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         const char *rest;
 124
 125         if (skip_prefix(refname, "refs/", &rest)) {
 126                 char *buf;
 127                 int result;
 128                 size_t restlen = strlen(rest);
 129
 130                 /* rest must not be empty, or start or end with "/" */
 131                 if (!restlen || *rest == '/' || rest[restlen - 1] == '/')
 132                         return 0;
 133
 134                 /*
 135                  * Does the refname try to escape refs/?
 136                  * For example: refs/foo/../bar is safe but refs/foo/../../bar
 137                  * is not.
 138                  */
 139                 buf = xmallocz(restlen);
 140                 result = !normalize_path_copy(buf, rest) && !strcmp(buf, rest);
 141                 free(buf);
 142                 return result;
 143         }
 144
 145         do {
 146                 if (!isupper(*refname) && *refname != '_')
 147                         return 0;
 148                 refname++;
 149         } while (*refname);
 150         return 1;
 151 }
 152
 153 char *resolve_refdup(const char *refname, int resolve_flags,
 154                      unsigned char *sha1, int *flags)
 155 {
 156         return xstrdup_or_null(resolve_ref_unsafe(refname, resolve_flags,
 157                                                   sha1, flags));
 158 }
 159
 160 /* The argument to filter_refs */
 161 struct ref_filter {
 162         const char *pattern;
 163         each_ref_fn *fn;
 164         void *cb_data;
 165 };
 166
 167 int read_ref_full(const char *refname, int resolve_flags, unsigned char *sha1, int *flags)
 168 {
 169         if (resolve_ref_unsafe(refname, resolve_flags, sha1, flags))
 170                 return 0;
 171         return -1;
 172 }
 173
 174 int read_ref(const char *refname, unsigned char *sha1)
 175 {
 176         return read_ref_full(refname, RESOLVE_REF_READING, sha1, NULL);
 177 }
 178
 179 int ref_exists(const char *refname)
 180 {
 181         unsigned char sha1[20];
 182         return !!resolve_ref_unsafe(refname, RESOLVE_REF_READING, sha1, NULL);
 183 }
 184
 185 static int filter_refs(const char *refname, const struct object_id *oid,
 186                            int flags, void *data)
 187 {
 188         struct ref_filter *filter = (struct ref_filter *)data;
 189
 190         if (wildmatch(filter->pattern, refname, 0, NULL))
 191                 return 0;
 192         return filter->fn(refname, oid, flags, filter->cb_data);
 193 }
 194
 195 enum peel_status peel_object(const unsigned char *name, unsigned char *sha1)
 196 {
 197         struct object *o = lookup_unknown_object(name);
 198
 199         if (o->type == OBJ_NONE) {
 200                 int type = sha1_object_info(name, NULL);
 201                 if (type < 0 || !object_as_type(o, type, 0))
 202                         return PEEL_INVALID;
 203         }
 204
 205         if (o->type != OBJ_TAG)
 206                 return PEEL_NON_TAG;
 207
 208         o = deref_tag_noverify(o);
 209         if (!o)
 210                 return PEEL_INVALID;
 211
 212         hashcpy(sha1, o->oid.hash);
 213         return PEEL_PEELED;
 214 }
 215
 216 struct warn_if_dangling_data {
 217         FILE *fp;
 218         const char *refname;
 219         const struct string_list *refnames;
 220         const char *msg_fmt;
 221 };
 222
 223 static int warn_if_dangling_symref(const char *refname, const struct object_id *oid,
 224                                    int flags, void *cb_data)
 225 {
 226         struct warn_if_dangling_data *d = cb_data;
 227         const char *resolves_to;
 228         struct object_id junk;
 229
 230         if (!(flags & REF_ISSYMREF))
 231                 return 0;
 232
 233         resolves_to = resolve_ref_unsafe(refname, 0, junk.hash, NULL);
 234         if (!resolves_to
 235             || (d->refname
 236                 ? strcmp(resolves_to, d->refname)
 237                 : !string_list_has_string(d->refnames, resolves_to))) {
 238                 return 0;
 239         }
 240
 241         fprintf(d->fp, d->msg_fmt, refname);
 242         fputc('\n', d->fp);
 243         return 0;
 244 }
 245
 246 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 247 {
 248         struct warn_if_dangling_data data;
 249
 250         data.fp = fp;
 251         data.refname = refname;
 252         data.refnames = NULL;
 253         data.msg_fmt = msg_fmt;
 254         for_each_rawref(warn_if_dangling_symref, &data);
 255 }
 256
 257 void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames)
 258 {
 259         struct warn_if_dangling_data data;
 260
 261         data.fp = fp;
 262         data.refname = NULL;
 263         data.refnames = refnames;
 264         data.msg_fmt = msg_fmt;
 265         for_each_rawref(warn_if_dangling_symref, &data);
