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 void add_pushurl(struct remote *remote, const char *pushurl)
 110 {
 111         ALLOC_GROW(remote->pushurl, remote->pushurl_nr + 1, remote->pushurl_alloc);
 112         remote->pushurl[remote->pushurl_nr++] = pushurl;
 113 }
 114
 115 static struct remote *make_remote(const char *name, int len)
 116 {
 117         struct remote *ret;
 118         int i;
 119
 120         for (i = 0; i < remotes_nr; i++) {
 121                 if (len ? (!strncmp(name, remotes[i]->name, len) &&
 122                            !remotes[i]->name[len]) :
 123                     !strcmp(name, remotes[i]->name))
 124                         return remotes[i];
 125         }
 126
 127         ret = xcalloc(1, sizeof(struct remote));
 128         ALLOC_GROW(remotes, remotes_nr + 1, remotes_alloc);
 129         remotes[remotes_nr++] = ret;
 130         if (len)
 131                 ret->name = xstrndup(name, len);
 132         else
 133                 ret->name = xstrdup(name);
 134         return ret;
 135 }
 136
 137 static void add_merge(struct branch *branch, const char *name)
 138 {
 139         ALLOC_GROW(branch->merge_name, branch->merge_nr + 1,
 140                    branch->merge_alloc);
 141         branch->merge_name[branch->merge_nr++] = name;
 142 }
 143
 144 static struct branch *make_branch(const char *name, int len)
 145 {
 146         struct branch *ret;
 147         int i;
 148         char *refname;
 149
 150         for (i = 0; i < branches_nr; i++) {
 151                 if (len ? (!strncmp(name, branches[i]->name, len) &&
 152                            !branches[i]->name[len]) :
 153                     !strcmp(name, branches[i]->name))
 154                         return branches[i];
 155         }
 156
 157         ALLOC_GROW(branches, branches_nr + 1, branches_alloc);
 158         ret = xcalloc(1, sizeof(struct branch));
 159         branches[branches_nr++] = ret;
 160         if (len)
 161                 ret->name = xstrndup(name, len);
 162         else
 163                 ret->name = xstrdup(name);
 164         refname = xmalloc(strlen(name) + strlen("refs/heads/") + 1);
 165         strcpy(refname, "refs/heads/");
 166         strcpy(refname + strlen("refs/heads/"), ret->name);
 167         ret->refname = refname;
 168
 169         return ret;
 170 }
 171
 172 static struct rewrite *make_rewrite(const char *base, int len)
 173 {
 174         struct rewrite *ret;
 175         int i;
 176
 177         for (i = 0; i < rewrite_nr; i++) {
 178                 if (len
 179                     ? (len == rewrite[i]->baselen &&
 180                        !strncmp(base, rewrite[i]->base, len))
 181                     : !strcmp(base, rewrite[i]->base))
 182                         return rewrite[i];
 183         }
 184
 185         ALLOC_GROW(rewrite, rewrite_nr + 1, rewrite_alloc);
 186         ret = xcalloc(1, sizeof(struct rewrite));
 187         rewrite[rewrite_nr++] = ret;
 188         if (len) {
 189                 ret->base = xstrndup(base, len);
 190                 ret->baselen = len;
 191         }
 192         else {
 193                 ret->base = xstrdup(base);
 194                 ret->baselen = strlen(base);
 195         }
 196         return ret;
 197 }
 198
 199 static void add_instead_of(struct rewrite *rewrite, const char *instead_of)
 200 {
 201         ALLOC_GROW(rewrite->instead_of, rewrite->instead_of_nr + 1, rewrite->instead_of_alloc);
 202         rewrite->instead_of[rewrite->instead_of_nr].s = instead_of;
 203         rewrite->instead_of[rewrite->instead_of_nr].len = strlen(instead_of);
 204         rewrite->instead_of_nr++;
 205 }
 206
 207 static void read_remotes_file(struct remote *remote)
 208 {
 209         FILE *f = fopen(git_path("remotes/%s", remote->name), "r");
 210
 211         if (!f)
 212                 return;
 213         remote->origin = REMOTE_REMOTES;
 214         while (fgets(buffer, BUF_SIZE, f)) {
 215                 int value_list;
 216                 char *s, *p;
 217
 218                 if (!prefixcmp(buffer, "URL:")) {
 219                         value_list = 0;
 220                         s = buffer + 4;
 221                 } else if (!prefixcmp(buffer, "Push:")) {
 222                         value_list = 1;
 223                         s = buffer + 5;
 224                 } else if (!prefixcmp(buffer, "Pull:")) {
 225                         value_list = 2;
 226                         s = buffer + 5;
 227                 } else
 228                         continue;
 229
 230                 while (isspace(*s))
 231                         s++;
 232                 if (!*s)
 233                         continue;
 234
 235                 p = s + strlen(s);
 236                 while (isspace(p[-1]))
 237                         *--p = 0;
 238
 239                 switch (value_list) {
 240                 case 0:
 241                         add_url_alias(remote, xstrdup(s));
 242                         break;
 243                 case 1:
 244                         add_push_refspec(remote, xstrdup(s));
 245                         break;
 246                 case 2:
 247                         add_fetch_refspec(remote, xstrdup(s));
 248                         break;
 249                 }
 250         }
 251         fclose(f);
 252 }
 253
 254 static void read_branches_file(struct remote *remote)
 255 {
 256         const char *slash = strchr(remote->name, '/');
 257         char *frag;
 258         struct strbuf branch = STRBUF_INIT;
 259         int n = slash ? slash - remote->name : 1000;
 260         FILE *f = fopen(git_path("branches/%.*s", n, remote->name), "r");
 261         char *s, *p;
 262         int len;
 263
 264         if (!f)
 265                 return;
 266         s = fgets(buffer, BUF_SIZE, f);
 267         fclose(f);
 268         if (!s)
 269                 return;
 270         while (isspace(*s))
 271                 s++;
 272         if (!*s)
 273                 return;
 274         remote->origin = REMOTE_BRANCHES;
 275         p = s + strlen(s);
 276         while (isspace(p[-1]))
 277                 *--p = 0;
 278         len = p - s;
 279         if (slash)
 280                 len += strlen(slash);
 281         p = xmalloc(len + 1);
 282         strcpy(p, s);
 283         if (slash)
 284                 strcat(p, slash);
 285
 286         /*
 287          * With "slash", e.g. "git fetch jgarzik/netdev-2.6" when
 288          * reading from $GIT_DIR/branches/jgarzik fetches "HEAD" from
 289          * the partial URL obtained from the branches file plus
 290          * "/netdev-2.6" and does not store it in any tracking ref.
