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 struct rewrites {
  32         struct rewrite **rewrite;
  33         int rewrite_alloc;
  34         int rewrite_nr;
  35 };
  36
  37 static struct remote **remotes;
  38 static int remotes_alloc;
  39 static int remotes_nr;
  40
  41 static struct branch **branches;
  42 static int branches_alloc;
  43 static int branches_nr;
  44
  45 static struct branch *current_branch;
  46 static const char *default_remote_name;
  47 static int explicit_default_remote_name;
  48
  49 static struct rewrites rewrites;
  50
  51 #define BUF_SIZE (2048)
  52 static char buffer[BUF_SIZE];
  53
  54 static const char *alias_url(const char *url, struct rewrites *r)
  55 {
  56         int i, j;
  57         char *ret;
  58         struct counted_string *longest;
  59         int longest_i;
  60
  61         longest = NULL;
  62         longest_i = -1;
  63         for (i = 0; i < r->rewrite_nr; i++) {
  64                 if (!r->rewrite[i])
  65                         continue;
  66                 for (j = 0; j < r->rewrite[i]->instead_of_nr; j++) {
  67                         if (!prefixcmp(url, r->rewrite[i]->instead_of[j].s) &&
  68                             (!longest ||
  69                              longest->len < r->rewrite[i]->instead_of[j].len)) {
  70                                 longest = &(r->rewrite[i]->instead_of[j]);
  71                                 longest_i = i;
  72                         }
  73                 }
  74         }
  75         if (!longest)
  76                 return url;
  77
  78         ret = xmalloc(r->rewrite[longest_i]->baselen +
  79                      (strlen(url) - longest->len) + 1);
  80         strcpy(ret, r->rewrite[longest_i]->base);
  81         strcpy(ret + r->rewrite[longest_i]->baselen, url + longest->len);
  82         return ret;
  83 }
  84
  85 static void add_push_refspec(struct remote *remote, const char *ref)
  86 {
  87         ALLOC_GROW(remote->push_refspec,
  88                    remote->push_refspec_nr + 1,
  89                    remote->push_refspec_alloc);
  90         remote->push_refspec[remote->push_refspec_nr++] = ref;
  91 }
  92
  93 static void add_fetch_refspec(struct remote *remote, const char *ref)
  94 {
  95         ALLOC_GROW(remote->fetch_refspec,
  96                    remote->fetch_refspec_nr + 1,
  97                    remote->fetch_refspec_alloc);
  98         remote->fetch_refspec[remote->fetch_refspec_nr++] = ref;
  99 }
 100
 101 static void add_url(struct remote *remote, const char *url)
 102 {
 103         ALLOC_GROW(remote->url, remote->url_nr + 1, remote->url_alloc);
 104         remote->url[remote->url_nr++] = url;
 105 }
 106
 107 static void add_url_alias(struct remote *remote, const char *url)
 108 {
 109         add_url(remote, alias_url(url, &rewrites));
 110 }
 111
 112 static void add_pushurl(struct remote *remote, const char *pushurl)
 113 {
 114         ALLOC_GROW(remote->pushurl, remote->pushurl_nr + 1, remote->pushurl_alloc);
 115         remote->pushurl[remote->pushurl_nr++] = pushurl;
 116 }
 117
 118 static struct remote *make_remote(const char *name, int len)
 119 {
 120         struct remote *ret;
 121         int i;
 122
 123         for (i = 0; i < remotes_nr; i++) {
 124                 if (len ? (!strncmp(name, remotes[i]->name, len) &&
 125                            !remotes[i]->name[len]) :
 126                     !strcmp(name, remotes[i]->name))
 127                         return remotes[i];
 128         }
 129
 130         ret = xcalloc(1, sizeof(struct remote));
 131         ALLOC_GROW(remotes, remotes_nr + 1, remotes_alloc);
 132         remotes[remotes_nr++] = ret;
 133         if (len)
 134                 ret->name = xstrndup(name, len);
 135         else
 136                 ret->name = xstrdup(name);
 137         return ret;
 138 }
 139
 140 static void add_merge(struct branch *branch, const char *name)
 141 {
 142         ALLOC_GROW(branch->merge_name, branch->merge_nr + 1,
 143                    branch->merge_alloc);
 144         branch->merge_name[branch->merge_nr++] = name;
 145 }
 146
 147 static struct branch *make_branch(const char *name, int len)
 148 {
 149         struct branch *ret;
 150         int i;
 151         char *refname;
 152
 153         for (i = 0; i < branches_nr; i++) {
 154                 if (len ? (!strncmp(name, branches[i]->name, len) &&
 155                            !branches[i]->name[len]) :
 156                     !strcmp(name, branches[i]->name))
 157                         return branches[i];
 158         }
 159
 160         ALLOC_GROW(branches, branches_nr + 1, branches_alloc);
 161         ret = xcalloc(1, sizeof(struct branch));
 162         branches[branches_nr++] = ret;
 163         if (len)
 164                 ret->name = xstrndup(name, len);
 165         else
 166                 ret->name = xstrdup(name);
 167         refname = xmalloc(strlen(name) + strlen("refs/heads/") + 1);
 168         strcpy(refname, "refs/heads/");
 169         strcpy(refname + strlen("refs/heads/"), ret->name);
 170         ret->refname = refname;
 171
 172         return ret;
 173 }
 174
 175 static struct rewrite *make_rewrite(struct rewrites *r, const char *base, int len)
 176 {
 177         struct rewrite *ret;
 178         int i;
 179
 180         for (i = 0; i < r->rewrite_nr; i++) {
 181                 if (len
 182                     ? (len == r->rewrite[i]->baselen &&
 183                        !strncmp(base, r->rewrite[i]->base, len))
 184                     : !strcmp(base, r->rewrite[i]->base))
 185                         return r->rewrite[i];
 186         }
 187
 188         ALLOC_GROW(r->rewrite, r->rewrite_nr + 1, r->rewrite_alloc);
 189         ret = xcalloc(1, sizeof(struct rewrite));
 190         r->rewrite[r->rewrite_nr++] = ret;
 191         if (len) {
 192                 ret->base = xstrndup(base, len);
 193                 ret->baselen = len;
 194         }
 195         else {
 196                 ret->base = xstrdup(base);
 197                 ret->baselen = strlen(base);
 198         }
 199         return ret;
 200 }
 201
 202 static void add_instead_of(struct rewrite *rewrite, const char *instead_of)
 203 {
 204         ALLOC_GROW(rewrite->instead_of, rewrite->instead_of_nr + 1, rewrite->instead_of_alloc);
 205         rewrite->instead_of[rewrite->instead_of_nr].s = instead_of;
 206         rewrite->instead_of[rewrite->instead_of_nr].len = strlen(instead_of);
