git.oblomov.eu Git - git/blob - 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 static int explicit_default_remote_name;
  43
  44 static struct rewrite **rewrite;
  45 static int rewrite_alloc;
  46 static int rewrite_nr;
  47
  48 #define BUF_SIZE (2048)
  49 static char buffer[BUF_SIZE];
  50
  51 static const char *alias_url(const char *url)
  52 {
  53         int i, j;
  54         char *ret;
  55         struct counted_string *longest;
  56         int longest_i;
  57
  58         longest = NULL;
  59         longest_i = -1;
  60         for (i = 0; i < rewrite_nr; i++) {
  61                 if (!rewrite[i])
  62                         continue;
  63                 for (j = 0; j < rewrite[i]->instead_of_nr; j++) {
  64                         if (!prefixcmp(url, rewrite[i]->instead_of[j].s) &&
  65                             (!longest ||
  66                              longest->len < rewrite[i]->instead_of[j].len)) {
  67                                 longest = &(rewrite[i]->instead_of[j]);
  68                                 longest_i = i;
  69                         }
  70                 }
  71         }
  72         if (!longest)
  73                 return url;
  74
  75         ret = xmalloc(rewrite[longest_i]->baselen +
  76                      (strlen(url) - longest->len) + 1);
  77         strcpy(ret, rewrite[longest_i]->base);
  78         strcpy(ret + rewrite[longest_i]->baselen, url + longest->len);
  79         return ret;
  80 }
  81
  82 static void add_push_refspec(struct remote *remote, const char *ref)
  83 {
  84         ALLOC_GROW(remote->push_refspec,
  85                    remote->push_refspec_nr + 1,
  86                    remote->push_refspec_alloc);
  87         remote->push_refspec[remote->push_refspec_nr++] = ref;
  88 }
  89
  90 static void add_fetch_refspec(struct remote *remote, const char *ref)
  91 {
  92         ALLOC_GROW(remote->fetch_refspec,
  93                    remote->fetch_refspec_nr + 1,
  94                    remote->fetch_refspec_alloc);
  95         remote->fetch_refspec[remote->fetch_refspec_nr++] = ref;
  96 }
  97
  98 static void add_url(struct remote *remote, const char *url)
  99 {
 100         ALLOC_GROW(remote->url, remote->url_nr + 1, remote->url_alloc);
 101         remote->url[remote->url_nr++] = url;
 102 }
 103
 104 static void add_url_alias(struct remote *remote, const char *url)
 105 {
 106         add_url(remote, alias_url(url));
 107 }
 108
 109 static struct remote *make_remote(const char *name, int len)
 110 {
 111         struct remote *ret;
 112         int i;
 113
 114         for (i = 0; i < remotes_nr; i++) {
 115                 if (len ? (!strncmp(name, remotes[i]->name, len) &&
 116                            !remotes[i]->name[len]) :
 117                     !strcmp(name, remotes[i]->name))
 118                         return remotes[i];
 119         }
 120
 121         ret = xcalloc(1, sizeof(struct remote));
 122         ALLOC_GROW(remotes, remotes_nr + 1, remotes_alloc);
 123         remotes[remotes_nr++] = ret;
 124         if (len)
 125                 ret->name = xstrndup(name, len);
 126         else
 127                 ret->name = xstrdup(name);
 128         return ret;
 129 }
 130
 131 static void add_merge(struct branch *branch, const char *name)
 132 {
 133         ALLOC_GROW(branch->merge_name, branch->merge_nr + 1,
 134                    branch->merge_alloc);
 135         branch->merge_name[branch->merge_nr++] = name;
 136 }
 137
 138 static struct branch *make_branch(const char *name, int len)
 139 {
 140         struct branch *ret;
 141         int i;
 142         char *refname;
 143
 144         for (i = 0; i < branches_nr; i++) {
 145                 if (len ? (!strncmp(name, branches[i]->name, len) &&
 146                            !branches[i]->name[len]) :
 147                     !strcmp(name, branches[i]->name))
 148                         return branches[i];
 149         }
 150
 151         ALLOC_GROW(branches, branches_nr + 1, branches_alloc);
 152         ret = xcalloc(1, sizeof(struct branch));
 153         branches[branches_nr++] = ret;
 154         if (len)
 155                 ret->name = xstrndup(name, len);
 156         else
 157                 ret->name = xstrdup(name);
 158         refname = xmalloc(strlen(name) + strlen("refs/heads/") + 1);
 159         strcpy(refname, "refs/heads/");
 160         strcpy(refname + strlen("refs/heads/"), ret->name);
 161         ret->refname = refname;
 162
 163         return ret;
 164 }
 165
 166 static struct rewrite *make_rewrite(const char *base, int len)
 167 {
 168         struct rewrite *ret;
 169         int i;
 170
 171         for (i = 0; i < rewrite_nr; i++) {
 172                 if (len
 173                     ? (len == rewrite[i]->baselen &&
 174                        !strncmp(base, rewrite[i]->base, len))
 175                     : !strcmp(base, rewrite[i]->base))
 176                         return rewrite[i];
 177         }
 178
 179         ALLOC_GROW(rewrite, rewrite_nr + 1, rewrite_alloc);
 180         ret = xcalloc(1, sizeof(struct rewrite));
 181         rewrite[rewrite_nr++] = ret;
 182         if (len) {
 183                 ret->base = xstrndup(base, len);
 184                 ret->baselen = len;
 185         }
 186         else {
 187                 ret->base = xstrdup(base);
 188                 ret->baselen = strlen(base);
 189         }
 190         return ret;
 191 }
 192
 193 static void add_instead_of(struct rewrite *rewrite, const char *instead_of)
 194 {
 195         ALLOC_GROW(rewrite->instead_of, rewrite->instead_of_nr + 1, rewrite->instead_of_alloc);
 196         rewrite->instead_of[rewrite->instead_of_nr].s = instead_of;
 197         rewrite->instead_of[rewrite->instead_of_nr].len = strlen(instead_of);
 198         rewrite->instead_of_nr++;
 199 }
 200
 201 static void read_remotes_file(struct remote *remote)
 202 {
 203         FILE *f = fopen(git_path("remotes/%s", remote->name), "r");
 204
 205         if (!f)
 206                 return;
 207         remote->origin = REMOTE_REMOTES;
