git.oblomov.eu Git - git/blob - transport-helper.c

   1 #include "cache.h"
   2 #include "transport.h"
   3 #include "quote.h"
   4 #include "run-command.h"
   5 #include "commit.h"
   6 #include "diff.h"
   7 #include "revision.h"
   8 #include "remote.h"
   9 #include "string-list.h"
  10 #include "thread-utils.h"
  11 #include "sigchain.h"
  12 #include "argv-array.h"
  13 #include "refs.h"
  14 #include "refspec.h"
  15 #include "transport-internal.h"
  16 #include "protocol.h"
  17
  18 static int debug;
  19
  20 struct helper_data {
  21         const char *name;
  22         struct child_process *helper;
  23         FILE *out;
  24         unsigned fetch : 1,
  25                 import : 1,
  26                 bidi_import : 1,
  27                 export : 1,
  28                 option : 1,
  29                 push : 1,
  30                 connect : 1,
  31                 stateless_connect : 1,
  32                 signed_tags : 1,
  33                 check_connectivity : 1,
  34                 no_disconnect_req : 1,
  35                 no_private_update : 1;
  36
  37         /*
  38          * As an optimization, the transport code may invoke fetch before
  39          * get_refs_list. If this happens, and if the transport helper doesn't
  40          * support connect or stateless_connect, we need to invoke
  41          * get_refs_list ourselves if we haven't already done so. Keep track of
  42          * whether we have invoked get_refs_list.
  43          */
  44         unsigned get_refs_list_called : 1;
  45
  46         char *export_marks;
  47         char *import_marks;
  48         /* These go from remote name (as in "list") to private name */
  49         struct refspec rs;
  50         /* Transport options for fetch-pack/send-pack (should one of
  51          * those be invoked).
  52          */
  53         struct git_transport_options transport_options;
  54 };
  55
  56 static void sendline(struct helper_data *helper, struct strbuf *buffer)
  57 {
  58         if (debug)
  59                 fprintf(stderr, "Debug: Remote helper: -> %s", buffer->buf);
  60         if (write_in_full(helper->helper->in, buffer->buf, buffer->len) < 0)
  61                 die_errno(_("full write to remote helper failed"));
  62 }
  63
  64 static int recvline_fh(FILE *helper, struct strbuf *buffer)
  65 {
  66         strbuf_reset(buffer);
  67         if (debug)
  68                 fprintf(stderr, "Debug: Remote helper: Waiting...\n");
  69         if (strbuf_getline(buffer, helper) == EOF) {
  70                 if (debug)
  71                         fprintf(stderr, "Debug: Remote helper quit.\n");
  72                 return 1;
  73         }
  74
  75         if (debug)
  76                 fprintf(stderr, "Debug: Remote helper: <- %s\n", buffer->buf);
  77         return 0;
  78 }
  79
  80 static int recvline(struct helper_data *helper, struct strbuf *buffer)
  81 {
  82         return recvline_fh(helper->out, buffer);
  83 }
  84
  85 static void write_constant(int fd, const char *str)
  86 {
  87         if (debug)
  88                 fprintf(stderr, "Debug: Remote helper: -> %s", str);
  89         if (write_in_full(fd, str, strlen(str)) < 0)
  90                 die_errno(_("full write to remote helper failed"));
  91 }
  92
  93 static const char *remove_ext_force(const char *url)
  94 {
  95         if (url) {
  96                 const char *colon = strchr(url, ':');
  97                 if (colon && colon[1] == ':')
  98                         return colon + 2;
  99         }
 100         return url;
 101 }
 102
 103 static void do_take_over(struct transport *transport)
 104 {
 105         struct helper_data *data;
 106         data = (struct helper_data *)transport->data;
 107         transport_take_over(transport, data->helper);
 108         fclose(data->out);
 109         free(data);
 110 }
 111
 112 static void standard_options(struct transport *t);
 113
 114 static struct child_process *get_helper(struct transport *transport)
 115 {
 116         struct helper_data *data = transport->data;
 117         struct strbuf buf = STRBUF_INIT;
 118         struct child_process *helper;
 119         int duped;
 120         int code;
 121
 122         if (data->helper)
 123                 return data->helper;
 124
 125         helper = xmalloc(sizeof(*helper));
 126         child_process_init(helper);
 127         helper->in = -1;
 128         helper->out = -1;
 129         helper->err = 0;
 130         argv_array_pushf(&helper->args, "git-remote-%s", data->name);
 131         argv_array_push(&helper->args, transport->remote->name);
 132         argv_array_push(&helper->args, remove_ext_force(transport->url));
 133         helper->git_cmd = 0;
 134         helper->silent_exec_failure = 1;
 135
 136         if (have_git_dir())
 137                 argv_array_pushf(&helper->env_array, "%s=%s",
 138                                  GIT_DIR_ENVIRONMENT, get_git_dir());
 139
 140         helper->trace2_child_class = helper->args.argv[0]; /* "remote-<name>" */
 141
 142         code = start_command(helper);
 143         if (code < 0 && errno == ENOENT)
 144                 die(_("unable to find remote helper for '%s'"), data->name);
 145         else if (code != 0)
 146                 exit(code);
 147
 148         data->helper = helper;
 149         data->no_disconnect_req = 0;
 150         refspec_init(&data->rs, REFSPEC_FETCH);
 151
 152         /*
 153          * Open the output as FILE* so strbuf_getline_*() family of
 154          * functions can be used.
 155          * Do this with duped fd because fclose() will close the fd,
 156          * and stuff like taking over will require the fd to remain.
