remote.c

   1 #include "cache.h"
   2 #include "remote.h"
   3 #include "refs.h"
   4 #include "commit.h"
   5 #include "diff.h"
   6 #include "revision.h"
   7 #include "dir.h"
   8 #include "tag.h"
   9
  10 static struct refspec s_tag_refspec = {
  11         0,
  12         1,
  13         0,
  14         "refs/tags/",
  15         "refs/tags/"
  16 };
  17
  18 const struct refspec *tag_refspec = &s_tag_refspec;
  19
  20 struct counted_string {
  21         size_t len;
  22         const char *s;
  23 };
  24 struct rewrite {
  25         const char *base;
  26         size_t baselen;
  27         struct counted_string *instead_of;
  28         int instead_of_nr;
  29         int instead_of_alloc;
  30 };
  31
  32 static struct remote **remotes;
  33 static int remotes_alloc;
  34 static int remotes_nr;
  35
  36 static struct branch **branches;
  37 static int branches_alloc;
  38 static int branches_nr;
  39
  40 static struct branch *current_branch;
  41 static const char *default_remote_name;
  42
  43 static struct rewrite **rewrite;
  44 static int rewrite_alloc;
  45 static int rewrite_nr;
  46
  47 #define BUF_SIZE (2048)
  48 static char buffer[BUF_SIZE];
  49
  50 static const char *alias_url(const char *url)
  51 {
  52         int i, j;
  53         char *ret;
  54         struct counted_string *longest;
  55         int longest_i;
  56
  57         longest = NULL;
  58         longest_i = -1;
  59         for (i = 0; i < rewrite_nr; i++) {
  60                 if (!rewrite[i])
  61                         continue;
  62                 for (j = 0; j < rewrite[i]->instead_of_nr; j++) {
  63                         if (!prefixcmp(url, rewrite[i]->instead_of[j].s) &&
  64                             (!longest ||
  65                              longest->len < rewrite[i]->instead_of[j].len)) {
  66                                 longest = &(rewrite[i]->instead_of[j]);
  67                                 longest_i = i;
  68                         }
  69                 }
  70         }
  71         if (!longest)
  72                 return url;
  73
  74         ret = xmalloc(rewrite[longest_i]->baselen +
  75                      (strlen(url) - longest->len) + 1);
  76         strcpy(ret, rewrite[longest_i]->base);
  77         strcpy(ret + rewrite[longest_i]->baselen, url + longest->len);
  78         return ret;
  79 }
  80
  81 static void add_push_refspec(struct remote *remote, const char *ref)
  82 {
  83         ALLOC_GROW(remote->push_refspec,
  84                    remote->push_refspec_nr + 1,
  85                    remote->push_refspec_alloc);
  86         remote->push_refspec[remote->push_refspec_nr++] = ref;
  87 }
  88
  89 static void add_fetch_refspec(struct remote *remote, const char *ref)
  90 {
  91         ALLOC_GROW(remote->fetch_refspec,
  92                    remote->fetch_refspec_nr + 1,
  93                    remote->fetch_refspec_alloc);
  94         remote->fetch_refspec[remote->fetch_refspec_nr++] = ref;
  95 }
  96
  97 static void add_url(struct remote *remote, const char *url)
  98 {
  99         ALLOC_GROW(remote->url, remote->url_nr + 1, remote->url_alloc);
 100         remote->url[remote->url_nr++] = url;
 101 }
 102
 103 static void add_url_alias(struct remote *remote, const char *url)
 104 {
 105         add_url(remote, alias_url(url));
 106 }
 107
 108 static struct remote *make_remote(const char *name, int len)
 109 {
 110         struct remote *ret;
 111         int i;
 112
 113         for (i = 0; i < remotes_nr; i++) {
 114                 if (len ? (!strncmp(name, remotes[i]->name, len) &&
 115                            !remotes[i]->name[len]) :
 116                     !strcmp(name, remotes[i]->name))
 117                         return remotes[i];
 118         }
 119
 120         ret = xcalloc(1, sizeof(struct remote));
 121         ALLOC_GROW(remotes, remotes_nr + 1, remotes_alloc);
 122         remotes[remotes_nr++] = ret;
 123         if (len)
 124                 ret->name = xstrndup(name, len);
 125         else
 126                 ret->name = xstrdup(name);
 127         return ret;
 128 }
 129
 130 static void add_merge(struct branch *branch, const char *name)
 131 {
 132         ALLOC_GROW(branch->merge_name, branch->merge_nr + 1,
 133                    branch->merge_alloc);
 134         branch->merge_name[branch->merge_nr++] = name;
 135 }
 136
 137 static struct branch *make_branch(const char *name, int len)
 138 {
 139         struct branch *ret;
 140         int i;
 141         char *refname;
 142
 143         for (i = 0; i < branches_nr; i++) {
 144                 if (len ? (!strncmp(name, branches[i]->name, len) &&
 145                            !branches[i]->name[len]) :
 146                     !strcmp(name, branches[i]->name))
 147                         return branches[i];
 148         }
 149
 150         ALLOC_GROW(branches, branches_nr + 1, branches_alloc);
 151         ret = xcalloc(1, sizeof(struct branch));
 152         branches[branches_nr++] = ret;
 153         if (len)
 154                 ret->name = xstrndup(name, len);
 155         else
 156                 ret->name = xstrdup(name);
 157         refname = xmalloc(strlen(name) + strlen("refs/heads/") + 1);
 158         strcpy(refname, "refs/heads/");
 159         strcpy(refname + strlen("refs/heads/"), ret->name);
 160         ret->refname = refname;
 161
 162         return ret;
 163 }
 164
 165 static struct rewrite *make_rewrite(const char *base, int len)
 166 {
 167         struct rewrite *ret;
 168         int i;
 169
 170         for (i = 0; i < rewrite_nr; i++) {
 171                 if (len
 172                     ? (len == rewrite[i]->baselen &&
 173                        !strncmp(base, rewrite[i]->base, len))
 174                     : !strcmp(base, rewrite[i]->base))
 175                         return rewrite[i];
 176         }
 177
 178         ALLOC_GROW(rewrite, rewrite_nr + 1, rewrite_alloc);
 179         ret = xcalloc(1, sizeof(struct rewrite));
 180         rewrite[rewrite_nr++] = ret;
 181         if (len) {
 182                 ret->base = xstrndup(base, len);
 183                 ret->baselen = len;
 184         }
 185         else {
 186                 ret->base = xstrdup(base);
 187                 ret->baselen = strlen(base);
 188         }
 189         return ret;
 190 }
 191
 192 static void add_instead_of(struct rewrite *rewrite, const char *instead_of)
 193 {
 194         ALLOC_GROW(rewrite->instead_of, rewrite->instead_of_nr + 1, rewrite->instead_of_alloc);