 266 }
 267
 268 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 269 {
 270         return for_each_ref_in("refs/tags/", fn, cb_data);
 271 }
 272
 273 int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 274 {
 275         return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
 276 }
 277
 278 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 279 {
 280         return for_each_ref_in("refs/heads/", fn, cb_data);
 281 }
 282
 283 int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 284 {
 285         return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
 286 }
 287
 288 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 289 {
 290         return for_each_ref_in("refs/remotes/", fn, cb_data);
 291 }
 292
 293 int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 294 {
 295         return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
 296 }
 297
 298 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
 299 {
 300         struct strbuf buf = STRBUF_INIT;
 301         int ret = 0;
 302         struct object_id oid;
 303         int flag;
 304
 305         strbuf_addf(&buf, "%sHEAD", get_git_namespace());
 306         if (!read_ref_full(buf.buf, RESOLVE_REF_READING, oid.hash, &flag))
 307                 ret = fn(buf.buf, &oid, flag, cb_data);
 308         strbuf_release(&buf);
 309
 310         return ret;
 311 }
 312
 313 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 314         const char *prefix, void *cb_data)
 315 {
 316         struct strbuf real_pattern = STRBUF_INIT;
 317         struct ref_filter filter;
 318         int ret;
 319
 320         if (!prefix && !starts_with(pattern, "refs/"))
 321                 strbuf_addstr(&real_pattern, "refs/");
 322         else if (prefix)
 323                 strbuf_addstr(&real_pattern, prefix);
 324         strbuf_addstr(&real_pattern, pattern);
 325
 326         if (!has_glob_specials(pattern)) {
 327                 /* Append implied '/' '*' if not present. */
 328                 strbuf_complete(&real_pattern, '/');
 329                 /* No need to check for '*', there is none. */
 330                 strbuf_addch(&real_pattern, '*');
 331         }
 332
 333         filter.pattern = real_pattern.buf;
 334         filter.fn = fn;
 335         filter.cb_data = cb_data;
 336         ret = for_each_ref(filter_refs, &filter);
 337
 338         strbuf_release(&real_pattern);
 339         return ret;
 340 }
 341
 342 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 343 {
 344         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
 345 }
 346
 347 const char *prettify_refname(const char *name)
 348 {
 349         return name + (
 350                 starts_with(name, "refs/heads/") ? 11 :
 351                 starts_with(name, "refs/tags/") ? 10 :
 352                 starts_with(name, "refs/remotes/") ? 13 :
 353                 0);
 354 }
 355
 356 static const char *ref_rev_parse_rules[] = {
 357         "%.*s",
 358         "refs/%.*s",
 359         "refs/tags/%.*s",
 360         "refs/heads/%.*s",
 361         "refs/remotes/%.*s",
 362         "refs/remotes/%.*s/HEAD",
 363         NULL
 364 };
 365
 366 int refname_match(const char *abbrev_name, const char *full_name)
 367 {
 368         const char **p;
 369         const int abbrev_name_len = strlen(abbrev_name);
 370
 371         for (p = ref_rev_parse_rules; *p; p++) {
 372                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
 373                         return 1;
 374                 }
 375         }
 376
 377         return 0;
 378 }
 379
 380 /*
 381  * *string and *len will only be substituted, and *string returned (for
 382  * later free()ing) if the string passed in is a magic short-hand form
 383  * to name a branch.
 384  */
 385 static char *substitute_branch_name(const char **string, int *len)
 386 {
 387         struct strbuf buf = STRBUF_INIT;
 388         int ret = interpret_branch_name(*string, *len, &buf);
 389
 390         if (ret == *len) {
 391                 size_t size;
 392                 *string = strbuf_detach(&buf, &size);
 393                 *len = size;
 394                 return (char *)*string;
 395         }
 396
 397         return NULL;
 398 }
 399
 400 int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
 401 {
 402         char *last_branch = substitute_branch_name(&str, &len);
 403         const char **p, *r;
 404         int refs_found = 0;
 405
 406         *ref = NULL;
 407         for (p = ref_rev_parse_rules; *p; p++) {
 408                 char fullref[PATH_MAX];
 409                 unsigned char sha1_from_ref[20];
 410                 unsigned char *this_result;
 411                 int flag;
 412
 413                 this_result = refs_found ? sha1_from_ref : sha1;
 414                 mksnpath(fullref, sizeof(fullref), *p, len, str);