 157          */
 158         duped = dup(helper->out);
 159         if (duped < 0)
 160                 die_errno(_("can't dup helper output fd"));
 161         data->out = xfdopen(duped, "r");
 162
 163         write_constant(helper->in, "capabilities\n");
 164
 165         while (1) {
 166                 const char *capname, *arg;
 167                 int mandatory = 0;
 168                 if (recvline(data, &buf))
 169                         exit(128);
 170
 171                 if (!*buf.buf)
 172                         break;
 173
 174                 if (*buf.buf == '*') {
 175                         capname = buf.buf + 1;
 176                         mandatory = 1;
 177                 } else
 178                         capname = buf.buf;
 179
 180                 if (debug)
 181                         fprintf(stderr, "Debug: Got cap %s\n", capname);
 182                 if (!strcmp(capname, "fetch"))
 183                         data->fetch = 1;
 184                 else if (!strcmp(capname, "option"))
 185                         data->option = 1;
 186                 else if (!strcmp(capname, "push"))
 187                         data->push = 1;
 188                 else if (!strcmp(capname, "import"))
 189                         data->import = 1;
 190                 else if (!strcmp(capname, "bidi-import"))
 191                         data->bidi_import = 1;
 192                 else if (!strcmp(capname, "export"))
 193                         data->export = 1;
 194                 else if (!strcmp(capname, "check-connectivity"))
 195                         data->check_connectivity = 1;
 196                 else if (skip_prefix(capname, "refspec ", &arg)) {
 197                         refspec_append(&data->rs, arg);
 198                 } else if (!strcmp(capname, "connect")) {
 199                         data->connect = 1;
 200                 } else if (!strcmp(capname, "stateless-connect")) {
 201                         data->stateless_connect = 1;
 202                 } else if (!strcmp(capname, "signed-tags")) {
 203                         data->signed_tags = 1;
 204                 } else if (skip_prefix(capname, "export-marks ", &arg)) {
 205                         data->export_marks = xstrdup(arg);
 206                 } else if (skip_prefix(capname, "import-marks ", &arg)) {
 207                         data->import_marks = xstrdup(arg);
 208                 } else if (starts_with(capname, "no-private-update")) {
 209                         data->no_private_update = 1;
 210                 } else if (mandatory) {
 211                         die(_("unknown mandatory capability %s; this remote "
 212                               "helper probably needs newer version of Git"),
 213                             capname);
 214                 }
 215         }
 216         if (!data->rs.nr && (data->import || data->bidi_import || data->export)) {
 217                 warning(_("this remote helper should implement refspec capability"));
 218         }
 219         strbuf_release(&buf);
 220         if (debug)
 221                 fprintf(stderr, "Debug: Capabilities complete.\n");
 222         standard_options(transport);
 223         return data->helper;
 224 }
 225
 226 static int disconnect_helper(struct transport *transport)
 227 {
 228         struct helper_data *data = transport->data;
 229         int res = 0;
 230
 231         if (data->helper) {
 232                 if (debug)
 233                         fprintf(stderr, "Debug: Disconnecting.\n");
 234                 if (!data->no_disconnect_req) {
 235                         /*
 236                          * Ignore write errors; there's nothing we can do,
 237                          * since we're about to close the pipe anyway. And the
 238                          * most likely error is EPIPE due to the helper dying
 239                          * to report an error itself.
 240                          */
 241                         sigchain_push(SIGPIPE, SIG_IGN);
 242                         xwrite(data->helper->in, "\n", 1);
 243                         sigchain_pop(SIGPIPE);
 244                 }
 245                 close(data->helper->in);
 246                 close(data->helper->out);
 247                 fclose(data->out);
 248                 res = finish_command(data->helper);
 249                 FREE_AND_NULL(data->helper);
 250         }
 251         return res;
 252 }
 253
 254 static const char *unsupported_options[] = {
 255         TRANS_OPT_UPLOADPACK,
 256         TRANS_OPT_RECEIVEPACK,
 257         TRANS_OPT_THIN,
 258         TRANS_OPT_KEEP
 259         };
 260
 261 static const char *boolean_options[] = {
 262         TRANS_OPT_THIN,
 263         TRANS_OPT_KEEP,
 264         TRANS_OPT_FOLLOWTAGS,
 265         TRANS_OPT_DEEPEN_RELATIVE
 266         };
 267
 268 static int strbuf_set_helper_option(struct helper_data *data,
 269                                     struct strbuf *buf)
 270 {
 271         int ret;
 272
 273         sendline(data, buf);
 274         if (recvline(data, buf))
 275                 exit(128);
 276
 277         if (!strcmp(buf->buf, "ok"))
 278                 ret = 0;
 279         else if (starts_with(buf->buf, "error"))
 280                 ret = -1;
 281         else if (!strcmp(buf->buf, "unsupported"))
 282                 ret = 1;
 283         else {
 284                 warning(_("%s unexpectedly said: '%s'"), data->name, buf->buf);
 285                 ret = 1;
 286         }
 287         return ret;
 288 }
 289
 290 static int string_list_set_helper_option(struct helper_data *data,
 291                                          const char *name,
 292                                          struct string_list *list)
 293 {
 294         struct strbuf buf = STRBUF_INIT;
 295         int i, ret = 0;
 296
 297         for (i = 0; i < list->nr; i++) {
 298                 strbuf_addf(&buf, "option %s ", name);
 299                 quote_c_style(list->items[i].string, &buf, NULL, 0);
 300                 strbuf_addch(&buf, '\n');
 301
 302                 if ((ret = strbuf_set_helper_option(data, &buf)))
 303                         break;
 304                 strbuf_reset(&buf);
 305         }
 306         strbuf_release(&buf);
 307         return ret;
 308 }
 309
 310 static int set_helper_option(struct transport *transport,
 311                           const char *name, const char *value)
 312 {
 313         struct helper_data *data = transport->data;
 314         struct strbuf buf = STRBUF_INIT;
 315         int i, ret, is_bool = 0;
 316
 317         get_helper(transport);
 318
 319         if (!data->option)
 320                 return 1;
 321
 322         if (!strcmp(name, "deepen-not"))
 323                 return string_list_set_helper_option(data, name,
 324                                                      (struct string_list *)value);
 325
 326         for (i = 0; i < ARRAY_SIZE(unsupported_options); i++) {
 327                 if (!strcmp(name, unsupported_options[i]))
 328                         return 1;
 329         }
 330
 331         for (i = 0; i < ARRAY_SIZE(boolean_options); i++) {
 332                 if (!strcmp(name, boolean_options[i])) {
 333                         is_bool = 1;
 334                         break;
 335                 }
 336         }
 337
 338         strbuf_addf(&buf, "option %s ", name);