 208         while (fgets(buffer, BUF_SIZE, f)) {
 209                 int value_list;
 210                 char *s, *p;
 211
 212                 if (!prefixcmp(buffer, "URL:")) {
 213                         value_list = 0;
 214                         s = buffer + 4;
 215                 } else if (!prefixcmp(buffer, "Push:")) {
 216                         value_list = 1;
 217                         s = buffer + 5;
 218                 } else if (!prefixcmp(buffer, "Pull:")) {
 219                         value_list = 2;
 220                         s = buffer + 5;
 221                 } else
 222                         continue;
 223
 224                 while (isspace(*s))
 225                         s++;
 226                 if (!*s)
 227                         continue;
 228
 229                 p = s + strlen(s);
 230                 while (isspace(p[-1]))
 231                         *--p = 0;
 232
 233                 switch (value_list) {
 234                 case 0:
 235                         add_url_alias(remote, xstrdup(s));
 236                         break;
 237                 case 1:
 238                         add_push_refspec(remote, xstrdup(s));
 239                         break;
 240                 case 2:
 241                         add_fetch_refspec(remote, xstrdup(s));
 242                         break;
 243                 }
 244         }
 245         fclose(f);
 246 }
 247
 248 static void read_branches_file(struct remote *remote)
 249 {
 250         const char *slash = strchr(remote->name, '/');
 251         char *frag;
 252         struct strbuf branch = STRBUF_INIT;
 253         int n = slash ? slash - remote->name : 1000;
 254         FILE *f = fopen(git_path("branches/%.*s", n, remote->name), "r");
 255         char *s, *p;
 256         int len;
 257
 258         if (!f)
 259                 return;
 260         s = fgets(buffer, BUF_SIZE, f);
 261         fclose(f);
 262         if (!s)
 263                 return;
 264         while (isspace(*s))
 265                 s++;
 266         if (!*s)
 267                 return;
 268         remote->origin = REMOTE_BRANCHES;
 269         p = s + strlen(s);
 270         while (isspace(p[-1]))
 271                 *--p = 0;
 272         len = p - s;
 273         if (slash)
 274                 len += strlen(slash);
 275         p = xmalloc(len + 1);
 276         strcpy(p, s);
 277         if (slash)
 278                 strcat(p, slash);
 279
 280         /*
 281          * With "slash", e.g. "git fetch jgarzik/netdev-2.6" when
 282          * reading from $GIT_DIR/branches/jgarzik fetches "HEAD" from
 283          * the partial URL obtained from the branches file plus
 284          * "/netdev-2.6" and does not store it in any tracking ref.
 285          * #branch specifier in the file is ignored.
 286          *
 287          * Otherwise, the branches file would have URL and optionally
 288          * #branch specified.  The "master" (or specified) branch is
 289          * fetched and stored in the local branch of the same name.
 290          */
 291         frag = strchr(p, '#');
 292         if (frag) {
 293                 *(frag++) = '\0';
 294                 strbuf_addf(&branch, "refs/heads/%s", frag);
 295         } else
 296                 strbuf_addstr(&branch, "refs/heads/master");
 297         if (!slash) {
 298                 strbuf_addf(&branch, ":refs/heads/%s", remote->name);
 299         } else {
 300                 strbuf_reset(&branch);
 301                 strbuf_addstr(&branch, "HEAD:");
 302         }
 303         add_url_alias(remote, p);
 304         add_fetch_refspec(remote, strbuf_detach(&branch, 0));
 305         /*
 306          * Cogito compatible push: push current HEAD to remote #branch
 307          * (master if missing)
 308          */
 309         strbuf_init(&branch, 0);
 310         strbuf_addstr(&branch, "HEAD");
 311         if (frag)
 312                 strbuf_addf(&branch, ":refs/heads/%s", frag);
 313         else
 314                 strbuf_addstr(&branch, ":refs/heads/master");
 315         add_push_refspec(remote, strbuf_detach(&branch, 0));
 316         remote->fetch_tags = 1; /* always auto-follow */
 317 }
 318
 319 static int handle_config(const char *key, const char *value, void *cb)
 320 {
 321         const char *name;
 322         const char *subkey;
 323         struct remote *remote;
 324         struct branch *branch;
 325         if (!prefixcmp(key, "branch.")) {
 326                 name = key + 7;
 327                 subkey = strrchr(name, '.');
 328                 if (!subkey)
 329                         return 0;
 330                 branch = make_branch(name, subkey - name);
 331                 if (!strcmp(subkey, ".remote")) {
 332                         if (!value)
 333                                 return config_error_nonbool(key);
 334                         branch->remote_name = xstrdup(value);
 335                         if (branch == current_branch) {
 336                                 default_remote_name = branch->remote_name;
 337                                 explicit_default_remote_name = 1;
 338                         }
 339                 } else if (!strcmp(subkey, ".merge")) {
 340                         if (!value)
 341                                 return config_error_nonbool(key);
 342                         add_merge(branch, xstrdup(value));
 343                 }
 344                 return 0;
 345         }
 346         if (!prefixcmp(key, "url.")) {
 347                 struct rewrite *rewrite;
 348                 name = key + 4;
 349                 subkey = strrchr(name, '.');
 350                 if (!subkey)
 351                         return 0;
 352                 rewrite = make_rewrite(name, subkey - name);
 353                 if (!strcmp(subkey, ".insteadof")) {
 354                         if (!value)
 355                                 return config_error_nonbool(key);
 356                         add_instead_of(rewrite, xstrdup(value));
 357                 }
 358         }
 359         if (prefixcmp(key,  "remote."))
