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
 129                 /*
 130                  * Does the refname try to escape refs/?
 131                  * For example: refs/foo/../bar is safe but refs/foo/../../bar
 132                  * is not.
 133                  */
 134                 buf = xmallocz(strlen(rest));
 135                 result = !normalize_path_copy(buf, rest);
 136                 free(buf);
 137                 return result;
 138         }
 139         while (*refname) {
 140                 if (!isupper(*refname) && *refname != '_')
 141                         return 0;
 142                 refname++;
 143         }
 144         return 1;
 145 }
 146
 147 char *resolve_refdup(const char *refname, int resolve_flags,
 148                      unsigned char *sha1, int *flags)
 149 {
 150         return xstrdup_or_null(resolve_ref_unsafe(refname, resolve_flags,
 151                                                   sha1, flags));
 152 }
 153
 154 /* The argument to filter_refs */
 155 struct ref_filter {
 156         const char *pattern;
 157         each_ref_fn *fn;
 158         void *cb_data;
 159 };
 160
 161 int read_ref_full(const char *refname, int resolve_flags, unsigned char *sha1, int *flags)
 162 {
 163         if (resolve_ref_unsafe(refname, resolve_flags, sha1, flags))
 164                 return 0;
 165         return -1;
 166 }
 167
 168 int read_ref(const char *refname, unsigned char *sha1)
 169 {
 170         return read_ref_full(refname, RESOLVE_REF_READING, sha1, NULL);
 171 }
 172
 173 int ref_exists(const char *refname)
 174 {
 175         unsigned char sha1[20];
 176         return !!resolve_ref_unsafe(refname, RESOLVE_REF_READING, sha1, NULL);
 177 }
 178
 179 static int filter_refs(const char *refname, const struct object_id *oid,
 180                            int flags, void *data)
 181 {
 182         struct ref_filter *filter = (struct ref_filter *)data;
 183
 184         if (wildmatch(filter->pattern, refname, 0, NULL))
 185                 return 0;
 186         return filter->fn(refname, oid, flags, filter->cb_data);
 187 }
 188
 189 enum peel_status peel_object(const unsigned char *name, unsigned char *sha1)
 190 {
 191         struct object *o = lookup_unknown_object(name);
 192
 193         if (o->type == OBJ_NONE) {
 194                 int type = sha1_object_info(name, NULL);
 195                 if (type < 0 || !object_as_type(o, type, 0))
 196                         return PEEL_INVALID;
 197         }
 198
 199         if (o->type != OBJ_TAG)
 200                 return PEEL_NON_TAG;
 201
 202         o = deref_tag_noverify(o);
 203         if (!o)
 204                 return PEEL_INVALID;
 205
 206         hashcpy(sha1, o->oid.hash);
 207         return PEEL_PEELED;
 208 }
 209
 210 struct warn_if_dangling_data {
 211         FILE *fp;
 212         const char *refname;
 213         const struct string_list *refnames;
 214         const char *msg_fmt;
 215 };
 216
 217 static int warn_if_dangling_symref(const char *refname, const struct object_id *oid,
 218                                    int flags, void *cb_data)
 219 {
 220         struct warn_if_dangling_data *d = cb_data;
 221         const char *resolves_to;
 222         struct object_id junk;
 223
 224         if (!(flags & REF_ISSYMREF))
 225                 return 0;
 226
 227         resolves_to = resolve_ref_unsafe(refname, 0, junk.hash, NULL);
 228         if (!resolves_to
 229             || (d->refname
 230                 ? strcmp(resolves_to, d->refname)
 231                 : !string_list_has_string(d->refnames, resolves_to))) {
 232                 return 0;
 233         }
 234
 235         fprintf(d->fp, d->msg_fmt, refname);
 236         fputc('\n', d->fp);
 237         return 0;
 238 }
 239
 240 void warn_dangling_symref(FILE *fp, const char *msg_fmt, const char *refname)
 241 {
 242         struct warn_if_dangling_data data;
 243
 244         data.fp = fp;
 245         data.refname = refname;
 246         data.refnames = NULL;
 247         data.msg_fmt = msg_fmt;
 248         for_each_rawref(warn_if_dangling_symref, &data);
 249 }
 250
 251 void warn_dangling_symrefs(FILE *fp, const char *msg_fmt, const struct string_list *refnames)