 415                 r = resolve_ref_unsafe(fullref, RESOLVE_REF_READING,
 416                                        this_result, &flag);
 417                 if (r) {
 418                         if (!refs_found++)
 419                                 *ref = xstrdup(r);
 420                         if (!warn_ambiguous_refs)
 421                                 break;
 422                 } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD")) {
 423                         warning("ignoring dangling symref %s.", fullref);
 424                 } else if ((flag & REF_ISBROKEN) && strchr(fullref, '/')) {
 425                         warning("ignoring broken ref %s.", fullref);
 426                 }
 427         }
 428         free(last_branch);
 429         return refs_found;
 430 }
 431
 432 int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
 433 {
 434         char *last_branch = substitute_branch_name(&str, &len);
 435         const char **p;
 436         int logs_found = 0;
 437
 438         *log = NULL;
 439         for (p = ref_rev_parse_rules; *p; p++) {
 440                 unsigned char hash[20];
 441                 char path[PATH_MAX];
 442                 const char *ref, *it;
 443
 444                 mksnpath(path, sizeof(path), *p, len, str);
 445                 ref = resolve_ref_unsafe(path, RESOLVE_REF_READING,
 446                                          hash, NULL);
 447                 if (!ref)
 448                         continue;
 449                 if (reflog_exists(path))
 450                         it = path;
 451                 else if (strcmp(ref, path) && reflog_exists(ref))
 452                         it = ref;
 453                 else
 454                         continue;
 455                 if (!logs_found++) {
 456                         *log = xstrdup(it);
 457                         hashcpy(sha1, hash);
 458                 }
 459                 if (!warn_ambiguous_refs)
 460                         break;
 461         }
 462         free(last_branch);
 463         return logs_found;
 464 }
 465
 466 static int is_per_worktree_ref(const char *refname)
 467 {
 468         return !strcmp(refname, "HEAD") ||
 469                 starts_with(refname, "refs/bisect/");
 470 }
 471
 472 static int is_pseudoref_syntax(const char *refname)
 473 {
 474         const char *c;
 475
 476         for (c = refname; *c; c++) {
 477                 if (!isupper(*c) && *c != '-' && *c != '_')
 478                         return 0;
 479         }
 480
 481         return 1;
 482 }
 483
 484 enum ref_type ref_type(const char *refname)
 485 {
 486         if (is_per_worktree_ref(refname))
 487                 return REF_TYPE_PER_WORKTREE;
 488         if (is_pseudoref_syntax(refname))
 489                 return REF_TYPE_PSEUDOREF;
 490        return REF_TYPE_NORMAL;
 491 }
 492
 493 static int write_pseudoref(const char *pseudoref, const unsigned char *sha1,
 494                            const unsigned char *old_sha1, struct strbuf *err)
 495 {
 496         const char *filename;
 497         int fd;
 498         static struct lock_file lock;
 499         struct strbuf buf = STRBUF_INIT;
 500         int ret = -1;
 501
 502         strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
 503
 504         filename = git_path("%s", pseudoref);
 505         fd = hold_lock_file_for_update(&lock, filename, LOCK_DIE_ON_ERROR);
 506         if (fd < 0) {
 507                 strbuf_addf(err, "could not open '%s' for writing: %s",
 508                             filename, strerror(errno));
 509                 return -1;
 510         }
 511
 512         if (old_sha1) {
 513                 unsigned char actual_old_sha1[20];
 514
 515                 if (read_ref(pseudoref, actual_old_sha1))
 516                         die("could not read ref '%s'", pseudoref);
 517                 if (hashcmp(actual_old_sha1, old_sha1)) {
 518                         strbuf_addf(err, "unexpected sha1 when writing '%s'", pseudoref);
 519                         rollback_lock_file(&lock);
 520                         goto done;
 521                 }
 522         }
 523
 524         if (write_in_full(fd, buf.buf, buf.len) != buf.len) {
 525                 strbuf_addf(err, "could not write to '%s'", filename);
 526                 rollback_lock_file(&lock);
 527                 goto done;
 528         }
 529
 530         commit_lock_file(&lock);
 531         ret = 0;
 532 done:
 533         strbuf_release(&buf);
 534         return ret;
 535 }
 536
 537 static int delete_pseudoref(const char *pseudoref, const unsigned char *old_sha1)
 538 {
 539         static struct lock_file lock;
 540         const char *filename;
 541
 542         filename = git_path("%s", pseudoref);
 543
 544         if (old_sha1 && !is_null_sha1(old_sha1)) {
 545                 int fd;
 546                 unsigned char actual_old_sha1[20];