 360                 return 0;
 361         name = key + 7;
 362         if (*name == '/') {
 363                 warning("Config remote shorthand cannot begin with '/': %s",
 364                         name);
 365                 return 0;
 366         }
 367         subkey = strrchr(name, '.');
 368         if (!subkey)
 369                 return error("Config with no key for remote %s", name);
 370         remote = make_remote(name, subkey - name);
 371         remote->origin = REMOTE_CONFIG;
 372         if (!strcmp(subkey, ".mirror"))
 373                 remote->mirror = git_config_bool(key, value);
 374         else if (!strcmp(subkey, ".skipdefaultupdate"))
 375                 remote->skip_default_update = git_config_bool(key, value);
 376
 377         else if (!strcmp(subkey, ".url")) {
 378                 const char *v;
 379                 if (git_config_string(&v, key, value))
 380                         return -1;
 381                 add_url(remote, v);
 382         } else if (!strcmp(subkey, ".push")) {
 383                 const char *v;
 384                 if (git_config_string(&v, key, value))
 385                         return -1;
 386                 add_push_refspec(remote, v);
 387         } else if (!strcmp(subkey, ".fetch")) {
 388                 const char *v;
 389                 if (git_config_string(&v, key, value))
 390                         return -1;
 391                 add_fetch_refspec(remote, v);
 392         } else if (!strcmp(subkey, ".receivepack")) {
 393                 const char *v;
 394                 if (git_config_string(&v, key, value))
 395                         return -1;
 396                 if (!remote->receivepack)
 397                         remote->receivepack = v;
 398                 else
 399                         error("more than one receivepack given, using the first");
 400         } else if (!strcmp(subkey, ".uploadpack")) {
 401                 const char *v;
 402                 if (git_config_string(&v, key, value))
 403                         return -1;
 404                 if (!remote->uploadpack)
 405                         remote->uploadpack = v;
 406                 else
 407                         error("more than one uploadpack given, using the first");
 408         } else if (!strcmp(subkey, ".tagopt")) {
 409                 if (!strcmp(value, "--no-tags"))
 410                         remote->fetch_tags = -1;
 411         } else if (!strcmp(subkey, ".proxy")) {
 412                 return git_config_string((const char **)&remote->http_proxy,
 413                                          key, value);
 414         }
 415         return 0;
 416 }
 417
 418 static void alias_all_urls(void)
 419 {
 420         int i, j;
 421         for (i = 0; i < remotes_nr; i++) {
 422                 if (!remotes[i])
 423                         continue;
 424                 for (j = 0; j < remotes[i]->url_nr; j++) {
 425                         remotes[i]->url[j] = alias_url(remotes[i]->url[j]);
 426                 }
 427         }
 428 }
 429
 430 static void read_config(void)
 431 {
 432         unsigned char sha1[20];
 433         const char *head_ref;
 434         int flag;
 435         if (default_remote_name) // did this already
 436                 return;
 437         default_remote_name = xstrdup("origin");
 438         current_branch = NULL;
 439         head_ref = resolve_ref("HEAD", sha1, 0, &flag);
 440         if (head_ref && (flag & REF_ISSYMREF) &&
 441             !prefixcmp(head_ref, "refs/heads/")) {
 442                 current_branch =
 443                         make_branch(head_ref + strlen("refs/heads/"), 0);
 444         }
 445         git_config(handle_config, NULL);
 446         alias_all_urls();
 447 }
 448
 449 /*
 450  * We need to make sure the tracking branches are well formed, but a
 451  * wildcard refspec in "struct refspec" must have a trailing slash. We
 452  * temporarily drop the trailing '/' while calling check_ref_format(),
 453  * and put it back.  The caller knows that a CHECK_REF_FORMAT_ONELEVEL
 454  * error return is Ok for a wildcard refspec.
 455  */
 456 static int verify_refname(char *name, int is_glob)
 457 {
 458         int result, len = -1;
 459
 460         if (is_glob) {
 461                 len = strlen(name);
 462                 assert(name[len - 1] == '/');
 463                 name[len - 1] = '\0';
 464         }
 465         result = check_ref_format(name);
 466         if (is_glob)
 467                 name[len - 1] = '/';
 468         return result;
 469 }
 470
 471 /*
 472  * This function frees a refspec array.
 473  * Warning: code paths should be checked to ensure that the src
 474  *          and dst pointers are always freeable pointers as well
 475  *          as the refspec pointer itself.
 476  */
 477 static void free_refspecs(struct refspec *refspec, int nr_refspec)
 478 {
 479         int i;
 480
 481         if (!refspec)
 482                 return;
 483
 484         for (i = 0; i < nr_refspec; i++) {
 485                 free(refspec[i].src);
 486                 free(refspec[i].dst);
 487         }
 488         free(refspec);
 489 }
 490
 491 static struct refspec *parse_refspec_internal(int nr_refspec, const char **refspec, int fetch, int verify)
 492 {
 493         int i;
 494         int st;
 495         struct refspec *rs = xcalloc(sizeof(*rs), nr_refspec);
 496
 497         for (i = 0; i < nr_refspec; i++) {
 498                 size_t llen;
 499                 int is_glob;
 500                 const char *lhs, *rhs;
 501
 502                 is_glob = 0;
 503
 504                 lhs = refspec[i];
 505                 if (*lhs == '+') {
 506                         rs[i].force = 1;
 507                         lhs++;
 508                 }
 509
 510                 rhs = strrchr(lhs, ':');
 511
 512                 /*
 513                  * Before going on, special case ":" (or "+:") as a refspec
 514                  * for matching refs.
 515                  */
 516                 if (!fetch && rhs == lhs && rhs[1] == '\0') {
 517                         rs[i].matching = 1;
 518                         continue;
 519                 }
 520
 521                 if (rhs) {
 522                         size_t rlen = strlen(++rhs);
 523                         is_glob = (2 <= rlen && !strcmp(rhs + rlen - 2, "/*"));
 524                         rs[i].dst = xstrndup(rhs, rlen - is_glob);
 525                 }
 526
 527                 llen = (rhs ? (rhs - lhs - 1) : strlen(lhs));
 528                 if (2 <= llen && !memcmp(lhs + llen - 2, "/*", 2)) {
 529                         if ((rhs && !is_glob) || (!rhs && fetch))
 530                                 goto invalid;
 531                         is_glob = 1;
 532                         llen--;
 533                 } else if (rhs && is_glob) {
 534                         goto invalid;
 535                 }
 536
 537                 rs[i].pattern = is_glob;
 538                 rs[i].src = xstrndup(lhs, llen);
 539
 540                 if (fetch) {
 541                         /*
 542                          * LHS
 543                          * - empty is allowed; it means HEAD.
 544                          * - otherwise it must be a valid looking ref.
 545                          */
 546                         if (!*rs[i].src)
 547                                 ; /* empty is ok */
 548                         else {
 549                                 st = verify_refname(rs[i].src, is_glob);
 550                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 551                                         goto invalid;
 552                         }
 553                         /*
 554                          * RHS
 555                          * - missing is ok, and is same as empty.
 556                          * - empty is ok; it means not to store.
 557                          * - otherwise it must be a valid looking ref.
 558                          */
 559                         if (!rs[i].dst) {
 560                                 ; /* ok */
 561                         } else if (!*rs[i].dst) {
 562                                 ; /* ok */
 563                         } else {
 564                                 st = verify_refname(rs[i].dst, is_glob);
 565                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 566                                         goto invalid;
 567                         }
 568                 } else {
 569                         /*
 570                          * LHS
 571                          * - empty is allowed; it means delete.
 572                          * - when wildcarded, it must be a valid looking ref.
 573                          * - otherwise, it must be an extended SHA-1, but
 574                          *   there is no existing way to validate this.