 339         if (is_bool)
 340                 strbuf_addstr(&buf, value ? "true" : "false");
 341         else
 342                 quote_c_style(value, &buf, NULL, 0);
 343         strbuf_addch(&buf, '\n');
 344
 345         ret = strbuf_set_helper_option(data, &buf);
 346         strbuf_release(&buf);
 347         return ret;
 348 }
 349
 350 static void standard_options(struct transport *t)
 351 {
 352         char buf[16];
 353         int v = t->verbose;
 354
 355         set_helper_option(t, "progress", t->progress ? "true" : "false");
 356
 357         xsnprintf(buf, sizeof(buf), "%d", v + 1);
 358         set_helper_option(t, "verbosity", buf);
 359
 360         switch (t->family) {
 361         case TRANSPORT_FAMILY_ALL:
 362                 /*
 363                  * this is already the default,
 364                  * do not break old remote helpers by setting "all" here
 365                  */
 366                 break;
 367         case TRANSPORT_FAMILY_IPV4:
 368                 set_helper_option(t, "family", "ipv4");
 369                 break;
 370         case TRANSPORT_FAMILY_IPV6:
 371                 set_helper_option(t, "family", "ipv6");
 372                 break;
 373         }
 374 }
 375
 376 static int release_helper(struct transport *transport)
 377 {
 378         int res = 0;
 379         struct helper_data *data = transport->data;
 380         refspec_clear(&data->rs);
 381         res = disconnect_helper(transport);
 382         free(transport->data);
 383         return res;
 384 }
 385
 386 static int fetch_with_fetch(struct transport *transport,
 387                             int nr_heads, struct ref **to_fetch)
 388 {
 389         struct helper_data *data = transport->data;
 390         int i;
 391         struct strbuf buf = STRBUF_INIT;
 392
 393         for (i = 0; i < nr_heads; i++) {
 394                 const struct ref *posn = to_fetch[i];
 395                 if (posn->status & REF_STATUS_UPTODATE)
 396                         continue;
 397
 398                 strbuf_addf(&buf, "fetch %s %s\n",
 399                             oid_to_hex(&posn->old_oid),
 400                             posn->symref ? posn->symref : posn->name);
 401         }
 402
 403         strbuf_addch(&buf, '\n');
 404         sendline(data, &buf);
 405
 406         while (1) {
 407                 if (recvline(data, &buf))
 408                         exit(128);
 409
 410                 if (starts_with(buf.buf, "lock ")) {
 411                         const char *name = buf.buf + 5;
 412                         if (transport->pack_lockfile)
 413                                 warning(_("%s also locked %s"), data->name, name);
 414                         else
 415                                 transport->pack_lockfile = xstrdup(name);
 416                 }
 417                 else if (data->check_connectivity &&
 418                          data->transport_options.check_self_contained_and_connected &&
 419                          !strcmp(buf.buf, "connectivity-ok"))
 420                         data->transport_options.self_contained_and_connected = 1;
 421                 else if (!buf.len)
 422                         break;
 423                 else
 424                         warning(_("%s unexpectedly said: '%s'"), data->name, buf.buf);
 425         }
 426         strbuf_release(&buf);
 427         return 0;
 428 }
 429
 430 static int get_importer(struct transport *transport, struct child_process *fastimport)
 431 {
 432         struct child_process *helper = get_helper(transport);
 433         struct helper_data *data = transport->data;
 434         int cat_blob_fd, code;
 435         child_process_init(fastimport);
 436         fastimport->in = xdup(helper->out);
 437         argv_array_push(&fastimport->args, "fast-import");
 438         argv_array_push(&fastimport->args, debug ? "--stats" : "--quiet");
 439
 440         if (data->bidi_import) {
 441                 cat_blob_fd = xdup(helper->in);
 442                 argv_array_pushf(&fastimport->args, "--cat-blob-fd=%d", cat_blob_fd);
 443         }
 444         fastimport->git_cmd = 1;
 445
 446         code = start_command(fastimport);
 447         return code;
 448 }
 449
 450 static int get_exporter(struct transport *transport,
 451                         struct child_process *fastexport,
 452                         struct string_list *revlist_args)
 453 {
 454         struct helper_data *data = transport->data;
 455         struct child_process *helper = get_helper(transport);
 456         int i;
 457
 458         child_process_init(fastexport);
 459
 460         /* we need to duplicate helper->in because we want to use it after
 461          * fastexport is done with it. */
 462         fastexport->out = dup(helper->in);
 463         argv_array_push(&fastexport->args, "fast-export");
 464         argv_array_push(&fastexport->args, "--use-done-feature");
 465         argv_array_push(&fastexport->args, data->signed_tags ?
 466                 "--signed-tags=verbatim" : "--signed-tags=warn-strip");
 467         if (data->export_marks)
 468                 argv_array_pushf(&fastexport->args, "--export-marks=%s.tmp", data->export_marks);
 469         if (data->import_marks)
 470                 argv_array_pushf(&fastexport->args, "--import-marks=%s", data->import_marks);
 471
 472         for (i = 0; i < revlist_args->nr; i++)
 473                 argv_array_push(&fastexport->args, revlist_args->items[i].string);
 474
 475         fastexport->git_cmd = 1;
 476         return start_command(fastexport);
 477 }
 478
 479 static int fetch_with_import(struct transport *transport,
 480                              int nr_heads, struct ref **to_fetch)
 481 {
 482         struct child_process fastimport;
 483         struct helper_data *data = transport->data;
 484         int i;
 485         struct ref *posn;
 486         struct strbuf buf = STRBUF_INIT;
 487
 488         get_helper(transport);
 489
 490         if (get_importer(transport, &fastimport))
 491                 die(_("couldn't run fast-import"));
 492
 493         for (i = 0; i < nr_heads; i++) {
 494                 posn = to_fetch[i];
 495                 if (posn->status & REF_STATUS_UPTODATE)
 496                         continue;
 497
 498                 strbuf_addf(&buf, "import %s\n",
 499                             posn->symref ? posn->symref : posn->name);
 500                 sendline(data, &buf);
 501                 strbuf_reset(&buf);
 502         }
 503
 504         write_constant(data->helper->in, "\n");
 505         /*
 506          * remote-helpers that advertise the bidi-import capability are required to
 507          * buffer the complete batch of import commands until this newline before
 508          * sending data to fast-import.
 509          * These helpers read back data from fast-import on their stdin, which could
 510          * be mixed with import commands, otherwise.
 511          */
 512
 513         if (finish_command(&fastimport))
 514                 die(_("error while running fast-import"));
 515
 516         /*
 517          * The fast-import stream of a remote helper that advertises
 518          * the "refspec" capability writes to the refs named after the
 519          * right hand side of the first refspec matching each ref we
 520          * were fetching.