 252 {
 253         struct warn_if_dangling_data data;
 254
 255         data.fp = fp;
 256         data.refname = NULL;
 257         data.refnames = refnames;
 258         data.msg_fmt = msg_fmt;
 259         for_each_rawref(warn_if_dangling_symref, &data);
 260 }
 261
 262 int for_each_tag_ref(each_ref_fn fn, void *cb_data)
 263 {
 264         return for_each_ref_in("refs/tags/", fn, cb_data);
 265 }
 266
 267 int for_each_tag_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 268 {
 269         return for_each_ref_in_submodule(submodule, "refs/tags/", fn, cb_data);
 270 }
 271
 272 int for_each_branch_ref(each_ref_fn fn, void *cb_data)
 273 {
 274         return for_each_ref_in("refs/heads/", fn, cb_data);
 275 }
 276
 277 int for_each_branch_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 278 {
 279         return for_each_ref_in_submodule(submodule, "refs/heads/", fn, cb_data);
 280 }
 281
 282 int for_each_remote_ref(each_ref_fn fn, void *cb_data)
 283 {
 284         return for_each_ref_in("refs/remotes/", fn, cb_data);
 285 }
 286
 287 int for_each_remote_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
 288 {
 289         return for_each_ref_in_submodule(submodule, "refs/remotes/", fn, cb_data);
 290 }
 291
 292 int head_ref_namespaced(each_ref_fn fn, void *cb_data)
 293 {
 294         struct strbuf buf = STRBUF_INIT;
 295         int ret = 0;
 296         struct object_id oid;
 297         int flag;
 298
 299         strbuf_addf(&buf, "%sHEAD", get_git_namespace());
 300         if (!read_ref_full(buf.buf, RESOLVE_REF_READING, oid.hash, &flag))
 301                 ret = fn(buf.buf, &oid, flag, cb_data);
 302         strbuf_release(&buf);
 303
 304         return ret;
 305 }
 306
 307 int for_each_glob_ref_in(each_ref_fn fn, const char *pattern,
 308         const char *prefix, void *cb_data)
 309 {
 310         struct strbuf real_pattern = STRBUF_INIT;
 311         struct ref_filter filter;
 312         int ret;
 313
 314         if (!prefix && !starts_with(pattern, "refs/"))
 315                 strbuf_addstr(&real_pattern, "refs/");
 316         else if (prefix)
 317                 strbuf_addstr(&real_pattern, prefix);
 318         strbuf_addstr(&real_pattern, pattern);
 319
 320         if (!has_glob_specials(pattern)) {
 321                 /* Append implied '/' '*' if not present. */
 322                 strbuf_complete(&real_pattern, '/');
 323                 /* No need to check for '*', there is none. */
 324                 strbuf_addch(&real_pattern, '*');
 325         }
 326
 327         filter.pattern = real_pattern.buf;
 328         filter.fn = fn;
 329         filter.cb_data = cb_data;
 330         ret = for_each_ref(filter_refs, &filter);
 331
 332         strbuf_release(&real_pattern);
 333         return ret;
 334 }
 335
 336 int for_each_glob_ref(each_ref_fn fn, const char *pattern, void *cb_data)
 337 {
 338         return for_each_glob_ref_in(fn, pattern, NULL, cb_data);
 339 }
 340
 341 const char *prettify_refname(const char *name)
 342 {
 343         return name + (
 344                 starts_with(name, "refs/heads/") ? 11 :
 345                 starts_with(name, "refs/tags/") ? 10 :
 346                 starts_with(name, "refs/remotes/") ? 13 :
 347                 0);
 348 }
 349
 350 static const char *ref_rev_parse_rules[] = {
 351         "%.*s",
 352         "refs/%.*s",
 353         "refs/tags/%.*s",
 354         "refs/heads/%.*s",
 355         "refs/remotes/%.*s",
 356         "refs/remotes/%.*s/HEAD",
 357         NULL
 358 };
 359
 360 int refname_match(const char *abbrev_name, const char *full_name)
 361 {
 362         const char **p;
 363         const int abbrev_name_len = strlen(abbrev_name);
 364
 365         for (p = ref_rev_parse_rules; *p; p++) {
 366                 if (!strcmp(full_name, mkpath(*p, abbrev_name_len, abbrev_name))) {
 367                         return 1;
 368                 }
 369         }
 370
 371         return 0;
 372 }
 373
 374 /*
 375  * *string and *len will only be substituted, and *string returned (for
 376  * later free()ing) if the string passed in is a magic short-hand form
 377  * to name a branch.