 575                          */
 576                         if (!*rs[i].src)
 577                                 ; /* empty is ok */
 578                         else if (is_glob) {
 579                                 st = verify_refname(rs[i].src, is_glob);
 580                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 581                                         goto invalid;
 582                         }
 583                         else
 584                                 ; /* anything goes, for now */
 585                         /*
 586                          * RHS
 587                          * - missing is allowed, but LHS then must be a
 588                          *   valid looking ref.
 589                          * - empty is not allowed.
 590                          * - otherwise it must be a valid looking ref.
 591                          */
 592                         if (!rs[i].dst) {
 593                                 st = verify_refname(rs[i].src, is_glob);
 594                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 595                                         goto invalid;
 596                         } else if (!*rs[i].dst) {
 597                                 goto invalid;
 598                         } else {
 599                                 st = verify_refname(rs[i].dst, is_glob);
 600                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 601                                         goto invalid;
 602                         }
 603                 }
 604         }
 605         return rs;
 606
 607  invalid:
 608         if (verify) {
 609                 /*
 610                  * nr_refspec must be greater than zero and i must be valid
 611                  * since it is only possible to reach this point from within
 612                  * the for loop above.
 613                  */
 614                 free_refspecs(rs, i+1);
 615                 return NULL;
 616         }
 617         die("Invalid refspec '%s'", refspec[i]);
 618 }
 619
 620 int valid_fetch_refspec(const char *fetch_refspec_str)
 621 {
 622         const char *fetch_refspec[] = { fetch_refspec_str };
 623         struct refspec *refspec;
 624
 625         refspec = parse_refspec_internal(1, fetch_refspec, 1, 1);
 626         free_refspecs(refspec, 1);
 627         return !!refspec;
 628 }
 629
 630 struct refspec *parse_fetch_refspec(int nr_refspec, const char **refspec)
 631 {
 632         return parse_refspec_internal(nr_refspec, refspec, 1, 0);
 633 }
 634
 635 static struct refspec *parse_push_refspec(int nr_refspec, const char **refspec)
 636 {
 637         return parse_refspec_internal(nr_refspec, refspec, 0, 0);
 638 }
 639
 640 static int valid_remote_nick(const char *name)
 641 {
 642         if (!name[0] || is_dot_or_dotdot(name))
 643                 return 0;
 644         return !strchr(name, '/'); /* no slash */
 645 }
 646
 647 struct remote *remote_get(const char *name)
 648 {
 649         struct remote *ret;
 650         int name_given = 0;
 651
 652         read_config();
 653         if (name)
 654                 name_given = 1;
 655         else {
 656                 name = default_remote_name;
 657                 name_given = explicit_default_remote_name;
 658         }
 659
 660         ret = make_remote(name, 0);
 661         if (valid_remote_nick(name)) {
 662                 if (!ret->url)
 663                         read_remotes_file(ret);
 664                 if (!ret->url)
 665                         read_branches_file(ret);
 666         }
 667         if (name_given && !ret->url)
 668                 add_url_alias(ret, name);
 669         if (!ret->url)
 670                 return NULL;
 671         ret->fetch = parse_fetch_refspec(ret->fetch_refspec_nr, ret->fetch_refspec);
 672         ret->push = parse_push_refspec(ret->push_refspec_nr, ret->push_refspec);
 673         return ret;
 674 }
 675
 676 int for_each_remote(each_remote_fn fn, void *priv)
 677 {
 678         int i, result = 0;
 679         read_config();
 680         for (i = 0; i < remotes_nr && !result; i++) {
 681                 struct remote *r = remotes[i];
 682                 if (!r)
 683                         continue;
 684                 if (!r->fetch)
 685                         r->fetch = parse_fetch_refspec(r->fetch_refspec_nr,
 686                                                        r->fetch_refspec);
 687                 if (!r->push)
 688                         r->push = parse_push_refspec(r->push_refspec_nr,
 689                                                      r->push_refspec);
 690                 result = fn(r, priv);
 691         }
 692         return result;
 693 }
 694
 695 void ref_remove_duplicates(struct ref *ref_map)
 696 {
 697         struct ref **posn;
 698         struct ref *next;
 699         for (; ref_map; ref_map = ref_map->next) {
 700                 if (!ref_map->peer_ref)
 701                         continue;
 702                 posn = &ref_map->next;
 703                 while (*posn) {
 704                         if ((*posn)->peer_ref &&
 705                             !strcmp((*posn)->peer_ref->name,
 706                                     ref_map->peer_ref->name)) {
 707                                 if (strcmp((*posn)->name, ref_map->name))
 708                                         die("%s tracks both %s and %s",
 709                                             ref_map->peer_ref->name,
 710                                             (*posn)->name, ref_map->name);
 711                                 next = (*posn)->next;
 712                                 free((*posn)->peer_ref);
 713                                 free(*posn);
 714                                 *posn = next;
 715                         } else {
 716                                 posn = &(*posn)->next;
 717                         }
 718                 }
 719         }
 720 }
 721
 722 int remote_has_url(struct remote *remote, const char *url)
 723 {
 724         int i;
 725         for (i = 0; i < remote->url_nr; i++) {
 726                 if (!strcmp(remote->url[i], url))
 727                         return 1;
 728         }
 729         return 0;
 730 }
 731
 732 int remote_find_tracking(struct remote *remote, struct refspec *refspec)
 733 {
 734         int find_src = refspec->src == NULL;
 735         char *needle, **result;
 736         int i;
 737
 738         if (find_src) {
 739                 if (!refspec->dst)
 740                         return error("find_tracking: need either src or dst");
 741                 needle = refspec->dst;
 742                 result = &refspec->src;
 743         } else {
 744                 needle = refspec->src;
 745                 result = &refspec->dst;
 746         }
 747
 748         for (i = 0; i < remote->fetch_refspec_nr; i++) {
 749                 struct refspec *fetch = &remote->fetch[i];
 750                 const char *key = find_src ? fetch->dst : fetch->src;
 751                 const char *value = find_src ? fetch->src : fetch->dst;
 752                 if (!fetch->dst)
 753                         continue;
 754                 if (fetch->pattern) {
 755                         if (!prefixcmp(needle, key)) {
 756                                 *result = xmalloc(strlen(value) +
 757                                                   strlen(needle) -