 195         rewrite->instead_of[rewrite->instead_of_nr].s = instead_of;
 196         rewrite->instead_of[rewrite->instead_of_nr].len = strlen(instead_of);
 197         rewrite->instead_of_nr++;
 198 }
 199
 200 static void read_remotes_file(struct remote *remote)
 201 {
 202         FILE *f = fopen(git_path("remotes/%s", remote->name), "r");
 203
 204         if (!f)
 205                 return;
 206         remote->origin = REMOTE_REMOTES;
 207         while (fgets(buffer, BUF_SIZE, f)) {
 208                 int value_list;
 209                 char *s, *p;
 210
 211                 if (!prefixcmp(buffer, "URL:")) {
 212                         value_list = 0;
 213                         s = buffer + 4;
 214                 } else if (!prefixcmp(buffer, "Push:")) {
 215                         value_list = 1;
 216                         s = buffer + 5;
 217                 } else if (!prefixcmp(buffer, "Pull:")) {
 218                         value_list = 2;
 219                         s = buffer + 5;
 220                 } else
 221                         continue;
 222
 223                 while (isspace(*s))
 224                         s++;
 225                 if (!*s)
 226                         continue;
 227
 228                 p = s + strlen(s);
 229                 while (isspace(p[-1]))
 230                         *--p = 0;
 231
 232                 switch (value_list) {
 233                 case 0:
 234                         add_url_alias(remote, xstrdup(s));
 235                         break;
 236                 case 1:
 237                         add_push_refspec(remote, xstrdup(s));
 238                         break;
 239                 case 2:
 240                         add_fetch_refspec(remote, xstrdup(s));
 241                         break;
 242                 }
 243         }
 244         fclose(f);
 245 }
 246
 247 static void read_branches_file(struct remote *remote)
 248 {
 249         const char *slash = strchr(remote->name, '/');
 250         char *frag;
 251         struct strbuf branch = STRBUF_INIT;
 252         int n = slash ? slash - remote->name : 1000;
 253         FILE *f = fopen(git_path("branches/%.*s", n, remote->name), "r");
 254         char *s, *p;
 255         int len;
 256
 257         if (!f)
 258                 return;
 259         s = fgets(buffer, BUF_SIZE, f);
 260         fclose(f);
 261         if (!s)
 262                 return;
 263         while (isspace(*s))
 264                 s++;
 265         if (!*s)
 266                 return;
 267         remote->origin = REMOTE_BRANCHES;
 268         p = s + strlen(s);
 269         while (isspace(p[-1]))
 270                 *--p = 0;
 271         len = p - s;
 272         if (slash)
 273                 len += strlen(slash);
 274         p = xmalloc(len + 1);
 275         strcpy(p, s);
 276         if (slash)
 277                 strcat(p, slash);
 278
 279         /*
 280          * With "slash", e.g. "git fetch jgarzik/netdev-2.6" when
 281          * reading from $GIT_DIR/branches/jgarzik fetches "HEAD" from
 282          * the partial URL obtained from the branches file plus
 283          * "/netdev-2.6" and does not store it in any tracking ref.
 284          * #branch specifier in the file is ignored.
 285          *
 286          * Otherwise, the branches file would have URL and optionally
 287          * #branch specified.  The "master" (or specified) branch is
 288          * fetched and stored in the local branch of the same name.
 289          */
 290         frag = strchr(p, '#');
 291         if (frag) {
 292                 *(frag++) = '\0';
 293                 strbuf_addf(&branch, "refs/heads/%s", frag);
 294         } else
 295                 strbuf_addstr(&branch, "refs/heads/master");
 296         if (!slash) {
 297                 strbuf_addf(&branch, ":refs/heads/%s", remote->name);
 298         } else {
 299                 strbuf_reset(&branch);
 300                 strbuf_addstr(&branch, "HEAD:");
 301         }
 302         add_url_alias(remote, p);
 303         add_fetch_refspec(remote, strbuf_detach(&branch, 0));
 304         /*
 305          * Cogito compatible push: push current HEAD to remote #branch
 306          * (master if missing)
 307          */
 308         strbuf_init(&branch, 0);
 309         strbuf_addstr(&branch, "HEAD");
 310         if (frag)
 311                 strbuf_addf(&branch, ":refs/heads/%s", frag);
 312         else
 313                 strbuf_addstr(&branch, ":refs/heads/master");
 314         add_push_refspec(remote, strbuf_detach(&branch, 0));
 315         remote->fetch_tags = 1; /* always auto-follow */
 316 }
 317
 318 static int handle_config(const char *key, const char *value, void *cb)
 319 {
 320         const char *name;
 321         const char *subkey;
 322         struct remote *remote;
 323         struct branch *branch;
 324         if (!prefixcmp(key, "branch.")) {
 325                 name = key + 7;
 326                 subkey = strrchr(name, '.');
 327                 if (!subkey)
 328                         return 0;
 329                 branch = make_branch(name, subkey - name);
 330                 if (!strcmp(subkey, ".remote")) {
 331                         if (!value)
 332                                 return config_error_nonbool(key);
 333                         branch->remote_name = xstrdup(value);
 334                         if (branch == current_branch)
 335                                 default_remote_name = branch->remote_name;
 336                 } else if (!strcmp(subkey, ".merge")) {
 337                         if (!value)
 338                                 return config_error_nonbool(key);
 339                         add_merge(branch, xstrdup(value));
 340                 }
 341                 return 0;
 342         }
 343         if (!prefixcmp(key, "url.")) {
 344                 struct rewrite *rewrite;
 345                 name = key + 4;
 346                 subkey = strrchr(name, '.');
 347                 if (!subkey)
 348                         return 0;
 349                 rewrite = make_rewrite(name, subkey - name);
 350                 if (!strcmp(subkey, ".insteadof")) {
 351                         if (!value)
 352                                 return config_error_nonbool(key);
 353                         add_instead_of(rewrite, xstrdup(value));
 354                 }
 355         }
 356         if (prefixcmp(key,  "remote."))