 207         rewrite->instead_of_nr++;
 208 }
 209
 210 static void read_remotes_file(struct remote *remote)
 211 {
 212         FILE *f = fopen(git_path("remotes/%s", remote->name), "r");
 213
 214         if (!f)
 215                 return;
 216         remote->origin = REMOTE_REMOTES;
 217         while (fgets(buffer, BUF_SIZE, f)) {
 218                 int value_list;
 219                 char *s, *p;
 220
 221                 if (!prefixcmp(buffer, "URL:")) {
 222                         value_list = 0;
 223                         s = buffer + 4;
 224                 } else if (!prefixcmp(buffer, "Push:")) {
 225                         value_list = 1;
 226                         s = buffer + 5;
 227                 } else if (!prefixcmp(buffer, "Pull:")) {
 228                         value_list = 2;
 229                         s = buffer + 5;
 230                 } else
 231                         continue;
 232
 233                 while (isspace(*s))
 234                         s++;
 235                 if (!*s)
 236                         continue;
 237
 238                 p = s + strlen(s);
 239                 while (isspace(p[-1]))
 240                         *--p = 0;
 241
 242                 switch (value_list) {
 243                 case 0:
 244                         add_url_alias(remote, xstrdup(s));
 245                         break;
 246                 case 1:
 247                         add_push_refspec(remote, xstrdup(s));
 248                         break;
 249                 case 2:
 250                         add_fetch_refspec(remote, xstrdup(s));
 251                         break;
 252                 }
 253         }
 254         fclose(f);
 255 }
 256
 257 static void read_branches_file(struct remote *remote)
 258 {
 259         const char *slash = strchr(remote->name, '/');
 260         char *frag;
 261         struct strbuf branch = STRBUF_INIT;
 262         int n = slash ? slash - remote->name : 1000;
 263         FILE *f = fopen(git_path("branches/%.*s", n, remote->name), "r");
 264         char *s, *p;
 265         int len;
 266
 267         if (!f)
 268                 return;
 269         s = fgets(buffer, BUF_SIZE, f);
 270         fclose(f);
 271         if (!s)
 272                 return;
 273         while (isspace(*s))
 274                 s++;
 275         if (!*s)
 276                 return;
 277         remote->origin = REMOTE_BRANCHES;
 278         p = s + strlen(s);
 279         while (isspace(p[-1]))
 280                 *--p = 0;
 281         len = p - s;
 282         if (slash)
 283                 len += strlen(slash);
 284         p = xmalloc(len + 1);
 285         strcpy(p, s);
 286         if (slash)
 287                 strcat(p, slash);
 288
 289         /*
 290          * With "slash", e.g. "git fetch jgarzik/netdev-2.6" when
 291          * reading from $GIT_DIR/branches/jgarzik fetches "HEAD" from
 292          * the partial URL obtained from the branches file plus
 293          * "/netdev-2.6" and does not store it in any tracking ref.
 294          * #branch specifier in the file is ignored.
 295          *
 296          * Otherwise, the branches file would have URL and optionally
 297          * #branch specified.  The "master" (or specified) branch is
 298          * fetched and stored in the local branch of the same name.
 299          */
 300         frag = strchr(p, '#');
 301         if (frag) {
 302                 *(frag++) = '\0';
 303                 strbuf_addf(&branch, "refs/heads/%s", frag);
 304         } else
 305                 strbuf_addstr(&branch, "refs/heads/master");
 306         if (!slash) {
 307                 strbuf_addf(&branch, ":refs/heads/%s", remote->name);
 308         } else {
 309                 strbuf_reset(&branch);
 310                 strbuf_addstr(&branch, "HEAD:");
 311         }
 312         add_url_alias(remote, p);
 313         add_fetch_refspec(remote, strbuf_detach(&branch, NULL));
 314         /*
 315          * Cogito compatible push: push current HEAD to remote #branch
 316          * (master if missing)
 317          */
 318         strbuf_init(&branch, 0);
 319         strbuf_addstr(&branch, "HEAD");
 320         if (frag)
 321                 strbuf_addf(&branch, ":refs/heads/%s", frag);
 322         else
 323                 strbuf_addstr(&branch, ":refs/heads/master");
 324         add_push_refspec(remote, strbuf_detach(&branch, NULL));
 325         remote->fetch_tags = 1; /* always auto-follow */
 326 }
 327
 328 static int handle_config(const char *key, const char *value, void *cb)
 329 {
 330         const char *name;
 331         const char *subkey;
 332         struct remote *remote;
 333         struct branch *branch;
 334         if (!prefixcmp(key, "branch.")) {
 335                 name = key + 7;
 336                 subkey = strrchr(name, '.');
 337                 if (!subkey)
 338                         return 0;
 339                 branch = make_branch(name, subkey - name);
 340                 if (!strcmp(subkey, ".remote")) {
 341                         if (!value)
 342                                 return config_error_nonbool(key);
 343                         branch->remote_name = xstrdup(value);
 344                         if (branch == current_branch) {
 345                                 default_remote_name = branch->remote_name;
 346                                 explicit_default_remote_name = 1;
 347                         }
 348                 } else if (!strcmp(subkey, ".merge")) {
 349                         if (!value)
 350                                 return config_error_nonbool(key);
 351                         add_merge(branch, xstrdup(value));
 352                 }
 353                 return 0;
 354         }
 355         if (!prefixcmp(key, "url.")) {
 356                 struct rewrite *rewrite;
 357                 name = key + 4;
 358                 subkey = strrchr(name, '.');
 359                 if (!subkey)
 360                         return 0;
 361                 rewrite = make_rewrite(&rewrites, name, subkey - name);
 362                 if (!strcmp(subkey, ".insteadof")) {
 363                         if (!value)
 364                                 return config_error_nonbool(key);
 365                         add_instead_of(rewrite, xstrdup(value));
 366                 }
 367         }
 368         if (prefixcmp(key,  "remote."))