 758                                                   strlen(key) + 1);
 759                                 strcpy(*result, value);
 760                                 strcpy(*result + strlen(value),
 761                                        needle + strlen(key));
 762                                 refspec->force = fetch->force;
 763                                 return 0;
 764                         }
 765                 } else if (!strcmp(needle, key)) {
 766                         *result = xstrdup(value);
 767                         refspec->force = fetch->force;
 768                         return 0;
 769                 }
 770         }
 771         return -1;
 772 }
 773
 774 static struct ref *alloc_ref_with_prefix(const char *prefix, size_t prefixlen,
 775                 const char *name)
 776 {
 777         size_t len = strlen(name);
 778         struct ref *ref = xcalloc(1, sizeof(struct ref) + prefixlen + len + 1);
 779         memcpy(ref->name, prefix, prefixlen);
 780         memcpy(ref->name + prefixlen, name, len);
 781         return ref;
 782 }
 783
 784 struct ref *alloc_ref(const char *name)
 785 {
 786         return alloc_ref_with_prefix("", 0, name);
 787 }
 788
 789 static struct ref *copy_ref(const struct ref *ref)
 790 {
 791         struct ref *cpy;
 792         size_t len;
 793         if (!ref)
 794                 return NULL;
 795         len = strlen(ref->name);
 796         cpy = xmalloc(sizeof(struct ref) + len + 1);
 797         memcpy(cpy, ref, sizeof(struct ref) + len + 1);
 798         cpy->next = NULL;
 799         cpy->symref = ref->symref ? xstrdup(ref->symref) : NULL;
 800         cpy->remote_status = ref->remote_status ? xstrdup(ref->remote_status) : NULL;
 801         cpy->peer_ref = copy_ref(ref->peer_ref);
 802         return cpy;
 803 }
 804
 805 struct ref *copy_ref_list(const struct ref *ref)
 806 {
 807         struct ref *ret = NULL;
 808         struct ref **tail = &ret;
 809         while (ref) {
 810                 *tail = copy_ref(ref);
 811                 ref = ref->next;
 812                 tail = &((*tail)->next);
 813         }
 814         return ret;
 815 }
 816
 817 static void free_ref(struct ref *ref)
 818 {
 819         if (!ref)
 820                 return;
 821         free_ref(ref->peer_ref);
 822         free(ref->remote_status);
 823         free(ref->symref);
 824         free(ref);
 825 }
 826
 827 void free_refs(struct ref *ref)
 828 {
 829         struct ref *next;
 830         while (ref) {
 831                 next = ref->next;
 832                 free_ref(ref);
 833                 ref = next;
 834         }
 835 }
 836
 837 static int count_refspec_match(const char *pattern,
 838                                struct ref *refs,
 839                                struct ref **matched_ref)
 840 {
 841         int patlen = strlen(pattern);
 842         struct ref *matched_weak = NULL;
 843         struct ref *matched = NULL;
 844         int weak_match = 0;
 845         int match = 0;
 846
 847         for (weak_match = match = 0; refs; refs = refs->next) {
 848                 char *name = refs->name;
 849                 int namelen = strlen(name);
 850
 851                 if (!refname_match(pattern, name, ref_rev_parse_rules))
 852                         continue;
 853
 854                 /* A match is "weak" if it is with refs outside
 855                  * heads or tags, and did not specify the pattern
 856                  * in full (e.g. "refs/remotes/origin/master") or at
 857                  * least from the toplevel (e.g. "remotes/origin/master");
 858                  * otherwise "git push $URL master" would result in
 859                  * ambiguity between remotes/origin/master and heads/master
 860                  * at the remote site.
 861                  */
 862                 if (namelen != patlen &&
 863                     patlen != namelen - 5 &&
 864                     prefixcmp(name, "refs/heads/") &&
 865                     prefixcmp(name, "refs/tags/")) {
 866                         /* We want to catch the case where only weak
 867                          * matches are found and there are multiple
 868                          * matches, and where more than one strong
 869                          * matches are found, as ambiguous.  One
 870                          * strong match with zero or more weak matches
 871                          * are acceptable as a unique match.
 872                          */
 873                         matched_weak = refs;
 874                         weak_match++;
 875                 }
 876                 else {
 877                         matched = refs;
 878                         match++;
 879                 }
 880         }
 881         if (!matched) {
 882                 *matched_ref = matched_weak;
 883                 return weak_match;
 884         }
 885         else {
 886                 *matched_ref = matched;
 887                 return match;
 888         }
 889 }
 890
 891 static void tail_link_ref(struct ref *ref, struct ref ***tail)
 892 {
 893         **tail = ref;
 894         while (ref->next)
 895                 ref = ref->next;
 896         *tail = &ref->next;
 897 }
 898
 899 static struct ref *try_explicit_object_name(const char *name)
 900 {
 901         unsigned char sha1[20];
 902         struct ref *ref;
 903
 904         if (!*name) {
 905                 ref = alloc_ref("(delete)");
 906                 hashclr(ref->new_sha1);
 907                 return ref;
 908         }
 909         if (get_sha1(name, sha1))
 910                 return NULL;
 911         ref = alloc_ref(name);
 912         hashcpy(ref->new_sha1, sha1);
 913         return ref;
 914 }
 915
 916 static struct ref *make_linked_ref(const char *name, struct ref ***tail)
 917 {
 918         struct ref *ret = alloc_ref(name);
 919         tail_link_ref(ret, tail);
 920         return ret;
 921 }
 922
 923 static char *guess_ref(const char *name, struct ref *peer)
 924 {
 925         struct strbuf buf = STRBUF_INIT;
 926         unsigned char sha1[20];
 927
 928         const char *r = resolve_ref(peer->name, sha1, 1, NULL);
 929         if (!r)
 930                 return NULL;
 931
 932         if (!prefixcmp(r, "refs/heads/"))
 933                 strbuf_addstr(&buf, "refs/heads/");
 934         else if (!prefixcmp(r, "refs/tags/"))
 935                 strbuf_addstr(&buf, "refs/tags/");
 936         else
 937                 return NULL;
 938
 939         strbuf_addstr(&buf, name);
 940         return strbuf_detach(&buf, NULL);
 941 }
 942
 943 static int match_explicit(struct ref *src, struct ref *dst,
 944                           struct ref ***dst_tail,
 945                           struct refspec *rs)
 946 {
 947         struct ref *matched_src, *matched_dst;
 948         int copy_src;
 949
 950         const char *dst_value = rs->dst;
 951         char *dst_guess;
 952
 953         if (rs->pattern || rs->matching)
 954                 return 0;
 955
 956         matched_src = matched_dst = NULL;
 957         switch (count_refspec_match(rs->src, src, &matched_src)) {
 958         case 1:
 959                 copy_src = 1;
 960                 break;
 961         case 0:
 962                 /* The source could be in the get_sha1() format
 963                  * not a reference name.  :refs/other is a
 964                  * way to delete 'other' ref at the remote end.