 521          *
 522          * (If no "refspec" capability was specified, for historical
 523          * reasons we default to the equivalent of *:*.)
 524          *
 525          * Store the result in to_fetch[i].old_sha1.  Callers such
 526          * as "git fetch" can use the value to write feedback to the
 527          * terminal, populate FETCH_HEAD, and determine what new value
 528          * should be written to peer_ref if the update is a
 529          * fast-forward or this is a forced update.
 530          */
 531         for (i = 0; i < nr_heads; i++) {
 532                 char *private, *name;
 533                 posn = to_fetch[i];
 534                 if (posn->status & REF_STATUS_UPTODATE)
 535                         continue;
 536                 name = posn->symref ? posn->symref : posn->name;
 537                 if (data->rs.nr)
 538                         private = apply_refspecs(&data->rs, name);
 539                 else
 540                         private = xstrdup(name);
 541                 if (private) {
 542                         if (read_ref(private, &posn->old_oid) < 0)
 543                                 die(_("could not read ref %s"), private);
 544                         free(private);
 545                 }
 546         }
 547         strbuf_release(&buf);
 548         return 0;
 549 }
 550
 551 static int run_connect(struct transport *transport, struct strbuf *cmdbuf)
 552 {
 553         struct helper_data *data = transport->data;
 554         int ret = 0;
 555         int duped;
 556         FILE *input;
 557         struct child_process *helper;
 558
 559         helper = get_helper(transport);
 560
 561         /*
 562          * Yes, dup the pipe another time, as we need unbuffered version
 563          * of input pipe as FILE*. fclose() closes the underlying fd and
 564          * stream buffering only can be changed before first I/O operation
 565          * on it.
 566          */
 567         duped = dup(helper->out);
 568         if (duped < 0)
 569                 die_errno(_("can't dup helper output fd"));
 570         input = xfdopen(duped, "r");
 571         setvbuf(input, NULL, _IONBF, 0);
 572
 573         sendline(data, cmdbuf);
 574         if (recvline_fh(input, cmdbuf))
 575                 exit(128);
 576
 577         if (!strcmp(cmdbuf->buf, "")) {
 578                 data->no_disconnect_req = 1;
 579                 if (debug)
 580                         fprintf(stderr, "Debug: Smart transport connection "
 581                                 "ready.\n");
 582                 ret = 1;
 583         } else if (!strcmp(cmdbuf->buf, "fallback")) {
 584                 if (debug)
 585                         fprintf(stderr, "Debug: Falling back to dumb "
 586                                 "transport.\n");
 587         } else {
 588                 die(_("unknown response to connect: %s"),
 589                     cmdbuf->buf);
 590         }
 591
 592         fclose(input);
 593         return ret;
 594 }
 595
 596 static int process_connect_service(struct transport *transport,
 597                                    const char *name, const char *exec)
 598 {
 599         struct helper_data *data = transport->data;
 600         struct strbuf cmdbuf = STRBUF_INIT;
 601         int ret = 0;
 602
 603         /*
 604          * Handle --upload-pack and friends. This is fire and forget...
 605          * just warn if it fails.
 606          */
 607         if (strcmp(name, exec)) {
 608                 int r = set_helper_option(transport, "servpath", exec);
 609                 if (r > 0)
 610                         warning(_("setting remote service path not supported by protocol"));
 611                 else if (r < 0)
 612                         warning(_("invalid remote service path"));
 613         }
 614
 615         if (data->connect) {
 616                 strbuf_addf(&cmdbuf, "connect %s\n", name);
 617                 ret = run_connect(transport, &cmdbuf);
 618         } else if (data->stateless_connect &&
 619                    (get_protocol_version_config() == protocol_v2) &&
 620                    !strcmp("git-upload-pack", name)) {
 621                 strbuf_addf(&cmdbuf, "stateless-connect %s\n", name);
 622                 ret = run_connect(transport, &cmdbuf);
 623                 if (ret)
 624                         transport->stateless_rpc = 1;
 625         }
 626
 627         strbuf_release(&cmdbuf);
 628         return ret;
 629 }
 630
 631 static int process_connect(struct transport *transport,
 632                                      int for_push)
 633 {
 634         struct helper_data *data = transport->data;
 635         const char *name;
 636         const char *exec;
 637
 638         name = for_push ? "git-receive-pack" : "git-upload-pack";
 639         if (for_push)
 640                 exec = data->transport_options.receivepack;
 641         else
 642                 exec = data->transport_options.uploadpack;
 643
 644         return process_connect_service(transport, name, exec);
 645 }
 646
 647 static int connect_helper(struct transport *transport, const char *name,
 648                    const char *exec, int fd[2])
 649 {
 650         struct helper_data *data = transport->data;
 651
 652         /* Get_helper so connect is inited. */
 653         get_helper(transport);
 654         if (!data->connect)
 655                 die(_("operation not supported by protocol"));
 656
 657         if (!process_connect_service(transport, name, exec))
 658                 die(_("can't connect to subservice %s"), name);
 659
 660         fd[0] = data->helper->out;
 661         fd[1] = data->helper->in;
 662         return 0;
 663 }
 664
 665 static struct ref *get_refs_list_using_list(struct transport *transport,
 666                                             int for_push);
 667
 668 static int fetch(struct transport *transport,
 669                  int nr_heads, struct ref **to_fetch)
 670 {
 671         struct helper_data *data = transport->data;
 672         int i, count;
 673
 674         get_helper(transport);
 675
 676         if (process_connect(transport, 0)) {
 677                 do_take_over(transport);
 678                 return transport->vtable->fetch(transport, nr_heads, to_fetch);
 679         }
 680
 681         if (!data->get_refs_list_called)
 682                 get_refs_list_using_list(transport, 0);
 683
 684         count = 0;
 685         for (i = 0; i < nr_heads; i++)
 686                 if (!(to_fetch[i]->status & REF_STATUS_UPTODATE))
 687                         count++;
 688
 689         if (!count)
 690                 return 0;
 691
 692         if (data->check_connectivity &&
 693             data->transport_options.check_self_contained_and_connected)