 291          * #branch specifier in the file is ignored.
 292          *
 293          * Otherwise, the branches file would have URL and optionally
 294          * #branch specified.  The "master" (or specified) branch is
 295          * fetched and stored in the local branch of the same name.
 296          */
 297         frag = strchr(p, '#');
 298         if (frag) {
 299                 *(frag++) = '\0';
 300                 strbuf_addf(&branch, "refs/heads/%s", frag);
 301         } else
 302                 strbuf_addstr(&branch, "refs/heads/master");
 303         if (!slash) {
 304                 strbuf_addf(&branch, ":refs/heads/%s", remote->name);
 305         } else {
 306                 strbuf_reset(&branch);
 307                 strbuf_addstr(&branch, "HEAD:");
 308         }
 309         add_url_alias(remote, p);
 310         add_fetch_refspec(remote, strbuf_detach(&branch, NULL));
 311         /*
 312          * Cogito compatible push: push current HEAD to remote #branch
 313          * (master if missing)
 314          */
 315         strbuf_init(&branch, 0);
 316         strbuf_addstr(&branch, "HEAD");
 317         if (frag)
 318                 strbuf_addf(&branch, ":refs/heads/%s", frag);
 319         else
 320                 strbuf_addstr(&branch, ":refs/heads/master");
 321         add_push_refspec(remote, strbuf_detach(&branch, NULL));
 322         remote->fetch_tags = 1; /* always auto-follow */
 323 }
 324
 325 static int handle_config(const char *key, const char *value, void *cb)
 326 {
 327         const char *name;
 328         const char *subkey;
 329         struct remote *remote;
 330         struct branch *branch;
 331         if (!prefixcmp(key, "branch.")) {
 332                 name = key + 7;
 333                 subkey = strrchr(name, '.');
 334                 if (!subkey)
 335                         return 0;
 336                 branch = make_branch(name, subkey - name);
 337                 if (!strcmp(subkey, ".remote")) {
 338                         if (!value)
 339                                 return config_error_nonbool(key);
 340                         branch->remote_name = xstrdup(value);
 341                         if (branch == current_branch) {
 342                                 default_remote_name = branch->remote_name;
 343                                 explicit_default_remote_name = 1;
 344                         }
 345                 } else if (!strcmp(subkey, ".merge")) {
 346                         if (!value)
 347                                 return config_error_nonbool(key);
 348                         add_merge(branch, xstrdup(value));
 349                 }
 350                 return 0;
 351         }
 352         if (!prefixcmp(key, "url.")) {
 353                 struct rewrite *rewrite;
 354                 name = key + 4;
 355                 subkey = strrchr(name, '.');
 356                 if (!subkey)
 357                         return 0;
 358                 rewrite = make_rewrite(name, subkey - name);
 359                 if (!strcmp(subkey, ".insteadof")) {
 360                         if (!value)
 361                                 return config_error_nonbool(key);
 362                         add_instead_of(rewrite, xstrdup(value));
 363                 }
 364         }
 365         if (prefixcmp(key,  "remote."))
 366                 return 0;
 367         name = key + 7;
 368         if (*name == '/') {
 369                 warning("Config remote shorthand cannot begin with '/': %s",
 370                         name);
 371                 return 0;
 372         }
 373         subkey = strrchr(name, '.');
 374         if (!subkey)
 375                 return 0;
 376         remote = make_remote(name, subkey - name);
 377         remote->origin = REMOTE_CONFIG;
 378         if (!strcmp(subkey, ".mirror"))
 379                 remote->mirror = git_config_bool(key, value);
 380         else if (!strcmp(subkey, ".skipdefaultupdate"))
 381                 remote->skip_default_update = git_config_bool(key, value);
 382
 383         else if (!strcmp(subkey, ".url")) {
 384                 const char *v;
 385                 if (git_config_string(&v, key, value))
 386                         return -1;
 387                 add_url(remote, v);
 388         } else if (!strcmp(subkey, ".pushurl")) {
 389                 const char *v;
 390                 if (git_config_string(&v, key, value))
 391                         return -1;
 392                 add_pushurl(remote, v);
 393         } else if (!strcmp(subkey, ".push")) {
 394                 const char *v;
 395                 if (git_config_string(&v, key, value))
 396                         return -1;
 397                 add_push_refspec(remote, v);
 398         } else if (!strcmp(subkey, ".fetch")) {
 399                 const char *v;
 400                 if (git_config_string(&v, key, value))
 401                         return -1;
 402                 add_fetch_refspec(remote, v);
 403         } else if (!strcmp(subkey, ".receivepack")) {
 404                 const char *v;
 405                 if (git_config_string(&v, key, value))
 406                         return -1;
 407                 if (!remote->receivepack)
 408                         remote->receivepack = v;
 409                 else
 410                         error("more than one receivepack given, using the first");
 411         } else if (!strcmp(subkey, ".uploadpack")) {
 412                 const char *v;
 413                 if (git_config_string(&v, key, value))
 414                         return -1;
 415                 if (!remote->uploadpack)
 416                         remote->uploadpack = v;
 417                 else
 418                         error("more than one uploadpack given, using the first");
 419         } else if (!strcmp(subkey, ".tagopt")) {
 420                 if (!strcmp(value, "--no-tags"))
 421                         remote->fetch_tags = -1;
 422         } else if (!strcmp(subkey, ".proxy")) {
 423                 return git_config_string((const char **)&remote->http_proxy,
 424                                          key, value);
 425         }
 426         return 0;
 427 }
 428
 429 static void alias_all_urls(void)
 430 {
 431         int i, j;
 432         for (i = 0; i < remotes_nr; i++) {
 433                 if (!remotes[i])
 434                         continue;
 435                 for (j = 0; j < remotes[i]->url_nr; j++) {
 436                         remotes[i]->url[j] = alias_url(remotes[i]->url[j]);
 437                 }
 438                 for (j = 0; j < remotes[i]->pushurl_nr; j++) {
 439                         remotes[i]->pushurl[j] = alias_url(remotes[i]->pushurl[j]);
 440                 }
 441         }
 442 }
 443
 444 static void read_config(void)
 445 {
 446         unsigned char sha1[20];
 447         const char *head_ref;
 448         int flag;
 449         if (default_remote_name) // did this already
 450                 return;
 451         default_remote_name = xstrdup("origin");
 452         current_branch = NULL;
 453         head_ref = resolve_ref("HEAD", sha1, 0, &flag);
 454         if (head_ref && (flag & REF_ISSYMREF) &&
 455             !prefixcmp(head_ref, "refs/heads/")) {
 456                 current_branch =
 457                         make_branch(head_ref + strlen("refs/heads/"), 0);
 458         }
 459         git_config(handle_config, NULL);
 460         alias_all_urls();
 461 }
 462
 463 /*
 464  * We need to make sure the tracking branches are well formed, but a
 465  * wildcard refspec in "struct refspec" must have a trailing slash. We
 466  * temporarily drop the trailing '/' while calling check_ref_format(),
 467  * and put it back.  The caller knows that a CHECK_REF_FORMAT_ONELEVEL
 468  * error return is Ok for a wildcard refspec.