 965                  */
 966                 matched_src = try_explicit_object_name(rs->src);
 967                 if (!matched_src)
 968                         return error("src refspec %s does not match any.", rs->src);
 969                 copy_src = 0;
 970                 break;
 971         default:
 972                 return error("src refspec %s matches more than one.", rs->src);
 973         }
 974
 975         if (!dst_value) {
 976                 unsigned char sha1[20];
 977                 int flag;
 978
 979                 dst_value = resolve_ref(matched_src->name, sha1, 1, &flag);
 980                 if (!dst_value ||
 981                     ((flag & REF_ISSYMREF) &&
 982                      prefixcmp(dst_value, "refs/heads/")))
 983                         die("%s cannot be resolved to branch.",
 984                             matched_src->name);
 985         }
 986
 987         switch (count_refspec_match(dst_value, dst, &matched_dst)) {
 988         case 1:
 989                 break;
 990         case 0:
 991                 if (!memcmp(dst_value, "refs/", 5))
 992                         matched_dst = make_linked_ref(dst_value, dst_tail);
 993                 else if((dst_guess = guess_ref(dst_value, matched_src)))
 994                         matched_dst = make_linked_ref(dst_guess, dst_tail);
 995                 else
 996                         error("unable to push to unqualified destination: %s\n"
 997                               "The destination refspec neither matches an "
 998                               "existing ref on the remote nor\n"
 999                               "begins with refs/, and we are unable to "
1000                               "guess a prefix based on the source ref.",
1001                               dst_value);
1002                 break;
1003         default:
1004                 matched_dst = NULL;
1005                 error("dst refspec %s matches more than one.",
1006                       dst_value);
1007                 break;
1008         }
1009         if (!matched_dst)
1010                 return -1;
1011         if (matched_dst->peer_ref)
1012                 return error("dst ref %s receives from more than one src.",
1013                       matched_dst->name);
1014         else {
1015                 matched_dst->peer_ref = copy_src ? copy_ref(matched_src) : matched_src;
1016                 matched_dst->force = rs->force;
1017         }
1018         return 0;
1019 }
1020
1021 static int match_explicit_refs(struct ref *src, struct ref *dst,
1022                                struct ref ***dst_tail, struct refspec *rs,
1023                                int rs_nr)
1024 {
1025         int i, errs;
1026         for (i = errs = 0; i < rs_nr; i++)
1027                 errs += match_explicit(src, dst, dst_tail, &rs[i]);
1028         return errs;
1029 }
1030
1031 static const struct refspec *check_pattern_match(const struct refspec *rs,
1032                                                  int rs_nr,
1033                                                  const struct ref *src)
1034 {
1035         int i;
1036         int matching_refs = -1;
1037         for (i = 0; i < rs_nr; i++) {
1038                 if (rs[i].matching &&
1039                     (matching_refs == -1 || rs[i].force)) {
1040                         matching_refs = i;
1041                         continue;
1042                 }
1043
1044                 if (rs[i].pattern && !prefixcmp(src->name, rs[i].src))
1045                         return rs + i;
1046         }
1047         if (matching_refs != -1)
1048                 return rs + matching_refs;
1049         else
1050                 return NULL;
1051 }
1052
1053 /*
1054  * Note. This is used only by "push"; refspec matching rules for
1055  * push and fetch are subtly different, so do not try to reuse it
1056  * without thinking.
1057  */
1058 int match_refs(struct ref *src, struct ref *dst, struct ref ***dst_tail,
1059                int nr_refspec, const char **refspec, int flags)
1060 {
1061         struct refspec *rs;
1062         int send_all = flags & MATCH_REFS_ALL;
1063         int send_mirror = flags & MATCH_REFS_MIRROR;
1064         int errs;
1065         static const char *default_refspec[] = { ":", 0 };
1066
1067         if (!nr_refspec) {
1068                 nr_refspec = 1;
1069                 refspec = default_refspec;
1070         }
1071         rs = parse_push_refspec(nr_refspec, (const char **) refspec);
1072         errs = match_explicit_refs(src, dst, dst_tail, rs, nr_refspec);
1073
1074         /* pick the remainder */
1075         for ( ; src; src = src->next) {
1076                 struct ref *dst_peer;
1077                 const struct refspec *pat = NULL;
1078                 char *dst_name;
1079                 if (src->peer_ref)
1080                         continue;
1081
1082                 pat = check_pattern_match(rs, nr_refspec, src);
1083                 if (!pat)
1084                         continue;
1085
1086                 if (pat->matching) {
1087                         /*
1088                          * "matching refs"; traditionally we pushed everything
1089                          * including refs outside refs/heads/ hierarchy, but
1090                          * that does not make much sense these days.
1091                          */
1092                         if (!send_mirror && prefixcmp(src->name, "refs/heads/"))
1093                                 continue;
1094                         dst_name = xstrdup(src->name);
1095
1096                 } else {
1097                         const char *dst_side = pat->dst ? pat->dst : pat->src;
1098                         dst_name = xmalloc(strlen(dst_side) +
1099                                            strlen(src->name) -
1100                                            strlen(pat->src) + 2);
1101                         strcpy(dst_name, dst_side);
1102                         strcat(dst_name, src->name + strlen(pat->src));
1103                 }
1104                 dst_peer = find_ref_by_name(dst, dst_name);
1105                 if (dst_peer) {
1106                         if (dst_peer->peer_ref)
1107                                 /* We're already sending something to this ref. */
1108                                 goto free_name;
1109
1110                 } else {
1111                         if (pat->matching && !(send_all || send_mirror))
1112                                 /*
1113                                  * Remote doesn't have it, and we have no
1114                                  * explicit pattern, and we don't have
1115                                  * --all nor --mirror.
