg);
 755                 free(transaction->updates[i]);
 756         }
 757         free(transaction->updates);
 758         free(transaction);
 759 }
 760
 761 static struct ref_update *add_update(struct ref_transaction *transaction,
 762                                      const char *refname)
 763 {
 764         size_t len = strlen(refname) + 1;
 765         struct ref_update *update = xcalloc(1, sizeof(*update) + len);
 766
 767         memcpy((char *)update->refname, refname, len); /* includes NUL */
 768         ALLOC_GROW(transaction->updates, transaction->nr + 1, transaction->alloc);
 769         transaction->updates[transaction->nr++] = update;
 770         return update;
 771 }
 772
 773 int ref_transaction_update(struct ref_transaction *transaction,
 774                            const char *refname,
 775                            const unsigned char *new_sha1,
 776                            const unsigned char *old_sha1,
 777                            unsigned int flags, const char *msg,
 778                            struct strbuf *err)
 779 {
 780         struct ref_update *update;
 781
 782         assert(err);
 783
 784         if (transaction->state != REF_TRANSACTION_OPEN)
 785                 die("BUG: update called for transaction that is not open");
 786
 787         if (new_sha1 && !is_null_sha1(new_sha1) &&
 788             check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
 789                 strbuf_addf(err, "refusing to update ref with bad name %s",
 790                             refname);
 791                 return -1;
 792         }
 793
 794         update = add_update(transaction, refname);
 795         if (new_sha1) {
 796                 hashcpy(update->new_sha1, new_sha1);
 797                 flags |= REF_HAVE_NEW;
 798         }
 799         if (old_sha1) {
 800                 hashcpy(update->old_sha1, old_sha1);
 801                 flags |= REF_HAVE_OLD;
 802         }
 803         update->flags = flags;
 804         if (msg)
 805                 update->msg = xstrdup(msg);
 806         return 0;
 807 }
 808
 809 int ref_transaction_create(struct ref_transaction *transaction,
 810                            const char *refname,
 811                            const unsigned char *new_sha1,
 812                            unsigned int flags, const char *msg,
 813                            struct strbuf *err)
 814 {
 815         if (!new_sha1 || is_null_sha1(new_sha1))
 816                 die("BUG: create called without valid new_sha1");
 817         return ref_transaction_update(transaction, refname, new_sha1,
 818                                       null_sha1, flags, msg, err);
 819 }
 820
 821 int ref_transaction_delete(struct ref_transaction *transaction,
 822                            const char *refname,
 823                            const unsigned char *old_sha1,
 824                            unsigned int flags, const char *msg,
 825                            struct strbuf *err)
 826 {
 827         if (old_sha1 && is_null_sha1(old_sha1))
 828                 die("BUG: delete called with old_sha1 set to zeros");
 829         return ref_transaction_update(transaction, refname,
 830                                       null_sha1, old_sha1,
 831                                       flags, msg, err);
 832 }
 833
 834 int ref_transaction_verify(struct ref_transaction *transaction,
 835                            const char *refname,
 836                            const unsigned char *old_sha1,
 837                            unsigned int flags,
 838                            struct strbuf *err)
 839 {
 840         if (!old_sha1)
 841                 die("BUG: verify called with old_sha1 set to NULL");
 842         return ref_transaction_update(transaction, refname,
 843                                       NULL, old_sha1,
 844                                       flags, NULL, err);
 845 }
 846
 847 int update_ref(const char *msg, const char *refname,
 848                const unsigned char *new_sha1, const unsigned char *old_sha1,
 849                unsigned int flags, enum action_on_err onerr)
 850 {
 851         struct ref_transaction *t = NULL;
 852         struct strbuf err = STRBUF_INIT;
 853         int ret = 0;
 854
 855         if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
 856                 ret = write_pseudoref(refname, new_sha1, old_sha1, &err);
 857         } else {