 357                 return 0;
 358         name = key + 7;
 359         if (*name == '/') {
 360                 warning("Config remote shorthand cannot begin with '/': %s",
 361                         name);
 362                 return 0;
 363         }
 364         subkey = strrchr(name, '.');
 365         if (!subkey)
 366                 return error("Config with no key for remote %s", name);
 367         remote = make_remote(name, subkey - name);
 368         remote->origin = REMOTE_CONFIG;
 369         if (!strcmp(subkey, ".mirror"))
 370                 remote->mirror = git_config_bool(key, value);
 371         else if (!strcmp(subkey, ".skipdefaultupdate"))
 372                 remote->skip_default_update = git_config_bool(key, value);
 373
 374         else if (!strcmp(subkey, ".url")) {
 375                 const char *v;
 376                 if (git_config_string(&v, key, value))
 377                         return -1;
 378                 add_url(remote, v);
 379         } else if (!strcmp(subkey, ".push")) {
 380                 const char *v;
 381                 if (git_config_string(&v, key, value))
 382                         return -1;
 383                 add_push_refspec(remote, v);
 384         } else if (!strcmp(subkey, ".fetch")) {
 385                 const char *v;
 386                 if (git_config_string(&v, key, value))
 387                         return -1;
 388                 add_fetch_refspec(remote, v);
 389         } else if (!strcmp(subkey, ".receivepack")) {
 390                 const char *v;
 391                 if (git_config_string(&v, key, value))
 392                         return -1;
 393                 if (!remote->receivepack)
 394                         remote->receivepack = v;
 395                 else
 396                         error("more than one receivepack given, using the first");
 397         } else if (!strcmp(subkey, ".uploadpack")) {
 398                 const char *v;
 399                 if (git_config_string(&v, key, value))
 400                         return -1;
 401                 if (!remote->uploadpack)
 402                         remote->uploadpack = v;
 403                 else
 404                         error("more than one uploadpack given, using the first");
 405         } else if (!strcmp(subkey, ".tagopt")) {
 406                 if (!strcmp(value, "--no-tags"))
 407                         remote->fetch_tags = -1;
 408         } else if (!strcmp(subkey, ".proxy")) {
 409                 return git_config_string((const char **)&remote->http_proxy,
 410                                          key, value);
 411         }
 412         return 0;
 413 }
 414
 415 static void alias_all_urls(void)
 416 {
 417         int i, j;
 418         for (i = 0; i < remotes_nr; i++) {
 419                 if (!remotes[i])
 420                         continue;
 421                 for (j = 0; j < remotes[i]->url_nr; j++) {
 422                         remotes[i]->url[j] = alias_url(remotes[i]->url[j]);
 423                 }
 424         }
 425 }
 426
 427 static void read_config(void)
 428 {
 429         unsigned char sha1[20];
 430         const char *head_ref;
 431         int flag;
 432         if (default_remote_name) // did this already
 433                 return;
 434         default_remote_name = xstrdup("origin");
 435         current_branch = NULL;
 436         head_ref = resolve_ref("HEAD", sha1, 0, &flag);
 437         if (head_ref && (flag & REF_ISSYMREF) &&
 438             !prefixcmp(head_ref, "refs/heads/")) {
 439                 current_branch =
 440                         make_branch(head_ref + strlen("refs/heads/"), 0);
 441         }
 442         git_config(handle_config, NULL);
 443         alias_all_urls();
 444 }
 445
 446 /*
 447  * We need to make sure the tracking branches are well formed, but a
 448  * wildcard refspec in "struct refspec" must have a trailing slash. We
 449  * temporarily drop the trailing '/' while calling check_ref_format(),
 450  * and put it back.  The caller knows that a CHECK_REF_FORMAT_ONELEVEL
 451  * error return is Ok for a wildcard refspec.
 452  */
 453 static int verify_refname(char *name, int is_glob)
 454 {
 455         int result, len = -1;
 456
 457         if (is_glob) {
 458                 len = strlen(name);
 459                 assert(name[len - 1] == '/');
 460                 name[len - 1] = '\0';
 461         }
 462         result = check_ref_format(name);
 463         if (is_glob)
 464                 name[len - 1] = '/';
 465         return result;
 466 }
 467
 468 /*
 469  * This function frees a refspec array.
 470  * Warning: code paths should be checked to ensure that the src
 471  *          and dst pointers are always freeable pointers as well
 472  *          as the refspec pointer itself.
 473  */
 474 static void free_refspecs(struct refspec *refspec, int nr_refspec)
 475 {
 476         int i;
 477
 478         if (!refspec)
 479                 return;
 480
 481         for (i = 0; i < nr_refspec; i++) {
 482                 free(refspec[i].src);
 483                 free(refspec[i].dst);
 484         }
 485         free(refspec);
 486 }
 487
 488 static struct refspec *parse_refspec_internal(int nr_refspec, const char **refspec, int fetch, int verify)
 489 {
 490         int i;
 491         int st;
 492         struct refspec *rs = xcalloc(sizeof(*rs), nr_refspec);
 493
 494         for (i = 0; i < nr_refspec; i++) {
 495                 size_t llen;
 496                 int is_glob;
 497                 const char *lhs, *rhs;
 498
 499                 llen = is_glob = 0;
 500
 501                 lhs = refspec[i];
 502                 if (*lhs == '+') {
 503                         rs[i].force = 1;
 504                         lhs++;
 505                 }
 506
 507                 rhs = strrchr(lhs, ':');
 508
 509                 /*
 510                  * Before going on, special case ":" (or "+:") as a refspec
 511                  * for matching refs.
 512                  */
 513                 if (!fetch && rhs == lhs && rhs[1] == '\0') {
 514                         rs[i].matching = 1;
 515                         continue;
 516                 }
 517
 518                 if (rhs) {
 519                         size_t rlen = strlen(++rhs);
 520                         is_glob = (2 <= rlen && !strcmp(rhs + rlen - 2, "/*"));
 521                         rs[i].dst = xstrndup(rhs, rlen - is_glob);
 522                 }
 523
 524                 llen = (rhs ? (rhs - lhs - 1) : strlen(lhs));
 525                 if (2 <= llen && !memcmp(lhs + llen - 2, "/*", 2)) {
 526                         if ((rhs && !is_glob) || (!rhs && fetch))
 527                                 goto invalid;
 528                         is_glob = 1;
 529                         llen--;
 530                 } else if (rhs && is_glob) {
 531                         goto invalid;
 532                 }
 533
 534                 rs[i].pattern = is_glob;
 535                 rs[i].src = xstrndup(lhs, llen);
 536
 537                 if (fetch) {
 538                         /*
 539                          * LHS
 540                          * - empty is allowed; it means HEAD.
 541                          * - otherwise it must be a valid looking ref.
 542                          */
 543                         if (!*rs[i].src)
 544                                 ; /* empty is ok */
 545                         else {
 546                                 st = verify_refname(rs[i].src, is_glob);
 547                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 548                                         goto invalid;
 549                         }
 550                         /*
 551                          * RHS
 552                          * - missing is ok, and is same as empty.
 553                          * - empty is ok; it means not to store.
 554                          * - otherwise it must be a valid looking ref.