 694                 set_helper_option(transport, "check-connectivity", "true");
 695
 696         if (transport->cloning)
 697                 set_helper_option(transport, "cloning", "true");
 698
 699         if (data->transport_options.update_shallow)
 700                 set_helper_option(transport, "update-shallow", "true");
 701
 702         if (data->transport_options.filter_options.choice) {
 703                 const char *spec = expand_list_objects_filter_spec(
 704                         &data->transport_options.filter_options);
 705                 set_helper_option(transport, "filter", spec);
 706         }
 707
 708         if (data->transport_options.negotiation_tips)
 709                 warning("Ignoring --negotiation-tip because the protocol does not support it.");
 710
 711         if (data->fetch)
 712                 return fetch_with_fetch(transport, nr_heads, to_fetch);
 713
 714         if (data->import)
 715                 return fetch_with_import(transport, nr_heads, to_fetch);
 716
 717         return -1;
 718 }
 719
 720 static int push_update_ref_status(struct strbuf *buf,
 721                                    struct ref **ref,
 722                                    struct ref *remote_refs)
 723 {
 724         char *refname, *msg;
 725         int status, forced = 0;
 726
 727         if (starts_with(buf->buf, "ok ")) {
 728                 status = REF_STATUS_OK;
 729                 refname = buf->buf + 3;
 730         } else if (starts_with(buf->buf, "error ")) {
 731                 status = REF_STATUS_REMOTE_REJECT;
 732                 refname = buf->buf + 6;
 733         } else
 734                 die(_("expected ok/error, helper said '%s'"), buf->buf);
 735
 736         msg = strchr(refname, ' ');
 737         if (msg) {
 738                 struct strbuf msg_buf = STRBUF_INIT;
 739                 const char *end;
 740
 741                 *msg++ = '\0';
 742                 if (!unquote_c_style(&msg_buf, msg, &end))
 743                         msg = strbuf_detach(&msg_buf, NULL);
 744                 else
 745                         msg = xstrdup(msg);
 746                 strbuf_release(&msg_buf);
 747
 748                 if (!strcmp(msg, "no match")) {
 749                         status = REF_STATUS_NONE;
 750                         FREE_AND_NULL(msg);
 751                 }
 752                 else if (!strcmp(msg, "up to date")) {
 753                         status = REF_STATUS_UPTODATE;
 754                         FREE_AND_NULL(msg);
 755                 }
 756                 else if (!strcmp(msg, "non-fast forward")) {
 757                         status = REF_STATUS_REJECT_NONFASTFORWARD;
 758                         FREE_AND_NULL(msg);
 759                 }
 760                 else if (!strcmp(msg, "already exists")) {
 761                         status = REF_STATUS_REJECT_ALREADY_EXISTS;
 762                         FREE_AND_NULL(msg);
 763                 }
 764                 else if (!strcmp(msg, "fetch first")) {
 765                         status = REF_STATUS_REJECT_FETCH_FIRST;
 766                         FREE_AND_NULL(msg);
 767                 }
 768                 else if (!strcmp(msg, "needs force")) {
 769                         status = REF_STATUS_REJECT_NEEDS_FORCE;
 770                         FREE_AND_NULL(msg);
 771                 }
 772                 else if (!strcmp(msg, "stale info")) {
 773                         status = REF_STATUS_REJECT_STALE;
 774                         FREE_AND_NULL(msg);
 775                 }
 776                 else if (!strcmp(msg, "forced update")) {
 777                         forced = 1;
 778                         FREE_AND_NULL(msg);
 779                 }
 780         }
 781
 782         if (*ref)
 783                 *ref = find_ref_by_name(*ref, refname);
 784         if (!*ref)
 785                 *ref = find_ref_by_name(remote_refs, refname);
 786         if (!*ref) {
 787                 warning(_("helper reported unexpected status of %s"), refname);
 788                 return 1;
 789         }
 790
 791         if ((*ref)->status != REF_STATUS_NONE) {
 792                 /*
 793                  * Earlier, the ref was marked not to be pushed, so ignore the ref
 794                  * status reported by the remote helper if the latter is 'no match'.
 795                  */
 796                 if (status == REF_STATUS_NONE)
 797                         return 1;
 798         }
 799
 800         (*ref)->status = status;
 801         (*ref)->forced_update |= forced;
 802         (*ref)->remote_status = msg;
 803         return !(status == REF_STATUS_OK);
 804 }
 805
 806 static int push_update_refs_status(struct helper_data *data,
 807                                     struct ref *remote_refs,
 808                                     int flags)
 809 {
 810         struct strbuf buf = STRBUF_INIT;
 811         struct ref *ref = remote_refs;
 812         int ret = 0;
 813
 814         for (;;) {
 815                 char *private;
 816
 817                 if (recvline(data, &buf)) {
 818                         ret = 1;
 819                         break;
 820                 }
 821
 822                 if (!buf.len)
 823                         break;
 824
 825                 if (push_update_ref_status(&buf, &ref, remote_refs))
 826                         continue;
 827
 828                 if (flags & TRANSPORT_PUSH_DRY_RUN || !data->rs.nr || data->no_private_update)
 829                         continue;
 830
 831                 /* propagate back the update to the remote namespace */
 832                 private = apply_refspecs(&data->rs, ref->name);
 833                 if (!private)
 834                         continue;
 835                 update_ref("update by helper", private, &ref->new_oid, NULL,
 836                            0, 0);
 837                 free(private);
 838         }
 839         strbuf_release(&buf);
 840         return ret;
 841 }
 842
 843 static void set_common_push_options(struct transport *transport,
 844                                    const char *name, int flags)
 845 {
 846         if (flags & TRANSPORT_PUSH_DRY_RUN) {
 847                 if (set_helper_option(transport, "dry-run", "true") != 0)
 848                         die(_("helper %s does not support dry-run"), name);
 849         } else if (flags & TRANSPORT_PUSH_CERT_ALWAYS) {
 850                 if (set_helper_option(transport, TRANS_OPT_PUSH_CERT, "true") != 0)
 851                         die(_("helper %s does not support --signed"), name);
 852         } else if (flags & TRANSPORT_PUSH_CERT_IF_ASKED) {
 853                 if (set_helper_option(transport, TRANS_OPT_PUSH_CERT, "if-asked") != 0)
 854                         die(_("helper %s does not support --signed=if-asked"), name);
 855         }