 378  */
 379 static char *substitute_branch_name(const char **string, int *len)
 380 {
 381         struct strbuf buf = STRBUF_INIT;
 382         int ret = interpret_branch_name(*string, *len, &buf);
 383
 384         if (ret == *len) {
 385                 size_t size;
 386                 *string = strbuf_detach(&buf, &size);
 387                 *len = size;
 388                 return (char *)*string;
 389         }
 390
 391         return NULL;
 392 }
 393
 394 int dwim_ref(const char *str, int len, unsigned char *sha1, char **ref)
 395 {
 396         char *last_branch = substitute_branch_name(&str, &len);
 397         const char **p, *r;
 398         int refs_found = 0;
 399
 400         *ref = NULL;
 401         for (p = ref_rev_parse_rules; *p; p++) {
 402                 char fullref[PATH_MAX];
 403                 unsigned char sha1_from_ref[20];
 404                 unsigned char *this_result;
 405                 int flag;
 406
 407                 this_result = refs_found ? sha1_from_ref : sha1;
 408                 mksnpath(fullref, sizeof(fullref), *p, len, str);
 409                 r = resolve_ref_unsafe(fullref, RESOLVE_REF_READING,
 410                                        this_result, &flag);
 411                 if (r) {
 412                         if (!refs_found++)
 413                                 *ref = xstrdup(r);
 414                         if (!warn_ambiguous_refs)
 415                                 break;
 416                 } else if ((flag & REF_ISSYMREF) && strcmp(fullref, "HEAD")) {
 417                         warning("ignoring dangling symref %s.", fullref);
 418                 } else if ((flag & REF_ISBROKEN) && strchr(fullref, '/')) {
 419                         warning("ignoring broken ref %s.", fullref);
 420                 }
 421         }
 422         free(last_branch);
 423         return refs_found;
 424 }
 425
 426 int dwim_log(const char *str, int len, unsigned char *sha1, char **log)
 427 {
 428         char *last_branch = substitute_branch_name(&str, &len);
 429         const char **p;
 430         int logs_found = 0;
 431
 432         *log = NULL;
 433         for (p = ref_rev_parse_rules; *p; p++) {
 434                 unsigned char hash[20];
 435                 char path[PATH_MAX];
 436                 const char *ref, *it;
 437
 438                 mksnpath(path, sizeof(path), *p, len, str);
 439                 ref = resolve_ref_unsafe(path, RESOLVE_REF_READING,
 440                                          hash, NULL);
 441                 if (!ref)
 442                         continue;
 443                 if (reflog_exists(path))
 444                         it = path;
 445                 else if (strcmp(ref, path) && reflog_exists(ref))
 446                         it = ref;
 447                 else
 448                         continue;
 449                 if (!logs_found++) {
 450                         *log = xstrdup(it);
 451                         hashcpy(sha1, hash);
 452                 }
 453                 if (!warn_ambiguous_refs)
 454                         break;
 455         }
 456         free(last_branch);
 457         return logs_found;
 458 }
 459
 460 static int is_per_worktree_ref(const char *refname)
 461 {
 462         return !strcmp(refname, "HEAD") ||
 463                 starts_with(refname, "refs/bisect/");
 464 }
 465
 466 static int is_pseudoref_syntax(const char *refname)
 467 {
 468         const char *c;
 469
 470         for (c = refname; *c; c++) {
 471                 if (!isupper(*c) && *c != '-' && *c != '_')
 472                         return 0;
 473         }
 474
 475         return 1;
 476 }
 477
 478 enum ref_type ref_type(const char *refname)
 479 {
 480         if (is_per_worktree_ref(refname))
 481                 return REF_TYPE_PER_WORKTREE;
 482         if (is_pseudoref_syntax(refname))
 483                 return REF_TYPE_PSEUDOREF;
 484        return REF_TYPE_NORMAL;
 485 }
 486