 547
 548                 fd = hold_lock_file_for_update(&lock, filename,
 549                                                LOCK_DIE_ON_ERROR);
 550                 if (fd < 0)
 551                         die_errno(_("Could not open '%s' for writing"), filename);
 552                 if (read_ref(pseudoref, actual_old_sha1))
 553                         die("could not read ref '%s'", pseudoref);
 554                 if (hashcmp(actual_old_sha1, old_sha1)) {
 555                         warning("Unexpected sha1 when deleting %s", pseudoref);
 556                         rollback_lock_file(&lock);
 557                         return -1;
 558                 }
 559
 560                 unlink(filename);
 561                 rollback_lock_file(&lock);
 562         } else {
 563                 unlink(filename);
 564         }
 565
 566         return 0;
 567 }
 568
 569 int delete_ref(const char *refname, const unsigned char *old_sha1,
 570                unsigned int flags)
 571 {
 572         struct ref_transaction *transaction;
 573         struct strbuf err = STRBUF_INIT;
 574
 575         if (ref_type(refname) == REF_TYPE_PSEUDOREF)
 576                 return delete_pseudoref(refname, old_sha1);
 577
 578         transaction = ref_transaction_begin(&err);
 579         if (!transaction ||
 580             ref_transaction_delete(transaction, refname, old_sha1,
 581                                    flags, NULL, &err) ||
 582             ref_transaction_commit(transaction, &err)) {
 583                 error("%s", err.buf);
 584                 ref_transaction_free(transaction);
 585                 strbuf_release(&err);
 586                 return 1;
 587         }
 588         ref_transaction_free(transaction);
 589         strbuf_release(&err);
 590         return 0;
 591 }
 592
 593 int copy_reflog_msg(char *buf, const char *msg)
 594 {
 595         char *cp = buf;
 596         char c;
 597         int wasspace = 1;
 598
 599         *cp++ = '\t';
 600         while ((c = *msg++)) {
 601                 if (wasspace && isspace(c))
 602                         continue;
 603                 wasspace = isspace(c);
 604                 if (wasspace)
 605                         c = ' ';
 606                 *cp++ = c;
 607         }
 608         while (buf < cp && isspace(cp[-1]))
 609                 cp--;
 610         *cp++ = '\n';
 611         return cp - buf;
 612 }
 613
 614 int should_autocreate_reflog(const char *refname)
 615 {
 616         if (!log_all_ref_updates)
 617                 return 0;
 618         return starts_with(refname, "refs/heads/") ||
 619                 starts_with(refname, "refs/remotes/") ||
 620                 starts_with(refname, "refs/notes/") ||
 621                 !strcmp(refname, "HEAD");
 622 }
 623
 624 int is_branch(const char *refname)
 625 {
 626         return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
 627 }
 628
 629 struct read_ref_at_cb {
 630         const char *refname;
 631         unsigned long at_time;
 632         int cnt;
 633         int reccnt;
 634         unsigned char *sha1;
 635         int found_it;
 636
 637         unsigned char osha1[20];
 638         unsigned char nsha1[20];
 639         int tz;
 640         unsigned long date;
 641         char **msg;
 642         unsigned long *cutoff_time;
 643         int *cutoff_tz;
 644         int *cutoff_cnt;
 645 };
 646
 647 static int read_ref_at_ent(unsigned char *osha1, unsigned char *nsha1,
 648                 const char *email, unsigned long timestamp, int tz,
 649                 const char *message, void *cb_data)
 650 {
 651         struct read_ref_at_cb *cb = cb_data;
 652
 653         cb->reccnt++;
 654         cb->tz = tz;
 655         cb->date = timestamp;
 656
 657         if (timestamp <= cb->at_time || cb->cnt == 0) {
 658                 if (cb->msg)
 659                         *cb->msg = xstrdup(message);
 660                 if (cb->cutoff_time)
 661                         *cb->cutoff_time = timestamp;
 662                 if (cb->cutoff_tz)
 663                         *cb->cutoff_tz = tz;
 664                 if (cb->cutoff_cnt)
 665                         *cb->cutoff_cnt = cb->reccnt - 1;
 666                 /*
 667                  * we have not yet updated cb->[n|o]sha1 so they still
 668                  * hold the values for the previous record.
 669                  */
 670                 if (!is_null_sha1(cb->osha1)) {
 671                         hashcpy(cb->sha1, nsha1);
 672                         if (hashcmp(cb->osha1, nsha1))
 673                                 warning("Log for ref %s has gap after %s.",
 674                                         cb->refname, show_date(cb->date, cb->tz, DATE_MODE(RFC2822)));
 675                 }
 676                 else if (cb->date == cb->at_time)