 856
 857         if (flags & TRANSPORT_PUSH_OPTIONS) {
 858                 struct string_list_item *item;
 859                 for_each_string_list_item(item, transport->push_options)
 860                         if (set_helper_option(transport, "push-option", item->string) != 0)
 861                                 die(_("helper %s does not support 'push-option'"), name);
 862         }
 863 }
 864
 865 static int push_refs_with_push(struct transport *transport,
 866                                struct ref *remote_refs, int flags)
 867 {
 868         int force_all = flags & TRANSPORT_PUSH_FORCE;
 869         int mirror = flags & TRANSPORT_PUSH_MIRROR;
 870         int atomic = flags & TRANSPORT_PUSH_ATOMIC;
 871         struct helper_data *data = transport->data;
 872         struct strbuf buf = STRBUF_INIT;
 873         struct ref *ref;
 874         struct string_list cas_options = STRING_LIST_INIT_DUP;
 875         struct string_list_item *cas_option;
 876
 877         get_helper(transport);
 878         if (!data->push)
 879                 return 1;
 880
 881         for (ref = remote_refs; ref; ref = ref->next) {
 882                 if (!ref->peer_ref && !mirror)
 883                         continue;
 884
 885                 /* Check for statuses set by set_ref_status_for_push() */
 886                 switch (ref->status) {
 887                 case REF_STATUS_REJECT_NONFASTFORWARD:
 888                 case REF_STATUS_REJECT_STALE:
 889                 case REF_STATUS_REJECT_ALREADY_EXISTS:
 890                         if (atomic) {
 891                                 string_list_clear(&cas_options, 0);
 892                                 return 0;
 893                         } else
 894                                 continue;
 895                 case REF_STATUS_UPTODATE:
 896                         continue;
 897                 default:
 898                         ; /* do nothing */
 899                 }
 900
 901                 if (force_all)
 902                         ref->force = 1;
 903
 904                 strbuf_addstr(&buf, "push ");
 905                 if (!ref->deletion) {
 906                         if (ref->force)
 907                                 strbuf_addch(&buf, '+');
 908                         if (ref->peer_ref)
 909                                 strbuf_addstr(&buf, ref->peer_ref->name);
 910                         else
 911                                 strbuf_addstr(&buf, oid_to_hex(&ref->new_oid));
 912                 }
 913                 strbuf_addch(&buf, ':');
 914                 strbuf_addstr(&buf, ref->name);
 915                 strbuf_addch(&buf, '\n');
 916
 917                 /*
 918                  * The "--force-with-lease" options without explicit
 919                  * values to expect have already been expanded into
 920                  * the ref->old_oid_expect[] field; we can ignore
 921                  * transport->smart_options->cas altogether and instead
 922                  * can enumerate them from the refs.
 923                  */
 924                 if (ref->expect_old_sha1) {
 925                         struct strbuf cas = STRBUF_INIT;
 926                         strbuf_addf(&cas, "%s:%s",
 927                                     ref->name, oid_to_hex(&ref->old_oid_expect));
 928                         string_list_append_nodup(&cas_options,
 929                                                  strbuf_detach(&cas, NULL));
 930                 }
 931         }
 932         if (buf.len == 0) {
 933                 string_list_clear(&cas_options, 0);
 934                 return 0;
 935         }
 936
 937         for_each_string_list_item(cas_option, &cas_options)
 938                 set_helper_option(transport, "cas", cas_option->string);
 939         set_common_push_options(transport, data->name, flags);
 940
 941         strbuf_addch(&buf, '\n');
 942         sendline(data, &buf);
 943         strbuf_release(&buf);
 944         string_list_clear(&cas_options, 0);
 945
 946         return push_update_refs_status(data, remote_refs, flags);
 947 }
 948
 949 static int push_refs_with_export(struct transport *transport,
 950                 struct ref *remote_refs, int flags)
 951 {
 952         struct ref *ref;
 953         struct child_process *helper, exporter;
 954         struct helper_data *data = transport->data;
 955         struct string_list revlist_args = STRING_LIST_INIT_DUP;
 956         struct strbuf buf = STRBUF_INIT;
 957
 958         if (!data->rs.nr)
 959                 die(_("remote-helper doesn't support push; refspec needed"));
 960
 961         set_common_push_options(transport, data->name, flags);
 962         if (flags & TRANSPORT_PUSH_FORCE) {
 963                 if (set_helper_option(transport, "force", "true") != 0)
 964                         warning(_("helper %s does not support 'force'"), data->name);
 965         }
 966
 967         helper = get_helper(transport);
 968
 969         write_constant(helper->in, "export\n");
 970
 971         for (ref = remote_refs; ref; ref = ref->next) {
 972                 char *private;
 973                 struct object_id oid;
 974
 975                 private = apply_refspecs(&data->rs, ref->name);
 976                 if (private && !get_oid(private, &oid)) {
 977                         strbuf_addf(&buf, "^%s", private);
 978                         string_list_append_nodup(&revlist_args,
 979                                                  strbuf_detach(&buf, NULL));
 980                         oidcpy(&ref->old_oid, &oid);
 981                 }
 982                 free(private);
 983
 984                 if (ref->peer_ref) {
 985                         if (strcmp(ref->name, ref->peer_ref->name)) {
 986                                 if (!ref->deletion) {
 987                                         const char *name;
 988                                         int flag;
 989
 990                                         /* Follow symbolic refs (mainly for HEAD). */
 991                                         name = resolve_ref_unsafe(ref->peer_ref->name,
 992                                                                   RESOLVE_REF_READING,
 993                                                                   &oid, &flag);
 994                                         if (!name || !(flag & REF_ISSYMREF))
 995                                                 name = ref->peer_ref->name;
 996
 997                                         strbuf_addf(&buf, "%s:%s", name, ref->name);
 998                                 } else
 999                                         strbuf_addf(&buf, ":%s", ref->name);
1000
1001                                 string_list_append(&revlist_args, "--refspec");
1002                                 string_list_append(&revlist_args, buf.buf);