 469  */
 470 static int verify_refname(char *name, int is_glob)
 471 {
 472         int result;
 473
 474         result = check_ref_format(name);
 475         if (is_glob && result == CHECK_REF_FORMAT_WILDCARD)
 476                 result = CHECK_REF_FORMAT_OK;
 477         return result;
 478 }
 479
 480 /*
 481  * This function frees a refspec array.
 482  * Warning: code paths should be checked to ensure that the src
 483  *          and dst pointers are always freeable pointers as well
 484  *          as the refspec pointer itself.
 485  */
 486 static void free_refspecs(struct refspec *refspec, int nr_refspec)
 487 {
 488         int i;
 489
 490         if (!refspec)
 491                 return;
 492
 493         for (i = 0; i < nr_refspec; i++) {
 494                 free(refspec[i].src);
 495                 free(refspec[i].dst);
 496         }
 497         free(refspec);
 498 }
 499
 500 static struct refspec *parse_refspec_internal(int nr_refspec, const char **refspec, int fetch, int verify)
 501 {
 502         int i;
 503         int st;
 504         struct refspec *rs = xcalloc(sizeof(*rs), nr_refspec);
 505
 506         for (i = 0; i < nr_refspec; i++) {
 507                 size_t llen;
 508                 int is_glob;
 509                 const char *lhs, *rhs;
 510
 511                 is_glob = 0;
 512
 513                 lhs = refspec[i];
 514                 if (*lhs == '+') {
 515                         rs[i].force = 1;
 516                         lhs++;
 517                 }
 518
 519                 rhs = strrchr(lhs, ':');
 520
 521                 /*
 522                  * Before going on, special case ":" (or "+:") as a refspec
 523                  * for matching refs.
 524                  */
 525                 if (!fetch && rhs == lhs && rhs[1] == '\0') {
 526                         rs[i].matching = 1;
 527                         continue;
 528                 }
 529
 530                 if (rhs) {
 531                         size_t rlen = strlen(++rhs);
 532                         is_glob = (1 <= rlen && strchr(rhs, '*'));
 533                         rs[i].dst = xstrndup(rhs, rlen);
 534                 }
 535
 536                 llen = (rhs ? (rhs - lhs - 1) : strlen(lhs));
 537                 if (1 <= llen && memchr(lhs, '*', llen)) {
 538                         if ((rhs && !is_glob) || (!rhs && fetch))
 539                                 goto invalid;
 540                         is_glob = 1;
 541                 } else if (rhs && is_glob) {
 542                         goto invalid;
 543                 }
 544
 545                 rs[i].pattern = is_glob;
 546                 rs[i].src = xstrndup(lhs, llen);
 547
 548                 if (fetch) {
 549                         /*
 550                          * LHS
 551                          * - empty is allowed; it means HEAD.
 552                          * - otherwise it must be a valid looking ref.
 553                          */
 554                         if (!*rs[i].src)
 555                                 ; /* empty is ok */
 556                         else {
 557                                 st = verify_refname(rs[i].src, is_glob);
 558                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 559                                         goto invalid;
 560                         }
 561                         /*
 562                          * RHS
 563                          * - missing is ok, and is same as empty.
 564                          * - empty is ok; it means not to store.
 565                          * - otherwise it must be a valid looking ref.
 566                          */
 567                         if (!rs[i].dst) {
 568                                 ; /* ok */
 569                         } else if (!*rs[i].dst) {
 570                                 ; /* ok */
 571                         } else {
 572                                 st = verify_refname(rs[i].dst, is_glob);
 573                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 574                                         goto invalid;
 575                         }
 576                 } else {
 577                         /*
 578                          * LHS
 579                          * - empty is allowed; it means delete.
 580                          * - when wildcarded, it must be a valid looking ref.
 581                          * - otherwise, it must be an extended SHA-1, but
 582                          *   there is no existing way to validate this.
 583                          */
 584                         if (!*rs[i].src)
 585                                 ; /* empty is ok */
 586                         else if (is_glob) {
 587                                 st = verify_refname(rs[i].src, is_glob);
 588                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 589                                         goto invalid;
 590                         }
 591                         else
 592                                 ; /* anything goes, for now */
 593                         /*
 594                          * RHS
 595                          * - missing is allowed, but LHS then must be a
 596                          *   valid looking ref.
 597                          * - empty is not allowed.
 598                          * - otherwise it must be a valid looking ref.
 599                          */
 600                         if (!rs[i].dst) {
 601                                 st = verify_refname(rs[i].src, is_glob);
 602                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 603                                         goto invalid;
 604                         } else if (!*rs[i].dst) {
 605                                 goto invalid;
 606                         } else {
 607                                 st = verify_refname(rs[i].dst, is_glob);
 608                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 609                                         goto invalid;
 610                         }
 611                 }
 612         }
 613         return rs;
 614
 615  invalid:
 616         if (verify) {
 617                 /*
 618                  * nr_refspec must be greater than zero and i must be valid
 619                  * since it is only possible to reach this point from within
 620                  * the for loop above.