 555                          */
 556                         if (!rs[i].dst) {
 557                                 ; /* ok */
 558                         } else if (!*rs[i].dst) {
 559                                 ; /* ok */
 560                         } else {
 561                                 st = verify_refname(rs[i].dst, is_glob);
 562                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 563                                         goto invalid;
 564                         }
 565                 } else {
 566                         /*
 567                          * LHS
 568                          * - empty is allowed; it means delete.
 569                          * - when wildcarded, it must be a valid looking ref.
 570                          * - otherwise, it must be an extended SHA-1, but
 571                          *   there is no existing way to validate this.
 572                          */
 573                         if (!*rs[i].src)
 574                                 ; /* empty is ok */
 575                         else if (is_glob) {
 576                                 st = verify_refname(rs[i].src, is_glob);
 577                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 578                                         goto invalid;
 579                         }
 580                         else
 581                                 ; /* anything goes, for now */
 582                         /*
 583                          * RHS
 584                          * - missing is allowed, but LHS then must be a
 585                          *   valid looking ref.
 586                          * - empty is not allowed.
 587                          * - otherwise it must be a valid looking ref.
 588                          */
 589                         if (!rs[i].dst) {
 590                                 st = verify_refname(rs[i].src, is_glob);
 591                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 592                                         goto invalid;
 593                         } else if (!*rs[i].dst) {
 594                                 goto invalid;
 595                         } else {
 596                                 st = verify_refname(rs[i].dst, is_glob);
 597                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 598                                         goto invalid;
 599                         }
 600                 }
 601         }
 602         return rs;
 603
 604  invalid:
 605         if (verify) {
 606                 /*
 607                  * nr_refspec must be greater than zero and i must be valid
 608                  * since it is only possible to reach this point from within
 609                  * the for loop above.
 610                  */
 611                 free_refspecs(rs, i+1);
 612                 return NULL;
 613         }
 614         die("Invalid refspec '%s'", refspec[i]);
 615 }
 616
 617 int valid_fetch_refspec(const char *fetch_refspec_str)
 618 {
 619         const char *fetch_refspec[] = { fetch_refspec_str };
 620         struct refspec *refspec;
 621
 622         refspec = parse_refspec_internal(1, fetch_refspec, 1, 1);
 623         free_refspecs(refspec, 1);
 624         return !!refspec;
 625 }
 626
 627 struct refspec *parse_fetch_refspec(int nr_refspec, const char **refspec)
 628 {
 629         return parse_refspec_internal(nr_refspec, refspec, 1, 0);
 630 }
 631
 632 static struct refspec *parse_push_refspec(int nr_refspec, const char **refspec)
 633 {
 634         return parse_refspec_internal(nr_refspec, refspec, 0, 0);
 635 }
 636
 637 static int valid_remote_nick(const char *name)
 638 {
 639         if (!name[0] || is_dot_or_dotdot(name))
 640                 return 0;
 641         return !strchr(name, '/'); /* no slash */
 642 }
 643
 644 struct remote *remote_get(const char *name)
 645 {
 646         struct remote *ret;
 647
 648         read_config();
 649         if (!name)
 650                 name = default_remote_name;
 651         ret = make_remote(name, 0);
 652         if (valid_remote_nick(name)) {
 653                 if (!ret->url)
 654                         read_remotes_file(ret);
 655                 if (!ret->url)
 656                         read_branches_file(ret);
 657         }
 658         if (!ret->url)
 659                 add_url_alias(ret, name);
 660         if (!ret->url)
 661                 return NULL;
 662         ret->fetch = parse_fetch_refspec(ret->fetch_refspec_nr, ret->fetch_refspec);
 663         ret->push = parse_push_refspec(ret->push_refspec_nr, ret->push_refspec);
 664         return ret;
 665 }
 666
 667 int for_each_remote(each_remote_fn fn, void *priv)
 668 {
 669         int i, result = 0;
 670         read_config();
 671         for (i = 0; i < remotes_nr && !result; i++) {
 672                 struct remote *r = remotes[i];
 673                 if (!r)
 674                         continue;
 675                 if (!r->fetch)
 676                         r->fetch = parse_fetch_refspec(r->fetch_refspec_nr,
 677                                                        r->fetch_refspec);
 678                 if (!r->push)
 679                         r->push = parse_push_refspec(r->push_refspec_nr,
 680                                                      r->push_refspec);
 681                 result = fn(r, priv);
 682         }
 683         return result;
 684 }
 685
 686 void ref_remove_duplicates(struct ref *ref_map)
 687 {
 688         struct ref **posn;
 689         struct ref *next;
 690         for (; ref_map; ref_map = ref_map->next) {
 691                 if (!ref_map->peer_ref)
 692                         continue;
 693                 posn = &ref_map->next;
 694                 while (*posn) {
 695                         if ((*posn)->peer_ref &&
 696                             !strcmp((*posn)->peer_ref->name,
 697                                     ref_map->peer_ref->name)) {
 698                                 if (strcmp((*posn)->name, ref_map->name))
 699                                         die("%s tracks both %s and %s",
 700                                             ref_map->peer_ref->name,
 701                                             (*posn)->name, ref_map->name);
 702                                 next = (*posn)->next;
 703                                 free((*posn)->peer_ref);
 704                                 free(*posn);
 705                                 *posn = next;
 706                         } else {
 707                                 posn = &(*posn)->next;
 708                         }
 709                 }
 710         }
 711 }
 712
 713 int remote_has_url(struct remote *remote, const char *url)
 714 {
 715         int i;
 716         for (i = 0; i < remote->url_nr; i++) {
 717                 if (!strcmp(remote->url[i], url))
 718                         return 1;
 719         }
 720         return 0;
 721 }
 722
 723 int remote_find_tracking(struct remote *remote, struct refspec *refspec)
 724 {
 725         int find_src = refspec->src == NULL;
 726         char *needle, **result;
 727         int i;
 728
 729         if (find_src) {
 730                 if (!refspec->dst)
 731                         return error("find_tracking: need either src or dst");
 732                 needle = refspec->dst;
 733                 result = &refspec->src;
 734         } else {
 735                 needle = refspec->src;
 736                 result = &refspec->dst;
 737         }
 738
 739         for (i = 0; i < remote->fetch_refspec_nr; i++) {
 740                 struct refspec *fetch = &remote->fetch[i];
 741                 const char *key = find_src ? fetch->dst : fetch->src;
 742                 const char *value = find_src ? fetch->src : fetch->dst;