 677                         hashcpy(cb->sha1, nsha1);
 678                 else if (hashcmp(nsha1, cb->sha1))
 679                         warning("Log for ref %s unexpectedly ended on %s.",
 680                                 cb->refname, show_date(cb->date, cb->tz,
 681                                                        DATE_MODE(RFC2822)));
 682                 hashcpy(cb->osha1, osha1);
 683                 hashcpy(cb->nsha1, nsha1);
 684                 cb->found_it = 1;
 685                 return 1;
 686         }
 687         hashcpy(cb->osha1, osha1);
 688         hashcpy(cb->nsha1, nsha1);
 689         if (cb->cnt > 0)
 690                 cb->cnt--;
 691         return 0;
 692 }
 693
 694 static int read_ref_at_ent_oldest(unsigned char *osha1, unsigned char *nsha1,
 695                                   const char *email, unsigned long timestamp,
 696                                   int tz, const char *message, void *cb_data)
 697 {
 698         struct read_ref_at_cb *cb = cb_data;
 699
 700         if (cb->msg)
 701                 *cb->msg = xstrdup(message);
 702         if (cb->cutoff_time)
 703                 *cb->cutoff_time = timestamp;
 704         if (cb->cutoff_tz)
 705                 *cb->cutoff_tz = tz;
 706         if (cb->cutoff_cnt)
 707                 *cb->cutoff_cnt = cb->reccnt;
 708         hashcpy(cb->sha1, osha1);
 709         if (is_null_sha1(cb->sha1))
 710                 hashcpy(cb->sha1, nsha1);
 711         /* We just want the first entry */
 712         return 1;
 713 }
 714
 715 int read_ref_at(const char *refname, unsigned int flags, unsigned long at_time, int cnt,
 716                 unsigned char *sha1, char **msg,
 717                 unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
 718 {
 719         struct read_ref_at_cb cb;
 720
 721         memset(&cb, 0, sizeof(cb));
 722         cb.refname = refname;
 723         cb.at_time = at_time;
 724         cb.cnt = cnt;
 725         cb.msg = msg;
 726         cb.cutoff_time = cutoff_time;
 727         cb.cutoff_tz = cutoff_tz;
 728         cb.cutoff_cnt = cutoff_cnt;
 729         cb.sha1 = sha1;
 730
 731         for_each_reflog_ent_reverse(refname, read_ref_at_ent, &cb);
 732
 733         if (!cb.reccnt) {
 734                 if (flags & GET_SHA1_QUIETLY)
 735                         exit(128);
 736                 else
 737                         die("Log for %s is empty.", refname);
 738         }
 739         if (cb.found_it)
 740                 return 0;
 741
 742         for_each_reflog_ent(refname, read_ref_at_ent_oldest, &cb);
 743
 744         return 1;
 745 }
 746
 747 struct ref_transaction *ref_transaction_begin(struct strbuf *err)
 748 {
 749         assert(err);
 750
 751         return xcalloc(1, sizeof(struct ref_transaction));
 752 }
 753
 754 void ref_transaction_free(struct ref_transaction *transaction)
 755 {
 756         int i;
 757
 758         if (!transaction)
 759                 return;
 760
 761         for (i = 0; i < transaction->nr; i++) {
 762                 free(transaction->updates[i]->msg);
 763                 free(transaction->updates[i]);
 764         }
 765         free(transaction->updates);
 766         free(transaction);
 767 }
 768
 769 struct ref_update *ref_transaction_add_update(
 770                 struct ref_transaction *transaction,
 771                 const char *refname, unsigned int flags,
 772                 const unsigned char *new_sha1,
 773                 const unsigned char *old_sha1,
 774                 const char *msg)
 775 {
 776         struct ref_update *update;
 777
 778         if (transaction->state != REF_TRANSACTION_OPEN)
 779                 die("BUG: update called for transaction that is not open");
 780
 781         if ((flags & REF_ISPRUNING) && !(flags & REF_NODEREF))
 782                 die("BUG: REF_ISPRUNING set without REF_NODEREF");
 783
 784         FLEX_ALLOC_STR(update, refname, refname);
 785         ALLOC_GROW(transaction->updates, transaction->nr + 1, transaction->alloc);
 786         transaction->updates[transaction->nr++] = update;
 787
 788         update->flags = flags;
 789
 790         if (flags & REF_HAVE_NEW)
 791                 hashcpy(update->new_sha1, new_sha1);
 792         if (flags & REF_HAVE_OLD)
 793                 hashcpy(update->old_sha1, old_sha1);
 794         update->msg = xstrdup_or_null(msg);
 795         return update;
 796 }
 797
 798 int ref_transaction_update(struct ref_transaction *transaction,
 799                            const char *refname,
 800                            const unsigned char *new_sha1,
 801                            const unsigned char *old_sha1,
 802                            unsigned int flags, const char *msg,
 803                            struct strbuf *err)
 804 {
 805         assert(err);
 806
 807         if ((new_sha1 && !is_null_sha1(new_sha1)) ?