 621                  */
 622                 free_refspecs(rs, i+1);
 623                 return NULL;
 624         }
 625         die("Invalid refspec '%s'", refspec[i]);
 626 }
 627
 628 int valid_fetch_refspec(const char *fetch_refspec_str)
 629 {
 630         const char *fetch_refspec[] = { fetch_refspec_str };
 631         struct refspec *refspec;
 632
 633         refspec = parse_refspec_internal(1, fetch_refspec, 1, 1);
 634         free_refspecs(refspec, 1);
 635         return !!refspec;
 636 }
 637
 638 struct refspec *parse_fetch_refspec(int nr_refspec, const char **refspec)
 639 {
 640         return parse_refspec_internal(nr_refspec, refspec, 1, 0);
 641 }
 642
 643 static struct refspec *parse_push_refspec(int nr_refspec, const char **refspec)
 644 {
 645         return parse_refspec_internal(nr_refspec, refspec, 0, 0);
 646 }
 647
 648 static int valid_remote_nick(const char *name)
 649 {
 650         if (!name[0] || is_dot_or_dotdot(name))
 651                 return 0;
 652         return !strchr(name, '/'); /* no slash */
 653 }
 654
 655 struct remote *remote_get(const char *name)
 656 {
 657         struct remote *ret;
 658         int name_given = 0;
 659
 660         read_config();
 661         if (name)
 662                 name_given = 1;
 663         else {
 664                 name = default_remote_name;
 665                 name_given = explicit_default_remote_name;
 666         }
 667
 668         ret = make_remote(name, 0);
 669         if (valid_remote_nick(name)) {
 670                 if (!ret->url)
 671                         read_remotes_file(ret);
 672                 if (!ret->url)
 673                         read_branches_file(ret);
 674         }
 675         if (name_given && !ret->url)
 676                 add_url_alias(ret, name);
 677         if (!ret->url)
 678                 return NULL;
 679         ret->fetch = parse_fetch_refspec(ret->fetch_refspec_nr, ret->fetch_refspec);
 680         ret->push = parse_push_refspec(ret->push_refspec_nr, ret->push_refspec);
 681         return ret;
 682 }
 683
 684 int remote_is_configured(const char *name)
 685 {
 686         int i;
 687         read_config();
 688
 689         for (i = 0; i < remotes_nr; i++)
 690                 if (!strcmp(name, remotes[i]->name))
 691                         return 1;
 692         return 0;
 693 }
 694
 695 int for_each_remote(each_remote_fn fn, void *priv)
 696 {
 697         int i, result = 0;
 698         read_config();
 699         for (i = 0; i < remotes_nr && !result; i++) {
 700                 struct remote *r = remotes[i];
 701                 if (!r)
 702                         continue;
 703                 if (!r->fetch)
 704                         r->fetch = parse_fetch_refspec(r->fetch_refspec_nr,
 705                                                        r->fetch_refspec);
 706                 if (!r->push)
 707                         r->push = parse_push_refspec(r->push_refspec_nr,
 708                                                      r->push_refspec);
 709                 result = fn(r, priv);
 710         }
 711         return result;
 712 }
 713
 714 void ref_remove_duplicates(struct ref *ref_map)
 715 {
 716         struct ref **posn;
 717         struct ref *next;
 718         for (; ref_map; ref_map = ref_map->next) {
 719                 if (!ref_map->peer_ref)
 720                         continue;
 721                 posn = &ref_map->next;
 722                 while (*posn) {
 723                         if ((*posn)->peer_ref &&
 724                             !strcmp((*posn)->peer_ref->name,
 725                                     ref_map->peer_ref->name)) {
 726                                 if (strcmp((*posn)->name, ref_map->name))
 727                                         die("%s tracks both %s and %s",
 728                                             ref_map->peer_ref->name,
 729                                             (*posn)->name, ref_map->name);
 730                                 next = (*posn)->next;
 731                                 free((*posn)->peer_ref);
 732                                 free(*posn);
 733                                 *posn = next;
 734                         } else {
 735                                 posn = &(*posn)->next;
 736                         }
 737                 }
 738         }
 739 }
 740
 741 int remote_has_url(struct remote *remote, const char *url)
 742 {
 743         int i;
 744         for (i = 0; i < remote->url_nr; i++) {
 745                 if (!strcmp(remote->url[i], url))
 746                         return 1;
 747         }
 748         return 0;
 749 }
 750
 751 static int match_name_with_pattern(const char *key, const char *name,
 752                                    const char *value, char **result)
 753 {
 754         const char *kstar = strchr(key, '*');
 755         size_t klen;
 756         size_t ksuffixlen;
 757         size_t namelen;
 758         int ret;
 759         if (!kstar)
 760                 die("Key '%s' of pattern had no '*'", key);
 761         klen = kstar - key;
 762         ksuffixlen = strlen(kstar + 1);
 763         namelen = strlen(name);
 764         ret = !strncmp(name, key, klen) && namelen >= klen + ksuffixlen &&
 765                 !memcmp(name + namelen - ksuffixlen, kstar + 1, ksuffixlen);
 766         if (ret && value) {
 767                 const char *vstar = strchr(value, '*');
 768                 size_t vlen;
 769                 size_t vsuffixlen;
 770                 if (!vstar)
 771                         die("Value '%s' of pattern has no '*'", value);
 772                 vlen = vstar - value;
 773                 vsuffixlen = strlen(vstar + 1);
 774                 *result = xmalloc(vlen + vsuffixlen +
 775                                   strlen(name) -
 776                                   klen - ksuffixlen + 1);
 777                 strncpy(*result, value, vlen);
 778                 strncpy(*result + vlen,
 779                         name + klen, namelen - klen - ksuffixlen);
 780                 strcpy(*result + vlen + namelen - klen - ksuffixlen,
 781                        vstar + 1);
 782         }
 783         return ret;
 784 }
 785
 786 int remote_find_tracking(struct remote *remote, struct refspec *refspec)
 787 {
 788         int find_src = refspec->src == NULL;
 789         char *needle, **result;
 790         int i;
 791
 792         if (find_src) {
 793                 if (!refspec->dst)
 794                         return error("find_tracking: need either src or dst");
 795                 needle = refspec->dst;
 796                 result = &refspec->src;
 797         } else {
 798                 needle = refspec->src;
 799                 result = &refspec->dst;
 800         }
 801
 802         for (i = 0; i < remote->fetch_refspec_nr; i++) {
 803                 struct refspec *fetch = &remote->fetch[i];
 804                 const char *key = find_src ? fetch->dst : fetch->src;
 805                 const char *value = find_src ? fetch->src : fetch->dst;
 806                 if (!fetch->dst)
 807                         continue;
 808                 if (fetch->pattern) {