 743                 if (!fetch->dst)
 744                         continue;
 745                 if (fetch->pattern) {
 746                         if (!prefixcmp(needle, key)) {
 747                                 *result = xmalloc(strlen(value) +
 748                                                   strlen(needle) -
 749                                                   strlen(key) + 1);
 750                                 strcpy(*result, value);
 751                                 strcpy(*result + strlen(value),
 752                                        needle + strlen(key));
 753                                 refspec->force = fetch->force;
 754                                 return 0;
 755                         }
 756                 } else if (!strcmp(needle, key)) {
 757                         *result = xstrdup(value);
 758                         refspec->force = fetch->force;
 759                         return 0;
 760                 }
 761         }
 762         return -1;
 763 }
 764
 765 static struct ref *alloc_ref_with_prefix(const char *prefix, size_t prefixlen,
 766                 const char *name)
 767 {
 768         size_t len = strlen(name);
 769         struct ref *ref = xcalloc(1, sizeof(struct ref) + prefixlen + len + 1);
 770         memcpy(ref->name, prefix, prefixlen);
 771         memcpy(ref->name + prefixlen, name, len);
 772         return ref;
 773 }
 774
 775 struct ref *alloc_ref(const char *name)
 776 {
 777         return alloc_ref_with_prefix("", 0, name);
 778 }
 779
 780 static struct ref *copy_ref(const struct ref *ref)
 781 {
 782         struct ref *cpy;
 783         size_t len;
 784         if (!ref)
 785                 return NULL;
 786         len = strlen(ref->name);
 787         cpy = xmalloc(sizeof(struct ref) + len + 1);
 788         memcpy(cpy, ref, sizeof(struct ref) + len + 1);
 789         cpy->next = NULL;
 790         cpy->symref = ref->symref ? xstrdup(ref->symref) : NULL;
 791         cpy->remote_status = ref->remote_status ? xstrdup(ref->remote_status) : NULL;
 792         cpy->peer_ref = copy_ref(ref->peer_ref);
 793         return cpy;
 794 }
 795
 796 struct ref *copy_ref_list(const struct ref *ref)
 797 {
 798         struct ref *ret = NULL;
 799         struct ref **tail = &ret;
 800         while (ref) {
 801                 *tail = copy_ref(ref);
 802                 ref = ref->next;
 803                 tail = &((*tail)->next);
 804         }
 805         return ret;
 806 }
 807
 808 static void free_ref(struct ref *ref)
 809 {
 810         if (!ref)
 811                 return;
 812         free_ref(ref->peer_ref);
 813         free(ref->remote_status);
 814         free(ref->symref);
 815         free(ref);
 816 }
 817
 818 void free_refs(struct ref *ref)
 819 {
 820         struct ref *next;
 821         while (ref) {
 822                 next = ref->next;
 823                 free_ref(ref);
 824                 ref = next;
 825         }
 826 }
 827
 828 static int count_refspec_match(const char *pattern,
 829                                struct ref *refs,
 830                                struct ref **matched_ref)
 831 {
 832         int patlen = strlen(pattern);
 833         struct ref *matched_weak = NULL;
 834         struct ref *matched = NULL;
 835         int weak_match = 0;
 836         int match = 0;
 837
 838         for (weak_match = match = 0; refs; refs = refs->next) {
 839                 char *name = refs->name;
 840                 int namelen = strlen(name);
 841
 842                 if (!refname_match(pattern, name, ref_rev_parse_rules))
 843                         continue;
 844
 845                 /* A match is "weak" if it is with refs outside
 846                  * heads or tags, and did not specify the pattern
 847                  * in full (e.g. "refs/remotes/origin/master") or at
 848                  * least from the toplevel (e.g. "remotes/origin/master");
 849                  * otherwise "git push $URL master" would result in
 850                  * ambiguity between remotes/origin/master and heads/master
 851                  * at the remote site.
 852                  */
 853                 if (namelen != patlen &&
 854                     patlen != namelen - 5 &&
 855                     prefixcmp(name, "refs/heads/") &&
 856                     prefixcmp(name, "refs/tags/")) {
 857                         /* We want to catch the case where only weak
 858                          * matches are found and there are multiple
 859                          * matches, and where more than one strong
 860                          * matches are found, as ambiguous.  One
 861                          * strong match with zero or more weak matches
 862                          * are acceptable as a unique match.
 863                          */
 864                         matched_weak = refs;
 865                         weak_match++;
 866                 }
 867                 else {
 868                         matched = refs;
 869                         match++;
 870                 }
 871         }
 872         if (!matched) {
 873                 *matched_ref = matched_weak;
 874                 return weak_match;
 875         }
 876         else {
 877                 *matched_ref = matched;
 878                 return match;
 879         }
 880 }
 881
 882 static void tail_link_ref(struct ref *ref, struct ref ***tail)
 883 {
 884         **tail = ref;
 885         while (ref->next)
 886                 ref = ref->next;
 887         *tail = &ref->next;
 888 }
 889
 890 static struct ref *try_explicit_object_name(const char *name)
 891 {
 892         unsigned char sha1[20];
 893         struct ref *ref;
 894
 895         if (!*name) {
 896                 ref = alloc_ref("(delete)");
 897                 hashclr(ref->new_sha1);
 898                 return ref;
 899         }
 900         if (get_sha1(name, sha1))
 901                 return NULL;
 902         ref = alloc_ref(name);
 903         hashcpy(ref->new_sha1, sha1);
 904         return ref;
 905 }
 906
 907 static struct ref *make_linked_ref(const char *name, struct ref ***tail)
 908 {
 909         struct ref *ret = alloc_ref(name);
 910         tail_link_ref(ret, tail);
 911         return ret;
 912 }
 913
 914 static char *guess_ref(const char *name, struct ref *peer)
 915 {
 916         struct strbuf buf = STRBUF_INIT;
 917         unsigned char sha1[20];
 918
 919         const char *r = resolve_ref(peer->name, sha1, 1, NULL);
 920         if (!r)
 921                 return NULL;
 922
 923         if (!prefixcmp(r, "refs/heads/"))
 924                 strbuf_addstr(&buf, "refs/heads/");
 925         else if (!prefixcmp(r, "refs/tags/"))
 926                 strbuf_addstr(&buf, "refs/tags/");
 927         else
 928                 return NULL;
 929
 930         strbuf_addstr(&buf, name);
 931         return strbuf_detach(&buf, NULL);
 932 }
 933
 934 static int match_explicit(struct ref *src, struct ref *dst,
 935                           struct ref ***dst_tail,
 936                           struct refspec *rs)
 937 {
 938         struct ref *matched_src, *matched_dst;
 939         int copy_src;
 940
 941         const char *dst_value = rs->dst;
 942         char *dst_guess;
 943
 944         if (rs->pattern || rs->matching)
 945                 return 0;
 946
 947         matched_src = matched_dst = NULL;
 948         switch (count_refspec_match(rs->src, src, &matched_src)) {
 949         case 1:
 950                 copy_src = 1;
 951                 break;
 952         case 0:
 953                 /* The source could be in the get_sha1() format
 954                  * not a reference name.  :refs/other is a
 955                  * way to delete 'other' ref at the remote end.
