connect.c

   1 #include "git-compat-util.h"
   2 #include "cache.h"
   3 #include "pkt-line.h"
   4 #include "quote.h"
   5 #include "refs.h"
   6 #include "run-command.h"
   7 #include "spawn-pipe.h"
   8
   9 static char *server_capabilities;
  10
  11 static int check_ref(const char *name, int len, unsigned int flags)
  12 {
  13         if (!flags)
  14                 return 1;
  15
  16         if (len < 5 || memcmp(name, "refs/", 5))
  17                 return 0;
  18
  19         /* Skip the "refs/" part */
  20         name += 5;
  21         len -= 5;
  22
  23         /* REF_NORMAL means that we don't want the magic fake tag refs */
  24         if ((flags & REF_NORMAL) && check_ref_format(name) < 0)
  25                 return 0;
  26
  27         /* REF_HEADS means that we want regular branch heads */
  28         if ((flags & REF_HEADS) && !memcmp(name, "heads/", 6))
  29                 return 1;
  30
  31         /* REF_TAGS means that we want tags */
  32         if ((flags & REF_TAGS) && !memcmp(name, "tags/", 5))
  33                 return 1;
  34
  35         /* All type bits clear means that we are ok with anything */
  36         return !(flags & ~REF_NORMAL);
  37 }
  38
  39 /*
  40  * Read all the refs from the other end
  41  */
  42 struct ref **get_remote_heads(int in, struct ref **list,
  43                               int nr_match, char **match,
  44                               unsigned int flags)
  45 {
  46         *list = NULL;
  47         for (;;) {
  48                 struct ref *ref;
  49                 unsigned char old_sha1[20];
  50                 static char buffer[1000];
  51                 char *name;
  52                 int len, name_len;
  53
  54                 len = packet_read_line(in, buffer, sizeof(buffer));
  55                 if (!len)
  56                         break;
  57                 if (buffer[len-1] == '\n')
  58                         buffer[--len] = 0;
  59
  60                 if (len < 42 || get_sha1_hex(buffer, old_sha1) || buffer[40] != ' ')
  61                         die("protocol error: expected sha/ref, got '%s'", buffer);
  62                 name = buffer + 41;
  63
  64                 name_len = strlen(name);
  65                 if (len != name_len + 41) {
  66                         if (server_capabilities)
  67                                 free(server_capabilities);
  68                         server_capabilities = xstrdup(name + name_len + 1);
  69                 }
  70
  71                 if (!check_ref(name, name_len, flags))
  72                         continue;
  73                 if (nr_match && !path_match(name, nr_match, match))
  74                         continue;
  75                 ref = xcalloc(1, sizeof(*ref) + len - 40);
  76                 hashcpy(ref->old_sha1, old_sha1);
  77                 memcpy(ref->name, buffer + 41, len - 40);
  78                 *list = ref;
  79                 list = &ref->next;
  80         }
  81         return list;
  82 }
  83
  84 int server_supports(const char *feature)
  85 {
  86         return server_capabilities &&
  87                 strstr(server_capabilities, feature) != NULL;
  88 }
  89
  90 int get_ack(int fd, unsigned char *result_sha1)
  91 {
  92         static char line[1000];
  93         int len = packet_read_line(fd, line, sizeof(line));
  94
  95         if (!len)
  96                 die("git-fetch-pack: expected ACK/NAK, got EOF");
  97         if (line[len-1] == '\n')
  98                 line[--len] = 0;
  99         if (!strcmp(line, "NAK"))
 100                 return 0;
 101         if (!prefixcmp(line, "ACK ")) {
 102                 if (!get_sha1_hex(line+4, result_sha1)) {
 103                         if (strstr(line+45, "continue"))
 104                                 return 2;
 105                         return 1;
 106                 }
 107         }
 108         die("git-fetch_pack: expected ACK/NAK, got '%s'", line);
 109 }
 110
 111 int path_match(const char *path, int nr, char **match)
 112 {
 113         int i;
 114         int pathlen = strlen(path);
 115
 116         for (i = 0; i < nr; i++) {
 117                 char *s = match[i];
 118                 int len = strlen(s);
 119
 120                 if (!len || len > pathlen)
 121                         continue;
 122                 if (memcmp(path + pathlen - len, s, len))
 123                         continue;
 124                 if (pathlen > len && path[pathlen - len - 1] != '/')
 125                         continue;
 126                 *s = 0;
 127                 return (i + 1);
 128         }
 129         return 0;
 130 }
 131
 132 struct refspec {
 133         char *src;
 134         char *dst;
 135         char force;
 136 };
 137
 138 /*
 139  * A:B means fast forward remote B with local A.