1116                                  */
1117                                 goto free_name;
1118
1119                         /* Create a new one and link it */
1120                         dst_peer = make_linked_ref(dst_name, dst_tail);
1121                         hashcpy(dst_peer->new_sha1, src->new_sha1);
1122                 }
1123                 dst_peer->peer_ref = copy_ref(src);
1124                 dst_peer->force = pat->force;
1125         free_name:
1126                 free(dst_name);
1127         }
1128         if (errs)
1129                 return -1;
1130         return 0;
1131 }
1132
1133 struct branch *branch_get(const char *name)
1134 {
1135         struct branch *ret;
1136
1137         read_config();
1138         if (!name || !*name || !strcmp(name, "HEAD"))
1139                 ret = current_branch;
1140         else
1141                 ret = make_branch(name, 0);
1142         if (ret && ret->remote_name) {
1143                 ret->remote = remote_get(ret->remote_name);
1144                 if (ret->merge_nr) {
1145                         int i;
1146                         ret->merge = xcalloc(sizeof(*ret->merge),
1147                                              ret->merge_nr);
1148                         for (i = 0; i < ret->merge_nr; i++) {
1149                                 ret->merge[i] = xcalloc(1, sizeof(**ret->merge));
1150                                 ret->merge[i]->src = xstrdup(ret->merge_name[i]);
1151                                 remote_find_tracking(ret->remote,
1152                                                      ret->merge[i]);
1153                         }
1154                 }
1155         }
1156         return ret;
1157 }
1158
1159 int branch_has_merge_config(struct branch *branch)
1160 {
1161         return branch && !!branch->merge;
1162 }
1163
1164 int branch_merge_matches(struct branch *branch,
1165                                  int i,
1166                                  const char *refname)
1167 {
1168         if (!branch || i < 0 || i >= branch->merge_nr)
1169                 return 0;
1170         return refname_match(branch->merge[i]->src, refname, ref_fetch_rules);
1171 }
1172
1173 static struct ref *get_expanded_map(const struct ref *remote_refs,
1174                                     const struct refspec *refspec)
1175 {
1176         const struct ref *ref;
1177         struct ref *ret = NULL;
1178         struct ref **tail = &ret;
1179
1180         int remote_prefix_len = strlen(refspec->src);
1181         int local_prefix_len = strlen(refspec->dst);
1182
1183         for (ref = remote_refs; ref; ref = ref->next) {
1184                 if (strchr(ref->name, '^'))
1185                         continue; /* a dereference item */
1186                 if (!prefixcmp(ref->name, refspec->src)) {
1187                         const char *match;
1188                         struct ref *cpy = copy_ref(ref);
1189                         match = ref->name + remote_prefix_len;
1190
1191                         cpy->peer_ref = alloc_ref_with_prefix(refspec->dst,
1192                                         local_prefix_len, match);
1193                         if (refspec->force)
1194                                 cpy->peer_ref->force = 1;
1195                         *tail = cpy;
1196                         tail = &cpy->next;
1197                 }
1198         }
1199
1200         return ret;
1201 }
1202
1203 static const struct ref *find_ref_by_name_abbrev(const struct ref *refs, const char *name)
1204 {
1205         const struct ref *ref;
1206         for (ref = refs; ref; ref = ref->next) {
1207                 if (refname_match(name, ref->name, ref_fetch_rules))
1208                         return ref;
1209         }
1210         return NULL;
1211 }
1212
1213 struct ref *get_remote_ref(const struct ref *remote_refs, const char *name)
1214 {
1215         const struct ref *ref = find_ref_by_name_abbrev(remote_refs, name);
1216
1217         if (!ref)
1218                 return NULL;
1219
1220         return copy_ref(ref);
1221 }
1222
1223 static struct ref *get_local_ref(const char *name)
1224 {
1225         if (!name)
1226                 return NULL;
1227
1228         if (!prefixcmp(name, "refs/"))
1229                 return alloc_ref(name);
1230
1231         if (!prefixcmp(name, "heads/") ||
1232             !prefixcmp(name, "tags/") ||
1233             !prefixcmp(name, "remotes/"))
1234                 return alloc_ref_with_prefix("refs/", 5, name);
1235
1236         return alloc_ref_with_prefix("refs/heads/", 11, name);
1237 }
1238
1239 int get_fetch_map(const struct ref *remote_refs,
1240                   const struct refspec *refspec,
1241                   struct ref ***tail,
1242                   int missing_ok)
1243 {
1244         struct ref *ref_map, **rmp;
1245
1246         if (refspec->pattern) {
1247                 ref_map = get_expanded_map(remote_refs, refspec);
1248         } else {
1249                 const char *name = refspec->src[0] ? refspec->src : "HEAD";
1250
1251                 ref_map = get_remote_ref(remote_refs, name);
1252                 if (!missing_ok && !ref_map)
1253                         die("Couldn't find remote ref %s", name);
1254                 if (ref_map) {
1255                         ref_map->peer_ref = get_local_ref(refspec->dst);
1256                         if (ref_map->peer_ref && refspec->force)
1257                                 ref_map->peer_ref->force = 1;
1258                 }
1259         }
1260
1261         for (rmp = &ref_map; *rmp; ) {
1262                 if ((*rmp)->peer_ref) {
1263                         int st = check_ref_format((*rmp)->peer_ref->name + 5);
1264                         if (st && st != CHECK_REF_FORMAT_ONELEVEL) {
1265                                 struct ref *ignore = *rmp;
1266                                 error("* Ignoring funny ref '%s' locally",
1267                                       (*rmp)->peer_ref->name);
1268                                 *rmp = (*rmp)->next;
1269                                 free(ignore->peer_ref);
1270                                 free(ignore);
1271                                 continue;
1272                         }
1273                 }
1274                 rmp = &((*rmp)->next);
1275         }
1276
1277         if (ref_map)
1278                 tail_link_ref(ref_map, tail);
1279
1280         return 0;
1281 }
1282
1283 int resolve_remote_symref(struct ref *ref, struct ref *list)
1284 {
1285         if (!ref->symref)
1286                 return 0;
1287         for (; list; list = list->next)
1288                 if (!strcmp(ref->symref, list->name)) {
1289                         hashcpy(ref->old_sha1, list->old_sha1);
1290                         return 0;
1291                 }
1292         return 1;
1293 }
1294
1295 static void unmark_and_free(struct commit_list *list, unsigned int mark)
1296 {
1297         while (list) {
1298                 struct commit_list *temp = list;
1299                 temp->item->object.flags &= ~mark;
1300                 list = temp->next;
1301                 free(temp);
1302         }
1303 }
1304
1305 int ref_newer(const unsigned char *new_sha1, const unsigned char *old_sha1)
1306 {
1307         struct object *o;
1308         struct commit *old, *new;
1309         struct commit_list *list, *used;
1310         int found = 0;
1311
1312         /* Both new and old must be commit-ish and new is descendant of
1313          * old.  Otherwise we require --force.