 956                  */
 957                 matched_src = try_explicit_object_name(rs->src);
 958                 if (!matched_src)
 959                         return error("src refspec %s does not match any.", rs->src);
 960                 copy_src = 0;
 961                 break;
 962         default:
 963                 return error("src refspec %s matches more than one.", rs->src);
 964         }
 965
 966         if (!dst_value) {
 967                 unsigned char sha1[20];
 968                 int flag;
 969
 970                 dst_value = resolve_ref(matched_src->name, sha1, 1, &flag);
 971                 if (!dst_value ||
 972                     ((flag & REF_ISSYMREF) &&
 973                      prefixcmp(dst_value, "refs/heads/")))
 974                         die("%s cannot be resolved to branch.",
 975                             matched_src->name);
 976         }
 977
 978         switch (count_refspec_match(dst_value, dst, &matched_dst)) {
 979         case 1:
 980                 break;
 981         case 0:
 982                 if (!memcmp(dst_value, "refs/", 5))
 983                         matched_dst = make_linked_ref(dst_value, dst_tail);
 984                 else if((dst_guess = guess_ref(dst_value, matched_src)))
 985                         matched_dst = make_linked_ref(dst_guess, dst_tail);
 986                 else
 987                         error("unable to push to unqualified destination: %s\n"
 988                               "The destination refspec neither matches an "
 989                               "existing ref on the remote nor\n"
 990                               "begins with refs/, and we are unable to "
 991                               "guess a prefix based on the source ref.",
 992                               dst_value);
 993                 break;
 994         default:
 995                 matched_dst = NULL;
 996                 error("dst refspec %s matches more than one.",
 997                       dst_value);
 998                 break;
 999         }
1000         if (!matched_dst)
1001                 return -1;
1002         if (matched_dst->peer_ref)
1003                 return error("dst ref %s receives from more than one src.",
1004                       matched_dst->name);
1005         else {
1006                 matched_dst->peer_ref = copy_src ? copy_ref(matched_src) : matched_src;
1007                 matched_dst->force = rs->force;
1008         }
1009         return 0;
1010 }
1011
1012 static int match_explicit_refs(struct ref *src, struct ref *dst,
1013                                struct ref ***dst_tail, struct refspec *rs,
1014                                int rs_nr)
1015 {
1016         int i, errs;
1017         for (i = errs = 0; i < rs_nr; i++)
1018                 errs += match_explicit(src, dst, dst_tail, &rs[i]);
1019         return errs;
1020 }
1021
1022 static const struct refspec *check_pattern_match(const struct refspec *rs,
1023                                                  int rs_nr,
1024                                                  const struct ref *src)
1025 {
1026         int i;
1027         int matching_refs = -1;
1028         for (i = 0; i < rs_nr; i++) {
1029                 if (rs[i].matching &&
1030                     (matching_refs == -1 || rs[i].force)) {
1031                         matching_refs = i;
1032                         continue;
1033                 }
1034
1035                 if (rs[i].pattern && !prefixcmp(src->name, rs[i].src))
1036                         return rs + i;
1037         }
1038         if (matching_refs != -1)
1039                 return rs + matching_refs;
1040         else
1041                 return NULL;
1042 }
1043
1044 /*
1045  * Note. This is used only by "push"; refspec matching rules for
1046  * push and fetch are subtly different, so do not try to reuse it
1047  * without thinking.
1048  */
1049 int match_refs(struct ref *src, struct ref *dst, struct ref ***dst_tail,
1050                int nr_refspec, const char **refspec, int flags)
1051 {
1052         struct refspec *rs;
1053         int send_all = flags & MATCH_REFS_ALL;
1054         int send_mirror = flags & MATCH_REFS_MIRROR;
1055         int errs;
1056         static const char *default_refspec[] = { ":", 0 };
1057
1058         if (!nr_refspec) {
1059                 nr_refspec = 1;
1060                 refspec = default_refspec;
1061         }
1062         rs = parse_push_refspec(nr_refspec, (const char **) refspec);
1063         errs = match_explicit_refs(src, dst, dst_tail, rs, nr_refspec);
1064
1065         /* pick the remainder */
1066         for ( ; src; src = src->next) {
1067                 struct ref *dst_peer;
1068                 const struct refspec *pat = NULL;
1069                 char *dst_name;
1070                 if (src->peer_ref)
1071                         continue;
1072
1073                 pat = check_pattern_match(rs, nr_refspec, src);
1074                 if (!pat)
1075                         continue;
1076
1077                 if (pat->matching) {
1078                         /*
1079                          * "matching refs"; traditionally we pushed everything
1080                          * including refs outside refs/heads/ hierarchy, but
1081                          * that does not make much sense these days.
1082                          */
1083                         if (!send_mirror && prefixcmp(src->name, "refs/heads/"))
1084                                 continue;
1085                         dst_name = xstrdup(src->name);
1086
1087                 } else {
1088                         const char *dst_side = pat->dst ? pat->dst : pat->src;
1089                         dst_name = xmalloc(strlen(dst_side) +
1090                                            strlen(src->name) -
1091                                            strlen(pat->src) + 2);
1092                         strcpy(dst_name, dst_side);
1093                         strcat(dst_name, src->name + strlen(pat->src));
1094                 }
1095                 dst_peer = find_ref_by_name(dst, dst_name);
1096                 if (dst_peer) {
1097                         if (dst_peer->peer_ref)
1098                                 /* We're already sending something to this ref. */
1099                                 goto free_name;
1100
1101                 } else {
1102                         if (pat->matching && !(send_all || send_mirror))
1103                                 /*
1104                                  * Remote doesn't have it, and we have no
1105                                  * explicit pattern, and we don't have
1106                                  * --all nor --mirror.