 140  * +A:B means overwrite remote B with local A.
 141  * +A is a shorthand for +A:A.
 142  * A is a shorthand for A:A.
 143  * :B means delete remote B.
 144  */
 145 static struct refspec *parse_ref_spec(int nr_refspec, char **refspec)
 146 {
 147         int i;
 148         struct refspec *rs = xcalloc(sizeof(*rs), (nr_refspec + 1));
 149         for (i = 0; i < nr_refspec; i++) {
 150                 char *sp, *dp, *ep;
 151                 sp = refspec[i];
 152                 if (*sp == '+') {
 153                         rs[i].force = 1;
 154                         sp++;
 155                 }
 156                 ep = strchr(sp, ':');
 157                 if (ep) {
 158                         dp = ep + 1;
 159                         *ep = 0;
 160                 }
 161                 else
 162                         dp = sp;
 163                 rs[i].src = sp;
 164                 rs[i].dst = dp;
 165         }
 166         rs[nr_refspec].src = rs[nr_refspec].dst = NULL;
 167         return rs;
 168 }
 169
 170 static int count_refspec_match(const char *pattern,
 171                                struct ref *refs,
 172                                struct ref **matched_ref)
 173 {
 174         int patlen = strlen(pattern);
 175         struct ref *matched_weak = NULL;
 176         struct ref *matched = NULL;
 177         int weak_match = 0;
 178         int match = 0;
 179
 180         for (weak_match = match = 0; refs; refs = refs->next) {
 181                 char *name = refs->name;
 182                 int namelen = strlen(name);
 183                 int weak_match;
 184
 185                 if (namelen < patlen ||
 186                     memcmp(name + namelen - patlen, pattern, patlen))
 187                         continue;
 188                 if (namelen != patlen && name[namelen - patlen - 1] != '/')
 189                         continue;
 190
 191                 /* A match is "weak" if it is with refs outside
 192                  * heads or tags, and did not specify the pattern
 193                  * in full (e.g. "refs/remotes/origin/master") or at
 194                  * least from the toplevel (e.g. "remotes/origin/master");
 195                  * otherwise "git push $URL master" would result in
 196                  * ambiguity between remotes/origin/master and heads/master
 197                  * at the remote site.
 198                  */
 199                 if (namelen != patlen &&
 200                     patlen != namelen - 5 &&
 201                     prefixcmp(name, "refs/heads/") &&
 202                     prefixcmp(name, "refs/tags/")) {
 203                         /* We want to catch the case where only weak
 204                          * matches are found and there are multiple
 205                          * matches, and where more than one strong
 206                          * matches are found, as ambiguous.  One
 207                          * strong match with zero or more weak matches
 208                          * are acceptable as a unique match.