1314          */
1315         o = deref_tag(parse_object(old_sha1), NULL, 0);
1316         if (!o || o->type != OBJ_COMMIT)
1317                 return 0;
1318         old = (struct commit *) o;
1319
1320         o = deref_tag(parse_object(new_sha1), NULL, 0);
1321         if (!o || o->type != OBJ_COMMIT)
1322                 return 0;
1323         new = (struct commit *) o;
1324
1325         if (parse_commit(new) < 0)
1326                 return 0;
1327
1328         used = list = NULL;
1329         commit_list_insert(new, &list);
1330         while (list) {
1331                 new = pop_most_recent_commit(&list, TMP_MARK);
1332                 commit_list_insert(new, &used);
1333                 if (new == old) {
1334                         found = 1;
1335                         break;
1336                 }
1337         }
1338         unmark_and_free(list, TMP_MARK);
1339         unmark_and_free(used, TMP_MARK);
1340         return found;
1341 }
1342
1343 /*
1344  * Return true if there is anything to report, otherwise false.
1345  */
1346 int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs)
1347 {
1348         unsigned char sha1[20];
1349         struct commit *ours, *theirs;
1350         char symmetric[84];
1351         struct rev_info revs;
1352         const char *rev_argv[10], *base;
1353         int rev_argc;
1354
1355         /*
1356          * Nothing to report unless we are marked to build on top of
1357          * somebody else.
1358          */
1359         if (!branch ||
1360             !branch->merge || !branch->merge[0] || !branch->merge[0]->dst)
1361                 return 0;
1362
1363         /*
1364          * If what we used to build on no longer exists, there is
1365          * nothing to report.
1366          */
1367         base = branch->merge[0]->dst;
1368         if (!resolve_ref(base, sha1, 1, NULL))
1369                 return 0;
1370         theirs = lookup_commit(sha1);
1371         if (!theirs)
1372                 return 0;
1373
1374         if (!resolve_ref(branch->refname, sha1, 1, NULL))
1375                 return 0;
1376         ours = lookup_commit(sha1);
1377         if (!ours)
1378                 return 0;
1379
1380         /* are we the same? */
1381         if (theirs == ours)
1382                 return 0;
1383
1384         /* Run "rev-list --left-right ours...theirs" internally... */
1385         rev_argc = 0;
1386         rev_argv[rev_argc++] = NULL;
1387         rev_argv[rev_argc++] = "--left-right";
1388         rev_argv[rev_argc++] = symmetric;
1389         rev_argv[rev_argc++] = "--";
1390         rev_argv[rev_argc] = NULL;
1391
1392         strcpy(symmetric, sha1_to_hex(ours->object.sha1));
1393         strcpy(symmetric + 40, "...");
1394         strcpy(symmetric + 43, sha1_to_hex(theirs->object.sha1));
1395
1396         init_revisions(&revs, NULL);
1397         setup_revisions(rev_argc, rev_argv, &revs, NULL);
1398         prepare_revision_walk(&revs);
1399
1400         /* ... and count the commits on each side. */
1401         *num_ours = 0;
1402         *num_theirs = 0;
1403         while (1) {
1404                 struct commit *c = get_revision(&revs);
1405                 if (!c)
1406                         break;
1407                 if (c->object.flags & SYMMETRIC_LEFT)
1408                         (*num_ours)++;
1409                 else
1410                         (*num_theirs)++;
1411         }
1412
1413         /* clear object flags smudged by the above traversal */
1414         clear_commit_marks(ours, ALL_REV_FLAGS);
1415         clear_commit_marks(theirs, ALL_REV_FLAGS);
1416         return 1;
1417 }
1418
1419 /*
1420  * Return true when there is anything to report, otherwise false.
1421  */
1422 int format_tracking_info(struct branch *branch, struct strbuf *sb)
1423 {
1424         int num_ours, num_theirs;
1425         const char *base;
1426
1427         if (!stat_tracking_info(branch, &num_ours, &num_theirs))
1428                 return 0;
1429
1430         base = branch->merge[0]->dst;
1431         if (!prefixcmp(base, "refs/remotes/")) {
1432                 base += strlen("refs/remotes/");
1433         }
1434         if (!num_theirs)
1435                 strbuf_addf(sb, "Your branch is ahead of '%s' "
1436                             "by %d commit%s.\n",
1437                             base, num_ours, (num_ours == 1) ? "" : "s");
1438         else if (!num_ours)
1439                 strbuf_addf(sb, "Your branch is behind '%s' "
1440                             "by %d commit%s, "
1441                             "and can be fast-forwarded.\n",
1442                             base, num_theirs, (num_theirs == 1) ? "" : "s");
1443         else
1444                 strbuf_addf(sb, "Your branch and '%s' have diverged,\n"
1445                             "and have %d and %d different commit(s) each, "
1446                             "respectively.\n",
1447                             base, num_ours, num_theirs);
1448         return 1;
1449 }
1450
1451 static int one_local_ref(const char *refname, const unsigned char *sha1, int flag, void *cb_data)
1452 {
1453         struct ref ***local_tail = cb_data;
1454         struct ref *ref;
1455         int len;
1456
1457         /* we already know it starts with refs/ to get here */
1458         if (check_ref_format(refname + 5))
1459                 return 0;
1460
1461         len = strlen(refname) + 1;
1462         ref = xcalloc(1, sizeof(*ref) + len);
1463         hashcpy(ref->new_sha1, sha1);
1464         memcpy(ref->name, refname, len);
1465         **local_tail = ref;
1466         *local_tail = &ref->next;
1467         return 0;
1468 }
1469
1470 struct ref *get_local_heads(void)
1471 {
1472         struct ref *local_refs, **local_tail = &local_refs;
1473         for_each_ref(one_local_ref, &local_tail);
1474         return local_refs;
1475 }
1476
1477 struct ref *guess_remote_head(const struct ref *head,
1478                               const struct ref *refs,
1479                               int all)
1480 {
1481         const struct ref *r;
1482         struct ref *list = NULL;
1483         struct ref **tail = &list;
1484
1485         if (!head)
1486                 return NULL;
1487
1488         /*
1489          * Some transports support directly peeking at
1490          * where HEAD points; if that is the case, then
1491          * we don't have to guess.
1492          */
1493         if (head->symref)
1494                 return copy_ref(find_ref_by_name(refs, head->symref));
1495
1496         /* If refs/heads/master could be right, it is. */
1497         if (!all) {
1498                 r = find_ref_by_name(refs, "refs/heads/master");
1499                 if (r && !hashcmp(r->old_sha1, head->old_sha1))
1500                         return copy_ref(r);
1501         }
1502
1503         /* Look for another ref that points there */
1504         for (r = refs; r; r = r->next) {
1505                 if (r != head && !hashcmp(r->old_sha1, head->old_sha1)) {
1506                         *tail = copy_ref(r);
1507                         tail = &((*tail)->next);
1508                         if (!all)
1509                                 break;
1510                 }
1511         }
1512
1513         return list;
1514 }