 369                 return 0;
 370         name = key + 7;
 371         if (*name == '/') {
 372                 warning("Config remote shorthand cannot begin with '/': %s",
 373                         name);
 374                 return 0;
 375         }
 376         subkey = strrchr(name, '.');
 377         if (!subkey)
 378                 return 0;
 379         remote = make_remote(name, subkey - name);
 380         remote->origin = REMOTE_CONFIG;
 381         if (!strcmp(subkey, ".mirror"))
 382                 remote->mirror = git_config_bool(key, value);
 383         else if (!strcmp(subkey, ".skipdefaultupdate"))
 384                 remote->skip_default_update = git_config_bool(key, value);
 385
 386         else if (!strcmp(subkey, ".url")) {
 387                 const char *v;
 388                 if (git_config_string(&v, key, value))
 389                         return -1;
 390                 add_url(remote, v);
 391         } else if (!strcmp(subkey, ".pushurl")) {
 392                 const char *v;
 393                 if (git_config_string(&v, key, value))
 394                         return -1;
 395                 add_pushurl(remote, v);
 396         } else if (!strcmp(subkey, ".push")) {
 397                 const char *v;
 398                 if (git_config_string(&v, key, value))
 399                         return -1;
 400                 add_push_refspec(remote, v);
 401         } else if (!strcmp(subkey, ".fetch")) {
 402                 const char *v;
 403                 if (git_config_string(&v, key, value))
 404                         return -1;
 405                 add_fetch_refspec(remote, v);
 406         } else if (!strcmp(subkey, ".receivepack")) {
 407                 const char *v;
 408                 if (git_config_string(&v, key, value))
 409                         return -1;
 410                 if (!remote->receivepack)
 411                         remote->receivepack = v;
 412                 else
 413                         error("more than one receivepack given, using the first");
 414         } else if (!strcmp(subkey, ".uploadpack")) {
 415                 const char *v;
 416                 if (git_config_string(&v, key, value))
 417                         return -1;
 418                 if (!remote->uploadpack)
 419                         remote->uploadpack = v;
 420                 else
 421                         error("more than one uploadpack given, using the first");
 422         } else if (!strcmp(subkey, ".tagopt")) {
 423                 if (!strcmp(value, "--no-tags"))
 424                         remote->fetch_tags = -1;
 425         } else if (!strcmp(subkey, ".proxy")) {
 426                 return git_config_string((const char **)&remote->http_proxy,
 427                                          key, value);
 428         }
 429         return 0;
 430 }
 431
 432 static void alias_all_urls(void)
 433 {
 434         int i, j;
 435         for (i = 0; i < remotes_nr; i++) {
 436                 if (!remotes[i])
 437                         continue;
 438                 for (j = 0; j < remotes[i]->url_nr; j++) {
 439                         remotes[i]->url[j] = alias_url(remotes[i]->url[j], &rewrites);
 440                 }
 441                 for (j = 0; j < remotes[i]->pushurl_nr; j++) {
 442                         remotes[i]->pushurl[j] = alias_url(remotes[i]->pushurl[j], &rewrites);
 443                 }
 444         }
 445 }
 446
 447 static void read_config(void)
 448 {
 449         unsigned char sha1[20];
 450         const char *head_ref;
 451         int flag;
 452         if (default_remote_name) // did this already
 453                 return;
 454         default_remote_name = xstrdup("origin");
 455         current_branch = NULL;
 456         head_ref = resolve_ref("HEAD", sha1, 0, &flag);
 457         if (head_ref && (flag & REF_ISSYMREF) &&
 458             !prefixcmp(head_ref, "refs/heads/")) {
 459                 current_branch =
 460                         make_branch(head_ref + strlen("refs/heads/"), 0);
 461         }
 462         git_config(handle_config, NULL);
 463         alias_all_urls();
 464 }
 465
 466 /*
 467  * We need to make sure the tracking branches are well formed, but a
 468  * wildcard refspec in "struct refspec" must have a trailing slash. We
 469  * temporarily drop the trailing '/' while calling check_ref_format(),
 470  * and put it back.  The caller knows that a CHECK_REF_FORMAT_ONELEVEL
 471  * error return is Ok for a wildcard refspec.
 472  */
 473 static int verify_refname(char *name, int is_glob)
 474 {
 475         int result;
 476
 477         result = check_ref_format(name);
 478         if (is_glob && result == CHECK_REF_FORMAT_WILDCARD)
 479                 result = CHECK_REF_FORMAT_OK;
 480         return result;
 481 }
 482
 483 /*
 484  * This function frees a refspec array.
 485  * Warning: code paths should be checked to ensure that the src
 486  *          and dst pointers are always freeable pointers as well
 487  *          as the refspec pointer itself.
 488  */
 489 static void free_refspecs(struct refspec *refspec, int nr_refspec)
 490 {
 491         int i;
 492
 493         if (!refspec)
 494                 return;
 495
 496         for (i = 0; i < nr_refspec; i++) {
 497                 free(refspec[i].src);
 498                 free(refspec[i].dst);
 499         }
 500         free(refspec);
 501 }
 502
 503 static struct refspec *parse_refspec_internal(int nr_refspec, const char **refspec, int fetch, int verify)
 504 {
 505         int i;
 506         int st;
 507         struct refspec *rs = xcalloc(sizeof(*rs), nr_refspec);
 508
 509         for (i = 0; i < nr_refspec; i++) {
 510                 size_t llen;
 511                 int is_glob;
 512                 const char *lhs, *rhs;
 513
 514                 is_glob = 0;
 515
 516                 lhs = refspec[i];
 517                 if (*lhs == '+') {
 518                         rs[i].force = 1;
 519                         lhs++;
 520                 }
 521
 522                 rhs = strrchr(lhs, ':');
 523
 524                 /*
 525                  * Before going on, special case ":" (or "+:") as a refspec
 526                  * for matching refs.
 527                  */
 528                 if (!fetch && rhs == lhs && rhs[1] == '\0') {
 529                         rs[i].matching = 1;
 530                         continue;
 531                 }
 532
 533                 if (rhs) {
 534                         size_t rlen = strlen(++rhs);
 535                         is_glob = (1 <= rlen && strchr(rhs, '*'));
 536                         rs[i].dst = xstrndup(rhs, rlen);
 537                 }
 538
 539                 llen = (rhs ? (rhs - lhs - 1) : strlen(lhs));
 540                 if (1 <= llen && memchr(lhs, '*', llen)) {
 541                         if ((rhs && !is_glob) || (!rhs && fetch))
 542                                 goto invalid;
 543                         is_glob = 1;
 544                 } else if (rhs && is_glob) {
 545                         goto invalid;
 546                 }
 547
 548                 rs[i].pattern = is_glob;
 549                 rs[i].src = xstrndup(lhs, llen);
 550
 551                 if (fetch) {
 552                         /*
 553                          * LHS
 554                          * - empty is allowed; it means HEAD.
 555                          * - otherwise it must be a valid looking ref.
 556                          */
 557                         if (!*rs[i].src)
 558                                 ; /* empty is ok */
 559                         else {
 560                                 st = verify_refname(rs[i].src, is_glob);
 561                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 562                                         goto invalid;
 563                         }
 564                         /*
 565                          * RHS
 566                          * - missing is ok, and is same as empty.
 567                          * - empty is ok; it means not to store.
 568                          * - otherwise it must be a valid looking ref.
 569                          */
 570                         if (!rs[i].dst) {
 571                                 ; /* ok */
 572                         } else if (!*rs[i].dst) {
 573                                 ; /* ok */
 574                         } else {
 575                                 st = verify_refname(rs[i].dst, is_glob);
 576                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 577                                         goto invalid;
 578                         }
 579                 } else {
 580                         /*
 581                          * LHS
 582                          * - empty is allowed; it means delete.
 583                          * - when wildcarded, it must be a valid looking ref.
 584                          * - otherwise, it must be an extended SHA-1, but
 585                          *   there is no existing way to validate this.