 209                          */
 210                         matched_weak = refs;
 211                         weak_match++;
 212                 }
 213                 else {
 214                         matched = refs;
 215                         match++;
 216                 }
 217         }
 218         if (!matched) {
 219                 *matched_ref = matched_weak;
 220                 return weak_match;
 221         }
 222         else {
 223                 *matched_ref = matched;
 224                 return match;
 225         }
 226 }
 227
 228 static void link_dst_tail(struct ref *ref, struct ref ***tail)
 229 {
 230         **tail = ref;
 231         *tail = &ref->next;
 232         **tail = NULL;
 233 }
 234
 235 static struct ref *try_explicit_object_name(const char *name)
 236 {
 237         unsigned char sha1[20];
 238         struct ref *ref;
 239         int len;
 240
 241         if (!*name) {
 242                 ref = xcalloc(1, sizeof(*ref) + 20);
 243                 strcpy(ref->name, "(delete)");
 244                 hashclr(ref->new_sha1);
 245                 return ref;
 246         }
 247         if (get_sha1(name, sha1))
 248                 return NULL;
 249         len = strlen(name) + 1;
 250         ref = xcalloc(1, sizeof(*ref) + len);
 251         memcpy(ref->name, name, len);
 252         hashcpy(ref->new_sha1, sha1);
 253         return ref;
 254 }
 255
 256 static int match_explicit_refs(struct ref *src, struct ref *dst,
 257                                struct ref ***dst_tail, struct refspec *rs)
 258 {
 259         int i, errs;
 260         for (i = errs = 0; rs[i].src; i++) {
 261                 struct ref *matched_src, *matched_dst;
 262
 263                 matched_src = matched_dst = NULL;
 264                 switch (count_refspec_match(rs[i].src, src, &matched_src)) {
 265                 case 1:
 266                         break;
 267                 case 0:
 268                         /* The source could be in the get_sha1() format
 269                          * not a reference name.  :refs/other is a
 270                          * way to delete 'other' ref at the remote end.
 271                          */
 272                         matched_src = try_explicit_object_name(rs[i].src);
 273                         if (matched_src)
 274                                 break;
 275                         errs = 1;
 276                         error("src refspec %s does not match any.",
 277                               rs[i].src);
 278                         break;
 279                 default:
 280                         errs = 1;
 281                         error("src refspec %s matches more than one.",
 282                               rs[i].src);
 283                         break;
 284                 }
 285                 switch (count_refspec_match(rs[i].dst, dst, &matched_dst)) {
 286                 case 1:
 287                         break;
 288                 case 0:
 289                         if (!memcmp(rs[i].dst, "refs/", 5)) {
 290                                 int len = strlen(rs[i].dst) + 1;
 291                                 matched_dst = xcalloc(1, sizeof(*dst) + len);
 292                                 memcpy(matched_dst->name, rs[i].dst, len);
 293                                 link_dst_tail(matched_dst, dst_tail);
 294                         }
 295                         else if (!strcmp(rs[i].src, rs[i].dst) &&
 296                                  matched_src) {
 297                                 /* pushing "master:master" when
 298                                  * remote does not have master yet.
 299                                  */
 300                                 int len = strlen(matched_src->name) + 1;
 301                                 matched_dst = xcalloc(1, sizeof(*dst) + len);
 302                                 memcpy(matched_dst->name, matched_src->name,
 303                                        len);
 304                                 link_dst_tail(matched_dst, dst_tail);
 305                         }
 306                         else {
 307                                 errs = 1;
 308                                 error("dst refspec %s does not match any "
 309                                       "existing ref on the remote and does "
 310                                       "not start with refs/.", rs[i].dst);
 311                         }
 312                         break;
 313                 default:
 314                         errs = 1;
 315                         error("dst refspec %s matches more than one.",
 316                               rs[i].dst);
 317                         break;
 318                 }
 319                 if (errs)
 320                         continue;
 321                 if (matched_dst->peer_ref) {