 809                         if (match_name_with_pattern(key, needle, value, result)) {
 810                                 refspec->force = fetch->force;
 811                                 return 0;
 812                         }
 813                 } else if (!strcmp(needle, key)) {
 814                         *result = xstrdup(value);
 815                         refspec->force = fetch->force;
 816                         return 0;
 817                 }
 818         }
 819         return -1;
 820 }
 821
 822 static struct ref *alloc_ref_with_prefix(const char *prefix, size_t prefixlen,
 823                 const char *name)
 824 {
 825         size_t len = strlen(name);
 826         struct ref *ref = xcalloc(1, sizeof(struct ref) + prefixlen + len + 1);
 827         memcpy(ref->name, prefix, prefixlen);
 828         memcpy(ref->name + prefixlen, name, len);
 829         return ref;
 830 }
 831
 832 struct ref *alloc_ref(const char *name)
 833 {
 834         return alloc_ref_with_prefix("", 0, name);
 835 }
 836
 837 static struct ref *copy_ref(const struct ref *ref)
 838 {
 839         struct ref *cpy;
 840         size_t len;
 841         if (!ref)
 842                 return NULL;
 843         len = strlen(ref->name);
 844         cpy = xmalloc(sizeof(struct ref) + len + 1);
 845         memcpy(cpy, ref, sizeof(struct ref) + len + 1);
 846         cpy->next = NULL;
 847         cpy->symref = ref->symref ? xstrdup(ref->symref) : NULL;
 848         cpy->remote_status = ref->remote_status ? xstrdup(ref->remote_status) : NULL;
 849         cpy->peer_ref = copy_ref(ref->peer_ref);
 850         return cpy;
 851 }
 852
 853 struct ref *copy_ref_list(const struct ref *ref)
 854 {
 855         struct ref *ret = NULL;
 856         struct ref **tail = &ret;
 857         while (ref) {
 858                 *tail = copy_ref(ref);
 859                 ref = ref->next;
 860                 tail = &((*tail)->next);
 861         }
 862         return ret;
 863 }
 864
 865 static void free_ref(struct ref *ref)
 866 {
 867         if (!ref)
 868                 return;
 869         free_ref(ref->peer_ref);
 870         free(ref->remote_status);
 871         free(ref->symref);
 872         free(ref);
 873 }
 874
 875 void free_refs(struct ref *ref)
 876 {
 877         struct ref *next;
 878         while (ref) {
 879                 next = ref->next;
 880                 free_ref(ref);
 881                 ref = next;
 882         }
 883 }
 884
 885 static int count_refspec_match(const char *pattern,
 886                                struct ref *refs,
 887                                struct ref **matched_ref)
 888 {
 889         int patlen = strlen(pattern);
 890         struct ref *matched_weak = NULL;
 891         struct ref *matched = NULL;
 892         int weak_match = 0;
 893         int match = 0;
 894
 895         for (weak_match = match = 0; refs; refs = refs->next) {
 896                 char *name = refs->name;
 897                 int namelen = strlen(name);
 898
 899                 if (!refname_match(pattern, name, ref_rev_parse_rules))
 900                         continue;
 901
 902                 /* A match is "weak" if it is with refs outside
 903                  * heads or tags, and did not specify the pattern
 904                  * in full (e.g. "refs/remotes/origin/master") or at
 905                  * least from the toplevel (e.g. "remotes/origin/master");
 906                  * otherwise "git push $URL master" would result in
 907                  * ambiguity between remotes/origin/master and heads/master
 908                  * at the remote site.
 909                  */
 910                 if (namelen != patlen &&
 911                     patlen != namelen - 5 &&
 912                     prefixcmp(name, "refs/heads/") &&
 913                     prefixcmp(name, "refs/tags/")) {
 914                         /* We want to catch the case where only weak
 915                          * matches are found and there are multiple
 916                          * matches, and where more than one strong
 917                          * matches are found, as ambiguous.  One
 918                          * strong match with zero or more weak matches
 919                          * are acceptable as a unique match.
 920                          */
 921                         matched_weak = refs;
 922                         weak_match++;
 923                 }
 924                 else {
 925                         matched = refs;
 926                         match++;
 927                 }
 928         }
 929         if (!matched) {
 930                 *matched_ref = matched_weak;
 931                 return weak_match;
 932         }
 933         else {
 934                 *matched_ref = matched;
 935                 return match;
 936         }
 937 }
 938
 939 static void tail_link_ref(struct ref *ref, struct ref ***tail)
 940 {
 941         **tail = ref;
 942         while (ref->next)
 943                 ref = ref->next;
 944         *tail = &ref->next;
 945 }
 946
 947 static struct ref *try_explicit_object_name(const char *name)
 948 {
 949         unsigned char sha1[20];
 950         struct ref *ref;
 951
 952         if (!*name) {
 953                 ref = alloc_ref("(delete)");
 954                 hashclr(ref->new_sha1);
 955                 return ref;
 956         }
 957         if (get_sha1(name, sha1))
 958                 return NULL;
 959         ref = alloc_ref(name);
 960         hashcpy(ref->new_sha1, sha1);
 961         return ref;
 962 }
 963
 964 static struct ref *make_linked_ref(const char *name, struct ref ***tail)
 965 {
 966         struct ref *ret = alloc_ref(name);
 967         tail_link_ref(ret, tail);
 968         return ret;
 969 }
 970
 971 static char *guess_ref(const char *name, struct ref *peer)
 972 {
 973         struct strbuf buf = STRBUF_INIT;
 974         unsigned char sha1[20];
 975
 976         const char *r = resolve_ref(peer->name, sha1, 1, NULL);
 977         if (!r)
 978                 return NULL;
 979
 980         if (!prefixcmp(r, "refs/heads/"))
 981                 strbuf_addstr(&buf, "refs/heads/");
 982         else if (!prefixcmp(r, "refs/tags/"))
 983                 strbuf_addstr(&buf, "refs/tags/");
 984         else
 985                 return NULL;
 986
 987         strbuf_addstr(&buf, name);
 988         return strbuf_detach(&buf, NULL);
 989 }
 990
 991 static int match_explicit(struct ref *src, struct ref *dst,
 992                           struct ref ***dst_tail,
 993                           struct refspec *rs)
 994 {
 995         struct ref *matched_src, *matched_dst;
 996         int copy_src;
 997
 998         const char *dst_value = rs->dst;
 999         char *dst_guess;
1000
1001         if (rs->pattern || rs->matching)
1002                 return 0;
1003
1004         matched_src = matched_dst = NULL;
1005         switch (count_refspec_match(rs->src, src, &matched_src)) {
1006         case 1:
1007                 copy_src = 1;
1008                 break;
1009         case 0:
1010                 /* The source could be in the get_sha1() format
1011                  * not a reference name.  :refs/other is a
1012                  * way to delete 'other' ref at the remote end.