 586                          */
 587                         if (!*rs[i].src)
 588                                 ; /* empty is ok */
 589                         else if (is_glob) {
 590                                 st = verify_refname(rs[i].src, is_glob);
 591                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 592                                         goto invalid;
 593                         }
 594                         else
 595                                 ; /* anything goes, for now */
 596                         /*
 597                          * RHS
 598                          * - missing is allowed, but LHS then must be a
 599                          *   valid looking ref.
 600                          * - empty is not allowed.
 601                          * - otherwise it must be a valid looking ref.
 602                          */
 603                         if (!rs[i].dst) {
 604                                 st = verify_refname(rs[i].src, is_glob);
 605                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 606                                         goto invalid;
 607                         } else if (!*rs[i].dst) {
 608                                 goto invalid;
 609                         } else {
 610                                 st = verify_refname(rs[i].dst, is_glob);
 611                                 if (st && st != CHECK_REF_FORMAT_ONELEVEL)
 612                                         goto invalid;
 613                         }
 614                 }
 615         }
 616         return rs;
 617
 618  invalid:
 619         if (verify) {
 620                 /*
 621                  * nr_refspec must be greater than zero and i must be valid
 622                  * since it is only possible to reach this point from within
 623                  * the for loop above.
 624                  */
 625                 free_refspecs(rs, i+1);
 626                 return NULL;
 627         }
 628         die("Invalid refspec '%s'", refspec[i]);
 629 }
 630
 631 int valid_fetch_refspec(const char *fetch_refspec_str)
 632 {
 633         const char *fetch_refspec[] = { fetch_refspec_str };
 634         struct refspec *refspec;
 635
 636         refspec = parse_refspec_internal(1, fetch_refspec, 1, 1);
 637         free_refspecs(refspec, 1);
 638         return !!refspec;
 639 }
 640
 641 struct refspec *parse_fetch_refspec(int nr_refspec, const char **refspec)
 642 {
 643         return parse_refspec_internal(nr_refspec, refspec, 1, 0);
 644 }
 645
 646 static struct refspec *parse_push_refspec(int nr_refspec, const char **refspec)
 647 {
 648         return parse_refspec_internal(nr_refspec, refspec, 0, 0);
 649 }
 650
 651 static int valid_remote_nick(const char *name)
 652 {
 653         if (!name[0] || is_dot_or_dotdot(name))
 654                 return 0;
 655         return !strchr(name, '/'); /* no slash */
 656 }
 657
 658 struct remote *remote_get(const char *name)
 659 {
 660         struct remote *ret;
 661         int name_given = 0;
 662
 663         read_config();
 664         if (name)
 665                 name_given = 1;
 666         else {
 667                 name = default_remote_name;
 668                 name_given = explicit_default_remote_name;
 669         }
 670
 671         ret = make_remote(name, 0);
 672         if (valid_remote_nick(name)) {
 673                 if (!ret->url)
 674                         read_remotes_file(ret);
 675                 if (!ret->url)
 676                         read_branches_file(ret);
 677         }
 678         if (name_given && !ret->url)
 679                 add_url_alias(ret, name);
 680         if (!ret->url)
 681                 return NULL;
 682         ret->fetch = parse_fetch_refspec(ret->fetch_refspec_nr, ret->fetch_refspec);
 683         ret->push = parse_push_refspec(ret->push_refspec_nr, ret->push_refspec);
 684         return ret;
 685 }
 686
 687 int remote_is_configured(const char *name)
 688 {
 689         int i;
 690         read_config();
 691
 692         for (i = 0; i < remotes_nr; i++)
 693                 if (!strcmp(name, remotes[i]->name))
 694                         return 1;
 695         return 0;
 696 }
 697
 698 int for_each_remote(each_remote_fn fn, void *priv)
 699 {
 700         int i, result = 0;
 701         read_config();
 702         for (i = 0; i < remotes_nr && !result; i++) {
 703                 struct remote *r = remotes[i];
 704                 if (!r)
 705                         continue;
 706                 if (!r->fetch)
 707                         r->fetch = parse_fetch_refspec(r->fetch_refspec_nr,
 708                                                        r->fetch_refspec);
 709                 if (!r->push)
 710                         r->push = parse_push_refspec(r->push_refspec_nr,
 711                                                      r->push_refspec);
 712                 result = fn(r, priv);
 713         }
 714         return result;
 715 }
 716
 717 void ref_remove_duplicates(struct ref *ref_map)
 718 {
 719         struct ref **posn;
 720         struct ref *next;
 721         for (; ref_map; ref_map = ref_map->next) {
 722                 if (!ref_map->peer_ref)
 723                         continue;
 724                 posn = &ref_map->next;
 725                 while (*posn) {
 726                         if ((*posn)->peer_ref &&
 727                             !strcmp((*posn)->peer_ref->name,
 728                                     ref_map->peer_ref->name)) {
 729                                 if (strcmp((*posn)->name, ref_map->name))
 730                                         die("%s tracks both %s and %s",
 731                                             ref_map->peer_ref->name,
 732                                             (*posn)->name, ref_map->name);
 733                                 next = (*posn)->next;
 734                                 free((*posn)->peer_ref);
 735                                 free(*posn);
 736                                 *posn = next;
 737                         } else {
 738                                 posn = &(*posn)->next;
 739                         }
 740                 }
 741         }
 742 }
 743
 744 int remote_has_url(struct remote *remote, const char *url)
 745 {
 746         int i;
 747         for (i = 0; i < remote->url_nr; i++) {
 748                 if (!strcmp(remote->url[i], url))
 749                         return 1;
 750         }
 751         return 0;
 752 }
 753
 754 static int match_name_with_pattern(const char *key, const char *name,
 755                                    const char *value, char **result)
 756 {
 757         const char *kstar = strchr(key, '*');
 758         size_t klen;
 759         size_t ksuffixlen;
 760         size_t namelen;
 761         int ret;
 762         if (!kstar)
 763                 die("Key '%s' of pattern had no '*'", key);
 764         klen = kstar - key;
 765         ksuffixlen = strlen(kstar + 1);
 766         namelen = strlen(name);
 767         ret = !strncmp(name, key, klen) && namelen >= klen + ksuffixlen &&
 768                 !memcmp(name + namelen - ksuffixlen, kstar + 1, ksuffixlen);
 769         if (ret && value) {
 770                 const char *vstar = strchr(value, '*');
 771                 size_t vlen;
 772                 size_t vsuffixlen;
 773                 if (!vstar)
 774                         die("Value '%s' of pattern has no '*'", value);
 775                 vlen = vstar - value;
 776                 vsuffixlen = strlen(vstar + 1);
 777                 *result = xmalloc(vlen + vsuffixlen +
 778                                   strlen(name) -
 779                                   klen - ksuffixlen + 1);
 780                 strncpy(*result, value, vlen);
 781                 strncpy(*result + vlen,
 782                         name + klen, namelen - klen - ksuffixlen);
 783                 strcpy(*result + vlen + namelen - klen - ksuffixlen,
 784                        vstar + 1);
 785         }
 786         return ret;
 787 }
 788
 789 int remote_find_tracking(struct remote *remote, struct refspec *refspec)