 322                         errs = 1;
 323                         error("dst ref %s receives from more than one src.",
 324                               matched_dst->name);
 325                 }
 326                 else {
 327                         matched_dst->peer_ref = matched_src;
 328                         matched_dst->force = rs[i].force;
 329                 }
 330         }
 331         return -errs;
 332 }
 333
 334 static struct ref *find_ref_by_name(struct ref *list, const char *name)
 335 {
 336         for ( ; list; list = list->next)
 337                 if (!strcmp(list->name, name))
 338                         return list;
 339         return NULL;
 340 }
 341
 342 int match_refs(struct ref *src, struct ref *dst, struct ref ***dst_tail,
 343                int nr_refspec, char **refspec, int all)
 344 {
 345         struct refspec *rs = parse_ref_spec(nr_refspec, refspec);
 346
 347         if (nr_refspec)
 348                 return match_explicit_refs(src, dst, dst_tail, rs);
 349
 350         /* pick the remainder */
 351         for ( ; src; src = src->next) {
 352                 struct ref *dst_peer;
 353                 if (src->peer_ref)
 354                         continue;
 355                 dst_peer = find_ref_by_name(dst, src->name);
 356                 if ((dst_peer && dst_peer->peer_ref) || (!dst_peer && !all))
 357                         continue;
 358                 if (!dst_peer) {
 359                         /* Create a new one and link it */
 360                         int len = strlen(src->name) + 1;
 361                         dst_peer = xcalloc(1, sizeof(*dst_peer) + len);
 362                         memcpy(dst_peer->name, src->name, len);
 363                         hashcpy(dst_peer->new_sha1, src->new_sha1);
 364                         link_dst_tail(dst_peer, dst_tail);
 365                 }
 366                 dst_peer->peer_ref = src;
 367         }
 368         return 0;
 369 }
 370
 371 enum protocol {
 372         PROTO_LOCAL = 1,
 373         PROTO_SSH,
 374         PROTO_GIT,
 375 };
 376
 377 static enum protocol get_protocol(const char *name)
 378 {
 379         if (!strcmp(name, "ssh"))
 380                 return PROTO_SSH;
 381         if (!strcmp(name, "git"))
 382                 return PROTO_GIT;
 383         if (!strcmp(name, "git+ssh"))
 384                 return PROTO_SSH;
 385         if (!strcmp(name, "ssh+git"))
 386                 return PROTO_SSH;
 387         die("I don't handle protocol '%s'", name);
 388 }
 389
 390 #define STR_(s) # s
 391 #define STR(s)  STR_(s)
 392
 393 #ifndef NO_IPV6
 394
 395 /*
 396  * Returns a connected socket() fd, or else die()s.
 397  */
 398 static int git_tcp_connect_sock(char *host)
 399 {
 400         int sockfd = -1, saved_errno = 0;
 401         char *colon, *end;
 402         const char *port = STR(DEFAULT_GIT_PORT);
 403         struct addrinfo hints, *ai0, *ai;
 404         int gai;
 405
 406         if (host[0] == '[') {
 407                 end = strchr(host + 1, ']');
 408                 if (end) {
 409                         *end = 0;
 410                         end++;
 411                         host++;
 412                 } else
 413                         end = host;
 414         } else
 415                 end = host;
 416         colon = strchr(end, ':');
 417
 418         if (colon) {
 419                 *colon = 0;
 420                 port = colon + 1;
 421                 if (!*port)
 422                         port = "<none>";
 423         }
 424
 425         memset(&hints, 0, sizeof(hints));
 426         hints.ai_socktype = SOCK_STREAM;
 427         hints.ai_protocol = IPPROTO_TCP;
 428
 429         gai = getaddrinfo(host, port, &hints, &ai);
 430         if (gai)
 431                 die("Unable to look up %s (port %s) (%s)", host, port, gai_strerror(gai));
 432
 433         for (ai0 = ai; ai; ai = ai->ai_next) {
 434                 sockfd = socket(ai->ai_family,
 435                                 ai->ai_socktype, ai->ai_protocol);
 436                 if (sockfd < 0) {
 437                         saved_errno = errno;
 438                         continue;
 439                 }
 440                 if (connect(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 441                         saved_errno = errno;
 442                         close(sockfd);
 443                         sockfd = -1;
 444                         continue;
 445                 }
 446                 break;
 447         }
 448
 449         freeaddrinfo(ai0);
 450
 451         if (sockfd < 0)
 452                 die("unable to connect a socket (%s)", strerror(saved_errno));
 453
 454         return sockfd;
 455 }
 456
 457 #else /* NO_IPV6 */
 458
 459 /*
 460  * Returns a connected socket() fd, or else die()s.