 487 static int write_pseudoref(const char *pseudoref, const unsigned char *sha1,
 488                            const unsigned char *old_sha1, struct strbuf *err)
 489 {
 490         const char *filename;
 491         int fd;
 492         static struct lock_file lock;
 493         struct strbuf buf = STRBUF_INIT;
 494         int ret = -1;
 495
 496         strbuf_addf(&buf, "%s\n", sha1_to_hex(sha1));
 497
 498         filename = git_path("%s", pseudoref);
 499         fd = hold_lock_file_for_update(&lock, filename, LOCK_DIE_ON_ERROR);
 500         if (fd < 0) {
 501                 strbuf_addf(err, "Could not open '%s' for writing: %s",
 502                             filename, strerror(errno));
 503                 return -1;
 504         }
 505
 506         if (old_sha1) {
 507                 unsigned char actual_old_sha1[20];
 508
 509                 if (read_ref(pseudoref, actual_old_sha1))
 510                         die("could not read ref '%s'", pseudoref);
 511                 if (hashcmp(actual_old_sha1, old_sha1)) {
 512                         strbuf_addf(err, "Unexpected sha1 when writing %s", pseudoref);
 513                         rollback_lock_file(&lock);
 514                         goto done;
 515                 }
 516         }
 517
 518         if (write_in_full(fd, buf.buf, buf.len) != buf.len) {
 519                 strbuf_addf(err, "Could not write to '%s'", filename);
 520                 rollback_lock_file(&lock);
 521                 goto done;
 522         }
 523
 524         commit_lock_file(&lock);
 525         ret = 0;
 526 done:
 527         strbuf_release(&buf);
 528         return ret;
 529 }
 530
 531 static int delete_pseudoref(const char *pseudoref, const unsigned char *old_sha1)
 532 {
 533         static struct lock_file lock;
 534         const char *filename;
 535
 536         filename = git_path("%s", pseudoref);
 537
 538         if (old_sha1 && !is_null_sha1(old_sha1)) {
 539                 int fd;
 540                 unsigned char actual_old_sha1[20];
 541
 542                 fd = hold_lock_file_for_update(&lock, filename,
 543                                                LOCK_DIE_ON_ERROR);
 544                 if (fd < 0)
 545                         die_errno(_("Could not open '%s' for writing"), filename);
 546                 if (read_ref(pseudoref, actual_old_sha1))
 547                         die("could not read ref '%s'", pseudoref);
 548                 if (hashcmp(actual_old_sha1, old_sha1)) {
 549                         warning("Unexpected sha1 when deleting %s", pseudoref);
 550                         rollback_lock_file(&lock);
 551                         return -1;
 552                 }
 553
 554                 unlink(filename);
 555                 rollback_lock_file(&lock);
 556         } else {
 557                 unlink(filename);
 558         }
 559
 560         return 0;
 561 }
 562
 563 int delete_ref(const char *refname, const unsigned char *old_sha1,
 564                unsigned int flags)
 565 {
 566         struct ref_transaction *transaction;
 567         struct strbuf err = STRBUF_INIT;
 568
 569         if (ref_type(refname) == REF_TYPE_PSEUDOREF)
 570                 return delete_pseudoref(refname, old_sha1);
 571
 572         transaction = ref_transaction_begin(&err);
 573         if (!transaction ||
 574             ref_transaction_delete(transaction, refname, old_sha1,
 575                                    flags, NULL, &err) ||
 576             ref_transaction_commit(transaction, &err)) {
 577                 error("%s", err.buf);
 578                 ref_transaction_free(transaction);
 579                 strbuf_release(&err);
 580                 return 1;
 581         }
 582         ref_transaction_free(transaction);
 583         strbuf_release(&err);
 584         return 0;
 585 }
 586
 587 int copy_reflog_msg(char *buf, const char *msg)
 588 {
 589         char *cp = buf;
 590         char c;
 591         int wasspace = 1;
 592
 593         *cp++ = '\t';