 808             check_refname_format(refname, REFNAME_ALLOW_ONELEVEL) :
 809             !refname_is_safe(refname)) {
 810                 strbuf_addf(err, "refusing to update ref with bad name '%s'",
 811                             refname);
 812                 return -1;
 813         }
 814
 815         flags |= (new_sha1 ? REF_HAVE_NEW : 0) | (old_sha1 ? REF_HAVE_OLD : 0);
 816
 817         ref_transaction_add_update(transaction, refname, flags,
 818                                    new_sha1, old_sha1, msg);
 819         return 0;
 820 }
 821
 822 int ref_transaction_create(struct ref_transaction *transaction,
 823                            const char *refname,
 824                            const unsigned char *new_sha1,
 825                            unsigned int flags, const char *msg,
 826                            struct strbuf *err)
 827 {
 828         if (!new_sha1 || is_null_sha1(new_sha1))
 829                 die("BUG: create called without valid new_sha1");
 830         return ref_transaction_update(transaction, refname, new_sha1,
 831                                       null_sha1, flags, msg, err);
 832 }
 833
 834 int ref_transaction_delete(struct ref_transaction *transaction,
 835                            const char *refname,
 836                            const unsigned char *old_sha1,
 837                            unsigned int flags, const char *msg,
 838                            struct strbuf *err)
 839 {
 840         if (old_sha1 && is_null_sha1(old_sha1))
 841                 die("BUG: delete called with old_sha1 set to zeros");
 842         return ref_transaction_update(transaction, refname,
 843                                       null_sha1, old_sha1,
 844                                       flags, msg, err);
 845 }
 846
 847 int ref_transaction_verify(struct ref_transaction *transaction,
 848                            const char *refname,
 849                            const unsigned char *old_sha1,
 850                            unsigned int flags,
 851                            struct strbuf *err)
 852 {
 853         if (!old_sha1)
 854                 die("BUG: verify called with old_sha1 set to NULL");
 855         return ref_transaction_update(transaction, refname,
 856                                       NULL, old_sha1,
 857                                       flags, NULL, err);
 858 }
 859
 860 int update_ref(const char *msg, const char *refname,
 861                const unsigned char *new_sha1, const unsigned char *old_sha1,
 862                unsigned int flags, enum action_on_err onerr)
 863 {
 864         struct ref_transaction *t = NULL;
 865         struct strbuf err = STRBUF_INIT;
 866         int ret = 0;
 867
 868         if (ref_type(refname) == REF_TYPE_PSEUDOREF) {
 869                 ret = write_pseudoref(refname, new_sha1, old_sha1, &err);
 870         } else {
 871                 t = ref_transaction_begin(&err);
 872                 if (!t ||
 873                     ref_transaction_update(t, refname, new_sha1, old_sha1,
 874                                            flags, msg, &err) ||
 875                     ref_transaction_commit(t, &err)) {
 876                         ret = 1;
 877                         ref_transaction_free(t);
 878                 }
 879         }
 880         if (ret) {
 881                 const char *str = "update_ref failed for ref '%s': %s";
 882
 883                 switch (onerr) {
 884                 case UPDATE_REFS_MSG_ON_ERR:
 885                         error(str, refname, err.buf);
 886                         break;
 887                 case UPDATE_REFS_DIE_ON_ERR:
 888                         die(str, refname, err.buf);
 889                         break;
 890                 case UPDATE_REFS_QUIET_ON_ERR:
 891                         break;
 892                 }
 893                 strbuf_release(&err);
 894                 return 1;
 895         }
 896         strbuf_release(&err);
 897         if (t)
 898                 ref_transaction_free(t);
 899         return 0;
 900 }
 901
 902 char *shorten_unambiguous_ref(const char *refname, int strict)
 903 {
 904         int i;
 905         static char **scanf_fmts;
 906         static int nr_rules;
 907         char *short_name;
 908
 909         if (!nr_rules) {
 910                 /*
 911                  * Pre-generate scanf formats from ref_rev_parse_rules[].
 912                  * Generate a format suitable for scanf from a
 913                  * ref_rev_parse_rules rule by interpolating "%s" at the
 914                  * location of the "%.*s".
 915                  */
 916                 size_t total_len = 0;
 917                 size_t offset = 0;
 918
 919                 /* the rule list is NULL terminated, count them first */
 920                 for (nr_rules = 0; ref_rev_parse_rules[nr_rules]; nr_rules++)
 921                         /* -2 for strlen("%.*s") - strlen("%s"); +1 for NUL */
 922                         total_len += strlen(ref_rev_parse_rules[nr_rules]) - 2 + 1;
 923
 924                 scanf_fmts = xmalloc(st_add(st_mult(sizeof(char *), nr_rules), total_len));
 925
 926                 offset = 0;
 927                 for (i = 0; i < nr_rules; i++) {
 928                         assert(offset < total_len);
 929                         scanf_fmts[i] = (char *)&scanf_fmts[nr_rules] + offset;
 930                         offset += snprintf(scanf_fmts[i], total_len - offset,
 931                                            ref_rev_parse_rules[i], 2, "%s") + 1;
 932                 }
 933         }
 934
 935         /* bail out if there are no rules */
 936         if (!nr_rules)
 937                 return xstrdup(refname);
 938
 939         /* buffer for scanf result, at most refname must fit */
 940         short_name = xstrdup(refname);
 941
 942         /* skip first rule, it will always match */
 943         for (i = nr_rules - 1; i > 0 ; --i) {
 944                 int j;
 945                 int rules_to_fail = i;
 946                 int short_name_len;
 947
 948                 if (1 != sscanf(refname, scanf_fmts[i], short_name))
 949                         continue;
 950
 951                 short_name_len = strlen(short_name);
 952
 953                 /*
 954                  * in strict mode, all (except the matched one) rules
 955                  * must fail to resolve to a valid non-ambiguous ref
 956                  */
 957                 if (strict)