 461  */
 462 static int git_tcp_connect_sock(char *host)
 463 {
 464         int sockfd = -1, saved_errno = 0;
 465         char *colon, *end;
 466         char *port = STR(DEFAULT_GIT_PORT), *ep;
 467         struct hostent *he;
 468         struct sockaddr_in sa;
 469         char **ap;
 470         unsigned int nport;
 471
 472         if (host[0] == '[') {
 473                 end = strchr(host + 1, ']');
 474                 if (end) {
 475                         *end = 0;
 476                         end++;
 477                         host++;
 478                 } else
 479                         end = host;
 480         } else
 481                 end = host;
 482         colon = strchr(end, ':');
 483
 484         if (colon) {
 485                 *colon = 0;
 486                 port = colon + 1;
 487         }
 488
 489         he = gethostbyname(host);
 490         if (!he)
 491                 die("Unable to look up %s (%s)", host, hstrerror(h_errno));
 492         nport = strtoul(port, &ep, 10);
 493         if ( ep == port || *ep ) {
 494                 /* Not numeric */
 495                 struct servent *se = getservbyname(port,"tcp");
 496                 if ( !se )
 497                         die("Unknown port %s\n", port);
 498                 nport = se->s_port;
 499         }
 500
 501         for (ap = he->h_addr_list; *ap; ap++) {
 502                 sockfd = socket(he->h_addrtype, SOCK_STREAM, 0);
 503                 if (sockfd < 0) {
 504                         saved_errno = errno;
 505                         continue;
 506                 }
 507
 508                 memset(&sa, 0, sizeof sa);
 509                 sa.sin_family = he->h_addrtype;
 510                 sa.sin_port = htons(nport);
 511                 memcpy(&sa.sin_addr, *ap, he->h_length);
 512
 513                 if (connect(sockfd, (struct sockaddr *)&sa, sizeof sa) < 0) {
 514                         saved_errno = errno;
 515                         close(sockfd);
 516                         sockfd = -1;
 517                         continue;
 518                 }
 519                 break;
 520         }
 521
 522         if (sockfd < 0)
 523                 die("unable to connect a socket (%s)", strerror(saved_errno));
 524
 525         return sockfd;
 526 }
 527
 528 #endif /* NO_IPV6 */
 529
 530
 531 static void git_tcp_connect(int fd[2], char *host)
 532 {
 533 #ifndef __MINGW32__
 534         int sockfd = git_tcp_connect_sock(host);
 535 #else
 536         int sockfd;
 537         WSADATA wsa;
 538
 539         if (WSAStartup(MAKEWORD(2,2), &wsa))
 540                 die("unable to initialize winsock subsystem, error %d",
 541                         WSAGetLastError());
 542         atexit((void(*)(void)) WSACleanup);
 543
 544         sockfd = git_tcp_connect_sock(host);
 545         /* convert into a file descriptor */
 546         if ((sockfd = _open_osfhandle(sockfd, O_RDWR|O_BINARY)) < 0)
 547                 die("unable to make a socket file descriptor: %s",
 548                         strerror(errno));
 549 #endif
 550
 551         fd[0] = sockfd;
 552         fd[1] = dup(sockfd);
 553 }
 554
 555
 556 static char *git_proxy_command;
 557 static const char *rhost_name;
 558 static int rhost_len;
 559
 560 static int git_proxy_command_options(const char *var, const char *value)
 561 {
 562         if (!strcmp(var, "core.gitproxy")) {
 563                 const char *for_pos;
 564                 int matchlen = -1;
 565                 int hostlen;
 566
 567                 if (git_proxy_command)
 568                         return 0;
 569                 /* [core]
 570                  * ;# matches www.kernel.org as well
 571                  * gitproxy = netcatter-1 for kernel.org
 572                  * gitproxy = netcatter-2 for sample.xz
 573                  * gitproxy = netcatter-default
 574                  */
 575                 for_pos = strstr(value, " for ");
 576                 if (!for_pos)
 577                         /* matches everybody */
 578                         matchlen = strlen(value);
 579                 else {
 580                         hostlen = strlen(for_pos + 5);
 581                         if (rhost_len < hostlen)
 582                                 matchlen = -1;
 583                         else if (!strncmp(for_pos + 5,
 584                                           rhost_name + rhost_len - hostlen,
 585                                           hostlen) &&
 586                                  ((rhost_len == hostlen) ||
 587                                   rhost_name[rhost_len - hostlen -1] == '.'))