1107                                  */
1108                                 goto free_name;
1109
1110                         /* Create a new one and link it */
1111                         dst_peer = make_linked_ref(dst_name, dst_tail);
1112                         hashcpy(dst_peer->new_sha1, src->new_sha1);
1113                 }
1114                 dst_peer->peer_ref = copy_ref(src);
1115                 dst_peer->force = pat->force;
1116         free_name:
1117                 free(dst_name);
1118         }
1119         if (errs)
1120                 return -1;
1121         return 0;
1122 }
1123
1124 struct branch *branch_get(const char *name)
1125 {
1126         struct branch *ret;
1127
1128         read_config();
1129         if (!name || !*name || !strcmp(name, "HEAD"))
1130                 ret = current_branch;
1131         else
1132                 ret = make_branch(name, 0);
1133         if (ret && ret->remote_name) {
1134                 ret->remote = remote_get(ret->remote_name);
1135                 if (ret->merge_nr) {
1136                         int i;
1137                         ret->merge = xcalloc(sizeof(*ret->merge),
1138                                              ret->merge_nr);
1139                         for (i = 0; i < ret->merge_nr; i++) {
1140                                 ret->merge[i] = xcalloc(1, sizeof(**ret->merge));
1141                                 ret->merge[i]->src = xstrdup(ret->merge_name[i]);
1142                                 remote_find_tracking(ret->remote,
1143                                                      ret->merge[i]);
1144                         }
1145                 }
1146         }
1147         return ret;
1148 }
1149
1150 int branch_has_merge_config(struct branch *branch)
1151 {
1152         return branch && !!branch->merge;
1153 }
1154
1155 int branch_merge_matches(struct branch *branch,
1156                                  int i,
1157                                  const char *refname)
1158 {
1159         if (!branch || i < 0 || i >= branch->merge_nr)
1160                 return 0;
1161         return refname_match(branch->merge[i]->src, refname, ref_fetch_rules);
1162 }
1163
1164 static struct ref *get_expanded_map(const struct ref *remote_refs,
1165                                     const struct refspec *refspec)
1166 {
1167         const struct ref *ref;
1168         struct ref *ret = NULL;
1169         struct ref **tail = &ret;
1170
1171         int remote_prefix_len = strlen(refspec->src);
1172         int local_prefix_len = strlen(refspec->dst);
1173
1174         for (ref = remote_refs; ref; ref = ref->next) {
1175                 if (strchr(ref->name, '^'))
1176                         continue; /* a dereference item */
1177                 if (!prefixcmp(ref->name, refspec->src)) {
1178                         const char *match;
1179                         struct ref *cpy = copy_ref(ref);
1180                         match = ref->name + remote_prefix_len;
1181
1182                         cpy->peer_ref = alloc_ref_with_prefix(refspec->dst,
1183                                         local_prefix_len, match);
1184                         if (refspec->force)
1185                                 cpy->peer_ref->force = 1;
1186                         *tail = cpy;
1187                         tail = &cpy->next;
1188                 }
1189         }
1190
1191         return ret;
1192 }
1193
1194 static const struct ref *find_ref_by_name_abbrev(const struct ref *refs, const char *name)
1195 {
1196         const struct ref *ref;
1197         for (ref = refs; ref; ref = ref->next) {
1198                 if (refname_match(name, ref->name, ref_fetch_rules))
1199                         return ref;
1200         }
1201         return NULL;
1202 }
1203
1204 struct ref *get_remote_ref(const struct ref *remote_refs, const char *name)
1205 {
1206         const struct ref *ref = find_ref_by_name_abbrev(remote_refs, name);
1207
1208         if (!ref)
1209                 return NULL;
1210
1211         return copy_ref(ref);
1212 }
1213
1214 static struct ref *get_local_ref(const char *name)
1215 {
1216         if (!name)
1217                 return NULL;
1218
1219         if (!prefixcmp(name, "refs/"))
1220                 return alloc_ref(name);
1221
1222         if (!prefixcmp(name, "heads/") ||
1223             !prefixcmp(name, "tags/") ||
1224             !prefixcmp(name, "remotes/"))
1225                 return alloc_ref_with_prefix("refs/", 5, name);
1226
1227         return alloc_ref_with_prefix("refs/heads/", 11, name);
1228 }
1229
1230 int get_fetch_map(const struct ref *remote_refs,
1231                   const struct refspec *refspec,
1232                   struct ref ***tail,
1233                   int missing_ok)
1234 {
1235         struct ref *ref_map, **rmp;
1236
1237         if (refspec->pattern) {
1238                 ref_map = get_expanded_map(remote_refs, refspec);
1239         } else {
1240                 const char *name = refspec->src[0] ? refspec->src : "HEAD";
1241
1242                 ref_map = get_remote_ref(remote_refs, name);
1243                 if (!missing_ok && !ref_map)
1244                         die("Couldn't find remote ref %s", name);
1245                 if (ref_map) {
1246                         ref_map->peer_ref = get_local_ref(refspec->dst);
1247                         if (ref_map->peer_ref && refspec->force)
1248                                 ref_map->peer_ref->force = 1;
1249                 }
1250         }
1251
1252         for (rmp = &ref_map; *rmp; ) {
1253                 if ((*rmp)->peer_ref) {
1254                         int st = check_ref_format((*rmp)->peer_ref->name + 5);
1255                         if (st && st != CHECK_REF_FORMAT_ONELEVEL) {
1256                                 struct ref *ignore = *rmp;
1257                                 error("* Ignoring funny ref '%s' locally",
1258                                       (*rmp)->peer_ref->name);
1259                                 *rmp = (*rmp)->next;
1260                                 free(ignore->peer_ref);
1261                                 free(ignore);
1262                                 continue;
1263                         }
1264                 }
1265                 rmp = &((*rmp)->next);
1266         }
1267
1268         if (ref_map)
1269                 tail_link_ref(ref_map, tail);
1270
1271         return 0;
1272 }
1273
1274 int resolve_remote_symref(struct ref *ref, struct ref *list)
1275 {
1276         if (!ref->symref)
1277                 return 0;
1278         for (; list; list = list->next)
1279                 if (!strcmp(ref->symref, list->name)) {
1280                         hashcpy(ref->old_sha1, list->old_sha1);
1281                         return 0;
1282                 }
1283         return 1;
1284 }
1285
1286 static void unmark_and_free(struct commit_list *list, unsigned int mark)
1287 {
1288         while (list) {
1289                 struct commit_list *temp = list;
1290                 temp->item->object.flags &= ~mark;
1291                 list = temp->next;
1292                 free(temp);
1293         }
1294 }
1295
1296 int ref_newer(const unsigned char *new_sha1, const unsigned char *old_sha1)
1297 {
1298         struct object *o;
1299         struct commit *old, *new;
1300         struct commit_list *list, *used;
1301         int found = 0;
1302
1303         /* Both new and old must be commit-ish and new is descendant of
1304          * old.  Otherwise we require --force.