 594         while ((c = *msg++)) {
 595                 if (wasspace && isspace(c))
 596                         continue;
 597                 wasspace = isspace(c);
 598                 if (wasspace)
 599                         c = ' ';
 600                 *cp++ = c;
 601         }
 602         while (buf < cp && isspace(cp[-1]))
 603                 cp--;
 604         *cp++ = '\n';
 605         return cp - buf;
 606 }
 607
 608 int should_autocreate_reflog(const char *refname)
 609 {
 610         if (!log_all_ref_updates)
 611                 return 0;
 612         return starts_with(refname, "refs/heads/") ||
 613                 starts_with(refname, "refs/remotes/") ||
 614                 starts_with(refname, "refs/notes/") ||
 615                 !strcmp(refname, "HEAD");
 616 }
 617
 618 int is_branch(const char *refname)
 619 {
 620         return !strcmp(refname, "HEAD") || starts_with(refname, "refs/heads/");
 621 }
 622
 623 struct read_ref_at_cb {
 624         const char *refname;
 625         unsigned long at_time;
 626         int cnt;
 627         int reccnt;
 628         unsigned char *sha1;
 629         int found_it;
 630
 631         unsigned char osha1[20];
 632         unsigned char nsha1[20];
 633         int tz;
 634         unsigned long date;
 635         char **msg;
 636         unsigned long *cutoff_time;
 637         int *cutoff_tz;
 638         int *cutoff_cnt;
 639 };
 640
 641 static int read_ref_at_ent(unsigned char *osha1, unsigned char *nsha1,
 642                 const char *email, unsigned long timestamp, int tz,
 643                 const char *message, void *cb_data)
 644 {
 645         struct read_ref_at_cb *cb = cb_data;
 646
 647         cb->reccnt++;
 648         cb->tz = tz;
 649         cb->date = timestamp;
 650
 651         if (timestamp <= cb->at_time || cb->cnt == 0) {
 652                 if (cb->msg)
 653                         *cb->msg = xstrdup(message);
 654                 if (cb->cutoff_time)
 655                         *cb->cutoff_time = timestamp;
 656                 if (cb->cutoff_tz)
 657                         *cb->cutoff_tz = tz;
 658                 if (cb->cutoff_cnt)
 659                         *cb->cutoff_cnt = cb->reccnt - 1;
 660                 /*
 661                  * we have not yet updated cb->[n|o]sha1 so they still
 662                  * hold the values for the previous record.
 663                  */
 664                 if (!is_null_sha1(cb->osha1)) {
 665                         hashcpy(cb->sha1, nsha1);
 666                         if (hashcmp(cb->osha1, nsha1))
 667                                 warning("Log for ref %s has gap after %s.",
 668                                         cb->refname, show_date(cb->date, cb->tz, DATE_MODE(RFC2822)));
 669                 }
 670                 else if (cb->date == cb->at_time)
 671                         hashcpy(cb->sha1, nsha1);
 672                 else if (hashcmp(nsha1, cb->sha1))
 673                         warning("Log for ref %s unexpectedly ended on %s.",
 674                                 cb->refname, show_date(cb->date, cb->tz,
 675                                                        DATE_MODE(RFC2822)));
 676                 hashcpy(cb->osha1, osha1);
 677                 hashcpy(cb->nsha1, nsha1);
 678                 cb->found_it = 1;
 679                 return 1;
 680         }
 681         hashcpy(cb->osha1, osha1);
 682         hashcpy(cb->nsha1, nsha1);
 683         if (cb->cnt > 0)
 684                 cb->cnt--;
 685         return 0;
 686 }
 687
 688 static int read_ref_at_ent_oldest(unsigned char *osha1, unsigned char *nsha1,
 689                                   const char *email, unsigned long timestamp,
 690                                   int tz, const char *message, void *cb_data)
 691 {
 692         struct read_ref_at_cb *cb = cb_data;
 693
 694         if (cb->msg)
 695                 *cb->msg = xstrdup(message);
 696         if (cb->cutoff_time)