 588                                 matchlen = for_pos - value;
 589                         else
 590                                 matchlen = -1;
 591                 }
 592                 if (0 <= matchlen) {
 593                         /* core.gitproxy = none for kernel.org */
 594                         if (matchlen == 4 &&
 595                             !memcmp(value, "none", 4))
 596                                 matchlen = 0;
 597                         git_proxy_command = xmalloc(matchlen + 1);
 598                         memcpy(git_proxy_command, value, matchlen);
 599                         git_proxy_command[matchlen] = 0;
 600                 }
 601                 return 0;
 602         }
 603
 604         return git_default_config(var, value);
 605 }
 606
 607 static int git_use_proxy(const char *host)
 608 {
 609         rhost_name = host;
 610         rhost_len = strlen(host);
 611         git_proxy_command = getenv("GIT_PROXY_COMMAND");
 612         git_config(git_proxy_command_options);
 613         rhost_name = NULL;
 614         return (git_proxy_command && *git_proxy_command);
 615 }
 616
 617 static void git_proxy_connect(int fd[2], char *host)
 618 {
 619         const char *port = STR(DEFAULT_GIT_PORT);
 620         char *colon, *end;
 621         const char *argv[4];
 622         struct child_process proxy;
 623
 624         if (host[0] == '[') {
 625                 end = strchr(host + 1, ']');
 626                 if (end) {
 627                         *end = 0;
 628                         end++;
 629                         host++;
 630                 } else
 631                         end = host;
 632         } else
 633                 end = host;
 634         colon = strchr(end, ':');
 635
 636         if (colon) {
 637                 *colon = 0;
 638                 port = colon + 1;
 639         }
 640
 641         argv[0] = git_proxy_command;
 642         argv[1] = host;
 643         argv[2] = port;
 644         argv[3] = NULL;
 645         memset(&proxy, 0, sizeof(proxy));
 646         proxy.argv = argv;
 647         proxy.in = -1;
 648         proxy.out = -1;
 649         if (start_command(&proxy))
 650                 die("cannot start proxy %s", argv[0]);
 651         fd[0] = proxy.out; /* read from proxy stdout */
 652         fd[1] = proxy.in;  /* write to proxy stdin */
 653 }
 654
 655 #define MAX_CMD_LEN 1024
 656
 657 /*
 658  * This returns 0 if the transport protocol does not need fork(2),
 659  * or a process id if it does.  Once done, finish the connection
 660  * with finish_connect() with the value returned from this function
 661  * (it is safe to call finish_connect() with 0 to support the former
 662  * case).
 663  *
 664  * Does not return a negative value on error; it just dies.
 665  */
 666 pid_t git_connect(int fd[2], char *url, const char *prog)
 667 {
 668         char *host, *path = url;
 669         char *end;
 670         int c;
 671         int pipefd[2][2];
 672         pid_t pid;
 673         enum protocol protocol = PROTO_LOCAL;
 674         int free_path = 0;
 675
 676         /* Without this we cannot rely on waitpid() to tell
 677          * what happened to our children.