1013                  */
1014                 matched_src = try_explicit_object_name(rs->src);
1015                 if (!matched_src)
1016                         return error("src refspec %s does not match any.", rs->src);
1017                 copy_src = 0;
1018                 break;
1019         default:
1020                 return error("src refspec %s matches more than one.", rs->src);
1021         }
1022
1023         if (!dst_value) {
1024                 unsigned char sha1[20];
1025                 int flag;
1026
1027                 dst_value = resolve_ref(matched_src->name, sha1, 1, &flag);
1028                 if (!dst_value ||
1029                     ((flag & REF_ISSYMREF) &&
1030                      prefixcmp(dst_value, "refs/heads/")))
1031                         die("%s cannot be resolved to branch.",
1032                             matched_src->name);
1033         }
1034
1035         switch (count_refspec_match(dst_value, dst, &matched_dst)) {
1036         case 1:
1037                 break;
1038         case 0:
1039                 if (!memcmp(dst_value, "refs/", 5))
1040                         matched_dst = make_linked_ref(dst_value, dst_tail);
1041                 else if((dst_guess = guess_ref(dst_value, matched_src)))
1042                         matched_dst = make_linked_ref(dst_guess, dst_tail);
1043                 else
1044                         error("unable to push to unqualified destination: %s\n"
1045                               "The destination refspec neither matches an "
1046                               "existing ref on the remote nor\n"
1047                               "begins with refs/, and we are unable to "
1048                               "guess a prefix based on the source ref.",
1049                               dst_value);
1050                 break;
1051         default:
1052                 matched_dst = NULL;
1053                 error("dst refspec %s matches more than one.",
1054                       dst_value);
1055                 break;
1056         }
1057         if (!matched_dst)
1058                 return -1;
1059         if (matched_dst->peer_ref)
1060                 return error("dst ref %s receives from more than one src.",
1061                       matched_dst->name);
1062         else {
1063                 matched_dst->peer_ref = copy_src ? copy_ref(matched_src) : matched_src;
1064                 matched_dst->force = rs->force;
1065         }
1066         return 0;
1067 }
1068
1069 static int match_explicit_refs(struct ref *src, struct ref *dst,
1070                                struct ref ***dst_tail, struct refspec *rs,
1071                                int rs_nr)
1072 {
1073         int i, errs;
1074         for (i = errs = 0; i < rs_nr; i++)
1075                 errs += match_explicit(src, dst, dst_tail, &rs[i]);
1076         return errs;
1077 }
1078
1079 static const struct refspec *check_pattern_match(const struct refspec *rs,
1080                                                  int rs_nr,
1081                                                  const struct ref *src)
1082 {
1083         int i;
1084         int matching_refs = -1;
1085         for (i = 0; i < rs_nr; i++) {
1086                 if (rs[i].matching &&
1087                     (matching_refs == -1 || rs[i].force)) {
1088                         matching_refs = i;
1089                         continue;
1090                 }
1091
1092                 if (rs[i].pattern && match_name_with_pattern(rs[i].src, src->name,
1093                                                              NULL, NULL))
1094                         return rs + i;
1095         }
1096         if (matching_refs != -1)
1097                 return rs + matching_refs;
1098         else
1099                 return NULL;
1100 }
1101
1102 static struct ref **tail_ref(struct ref **head)
1103 {
1104         struct ref **tail = head;
1105         while (*tail)
1106                 tail = &((*tail)->next);
1107         return tail;
1108 }
1109
1110 /*
1111  * Note. This is used only by "push"; refspec matching rules for
1112  * push and fetch are subtly different, so do not try to reuse it
1113  * without thinking.
1114  */
1115 int match_refs(struct ref *src, struct ref **dst,
1116                int nr_refspec, const char **refspec, int flags)
1117 {
1118         struct refspec *rs;
1119         int send_all = flags & MATCH_REFS_ALL;
1120         int send_mirror = flags & MATCH_REFS_MIRROR;
1121         int errs;
1122         static const char *default_refspec[] = { ":", NULL };
1123         struct ref **dst_tail = tail_ref(dst);
1124
1125         if (!nr_refspec) {
1126                 nr_refspec = 1;
1127                 refspec = default_refspec;
1128         }
1129         rs = parse_push_refspec(nr_refspec, (const char **) refspec);
1130         errs = match_explicit_refs(src, *dst, &dst_tail, rs, nr_refspec);
1131
1132         /* pick the remainder */
1133         for ( ; src; src = src->next) {
1134                 struct ref *dst_peer;
1135                 const struct refspec *pat = NULL;
1136                 char *dst_name;
1137                 if (src->peer_ref)
1138                         continue;
1139
1140                 pat = check_pattern_match(rs, nr_refspec, src);
1141                 if (!pat)
1142                         continue;
1143
1144                 if (pat->matching) {
1145                         /*
1146                          * "matching refs"; traditionally we pushed everything
1147                          * including refs outside refs/heads/ hierarchy, but
1148                          * that does not make much sense these days.
1149                          */
1150                         if (!send_mirror && prefixcmp(src->name, "refs/heads/"))
1151                                 continue;
1152                         dst_name = xstrdup(src->name);
1153
1154                 } else {
1155                         const char *dst_side = pat->dst ? pat->dst : pat->src;
1156                         if (!match_name_with_pattern(pat->src, src->name,
1157                                                      dst_side, &dst_name))
1158                                 die("Didn't think it matches any more");
1159                 }
1160                 dst_peer = find_ref_by_name(*dst, dst_name);
1161                 if (dst_peer) {
1162                         if (dst_peer->peer_ref)
1163                                 /* We're already sending something to this ref. */
1164                                 goto free_name;
1165
1166                 } else {
1167                         if (pat->matching && !(send_all || send_mirror))
1168                                 /*
1169                                  * Remote doesn't have it, and we have no
1170                                  * explicit pattern, and we don't have
1171                                  * --all nor --mirror.
1172                                  */
1173                                 goto free_name;
1174
1175                         /* Create a new one and link it */
1176                         dst_peer = make_linked_ref(dst_name, &dst_tail);
1177                         hashcpy(dst_peer->new_sha1, src->new_sha1);
1178                 }
1179                 dst_peer->peer_ref = copy_ref(src);
1180                 dst_peer->force = pat->force;
1181         free_name:
1182                 free(dst_name);
1183         }
1184         if (errs)
1185                 return -1;
1186         return 0;
1187 }
1188
1189 struct branch *branch_get(const char *name)
1190 {
1191         struct branch *ret;
1192
1193         read_config();
1194         if (!name || !*name || !strcmp(name, "HEAD"))
1195                 ret = current_branch;
1196         else
1197                 ret = make_branch(name, 0);
1198         if (ret && ret->remote_name) {
1199                 ret->remote = remote_get(ret->remote_name);
1200                 if (ret->merge_nr) {
1201                         int i;
1202                         ret->merge = xcalloc(sizeof(*ret->merge),
1203                                              ret->merge_nr);
1204                         for (i = 0; i < ret->merge_nr; i++) {
1205                                 ret->merge[i] = xcalloc(1, sizeof(**ret->merge));
1206                                 ret->merge[i]->src = xstrdup(ret->merge_name[i]);
1207                                 if (remote_find_tracking(ret->remote, ret->merge[i])
1208                                     && !strcmp(ret->remote_name, "."))