 697                 *cb->cutoff_time = timestamp;
 698         if (cb->cutoff_tz)
 699                 *cb->cutoff_tz = tz;
 700         if (cb->cutoff_cnt)
 701                 *cb->cutoff_cnt = cb->reccnt;
 702         hashcpy(cb->sha1, osha1);
 703         if (is_null_sha1(cb->sha1))
 704                 hashcpy(cb->sha1, nsha1);
 705         /* We just want the first entry */
 706         return 1;
 707 }
 708
 709 int read_ref_at(const char *refname, unsigned int flags, unsigned long at_time, int cnt,
 710                 unsigned char *sha1, char **msg,
 711                 unsigned long *cutoff_time, int *cutoff_tz, int *cutoff_cnt)
 712 {
 713         struct read_ref_at_cb cb;
 714
 715         memset(&cb, 0, sizeof(cb));
 716         cb.refname = refname;
 717         cb.at_time = at_time;
 718         cb.cnt = cnt;
 719         cb.msg = msg;
 720         cb.cutoff_time = cutoff_time;
 721         cb.cutoff_tz = cutoff_tz;
 722         cb.cutoff_cnt = cutoff_cnt;
 723         cb.sha1 = sha1;
 724
 725         for_each_reflog_ent_reverse(refname, read_ref_at_ent, &cb);
 726
 727         if (!cb.reccnt) {
 728                 if (flags & GET_SHA1_QUIETLY)
 729                         exit(128);
 730                 else
 731                         die("Log for %s is empty.", refname);
 732         }
 733         if (cb.found_it)
 734                 return 0;
 735
 736         for_each_reflog_ent(refname, read_ref_at_ent_oldest, &cb);
 737
 738         return 1;
 739 }
 740
 741 struct ref_transaction *ref_transaction_begin(struct strbuf *err)
 742 {
 743         assert(err);
 744
 745         return xcalloc(1, sizeof(struct ref_transaction));
 746 }
 747
 748 void ref_transaction_free(struct ref_transaction *transaction)
 749 {
 750         int i;
 751
 752         if (!transaction)
 753                 return;
 754
 755         for (i = 0; i < transaction->nr; i++) {
 756                 free(transaction->updates[i]->msg);
 757                 free(transaction->updates[i]);
 758         }
 759         free(transaction->updates);
 760         free(transaction);
 761 }
 762
 763 static struct ref_update *add_update(struct ref_transaction *transaction,
 764                                      const char *refname)
 765 {
 766         struct ref_update *update;
 767         FLEX_ALLOC_STR(update, refname, refname);
 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(st_add(st_mult(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 }
1085
1086 int head_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1087 {
1088         struct object_id oid;
1089         int flag;
1090
1091         if (submodule) {
1092                 if (resolve_gitlink_ref(submodule, "HEAD", oid.hash) == 0)
1093                         return fn("HEAD", &oid, 0, cb_data);
1094
1095                 return 0;
1096         }
1097
1098         if (!read_ref_full("HEAD", RESOLVE_REF_READING, oid.hash, &flag))
1099                 return fn("HEAD", &oid, flag, cb_data);
1100
1101         return 0;
1102 }
1103
1104 int head_ref(each_ref_fn fn, void *cb_data)
1105 {
1106         return head_ref_submodule(NULL, fn, cb_data);
1107 }
1108
1109 int for_each_ref(each_ref_fn fn, void *cb_data)
1110 {
1111         return do_for_each_ref(NULL, "", fn, 0, 0, cb_data);
1112 }
1113
1114 int for_each_ref_submodule(const char *submodule, each_ref_fn fn, void *cb_data)
1115 {
1116         return do_for_each_ref(submodule, "", fn, 0, 0, cb_data);
1117 }
1118
1119 int for_each_ref_in(const char *prefix, each_ref_fn fn, void *cb_data)
1120 {
1121         return do_for_each_ref(NULL, prefix, fn, strlen(prefix), 0, cb_data);
1122 }
1123
1124 int for_each_fullref_in(const char *prefix, each_ref_fn fn, void *cb_data, unsigned int broken)
1125 {
1126         unsigned int flag = 0;
1127
1128         if (broken)
1129                 flag = DO_FOR_EACH_INCLUDE_BROKEN;
1130         return do_for_each_ref(NULL, prefix, fn, 0, flag, cb_data);
1131 }
1132