 678          */
 679         signal(SIGCHLD, SIG_DFL);
 680
 681         host = strstr(url, "://");
 682         if(host) {
 683                 *host = '\0';
 684                 protocol = get_protocol(url);
 685                 host += 3;
 686                 c = '/';
 687         } else {
 688                 host = url;
 689                 c = ':';
 690         }
 691
 692         if (host[0] == '[') {
 693                 end = strchr(host + 1, ']');
 694                 if (end) {
 695                         *end = 0;
 696                         end++;
 697                         host++;
 698                 } else
 699                         end = host;
 700         } else
 701                 end = host;
 702
 703         path = strchr(end, c);
 704         if (c == ':') {
 705                 /* host must have at least 2 chars to catch DOS C:/path */
 706                 if (path && path - end > 1) {
 707                         protocol = PROTO_SSH;
 708                         *path++ = '\0';
 709                 } else
 710                         path = host;
 711         }
 712
 713         if (!path || !*path)
 714                 die("No path specified. See 'man git-pull' for valid url syntax");
 715
 716         /*
 717          * null-terminate hostname and point path to ~ for URL's like this:
 718          *    ssh://host.xz/~user/repo
 719          */
 720         if (protocol != PROTO_LOCAL && host != url) {
 721                 char *ptr = path;
 722                 if (path[1] == '~')
 723                         path++;
 724                 else {
 725                         path = xstrdup(ptr);
 726                         free_path = 1;
 727                 }
 728
 729                 *ptr = '\0';
 730         }
 731
 732         if (protocol == PROTO_GIT) {
 733                 /* These underlying connection commands die() if they
 734                  * cannot connect.
 735                  */
 736                 char *target_host = xstrdup(host);
 737                 if (git_use_proxy(host))
 738                         git_proxy_connect(fd, host);
 739                 else
 740                         git_tcp_connect(fd, host);
 741                 /*
 742                  * Separate original protocol components prog and path
 743                  * from extended components with a NUL byte.
 744                  */
 745                 packet_write(fd[1],
 746                              "%s %s%chost=%s%c",
 747                              prog, path, 0,
 748                              target_host, 0);
 749                 free(target_host);
 750                 if (free_path)
 751                         free(path);
 752                 return 0;
 753         }
 754
 755         if (pipe(pipefd[0]) < 0 || pipe(pipefd[1]) < 0)
 756                 die("unable to create pipe pair for communication");
 757
 758         char command[MAX_CMD_LEN];
 759         char *posn = command;
 760         int size = MAX_CMD_LEN;
 761         int of = 0;
 762
 763         of |= add_to_string(&posn, &size, prog, 0);
 764         of |= add_to_string(&posn, &size, " ", 0);
 765         of |= add_to_string(&posn, &size, path, 1);
 766
 767         if (of)
 768                 die("command line too long");
 769
 770         if (protocol == PROTO_SSH) {
 771                 const char *argv[] = { NULL, host, command, NULL };
 772                 const char *ssh = getenv("GIT_SSH");
 773                 if (!ssh) ssh = "ssh";
 774                 pid = spawnvpe_pipe(ssh, argv, environ, pipefd[1], pipefd[0]);
 775         }
 776         else {
 777                 const char *argv[] = { NULL, "-c", command, NULL };
 778                 const char **env = copy_environ();
 779                 env_unsetenv(env, ALTERNATE_DB_ENVIRONMENT);
 780                 env_unsetenv(env, DB_ENVIRONMENT);
 781                 env_unsetenv(env, GIT_DIR_ENVIRONMENT);
 782                 env_unsetenv(env, GRAFT_ENVIRONMENT);
 783                 env_unsetenv(env, INDEX_ENVIRONMENT);
 784                 pid = spawnvpe_pipe("sh", argv, env, pipefd[1], pipefd[0]);
 785         }
 786         if (pid < 0)
 787                 die("unable to fork");
 788         fd[0] = pipefd[0][0];
 789         fd[1] = pipefd[1][1];
 790         if (free_path)
 791                 free(path);
 792         return pid;
 793 }
 794
 795 int finish_connect(pid_t pid)
 796 {
 797         if (pid == 0)
 798                 return 0;
 799
 800         while (waitpid(pid, NULL, 0) < 0) {
 801                 if (errno != EINTR)
 802                         return -1;
 803         }
 804         return 0;
 805 }