1305          */
1306         o = deref_tag(parse_object(old_sha1), NULL, 0);
1307         if (!o || o->type != OBJ_COMMIT)
1308                 return 0;
1309         old = (struct commit *) o;
1310
1311         o = deref_tag(parse_object(new_sha1), NULL, 0);
1312         if (!o || o->type != OBJ_COMMIT)
1313                 return 0;
1314         new = (struct commit *) o;
1315
1316         if (parse_commit(new) < 0)
1317                 return 0;
1318
1319         used = list = NULL;
1320         commit_list_insert(new, &list);
1321         while (list) {
1322                 new = pop_most_recent_commit(&list, TMP_MARK);
1323                 commit_list_insert(new, &used);
1324                 if (new == old) {
1325                         found = 1;
1326                         break;
1327                 }
1328         }
1329         unmark_and_free(list, TMP_MARK);
1330         unmark_and_free(used, TMP_MARK);
1331         return found;
1332 }
1333
1334 /*
1335  * Return true if there is anything to report, otherwise false.
1336  */
1337 int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs)
1338 {
1339         unsigned char sha1[20];
1340         struct commit *ours, *theirs;
1341         char symmetric[84];
1342         struct rev_info revs;
1343         const char *rev_argv[10], *base;
1344         int rev_argc;
1345
1346         /*
1347          * Nothing to report unless we are marked to build on top of
1348          * somebody else.
1349          */
1350         if (!branch ||
1351             !branch->merge || !branch->merge[0] || !branch->merge[0]->dst)
1352                 return 0;
1353
1354         /*
1355          * If what we used to build on no longer exists, there is
1356          * nothing to report.
1357          */
1358         base = branch->merge[0]->dst;
1359         if (!resolve_ref(base, sha1, 1, NULL))
1360                 return 0;
1361         theirs = lookup_commit(sha1);
1362         if (!theirs)
1363                 return 0;
1364
1365         if (!resolve_ref(branch->refname, sha1, 1, NULL))
1366                 return 0;
1367         ours = lookup_commit(sha1);
1368         if (!ours)
1369                 return 0;
1370
1371         /* are we the same? */
1372         if (theirs == ours)
1373                 return 0;
1374
1375         /* Run "rev-list --no-merges --left-right ours...theirs" internally... */
1376         rev_argc = 0;
1377         rev_argv[rev_argc++] = NULL;
1378         rev_argv[rev_argc++] = "--no-merges";
1379         rev_argv[rev_argc++] = "--left-right";
1380         rev_argv[rev_argc++] = symmetric;
1381         rev_argv[rev_argc++] = "--";
1382         rev_argv[rev_argc] = NULL;
1383
1384         strcpy(symmetric, sha1_to_hex(ours->object.sha1));
1385         strcpy(symmetric + 40, "...");
1386         strcpy(symmetric + 43, sha1_to_hex(theirs->object.sha1));
1387
1388         init_revisions(&revs, NULL);
1389         setup_revisions(rev_argc, rev_argv, &revs, NULL);
1390         prepare_revision_walk(&revs);
1391
1392         /* ... and count the commits on each side. */
1393         *num_ours = 0;
1394         *num_theirs = 0;
1395         while (1) {
1396                 struct commit *c = get_revision(&revs);
1397                 if (!c)
1398                         break;
1399                 if (c->object.flags & SYMMETRIC_LEFT)
1400                         (*num_ours)++;
1401                 else
1402                         (*num_theirs)++;
1403         }
1404
1405         /* clear object flags smudged by the above traversal */
1406         clear_commit_marks(ours, ALL_REV_FLAGS);
1407         clear_commit_marks(theirs, ALL_REV_FLAGS);
1408         return 1;
1409 }
1410
1411 /*
1412  * Return true when there is anything to report, otherwise false.
1413  */
1414 int format_tracking_info(struct branch *branch, struct strbuf *sb)
1415 {
1416         int num_ours, num_theirs;
1417         const char *base;
1418
1419         if (!stat_tracking_info(branch, &num_ours, &num_theirs))
1420                 return 0;
1421
1422         base = branch->merge[0]->dst;
1423         if (!prefixcmp(base, "refs/remotes/")) {
1424                 base += strlen("refs/remotes/");
1425         }
1426         if (!num_theirs)
1427                 strbuf_addf(sb, "Your branch is ahead of '%s' "
1428                             "by %d commit%s.\n",
1429                             base, num_ours, (num_ours == 1) ? "" : "s");
1430         else if (!num_ours)
1431                 strbuf_addf(sb, "Your branch is behind '%s' "
1432                             "by %d commit%s, "
1433                             "and can be fast-forwarded.\n",
1434                             base, num_theirs, (num_theirs == 1) ? "" : "s");
1435         else
1436                 strbuf_addf(sb, "Your branch and '%s' have diverged,\n"
1437                             "and have %d and %d different commit(s) each, "
1438                             "respectively.\n",
1439                             base, num_ours, num_theirs);
1440         return 1;
1441 }
1442
1443 static int one_local_ref(const char *refname, const unsigned char *sha1, int flag, void *cb_data)
1444 {
1445         struct ref ***local_tail = cb_data;
1446         struct ref *ref;
1447         int len;
1448
1449         /* we already know it starts with refs/ to get here */
1450         if (check_ref_format(refname + 5))
1451                 return 0;
1452
1453         len = strlen(refname) + 1;
1454         ref = xcalloc(1, sizeof(*ref) + len);
1455         hashcpy(ref->new_sha1, sha1);
1456         memcpy(ref->name, refname, len);
1457         **local_tail = ref;
1458         *local_tail = &ref->next;
1459         return 0;
1460 }
1461
1462 struct ref *get_local_heads(void)
1463 {
1464         struct ref *local_refs, **local_tail = &local_refs;
1465         for_each_ref(one_local_ref, &local_tail);
1466         return local_refs;
1467 }
1468
1469 struct ref *guess_remote_head(const struct ref *head,
1470                               const struct ref *refs,
1471                               int all)
1472 {
1473         const struct ref *r;
1474         struct ref *list = NULL;
1475         struct ref **tail = &list;
1476
1477         if (!head)
1478                 return NULL;
1479
1480         /*
1481          * Some transports support directly peeking at
1482          * where HEAD points; if that is the case, then
1483          * we don't have to guess.
1484          */
1485         if (head->symref)
1486                 return copy_ref(find_ref_by_name(refs, head->symref));
1487
1488         /* If refs/heads/master could be right, it is. */
1489         if (!all) {
1490                 r = find_ref_by_name(refs, "refs/heads/master");
1491                 if (r && !hashcmp(r->old_sha1, head->old_sha1))
1492                         return copy_ref(r);
1493         }
1494
1495         /* Look for another ref that points there */
1496         for (r = refs; r; r = r->next) {
1497                 if (r != head && !hashcmp(r->old_sha1, head->old_sha1)) {
1498                         *tail = copy_ref(r);
1499                         tail = &((*tail)->next);
1500                         if (!all)
1501                                 break;
1502                 }
1503         }
1504
1505         return list;
1506 }