1133 int for_each_ref_in_submodule(const char *submodule, const char *prefix,
1134                 each_ref_fn fn, void *cb_data)
1135 {
1136         return do_for_each_ref(submodule, prefix, fn, strlen(prefix), 0, cb_data);
1137 }
1138
1139 int for_each_replace_ref(each_ref_fn fn, void *cb_data)
1140 {
1141         return do_for_each_ref(NULL, git_replace_ref_base, fn,
1142                                strlen(git_replace_ref_base), 0, cb_data);
1143 }
1144
1145 int for_each_namespaced_ref(each_ref_fn fn, void *cb_data)
1146 {
1147         struct strbuf buf = STRBUF_INIT;
1148         int ret;
1149         strbuf_addf(&buf, "%srefs/", get_git_namespace());
1150         ret = do_for_each_ref(NULL, buf.buf, fn, 0, 0, cb_data);
1151         strbuf_release(&buf);
1152         return ret;
1153 }
1154
1155 int for_each_rawref(each_ref_fn fn, void *cb_data)
1156 {
1157         return do_for_each_ref(NULL, "", fn, 0,
1158                                DO_FOR_EACH_INCLUDE_BROKEN, cb_data);
1159 }
1160
1161 /* This function needs to return a meaningful errno on failure */
1162 const char *resolve_ref_unsafe(const char *refname, int resolve_flags,
1163                                unsigned char *sha1, int *flags)
1164 {
1165         static struct strbuf sb_refname = STRBUF_INIT;
1166         int unused_flags;
1167         int symref_count;
1168
1169         if (!flags)
1170                 flags = &unused_flags;
1171
1172         *flags = 0;
1173
1174         if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1175                 if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1176                     !refname_is_safe(refname)) {
1177                         errno = EINVAL;
1178                         return NULL;
1179                 }
1180
1181                 /*
1182                  * dwim_ref() uses REF_ISBROKEN to distinguish between
1183                  * missing refs and refs that were present but invalid,
1184                  * to complain about the latter to stderr.
1185                  *
1186                  * We don't know whether the ref exists, so don't set
1187                  * REF_ISBROKEN yet.
1188                  */
1189                 *flags |= REF_BAD_NAME;
1190         }
1191
1192         for (symref_count = 0; symref_count < SYMREF_MAXDEPTH; symref_count++) {
1193                 unsigned int read_flags = 0;
1194
1195                 if (read_raw_ref(refname, sha1, &sb_refname, &read_flags)) {
1196                         *flags |= read_flags;
1197                         if (errno != ENOENT || (resolve_flags & RESOLVE_REF_READING))
1198                                 return NULL;
1199                         hashclr(sha1);
1200                         if (*flags & REF_BAD_NAME)
1201                                 *flags |= REF_ISBROKEN;
1202                         return refname;
1203                 }
1204
1205                 *flags |= read_flags;
1206
1207                 if (!(read_flags & REF_ISSYMREF)) {
1208                         if (*flags & REF_BAD_NAME) {
1209                                 hashclr(sha1);
1210                                 *flags |= REF_ISBROKEN;
1211                         }
1212                         return refname;
1213                 }
1214
1215                 refname = sb_refname.buf;
1216                 if (resolve_flags & RESOLVE_REF_NO_RECURSE) {
1217                         hashclr(sha1);
1218                         return refname;
1219                 }
1220                 if (check_refname_format(refname, REFNAME_ALLOW_ONELEVEL)) {
1221                         if (!(resolve_flags & RESOLVE_REF_ALLOW_BAD_NAME) ||
1222                             !refname_is_safe(refname)) {
1223                                 errno = EINVAL;
1224                                 return NULL;
1225                         }
1226
1227                         *flags |= REF_ISBROKEN | REF_BAD_NAME;
1228                 }
1229         }
1230
1231         errno = ELOOP;
1232         return NULL;
1233 }