 958                         rules_to_fail = nr_rules;
 959
 960                 /*
 961                  * check if the short name resolves to a valid ref,
 962                  * but use only rules prior to the matched one
 963                  */
 964                 for (j = 0; j < rules_to_fail; j++) {
 965                         const char *rule = ref_rev_parse_rules[j];
 966                         char refname[PATH_MAX];
 967
 968                         /* skip matched rule */
 969                         if (i == j)
 970                                 continue;
 971
 972                         /*
 973                          * the short name is ambiguous, if it resolves
 974                          * (with this previous rule) to a valid ref
 975                          * read_ref() returns 0 on success
 976                          */
 977                         mksnpath(refname, sizeof(refname),
 978                                  rule, short_name_len, short_name);
 979                         if (ref_exists(refname))
 980                                 break;
 981                 }
 982
 983                 /*
 984                  * short name is non-ambiguous if all previous rules
 985                  * haven't resolved to a valid ref
 986                  */
 987                 if (j == rules_to_fail)
 988                         return short_name;
 989         }
 990
 991         free(short_name);
 992         return xstrdup(refname);
 993 }
 994
 995 static struct string_list *hide_refs;
 996
 997 int parse_hide_refs_config(const char *var, const char *value, const char *section)
 998 {
 999         if (!strcmp("transfer.hiderefs", var) ||
1000             /* NEEDSWORK: use parse_config_key() once both are merged */
1001             (starts_with(var, section) && var[strlen(section)] == '.' &&
1002              !strcmp(var + strlen(section), ".hiderefs"))) {
1003                 char *ref;
1004                 int len;
1005
1006                 if (!value)
1007                         return config_error_nonbool(var);
1008                 ref = xstrdup(value);
1009                 len = strlen(ref);
1010                 while (len && ref[len - 1] == '/')
1011                         ref[--len] = '\0';
1012                 if (!hide_refs) {
1013                         hide_refs = xcalloc(1, sizeof(*hide_refs));
1014                         hide_refs->strdup_strings = 1;
1015                 }
1016                 string_list_append(hide_refs, ref);
1017         }
1018         return 0;
1019 }
1020
1021 int ref_is_hidden(const char *refname, const char *refname_full)
1022 {
1023         int i;
1024
1025         if (!hide_refs)
1026                 return 0;
1027         for (i = hide_refs->nr - 1; i >= 0; i--) {
1028                 const char *match = hide_refs->items[i].string;
1029                 const char *subject;
1030                 int neg = 0;
1031                 int len;
1032
1033                 if (*match == '!') {
1034                         neg = 1;
1035                         match++;
1036                 }
1037
1038                 if (*match == '^') {
1039                         subject = refname_full;
1040                         match++;
1041                 } else {
1042                         subject = refname;
1043                 }
1044
1045                 /* refname can be NULL when namespaces are used. */
1046                 if (!subject || !starts_with(subject, match))
1047                         continue;
1048                 len = strlen(match);
1049                 if (!subject[len] || subject[len] == '/')
1050                         return !neg;
1051         }
1052         return 0;
1053 }
1054
1055 const char *find_descendant_ref(const char *dirname,
1056                                 const struct string_list *extras,
1057                                 const struct string_list *skip)
1058 {
1059         int pos;
1060
1061         if (!extras)
1062                 return NULL;
1063
1064         /*
1065          * Look at the place where dirname would be inserted into
1066          * extras. If there is an entry at that position that starts
1067          * with dirname (remember, dirname includes the trailing
1068          * slash) and is not in skip, then we have a conflict.
1069          */
1070         for (pos = string_list_find_insert_index(extras, dirname, 0);
1071              pos < extras->nr; pos++) {
1072                 const char *extra_refname = extras->items[pos].string;
1073
1074                 if (!starts_with(extra_refname, dirname))
1075                         break;
1076
1077                 if (!skip || !string_list_has_string(skip, extra_refname))
1078                         return extra_refname;
1079         }
1080         return NULL;
1081 }
1082
1083 int rename_ref_available(const char *oldname, const char *newname)
1084 {
1085         struct string_list skip = STRING_LIST_INIT_NODUP;
1086         struct strbuf err = STRBUF_INIT;
1087         int ret;
1088
1089         string_list_insert(&skip, oldname);
1090         ret = !verify_refname_available(newname, NULL, &skip, &err);
1091         if (!ret)
1092                 error("%s", err.buf);
1093
1094         string_list_clear(&skip, 0);
1095         strbuf_release(&err);
1096         return ret;
1097 }
1098
1099 int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1100 {
1101         struct object_id oid;
1102         int flag;
1103
1104         if (submodule) {
1105                 if (resolve_gitlink_ref(submodule, "HEAD", oid.hash) == 0)
1106                         return fn("HEAD", &oid, 0, cb_data);
1107
1108                 return 0;
1109         }
1110
1111         if (!read_ref_full("HEAD", RESOLVE_REF_READING, oid.hash, &flag))
1112                 return fn("HEAD", &oid, flag, cb_data);
1113
1114         return 0;
1115 }
1116
1117 int head_ref(each_ref_fn fn, void *cb_data)
1118 {
1119         return head_ref_submodule(NULL, fn, cb_data);
1120 }
1121
1122 /*
1123  * Call fn for each reference in the specified submodule for which the
1124  * refname begins with prefix. If trim is non-zero, then trim that
1125  * many characters off the beginning of each refname before passing
1126  * the refname to fn. flags can be DO_FOR_EACH_INCLUDE_BROKEN to
1127  * include broken references in the iteration. If fn ever returns a
1128  * non-zero value, stop the iteration and return that value;
1129  * otherwise, return 0.