 790 {
 791         int find_src = refspec->src == NULL;
 792         char *needle, **result;
 793         int i;
 794
 795         if (find_src) {
 796                 if (!refspec->dst)
 797                         return error("find_tracking: need either src or dst");
 798                 needle = refspec->dst;
 799                 result = &refspec->src;
 800         } else {
 801                 needle = refspec->src;
 802                 result = &refspec->dst;
 803         }
 804
 805         for (i = 0; i < remote->fetch_refspec_nr; i++) {
 806                 struct refspec *fetch = &remote->fetch[i];
 807                 const char *key = find_src ? fetch->dst : fetch->src;
 808                 const char *value = find_src ? fetch->src : fetch->dst;
 809                 if (!fetch->dst)
 810                         continue;
 811                 if (fetch->pattern) {
 812                         if (match_name_with_pattern(key, needle, value, result)) {
 813                                 refspec->force = fetch->force;
 814                                 return 0;
 815                         }
 816                 } else if (!strcmp(needle, key)) {
 817                         *result = xstrdup(value);
 818                         refspec->force = fetch->force;
 819                         return 0;
 820                 }
 821         }
 822         return -1;
 823 }
 824
 825 static struct ref *alloc_ref_with_prefix(const char *prefix, size_t prefixlen,
 826                 const char *name)
 827 {
 828         size_t len = strlen(name);
 829         struct ref *ref = xcalloc(1, sizeof(struct ref) + prefixlen + len + 1);
 830         memcpy(ref->name, prefix, prefixlen);
 831         memcpy(ref->name + prefixlen, name, len);
 832         return ref;
 833 }
 834
 835 struct ref *alloc_ref(const char *name)
 836 {
 837         return alloc_ref_with_prefix("", 0, name);
 838 }
 839
 840 static struct ref *copy_ref(const struct ref *ref)
 841 {
 842         struct ref *cpy;
 843         size_t len;
 844         if (!ref)
 845                 return NULL;
 846         len = strlen(ref->name);
 847         cpy = xmalloc(sizeof(struct ref) + len + 1);
 848         memcpy(cpy, ref, sizeof(struct ref) + len + 1);
 849         cpy->next = NULL;
 850         cpy->symref = ref->symref ? xstrdup(ref->symref) : NULL;
 851         cpy->remote_status = ref->remote_status ? xstrdup(ref->remote_status) : NULL;
 852         cpy->peer_ref = copy_ref(ref->peer_ref);
 853         return cpy;
 854 }
 855
 856 struct ref *copy_ref_list(const struct ref *ref)
 857 {
 858         struct ref *ret = NULL;
 859         struct ref **tail = &ret;
 860         while (ref) {
 861                 *tail = copy_ref(ref);
 862                 ref = ref->next;
 863                 tail = &((*tail)->next);
 864         }
 865         return ret;
 866 }
 867
 868 static void free_ref(struct ref *ref)
 869 {
 870         if (!ref)
 871                 return;
 872         free_ref(ref->peer_ref);
 873         free(ref->remote_status);
 874         free(ref->symref);
 875         free(ref);
 876 }
 877
 878 void free_refs(struct ref *ref)
 879 {
 880         struct ref *next;
 881         while (ref) {
 882                 next = ref->next;
 883                 free_ref(ref);
 884                 ref = next;
 885         }
 886 }
 887
 888 static int count_refspec_match(const char *pattern,
 889                                struct ref *refs,
 890                                struct ref **matched_ref)
 891 {
 892         int patlen = strlen(pattern);
 893         struct ref *matched_weak = NULL;
 894         struct ref *matched = NULL;
 895         int weak_match = 0;
 896         int match = 0;
 897
 898         for (weak_match = match = 0; refs; refs = refs->next) {
 899                 char *name = refs->name;
 900                 int namelen = strlen(name);
 901
 902                 if (!refname_match(pattern, name, ref_rev_parse_rules))
 903                         continue;
 904
 905                 /* A match is "weak" if it is with refs outside
 906                  * heads or tags, and did not specify the pattern
 907                  * in full (e.g. "refs/remotes/origin/master") or at
 908                  * least from the toplevel (e.g. "remotes/origin/master");
 909                  * otherwise "git push $URL master" would result in
 910                  * ambiguity between remotes/origin/master and heads/master
 911                  * at the remote site.
 912                  */
 913                 if (namelen != patlen &&
 914                     patlen != namelen - 5 &&
 915                     prefixcmp(name, "refs/heads/") &&
 916                     prefixcmp(name, "refs/tags/")) {
 917                         /* We want to catch the case where only weak
 918                          * matches are found and there are multiple
 919                          * matches, and where more than one strong
 920                          * matches are found, as ambiguous.  One
 921                          * strong match with zero or more weak matches
 922                          * are acceptable as a unique match.
 923                          */
 924                         matched_weak = refs;
 925                         weak_match++;
 926                 }
 927                 else {
 928                         matched = refs;
 929                         match++;
 930                 }
 931         }
 932         if (!matched) {
 933                 *matched_ref = matched_weak;
 934                 return weak_match;
 935         }
 936         else {
 937                 *matched_ref = matched;
 938                 return match;
 939         }
 940 }
 941
 942 static void tail_link_ref(struct ref *ref, struct ref ***tail)
 943 {
 944         **tail = ref;
 945         while (ref->next)
 946                 ref = ref->next;
 947         *tail = &ref->next;
 948 }
 949
 950 static struct ref *try_explicit_object_name(const char *name)
 951 {
 952         unsigned char sha1[20];
 953         struct ref *ref;
 954
 955         if (!*name) {
 956                 ref = alloc_ref("(delete)");
 957                 hashclr(ref->new_sha1);
 958                 return ref;
 959         }
 960         if (get_sha1(name, sha1))
 961                 return NULL;
 962         ref = alloc_ref(name);
 963         hashcpy(ref->new_sha1, sha1);
 964         return ref;
 965 }
 966
 967 static struct ref *make_linked_ref(const char *name, struct ref ***tail)
 968 {
 969         struct ref *ret = alloc_ref(name);
 970         tail_link_ref(ret, tail);
 971         return ret;
 972 }
 973
 974 static char *guess_ref(const char *name, struct ref *peer)
 975 {
 976         struct strbuf buf = STRBUF_INIT;
 977         unsigned char sha1[20];
 978
 979         const char *r = resolve_ref(peer->name, sha1, 1, NULL);
 980         if (!r)
 981                 return NULL;
 982
 983         if (!prefixcmp(r, "refs/heads/"))
 984                 strbuf_addstr(&buf, "refs/heads/");
 985         else if (!prefixcmp(r, "refs/tags/"))
 986                 strbuf_addstr(&buf, "refs/tags/");
 987         else
 988                 return NULL;
 989
 990         strbuf_addstr(&buf, name);
 991         return strbuf_detach(&buf, NULL);
 992 }
 993
 994 static int match_explicit(struct ref *src, struct ref *dst,
 995                           struct ref ***dst_tail,
 996                           struct refspec *rs)
 997 {
 998         struct ref *matched_src, *matched_dst;
 999         int copy_src;
1000
1001         const char *dst_value = rs->dst;
1002         char *dst_guess;
1003
1004         if (rs->pattern || rs->matching)
1005                 return 0;
1006
1007         matched_src = matched_dst = NULL;
1008         switch (count_refspec_match(rs->src, src, &matched_src)) {
1009         case 1:
1010                 copy_src = 1;
1011                 break;
1012         case 0:
1013                 /* The source could be in the get_sha1() format
1014                  * not a reference name.  :refs/other is a
1015                  * way to delete 'other' ref at the remote end.