1209                                         ret->merge[i]->dst = xstrdup(ret->merge_name[i]);
1210                         }
1211                 }
1212         }
1213         return ret;
1214 }
1215
1216 int branch_has_merge_config(struct branch *branch)
1217 {
1218         return branch && !!branch->merge;
1219 }
1220
1221 int branch_merge_matches(struct branch *branch,
1222                                  int i,
1223                                  const char *refname)
1224 {
1225         if (!branch || i < 0 || i >= branch->merge_nr)
1226                 return 0;
1227         return refname_match(branch->merge[i]->src, refname, ref_fetch_rules);
1228 }
1229
1230 static struct ref *get_expanded_map(const struct ref *remote_refs,
1231                                     const struct refspec *refspec)
1232 {
1233         const struct ref *ref;
1234         struct ref *ret = NULL;
1235         struct ref **tail = &ret;
1236
1237         char *expn_name;
1238
1239         for (ref = remote_refs; ref; ref = ref->next) {
1240                 if (strchr(ref->name, '^'))
1241                         continue; /* a dereference item */
1242                 if (match_name_with_pattern(refspec->src, ref->name,
1243                                             refspec->dst, &expn_name)) {
1244                         struct ref *cpy = copy_ref(ref);
1245
1246                         cpy->peer_ref = alloc_ref(expn_name);
1247                         free(expn_name);
1248                         if (refspec->force)
1249                                 cpy->peer_ref->force = 1;
1250                         *tail = cpy;
1251                         tail = &cpy->next;
1252                 }
1253         }
1254
1255         return ret;
1256 }
1257
1258 static const struct ref *find_ref_by_name_abbrev(const struct ref *refs, const char *name)
1259 {
1260         const struct ref *ref;
1261         for (ref = refs; ref; ref = ref->next) {
1262                 if (refname_match(name, ref->name, ref_fetch_rules))
1263                         return ref;
1264         }
1265         return NULL;
1266 }
1267
1268 struct ref *get_remote_ref(const struct ref *remote_refs, const char *name)
1269 {
1270         const struct ref *ref = find_ref_by_name_abbrev(remote_refs, name);
1271
1272         if (!ref)
1273                 return NULL;
1274
1275         return copy_ref(ref);
1276 }
1277
1278 static struct ref *get_local_ref(const char *name)
1279 {
1280         if (!name)
1281                 return NULL;
1282
1283         if (!prefixcmp(name, "refs/"))
1284                 return alloc_ref(name);
1285
1286         if (!prefixcmp(name, "heads/") ||
1287             !prefixcmp(name, "tags/") ||
1288             !prefixcmp(name, "remotes/"))
1289                 return alloc_ref_with_prefix("refs/", 5, name);
1290
1291         return alloc_ref_with_prefix("refs/heads/", 11, name);
1292 }
1293
1294 int get_fetch_map(const struct ref *remote_refs,
1295                   const struct refspec *refspec,
1296                   struct ref ***tail,
1297                   int missing_ok)
1298 {
1299         struct ref *ref_map, **rmp;
1300
1301         if (refspec->pattern) {
1302                 ref_map = get_expanded_map(remote_refs, refspec);
1303         } else {
1304                 const char *name = refspec->src[0] ? refspec->src : "HEAD";
1305
1306                 ref_map = get_remote_ref(remote_refs, name);
1307                 if (!missing_ok && !ref_map)
1308                         die("Couldn't find remote ref %s", name);
1309                 if (ref_map) {
1310                         ref_map->peer_ref = get_local_ref(refspec->dst);
1311                         if (ref_map->peer_ref && refspec->force)
1312                                 ref_map->peer_ref->force = 1;
1313                 }
1314         }
1315
1316         for (rmp = &ref_map; *rmp; ) {
1317                 if ((*rmp)->peer_ref) {
1318                         int st = check_ref_format((*rmp)->peer_ref->name + 5);
1319                         if (st && st != CHECK_REF_FORMAT_ONELEVEL) {
1320                                 struct ref *ignore = *rmp;
1321                                 error("* Ignoring funny ref '%s' locally",
1322                                       (*rmp)->peer_ref->name);
1323                                 *rmp = (*rmp)->next;
1324                                 free(ignore->peer_ref);
1325                                 free(ignore);
1326                                 continue;
1327                         }
1328                 }
1329                 rmp = &((*rmp)->next);
1330         }
1331
1332         if (ref_map)
1333                 tail_link_ref(ref_map, tail);
1334
1335         return 0;
1336 }
1337
1338 int resolve_remote_symref(struct ref *ref, struct ref *list)
1339 {
1340         if (!ref->symref)
1341                 return 0;
1342         for (; list; list = list->next)
1343                 if (!strcmp(ref->symref, list->name)) {
1344                         hashcpy(ref->old_sha1, list->old_sha1);
1345                         return 0;
1346                 }
1347         return 1;
1348 }
1349
1350 static void unmark_and_free(struct commit_list *list, unsigned int mark)
1351 {
1352         while (list) {
1353                 struct commit_list *temp = list;
1354                 temp->item->object.flags &= ~mark;
1355                 list = temp->next;
1356                 free(temp);
1357         }
1358 }
1359
1360 int ref_newer(const unsigned char *new_sha1, const unsigned char *old_sha1)
1361 {
1362         struct object *o;
1363         struct commit *old, *new;
1364         struct commit_list *list, *used;
1365         int found = 0;
1366
1367         /* Both new and old must be commit-ish and new is descendant of
1368          * old.  Otherwise we require --force.