1130  */
1131 static int do_for_each_ref(const char *submodule, const char *prefix,
1132                            each_ref_fn fn, int trim, int flags, void *cb_data)
1133 {
1134         struct ref_iterator *iter;
1135
1136         iter = files_ref_iterator_begin(submodule, prefix, flags);
1137         iter = prefix_ref_iterator_begin(iter, prefix, trim);
1138
1139         return do_for_each_ref_iterator(iter, fn, cb_data);
1140 }
1141
1142 int for_each_ref(each_ref_fn fn, void *cb_data)
1143 {
1144         return do_for_each_ref(NULL, "", fn, 0, 0, cb_data);
1145 }
1146
1147 int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1148 {
1149         return do_for_each_ref(submodule, "", fn, 0, 0, cb_data);
1150 }
1151
1152 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
1153 {
1154         return do_for_each_ref(NULL, prefix, fn, strlen(prefix), 0, cb_data);
1155 }
1156
1157 int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data, unsigned int broken)
1158 {
1159         unsigned int flag = 0;
1160
1161         if (broken)
1162                 flag = DO_FOR_EACH_INCLUDE_BROKEN;
1163         return do_for_each_ref(NULL, prefix, fn, 0, flag, cb_data);
1164 }
1165
1166 int for_each_ref_in_submodule(const char *submodule, const char *prefix,
1167                 each_ref_fn fn, void *cb_data)
1168 {
1169         return do_for_each_ref(submodule, prefix, fn, strlen(prefix), 0, cb_data);
1170 }
1171
1172 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
1173 {
1174         return do_for_each_ref(NULL, git_replace_ref_base, fn,
1175                                strlen(git_replace_ref_base), 0, cb_data);
1176 }
1177
1178 int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
1179 {
1180         struct strbuf buf = STRBUF_INIT;
1181         int ret;
1182         strbuf_addf(&buf, "%srefs/", get_git_namespace());
1183         ret = do_for_each_ref(NULL, buf.buf, fn, 0, 0, cb_data);
1184         strbuf_release(&buf);
1185         return ret;
1186 }
1187
1188 int for_each_rawref(each_ref_fn fn, void *cb_data)
1189 {
1190         return do_for_each_ref(NULL, "", fn, 0,
1191                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1192 }
1193
1194 /* This function needs to return a meaningful errno on failure */
1195 const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
1196                                unsigned char *sha1, int *flags)
1197 {
1198         static struct strbuf sb_refname = STRBUF_INIT;
1199         int unused_flags;
1200         int symref_count;
1201
1202         if (!flags)
1203                 flags = &unused_flags;
1204
1205         *flags = 0;
1206
1207         if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1208                 if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1209                     !refname_is_safe(refname)) {
1210                         errno = EINVAL;
1211                         return NULL;
1212                 }
1213
1214                 /*
1215                  * dwim_ref() uses REF_ISBROKEN to distinguish between
1216                  * missing refs and refs that were present but invalid,
1217                  * to complain about the latter to stderr.
1218                  *
1219                  * We don't know whether the ref exists, so don't set
1220                  * REF_ISBROKEN yet.
1221                  */
1222                 *flags |= REF_BAD_NAME;
1223         }
1224
1225         for (symref_count = 0; symref_count < SYMREF_MAXDEPTH; symref_count++) {
1226                 unsigned int read_flags = 0;
1227
1228                 if (read_raw_ref(refname, sha1, &sb_refname, &read_flags)) {
1229                         *flags |= read_flags;
1230                         if (errno != ENOENT || (resolve_flags & RESOLVE_REF_READING))
1231                                 return NULL;
1232                         hashclr(sha1);
1233                         if (*flags & REF_BAD_NAME)
1234                                 *flags |= REF_ISBROKEN;
1235                         return refname;
1236                 }
1237
1238                 *flags |= read_flags;
1239
1240                 if (!(read_flags & REF_ISSYMREF)) {
1241                         if (*flags & REF_BAD_NAME) {
1242                                 hashclr(sha1);
1243                                 *flags |= REF_ISBROKEN;
1244                         }
1245                         return refname;
1246                 }
1247
1248                 refname = sb_refname.buf;
1249                 if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
1250                         hashclr(sha1);
1251                         return refname;
1252                 }
1253                 if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1254                         if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1255                             !refname_is_safe(refname)) {
1256                                 errno = EINVAL;
1257                                 return NULL;
1258                         }
1259
1260                         *flags |= REF_ISBROKEN | REF_BAD_NAME;
1261                 }
1262         }
1263
1264         errno = ELOOP;
1265         return NULL;
1266 }