1016                  */
1017                 matched_src = try_explicit_object_name(rs->src);
1018                 if (!matched_src)
1019                         return error("src refspec %s does not match any.", rs->src);
1020                 copy_src = 0;
1021                 break;
1022         default:
1023                 return error("src refspec %s matches more than one.", rs->src);
1024         }
1025
1026         if (!dst_value) {
1027                 unsigned char sha1[20];
1028                 int flag;
1029
1030                 dst_value = resolve_ref(matched_src->name, sha1, 1, &flag);
1031                 if (!dst_value ||
1032                     ((flag & REF_ISSYMREF) &&
1033                      prefixcmp(dst_value, "refs/heads/")))
1034                         die("%s cannot be resolved to branch.",
1035                             matched_src->name);
1036         }
1037
1038         switch (count_refspec_match(dst_value, dst, &matched_dst)) {
1039         case 1:
1040                 break;
1041         case 0:
1042                 if (!memcmp(dst_value, "refs/", 5))
1043                         matched_dst = make_linked_ref(dst_value, dst_tail);
1044                 else if ((dst_guess = guess_ref(dst_value, matched_src)))
1045                         matched_dst = make_linked_ref(dst_guess, dst_tail);
1046                 else
1047                         error("unable to push to unqualified destination: %s\n"
1048                               "The destination refspec neither matches an "
1049                               "existing ref on the remote nor\n"
1050                               "begins with refs/, and we are unable to "
1051                               "guess a prefix based on the source ref.",
1052                               dst_value);
1053                 break;
1054         default:
1055                 matched_dst = NULL;
1056                 error("dst refspec %s matches more than one.",
1057                       dst_value);
1058                 break;
1059         }
1060         if (!matched_dst)
1061                 return -1;
1062         if (matched_dst->peer_ref)
1063                 return error("dst ref %s receives from more than one src.",
1064                       matched_dst->name);
1065         else {
1066                 matched_dst->peer_ref = copy_src ? copy_ref(matched_src) : matched_src;
1067                 matched_dst->force = rs->force;
1068         }
1069         return 0;
1070 }
1071
1072 static int match_explicit_refs(struct ref *src, struct ref *dst,
1073                                struct ref ***dst_tail, struct refspec *rs,
1074                                int rs_nr)
1075 {
1076         int i, errs;
1077         for (i = errs = 0; i < rs_nr; i++)
1078                 errs += match_explicit(src, dst, dst_tail, &rs[i]);
1079         return errs;
1080 }
1081
1082 static const struct refspec *check_pattern_match(const struct refspec *rs,
1083                                                  int rs_nr,
1084                                                  const struct ref *src)
1085 {
1086         int i;
1087         int matching_refs = -1;
1088         for (i = 0; i < rs_nr; i++) {
1089                 if (rs[i].matching &&
1090                     (matching_refs == -1 || rs[i].force)) {
1091                         matching_refs = i;
1092                         continue;
1093                 }
1094
1095                 if (rs[i].pattern && match_name_with_pattern(rs[i].src, src->name,
1096                                                              NULL, NULL))
1097                         return rs + i;
1098         }
1099         if (matching_refs != -1)
1100                 return rs + matching_refs;
1101         else
1102                 return NULL;
1103 }
1104
1105 static struct ref **tail_ref(struct ref **head)
1106 {
1107         struct ref **tail = head;
1108         while (*tail)
1109                 tail = &((*tail)->next);
1110         return tail;
1111 }
1112
1113 /*
1114  * Note. This is used only by "push"; refspec matching rules for
1115  * push and fetch are subtly different, so do not try to reuse it
1116  * without thinking.
1117  */
1118 int match_refs(struct ref *src, struct ref **dst,
1119                int nr_refspec, const char **refspec, int flags)
1120 {
1121         struct refspec *rs;
1122         int send_all = flags & MATCH_REFS_ALL;
1123         int send_mirror = flags & MATCH_REFS_MIRROR;
1124         int errs;
1125         static const char *default_refspec[] = { ":", NULL };
1126         struct ref **dst_tail = tail_ref(dst);
1127
1128         if (!nr_refspec) {
1129                 nr_refspec = 1;
1130                 refspec = default_refspec;
1131         }
1132         rs = parse_push_refspec(nr_refspec, (const char **) refspec);
1133         errs = match_explicit_refs(src, *dst, &dst_tail, rs, nr_refspec);
1134
1135         /* pick the remainder */
1136         for ( ; src; src = src->next) {
1137                 struct ref *dst_peer;
1138                 const struct refspec *pat = NULL;
1139                 char *dst_name;
1140                 if (src->peer_ref)
1141                         continue;
1142
1143                 pat = check_pattern_match(rs, nr_refspec, src);
1144                 if (!pat)
1145                         continue;
1146
1147                 if (pat->matching) {
1148                         /*
1149                          * "matching refs"; traditionally we pushed everything
1150                          * including refs outside refs/heads/ hierarchy, but
1151                          * that does not make much sense these days.
1152                          */
1153                         if (!send_mirror && prefixcmp(src->name, "refs/heads/"))
1154                                 continue;
1155                         dst_name = xstrdup(src->name);
1156
1157                 } else {
1158                         const char *dst_side = pat->dst ? pat->dst : pat->src;
1159                         if (!match_name_with_pattern(pat->src, src->name,
1160                                                      dst_side, &dst_name))
1161                                 die("Didn't think it matches any more");
1162                 }
1163                 dst_peer = find_ref_by_name(*dst, dst_name);
1164                 if (dst_peer) {
1165                         if (dst_peer->peer_ref)
1166                                 /* We're already sending something to this ref. */
1167                                 goto free_name;
1168
1169                 } else {
1170                         if (pat->matching && !(send_all || send_mirror))
1171                                 /*
1172                                  * Remote doesn't have it, and we have no
1173                                  * explicit pattern, and we don't have
1174                                  * --all nor --mirror.