 858                 t = ref_transaction_begin(&err);
 859                 if (!t ||
 860                     ref_transaction_update(t, refname, new_sha1, old_sha1,
 861                                            flags, msg, &err) ||
 862                     ref_transaction_commit(t, &err)) {
 863                         ret = 1;
 864                         ref_transaction_free(t);
 865                 }
 866         }
 867         if (ret) {
 868                 const char *str = "update_ref failed for ref '%s': %s";
 869
 870                 switch (onerr) {
 871                 case UPDATE_REFS_MSG_ON_ERR:
 872                         error(str, refname, err.buf);
 873                         break;
 874                 case UPDATE_REFS_DIE_ON_ERR:
 875                         die(str, refname, err.buf);
 876                         break;
 877                 case UPDATE_REFS_QUIET_ON_ERR:
 878                         break;
 879                 }
 880                 strbuf_release(&err);
 881                 return 1;
 882         }
 883         strbuf_release(&err);
 884         if (t)
 885                 ref_transaction_free(t);
 886         return 0;
 887 }
 888
 889 char *shorten_unambiguous_ref(const char *refname, int strict)
 890 {
 891         int i;
 892         static char **scanf_fmts;
 893         static int nr_rules;
 894         char *short_name;
 895
 896         if (!nr_rules) {
 897                 /*
 898                  * Pre-generate scanf formats from ref_rev_parse_rules[].
 899                  * Generate a format suitable for scanf from a
 900                  * ref_rev_parse_rules rule by interpolating "%s" at the
 901                  * location of the "%.*s".
 902                  */
 903                 size_t total_len = 0;
 904                 size_t offset = 0;
 905
 906                 /* the rule list is NULL terminated, count them first */
 907                 for (nr_rules = 0; ref_rev_parse_rules[nr_rules]; nr_rules++)
 908                         /* -2 for strlen("%.*s") - strlen("%s"); +1 for NUL */
 909                         total_len += strlen(ref_rev_parse_rules[nr_rules]) - 2 + 1;
 910
 911                 scanf_fmts = xmalloc(nr_rules * sizeof(char *) + total_len);
 912
 913                 offset = 0;
 914                 for (i = 0; i < nr_rules; i++) {
 915                         assert(offset < total_len);
 916                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules] + offset;
 917                         offset += snprintf(scanf_fmts[i], total_len - offset,
 918                                            ref_rev_parse_rules[i], 2, "%s") + 1;
 919                 }
 920         }
 921
 922         /* bail out if there are no rules */
 923         if (!nr_rules)
 924                 return xstrdup(refname);
 925
 926         /* buffer for scanf result, at most refname must fit */
 927         short_name = xstrdup(refname);
 928
 929         /* skip first rule, it will always match */
 930         for (i = nr_rules - 1; i > 0 ; --i) {
 931                 int j;
 932                 int rules_to_fail = i;
 933                 int short_name_len;
 934
 935                 if (1 != sscanf(refname, scanf_fmts[i], short_name))
 936                         continue;
 937
 938                 short_name_len = strlen(short_name);
 939
 940                 /*
 941                  * in strict mode, all (except the matched one) rules
 942                  * must fail to resolve to a valid non-ambiguous ref
 943                  */
 944                 if (strict)
 945                         rules_to_fail = nr_rules;
 946
 947                 /*
 948                  * check if the short name resolves to a valid ref,
 949                  * but use only rules prior to the matched one
 950                  */
 951                 for (j = 0; j < rules_to_fail; j++) {
 952                         const char *rule = ref_rev_parse_rules[j];
 953                         char refname[PATH_MAX];
 954
 955                         /* skip matched rule */
 956                         if (i == j)
 957                                 continue;
 958
 959                         /*
 960                          * the short name is ambiguous, if it resolves
 961                          * (with this previous rule) to a valid ref
 962                          * read_ref() returns 0 on success
 963                          */