1369          */
1370         o = deref_tag(parse_object(old_sha1), NULL, 0);
1371         if (!o || o->type != OBJ_COMMIT)
1372                 return 0;
1373         old = (struct commit *) o;
1374
1375         o = deref_tag(parse_object(new_sha1), NULL, 0);
1376         if (!o || o->type != OBJ_COMMIT)
1377                 return 0;
1378         new = (struct commit *) o;
1379
1380         if (parse_commit(new) < 0)
1381                 return 0;
1382
1383         used = list = NULL;
1384         commit_list_insert(new, &list);
1385         while (list) {
1386                 new = pop_most_recent_commit(&list, TMP_MARK);
1387                 commit_list_insert(new, &used);
1388                 if (new == old) {
1389                         found = 1;
1390                         break;
1391                 }
1392         }
1393         unmark_and_free(list, TMP_MARK);
1394         unmark_and_free(used, TMP_MARK);
1395         return found;
1396 }
1397
1398 /*
1399  * Return true if there is anything to report, otherwise false.
1400  */
1401 int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs)
1402 {
1403         unsigned char sha1[20];
1404         struct commit *ours, *theirs;
1405         char symmetric[84];
1406         struct rev_info revs;
1407         const char *rev_argv[10], *base;
1408         int rev_argc;
1409
1410         /*
1411          * Nothing to report unless we are marked to build on top of
1412          * somebody else.
1413          */
1414         if (!branch ||
1415             !branch->merge || !branch->merge[0] || !branch->merge[0]->dst)
1416                 return 0;
1417
1418         /*
1419          * If what we used to build on no longer exists, there is
1420          * nothing to report.
1421          */
1422         base = branch->merge[0]->dst;
1423         if (!resolve_ref(base, sha1, 1, NULL))
1424                 return 0;
1425         theirs = lookup_commit_reference(sha1);
1426         if (!theirs)
1427                 return 0;
1428
1429         if (!resolve_ref(branch->refname, sha1, 1, NULL))
1430                 return 0;
1431         ours = lookup_commit_reference(sha1);
1432         if (!ours)
1433                 return 0;
1434
1435         /* are we the same? */
1436         if (theirs == ours)
1437                 return 0;
1438
1439         /* Run "rev-list --left-right ours...theirs" internally... */
1440         rev_argc = 0;
1441         rev_argv[rev_argc++] = NULL;
1442         rev_argv[rev_argc++] = "--left-right";
1443         rev_argv[rev_argc++] = symmetric;
1444         rev_argv[rev_argc++] = "--";
1445         rev_argv[rev_argc] = NULL;
1446
1447         strcpy(symmetric, sha1_to_hex(ours->object.sha1));
1448         strcpy(symmetric + 40, "...");
1449         strcpy(symmetric + 43, sha1_to_hex(theirs->object.sha1));
1450
1451         init_revisions(&revs, NULL);
1452         setup_revisions(rev_argc, rev_argv, &revs, NULL);
1453         prepare_revision_walk(&revs);
1454
1455         /* ... and count the commits on each side. */
1456         *num_ours = 0;
1457         *num_theirs = 0;
1458         while (1) {
1459                 struct commit *c = get_revision(&revs);
1460                 if (!c)
1461                         break;
1462                 if (c->object.flags & SYMMETRIC_LEFT)
1463                         (*num_ours)++;
1464                 else
1465                         (*num_theirs)++;
1466         }
1467
1468         /* clear object flags smudged by the above traversal */
1469         clear_commit_marks(ours, ALL_REV_FLAGS);
1470         clear_commit_marks(theirs, ALL_REV_FLAGS);
1471         return 1;
1472 }
1473
1474 /*
1475  * Return true when there is anything to report, otherwise false.
1476  */
1477 int format_tracking_info(struct branch *branch, struct strbuf *sb)
1478 {
1479         int num_ours, num_theirs;
1480         const char *base;
1481
1482         if (!stat_tracking_info(branch, &num_ours, &num_theirs))
1483                 return 0;
1484
1485         base = branch->merge[0]->dst;
1486         base = shorten_unambiguous_ref(base, 0);
1487         if (!num_theirs)
1488                 strbuf_addf(sb, "Your branch is ahead of '%s' "
1489                             "by %d commit%s.\n",
1490                             base, num_ours, (num_ours == 1) ? "" : "s");
1491         else if (!num_ours)
1492                 strbuf_addf(sb, "Your branch is behind '%s' "
1493                             "by %d commit%s, "
1494                             "and can be fast-forwarded.\n",
1495                             base, num_theirs, (num_theirs == 1) ? "" : "s");
1496         else
1497                 strbuf_addf(sb, "Your branch and '%s' have diverged,\n"
1498                             "and have %d and %d different commit(s) each, "
1499                             "respectively.\n",
1500                             base, num_ours, num_theirs);
1501         return 1;
1502 }
1503
1504 static int one_local_ref(const char *refname, const unsigned char *sha1, int flag, void *cb_data)
1505 {
1506         struct ref ***local_tail = cb_data;
1507         struct ref *ref;
1508         int len;
1509
1510         /* we already know it starts with refs/ to get here */
1511         if (check_ref_format(refname + 5))
1512                 return 0;
1513
1514         len = strlen(refname) + 1;
1515         ref = xcalloc(1, sizeof(*ref) + len);
1516         hashcpy(ref->new_sha1, sha1);
1517         memcpy(ref->name, refname, len);
1518         **local_tail = ref;
1519         *local_tail = &ref->next;
1520         return 0;
1521 }
1522
1523 struct ref *get_local_heads(void)
1524 {
1525         struct ref *local_refs = NULL, **local_tail = &local_refs;
1526         for_each_ref(one_local_ref, &local_tail);
1527         return local_refs;
1528 }
1529
1530 struct ref *guess_remote_head(const struct ref *head,
1531                               const struct ref *refs,
1532                               int all)
1533 {
1534         const struct ref *r;
1535         struct ref *list = NULL;
1536         struct ref **tail = &list;
1537
1538         if (!head)
1539                 return NULL;
1540
1541         /*
1542          * Some transports support directly peeking at
1543          * where HEAD points; if that is the case, then
1544          * we don't have to guess.
1545          */
1546         if (head->symref)
1547                 return copy_ref(find_ref_by_name(refs, head->symref));
1548
1549         /* If refs/heads/master could be right, it is. */
1550         if (!all) {
1551                 r = find_ref_by_name(refs, "refs/heads/master");
1552                 if (r && !hashcmp(r->old_sha1, head->old_sha1))
1553                         return copy_ref(r);
1554         }
1555
1556         /* Look for another ref that points there */
1557         for (r = refs; r; r = r->next) {
1558                 if (r != head && !hashcmp(r->old_sha1, head->old_sha1)) {
1559                         *tail = copy_ref(r);
1560                         tail = &((*tail)->next);
1561                         if (!all)
1562                                 break;
1563                 }
1564         }
1565
1566         return list;
1567 }