1175                                  */
1176                                 goto free_name;
1177
1178                         /* Create a new one and link it */
1179                         dst_peer = make_linked_ref(dst_name, &dst_tail);
1180                         hashcpy(dst_peer->new_sha1, src->new_sha1);
1181                 }
1182                 dst_peer->peer_ref = copy_ref(src);
1183                 dst_peer->force = pat->force;
1184         free_name:
1185                 free(dst_name);
1186         }
1187         if (errs)
1188                 return -1;
1189         return 0;
1190 }
1191
1192 struct branch *branch_get(const char *name)
1193 {
1194         struct branch *ret;
1195
1196         read_config();
1197         if (!name || !*name || !strcmp(name, "HEAD"))
1198                 ret = current_branch;
1199         else
1200                 ret = make_branch(name, 0);
1201         if (ret && ret->remote_name) {
1202                 ret->remote = remote_get(ret->remote_name);
1203                 if (ret->merge_nr) {
1204                         int i;
1205                         ret->merge = xcalloc(sizeof(*ret->merge),
1206                                              ret->merge_nr);
1207                         for (i = 0; i < ret->merge_nr; i++) {
1208                                 ret->merge[i] = xcalloc(1, sizeof(**ret->merge));
1209                                 ret->merge[i]->src = xstrdup(ret->merge_name[i]);
1210                                 if (remote_find_tracking(ret->remote, ret->merge[i])
1211                                     && !strcmp(ret->remote_name, "."))
1212                                         ret->merge[i]->dst = xstrdup(ret->merge_name[i]);
1213                         }
1214                 }
1215         }
1216         return ret;
1217 }
1218
1219 int branch_has_merge_config(struct branch *branch)
1220 {
1221         return branch && !!branch->merge;
1222 }
1223
1224 int branch_merge_matches(struct branch *branch,
1225                                  int i,
1226                                  const char *refname)
1227 {
1228         if (!branch || i < 0 || i >= branch->merge_nr)
1229                 return 0;
1230         return refname_match(branch->merge[i]->src, refname, ref_fetch_rules);
1231 }
1232
1233 static struct ref *get_expanded_map(const struct ref *remote_refs,
1234                                     const struct refspec *refspec)
1235 {
1236         const struct ref *ref;
1237         struct ref *ret = NULL;
1238         struct ref **tail = &ret;
1239
1240         char *expn_name;
1241
1242         for (ref = remote_refs; ref; ref = ref->next) {
1243                 if (strchr(ref->name, '^'))
1244                         continue; /* a dereference item */
1245                 if (match_name_with_pattern(refspec->src, ref->name,
1246                                             refspec->dst, &expn_name)) {
1247                         struct ref *cpy = copy_ref(ref);
1248
1249                         cpy->peer_ref = alloc_ref(expn_name);
1250                         free(expn_name);
1251                         if (refspec->force)
1252                                 cpy->peer_ref->force = 1;
1253                         *tail = cpy;
1254                         tail = &cpy->next;
1255                 }
1256         }
1257
1258         return ret;
1259 }
1260
1261 static const struct ref *find_ref_by_name_abbrev(const struct ref *refs, const char *name)
1262 {
1263         const struct ref *ref;
1264         for (ref = refs; ref; ref = ref->next) {
1265                 if (refname_match(name, ref->name, ref_fetch_rules))
1266                         return ref;
1267         }
1268         return NULL;
1269 }
1270
1271 struct ref *get_remote_ref(const struct ref *remote_refs, const char *name)
1272 {
1273         const struct ref *ref = find_ref_by_name_abbrev(remote_refs, name);
1274
1275         if (!ref)
1276                 return NULL;
1277
1278         return copy_ref(ref);
1279 }
1280
1281 static struct ref *get_local_ref(const char *name)
1282 {
1283         if (!name || name[0] == '\0')
1284                 return NULL;
1285
1286         if (!prefixcmp(name, "refs/"))
1287                 return alloc_ref(name);
1288
1289         if (!prefixcmp(name, "heads/") ||
1290             !prefixcmp(name, "tags/") ||
1291             !prefixcmp(name, "remotes/"))
1292                 return alloc_ref_with_prefix("refs/", 5, name);
1293
1294         return alloc_ref_with_prefix("refs/heads/", 11, name);
1295 }
1296
1297 int get_fetch_map(const struct ref *remote_refs,
1298                   const struct refspec *refspec,
1299                   struct ref ***tail,
1300                   int missing_ok)
1301 {
1302         struct ref *ref_map, **rmp;
1303
1304         if (refspec->pattern) {
1305                 ref_map = get_expanded_map(remote_refs, refspec);
1306         } else {
1307                 const char *name = refspec->src[0] ? refspec->src : "HEAD";
1308
1309                 ref_map = get_remote_ref(remote_refs, name);
1310                 if (!missing_ok && !ref_map)
1311                         die("Couldn't find remote ref %s", name);
1312                 if (ref_map) {
1313                         ref_map->peer_ref = get_local_ref(refspec->dst);
1314                         if (ref_map->peer_ref && refspec->force)
1315                                 ref_map->peer_ref->force = 1;
1316                 }
1317         }
1318
1319         for (rmp = &ref_map; *rmp; ) {
1320                 if ((*rmp)->peer_ref) {
1321                         int st = check_ref_format((*rmp)->peer_ref->name + 5);
1322                         if (st && st != CHECK_REF_FORMAT_ONELEVEL) {
1323                                 struct ref *ignore = *rmp;
1324                                 error("* Ignoring funny ref '%s' locally",
1325                                       (*rmp)->peer_ref->name);
1326                                 *rmp = (*rmp)->next;
1327                                 free(ignore->peer_ref);
1328                                 free(ignore);
1329                                 continue;
1330                         }
1331                 }
1332                 rmp = &((*rmp)->next);
1333         }
1334
1335         if (ref_map)
1336                 tail_link_ref(ref_map, tail);
1337
1338         return 0;
1339 }
1340
1341 int resolve_remote_symref(struct ref *ref, struct ref *list)
1342 {
1343         if (!ref->symref)
1344                 return 0;
1345         for (; list; list = list->next)
1346                 if (!strcmp(ref->symref, list->name)) {
1347                         hashcpy(ref->old_sha1, list->old_sha1);
1348                         return 0;
1349                 }
1350         return 1;
1351 }
1352
1353 static void unmark_and_free(struct commit_list *list, unsigned int mark)
1354 {
1355         while (list) {
1356                 struct commit_list *temp = list;
1357                 temp->item->object.flags &= ~mark;
1358                 list = temp->next;
1359                 free(temp);
1360         }
1361 }
1362
1363 int ref_newer(const unsigned char *new_sha1, const unsigned char *old_sha1)
1364 {
1365         struct object *o;
1366         struct commit *old, *new;
1367         struct commit_list *list, *used;
1368         int found = 0;
1369
1370         /* Both new and old must be commit-ish and new is descendant of
1371          * old.  Otherwise we require --force.