 964                         mksnpath(refname, sizeof(refname),
 965                                  rule, short_name_len, short_name);
 966                         if (ref_exists(refname))
 967                                 break;
 968                 }
 969
 970                 /*
 971                  * short name is non-ambiguous if all previous rules
 972                  * haven't resolved to a valid ref
 973                  */
 974                 if (j == rules_to_fail)
 975                         return short_name;
 976         }
 977
 978         free(short_name);
 979         return xstrdup(refname);
 980 }
 981
 982 static struct string_list *hide_refs;
 983
 984 int parse_hide_refs_config(const char *var, const char *value, const char *section)
 985 {
 986         if (!strcmp("transfer.hiderefs", var) ||
 987             /* NEEDSWORK: use parse_config_key() once both are merged */
 988             (starts_with(var, section) && var[strlen(section)] == '.' &&
 989              !strcmp(var + strlen(section), ".hiderefs"))) {
 990                 char *ref;
 991                 int len;
 992
 993                 if (!value)
 994                         return config_error_nonbool(var);
 995                 ref = xstrdup(value);
 996                 len = strlen(ref);
 997                 while (len && ref[len - 1] == '/')
 998                         ref[--len] = '\0';
 999                 if (!hide_refs) {
1000                         hide_refs = xcalloc(1, sizeof(*hide_refs));
1001                         hide_refs->strdup_strings = 1;
1002                 }
1003                 string_list_append(hide_refs, ref);
1004         }
1005         return 0;
1006 }
1007
1008 int ref_is_hidden(const char *refname, const char *refname_full)
1009 {
1010         int i;
1011
1012         if (!hide_refs)
1013                 return 0;
1014         for (i = hide_refs->nr - 1; i >= 0; i--) {
1015                 const char *match = hide_refs->items[i].string;
1016                 const char *subject;
1017                 int neg = 0;
1018                 int len;
1019
1020                 if (*match == '!') {
1021                         neg = 1;
1022                         match++;
1023                 }
1024
1025                 if (*match == '^') {
1026                         subject = refname_full;
1027                         match++;
1028                 } else {
1029                         subject = refname;
1030                 }
1031
1032                 /* refname can be NULL when namespaces are used. */
1033                 if (!subject || !starts_with(subject, match))
1034                         continue;
1035                 len = strlen(match);
1036                 if (!subject[len] || subject[len] == '/')
1037                         return !neg;
1038         }
1039         return 0;
1040 }
1041
1042 const char *find_descendant_ref(const char *dirname,
1043                                 const struct string_list *extras,
1044                                 const struct string_list *skip)
1045 {
1046         int pos;
1047
1048         if (!extras)
1049                 return NULL;
1050
1051         /*
1052          * Look at the place where dirname would be inserted into
1053          * extras. If there is an entry at that position that starts
1054          * with dirname (remember, dirname includes the trailing
1055          * slash) and is not in skip, then we have a conflict.
1056          */
1057         for (pos = string_list_find_insert_index(extras, dirname, 0);
1058              pos < extras->nr; pos++) {
1059                 const char *extra_refname = extras->items[pos].string;
1060
1061                 if (!starts_with(extra_refname, dirname))
1062                         break;
1063
1064                 if (!skip || !string_list_has_string(skip, extra_refname))
1065                         return extra_refname;
1066         }
1067         return NULL;
1068 }
1069
1070 int rename_ref_available(const char *oldname, const char *newname)
1071 {
1072         struct string_list skip = STRING_LIST_INIT_NODUP;
1073         struct strbuf err = STRBUF_INIT;
1074         int ret;
1075
1076         string_list_insert(&skip, oldname);
1077         ret = !verify_refname_available(newname, NULL, &skip, &err);
1078         if (!ret)
1079                 error("%s", err.buf);
1080
1081         string_list_clear(&skip, 0);
1082         strbuf_release(&err);
1083         return ret;
1084 }