1003                                 strbuf_release(&buf);
1004                         }
1005                         if (!ref->deletion)
1006                                 string_list_append(&revlist_args, ref->peer_ref->name);
1007                 }
1008         }
1009
1010         if (get_exporter(transport, &exporter, &revlist_args))
1011                 die(_("couldn't run fast-export"));
1012
1013         string_list_clear(&revlist_args, 1);
1014
1015         if (finish_command(&exporter))
1016                 die(_("error while running fast-export"));
1017         if (push_update_refs_status(data, remote_refs, flags))
1018                 return 1;
1019
1020         if (data->export_marks) {
1021                 strbuf_addf(&buf, "%s.tmp", data->export_marks);
1022                 rename(buf.buf, data->export_marks);
1023                 strbuf_release(&buf);
1024         }
1025
1026         return 0;
1027 }
1028
1029 static int push_refs(struct transport *transport,
1030                 struct ref *remote_refs, int flags)
1031 {
1032         struct helper_data *data = transport->data;
1033
1034         if (process_connect(transport, 1)) {
1035                 do_take_over(transport);
1036                 return transport->vtable->push_refs(transport, remote_refs, flags);
1037         }
1038
1039         if (!remote_refs) {
1040                 fprintf(stderr,
1041                         _("No refs in common and none specified; doing nothing.\n"
1042                           "Perhaps you should specify a branch such as 'master'.\n"));
1043                 return 0;
1044         }
1045
1046         if (data->push)
1047                 return push_refs_with_push(transport, remote_refs, flags);
1048
1049         if (data->export)
1050                 return push_refs_with_export(transport, remote_refs, flags);
1051
1052         return -1;
1053 }
1054
1055
1056 static int has_attribute(const char *attrs, const char *attr)
1057 {
1058         int len;
1059         if (!attrs)
1060                 return 0;
1061
1062         len = strlen(attr);
1063         for (;;) {
1064                 const char *space = strchrnul(attrs, ' ');
1065                 if (len == space - attrs && !strncmp(attrs, attr, len))
1066                         return 1;
1067                 if (!*space)
1068                         return 0;
1069                 attrs = space + 1;
1070         }
1071 }
1072
1073 static struct ref *get_refs_list(struct transport *transport, int for_push,
1074                                  const struct argv_array *ref_prefixes)
1075 {
1076         get_helper(transport);
1077
1078         if (process_connect(transport, for_push)) {
1079                 do_take_over(transport);
1080                 return transport->vtable->get_refs_list(transport, for_push, ref_prefixes);
1081         }
1082
1083         return get_refs_list_using_list(transport, for_push);
1084 }
1085
1086 static struct ref *get_refs_list_using_list(struct transport *transport,
1087                                             int for_push)
1088 {
1089         struct helper_data *data = transport->data;
1090         struct child_process *helper;
1091         struct ref *ret = NULL;
1092         struct ref **tail = &ret;
1093         struct ref *posn;
1094         struct strbuf buf = STRBUF_INIT;
1095
1096         data->get_refs_list_called = 1;
1097         helper = get_helper(transport);
1098
1099         if (data->push && for_push)
1100                 write_str_in_full(helper->in, "list for-push\n");
1101         else
1102                 write_str_in_full(helper->in, "list\n");
1103
1104         while (1) {
1105                 char *eov, *eon;
1106                 if (recvline(data, &buf))
1107                         exit(128);
1108
1109                 if (!*buf.buf)
1110                         break;
1111
1112                 eov = strchr(buf.buf, ' ');
1113                 if (!eov)
1114                         die(_("malformed response in ref list: %s"), buf.buf);
1115                 eon = strchr(eov + 1, ' ');
1116                 *eov = '\0';
1117                 if (eon)
1118                         *eon = '\0';
1119                 *tail = alloc_ref(eov + 1);
1120                 if (buf.buf[0] == '@')
1121                         (*tail)->symref = xstrdup(buf.buf + 1);
1122                 else if (buf.buf[0] != '?')
1123                         get_oid_hex(buf.buf, &(*tail)->old_oid);
1124                 if (eon) {
1125                         if (has_attribute(eon + 1, "unchanged")) {
1126                                 (*tail)->status |= REF_STATUS_UPTODATE;
1127                                 if (read_ref((*tail)->name, &(*tail)->old_oid) < 0)
1128                                         die(_("could not read ref %s"),
1129                                             (*tail)->name);
1130                         }
1131                 }
1132                 tail = &((*tail)->next);
1133         }
1134         if (debug)
1135                 fprintf(stderr, "Debug: Read ref listing.\n");
1136         strbuf_release(&buf);
1137
1138         for (posn = ret; posn; posn = posn->next)
1139                 resolve_remote_symref(posn, ret);
1140
1141         return ret;
1142 }
1143
1144 static struct transport_vtable vtable = {
1145         set_helper_option,
1146         get_refs_list,
1147         fetch,
1148         push_refs,
1149         connect_helper,
1150         release_helper
1151 };
1152
1153 int transport_helper_init(struct transport *transport, const char *name)
1154 {
1155         struct helper_data *data = xcalloc(1, sizeof(*data));
1156         data->name = name;
1157
1158         transport_check_allowed(name);
1159
1160         if (getenv("GIT_TRANSPORT_HELPER_DEBUG"))
1161                 debug = 1;
1162
1163         transport->data = data;
1164         transport->vtable = &vtable;
1165         transport->smart_options = &(data->transport_options);
1166         return 0;
1167 }
1168
1169 /*
1170  * Linux pipes can buffer 65536 bytes at once (and most platforms can
1171  * buffer less), so attempt reads and writes with up to that size.
1172  */
1173 #define BUFFERSIZE 65536
1174 /* This should be enough to hold debugging message. */
1175 #define PBUFFERSIZE 8192
1176
1177 /* Print bidirectional transfer loop debug message. */
1178 __attribute__((format (printf, 1, 2)))
1179 static void transfer_debug(const char *fmt, ...)
1180 {
1181         /*
1182          * NEEDSWORK: This function is sometimes used from multiple threads, and
1183          * we end up using debug_enabled racily. That "should not matter" since
1184          * we always write the same value, but it's still wrong. This function
1185          * is listed in .tsan-suppressions for the time being.