1372          */
1373         o = deref_tag(parse_object(old_sha1), NULL, 0);
1374         if (!o || o->type != OBJ_COMMIT)
1375                 return 0;
1376         old = (struct commit *) o;
1377
1378         o = deref_tag(parse_object(new_sha1), NULL, 0);
1379         if (!o || o->type != OBJ_COMMIT)
1380                 return 0;
1381         new = (struct commit *) o;
1382
1383         if (parse_commit(new) < 0)
1384                 return 0;
1385
1386         used = list = NULL;
1387         commit_list_insert(new, &list);
1388         while (list) {
1389                 new = pop_most_recent_commit(&list, TMP_MARK);
1390                 commit_list_insert(new, &used);
1391                 if (new == old) {
1392                         found = 1;
1393                         break;
1394                 }
1395         }
1396         unmark_and_free(list, TMP_MARK);
1397         unmark_and_free(used, TMP_MARK);
1398         return found;
1399 }
1400
1401 /*
1402  * Return true if there is anything to report, otherwise false.
1403  */
1404 int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs)
1405 {
1406         unsigned char sha1[20];
1407         struct commit *ours, *theirs;
1408         char symmetric[84];
1409         struct rev_info revs;
1410         const char *rev_argv[10], *base;
1411         int rev_argc;
1412
1413         /*
1414          * Nothing to report unless we are marked to build on top of
1415          * somebody else.
1416          */
1417         if (!branch ||
1418             !branch->merge || !branch->merge[0] || !branch->merge[0]->dst)
1419                 return 0;
1420
1421         /*
1422          * If what we used to build on no longer exists, there is
1423          * nothing to report.
1424          */
1425         base = branch->merge[0]->dst;
1426         if (!resolve_ref(base, sha1, 1, NULL))
1427                 return 0;
1428         theirs = lookup_commit_reference(sha1);
1429         if (!theirs)
1430                 return 0;
1431
1432         if (!resolve_ref(branch->refname, sha1, 1, NULL))
1433                 return 0;
1434         ours = lookup_commit_reference(sha1);
1435         if (!ours)
1436                 return 0;
1437
1438         /* are we the same? */
1439         if (theirs == ours)
1440                 return 0;
1441
1442         /* Run "rev-list --left-right ours...theirs" internally... */
1443         rev_argc = 0;
1444         rev_argv[rev_argc++] = NULL;
1445         rev_argv[rev_argc++] = "--left-right";
1446         rev_argv[rev_argc++] = symmetric;
1447         rev_argv[rev_argc++] = "--";
1448         rev_argv[rev_argc] = NULL;
1449
1450         strcpy(symmetric, sha1_to_hex(ours->object.sha1));
1451         strcpy(symmetric + 40, "...");
1452         strcpy(symmetric + 43, sha1_to_hex(theirs->object.sha1));
1453
1454         init_revisions(&revs, NULL);
1455         setup_revisions(rev_argc, rev_argv, &revs, NULL);
1456         prepare_revision_walk(&revs);
1457
1458         /* ... and count the commits on each side. */
1459         *num_ours = 0;
1460         *num_theirs = 0;
1461         while (1) {
1462                 struct commit *c = get_revision(&revs);
1463                 if (!c)
1464                         break;
1465                 if (c->object.flags & SYMMETRIC_LEFT)
1466                         (*num_ours)++;
1467                 else
1468                         (*num_theirs)++;
1469         }
1470
1471         /* clear object flags smudged by the above traversal */
1472         clear_commit_marks(ours, ALL_REV_FLAGS);
1473         clear_commit_marks(theirs, ALL_REV_FLAGS);
1474         return 1;
1475 }
1476
1477 /*
1478  * Return true when there is anything to report, otherwise false.
1479  */
1480 int format_tracking_info(struct branch *branch, struct strbuf *sb)
1481 {
1482         int num_ours, num_theirs;
1483         const char *base;
1484
1485         if (!stat_tracking_info(branch, &num_ours, &num_theirs))
1486                 return 0;
1487
1488         base = branch->merge[0]->dst;
1489         base = shorten_unambiguous_ref(base, 0);
1490         if (!num_theirs)
1491                 strbuf_addf(sb, "Your branch is ahead of '%s' "
1492                             "by %d commit%s.\n",
1493                             base, num_ours, (num_ours == 1) ? "" : "s");
1494         else if (!num_ours)
1495                 strbuf_addf(sb, "Your branch is behind '%s' "
1496                             "by %d commit%s, "
1497                             "and can be fast-forwarded.\n",
1498                             base, num_theirs, (num_theirs == 1) ? "" : "s");
1499         else
1500                 strbuf_addf(sb, "Your branch and '%s' have diverged,\n"
1501                             "and have %d and %d different commit(s) each, "
1502                             "respectively.\n",
1503                             base, num_ours, num_theirs);
1504         return 1;
1505 }
1506
1507 static int one_local_ref(const char *refname, const unsigned char *sha1, int flag, void *cb_data)
1508 {
1509         struct ref ***local_tail = cb_data;
1510         struct ref *ref;
1511         int len;
1512
1513         /* we already know it starts with refs/ to get here */
1514         if (check_ref_format(refname + 5))
1515                 return 0;
1516
1517         len = strlen(refname) + 1;
1518         ref = xcalloc(1, sizeof(*ref) + len);
1519         hashcpy(ref->new_sha1, sha1);
1520         memcpy(ref->name, refname, len);
1521         **local_tail = ref;
1522         *local_tail = &ref->next;
1523         return 0;
1524 }
1525
1526 struct ref *get_local_heads(void)
1527 {
1528         struct ref *local_refs = NULL, **local_tail = &local_refs;
1529         for_each_ref(one_local_ref, &local_tail);
1530         return local_refs;
1531 }
1532
1533 struct ref *guess_remote_head(const struct ref *head,
1534                               const struct ref *refs,
1535                               int all)
1536 {
1537         const struct ref *r;
1538         struct ref *list = NULL;
1539         struct ref **tail = &list;
1540
1541         if (!head)
1542                 return NULL;
1543
1544         /*
1545          * Some transports support directly peeking at
1546          * where HEAD points; if that is the case, then
1547          * we don't have to guess.
1548          */
1549         if (head->symref)
1550                 return copy_ref(find_ref_by_name(refs, head->symref));
1551
1552         /* If refs/heads/master could be right, it is. */
1553         if (!all) {
1554                 r = find_ref_by_name(refs, "refs/heads/master");
1555                 if (r && !hashcmp(r->old_sha1, head->old_sha1))
1556                         return copy_ref(r);
1557         }
1558
1559         /* Look for another ref that points there */
1560         for (r = refs; r; r = r->next) {
1561                 if (r != head && !hashcmp(r->old_sha1, head->old_sha1)) {
1562                         *tail = copy_ref(r);
1563                         tail = &((*tail)->next);
1564                         if (!all)
1565                                 break;
1566                 }
1567         }
1568
1569         return list;
1570 }