1186          */
1187
1188         va_list args;
1189         char msgbuf[PBUFFERSIZE];
1190         static int debug_enabled = -1;
1191
1192         if (debug_enabled < 0)
1193                 debug_enabled = getenv("GIT_TRANSLOOP_DEBUG") ? 1 : 0;
1194         if (!debug_enabled)
1195                 return;
1196
1197         va_start(args, fmt);
1198         vsnprintf(msgbuf, PBUFFERSIZE, fmt, args);
1199         va_end(args);
1200         fprintf(stderr, "Transfer loop debugging: %s\n", msgbuf);
1201 }
1202
1203 /* Stream state: More data may be coming in this direction. */
1204 #define SSTATE_TRANSFERRING 0
1205 /*
1206  * Stream state: No more data coming in this direction, flushing rest of
1207  * data.
1208  */
1209 #define SSTATE_FLUSHING 1
1210 /* Stream state: Transfer in this direction finished. */
1211 #define SSTATE_FINISHED 2
1212
1213 #define STATE_NEEDS_READING(state) ((state) <= SSTATE_TRANSFERRING)
1214 #define STATE_NEEDS_WRITING(state) ((state) <= SSTATE_FLUSHING)
1215 #define STATE_NEEDS_CLOSING(state) ((state) == SSTATE_FLUSHING)
1216
1217 /* Unidirectional transfer. */
1218 struct unidirectional_transfer {
1219         /* Source */
1220         int src;
1221         /* Destination */
1222         int dest;
1223         /* Is source socket? */
1224         int src_is_sock;
1225         /* Is destination socket? */
1226         int dest_is_sock;
1227         /* Transfer state (TRANSFERRING/FLUSHING/FINISHED) */
1228         int state;
1229         /* Buffer. */
1230         char buf[BUFFERSIZE];
1231         /* Buffer used. */
1232         size_t bufuse;
1233         /* Name of source. */
1234         const char *src_name;
1235         /* Name of destination. */
1236         const char *dest_name;
1237 };
1238
1239 /* Closes the target (for writing) if transfer has finished. */
1240 static void udt_close_if_finished(struct unidirectional_transfer *t)
1241 {
1242         if (STATE_NEEDS_CLOSING(t->state) && !t->bufuse) {
1243                 t->state = SSTATE_FINISHED;
1244                 if (t->dest_is_sock)
1245                         shutdown(t->dest, SHUT_WR);
1246                 else
1247                         close(t->dest);
1248                 transfer_debug("Closed %s.", t->dest_name);
1249         }
1250 }
1251
1252 /*
1253  * Tries to read data from source into buffer. If buffer is full,
1254  * no data is read. Returns 0 on success, -1 on error.
1255  */
1256 static int udt_do_read(struct unidirectional_transfer *t)
1257 {
1258         ssize_t bytes;
1259
1260         if (t->bufuse == BUFFERSIZE)
1261                 return 0;       /* No space for more. */
1262
1263         transfer_debug("%s is readable", t->src_name);
1264         bytes = xread(t->src, t->buf + t->bufuse, BUFFERSIZE - t->bufuse);
1265         if (bytes < 0) {
1266                 error_errno(_("read(%s) failed"), t->src_name);
1267                 return -1;
1268         } else if (bytes == 0) {
1269                 transfer_debug("%s EOF (with %i bytes in buffer)",
1270                         t->src_name, (int)t->bufuse);
1271                 t->state = SSTATE_FLUSHING;
1272         } else if (bytes > 0) {
1273                 t->bufuse += bytes;
1274                 transfer_debug("Read %i bytes from %s (buffer now at %i)",
1275                         (int)bytes, t->src_name, (int)t->bufuse);
1276         }
1277         return 0;
1278 }
1279
1280 /* Tries to write data from buffer into destination. If buffer is empty,
1281  * no data is written. Returns 0 on success, -1 on error.
1282  */
1283 static int udt_do_write(struct unidirectional_transfer *t)
1284 {
1285         ssize_t bytes;
1286
1287         if (t->bufuse == 0)
1288                 return 0;       /* Nothing to write. */
1289
1290         transfer_debug("%s is writable", t->dest_name);
1291         bytes = xwrite(t->dest, t->buf, t->bufuse);
1292         if (bytes < 0) {
1293                 error_errno(_("write(%s) failed"), t->dest_name);
1294                 return -1;
1295         } else if (bytes > 0) {
1296                 t->bufuse -= bytes;
1297                 if (t->bufuse)
1298                         memmove(t->buf, t->buf + bytes, t->bufuse);
1299                 transfer_debug("Wrote %i bytes to %s (buffer now at %i)",
1300                         (int)bytes, t->dest_name, (int)t->bufuse);
1301         }
1302         return 0;
1303 }
1304
1305
1306 /* State of bidirectional transfer loop. */
1307 struct bidirectional_transfer_state {
1308         /* Direction from program to git. */
1309         struct unidirectional_transfer ptg;
1310         /* Direction from git to program. */
1311         struct unidirectional_transfer gtp;
1312 };
1313
1314 static void *udt_copy_task_routine(void *udt)
1315 {
1316         struct unidirectional_transfer *t = (struct unidirectional_transfer *)udt;
1317         while (t->state != SSTATE_FINISHED) {
1318                 if (STATE_NEEDS_READING(t->state))
1319                         if (udt_do_read(t))
1320                                 return NULL;
1321                 if (STATE_NEEDS_WRITING(t->state))
1322                         if (udt_do_write(t))
1323                                 return NULL;
1324                 if (STATE_NEEDS_CLOSING(t->state))
1325                         udt_close_if_finished(t);
1326         }
1327         return udt;     /* Just some non-NULL value. */
1328 }
1329
1330 #ifndef NO_PTHREADS
1331
1332 /*
1333  * Join thread, with appropriate errors on failure. Name is name for the
1334  * thread (for error messages). Returns 0 on success, 1 on failure.
1335  */
1336 static int tloop_join(pthread_t thread, const char *name)
1337 {
1338         int err;
1339         void *tret;
1340         err = pthread_join(thread, &tret);
1341         if (!tret) {
1342                 error(_("%s thread failed"), name);
1343                 return 1;
1344         }
1345         if (err) {
1346                 error(_("%s thread failed to join: %s"), name, strerror(err));
1347                 return 1;
1348         }
1349         return 0;
1350 }
1351
1352 /*
1353  * Spawn the transfer tasks and then wait for them. Returns 0 on success,
1354  * -1 on failure.
1355  */
1356 static int tloop_spawnwait_tasks(struct bidirectional_transfer_state *s)
1357 {
1358         pthread_t gtp_thread;
1359         pthread_t ptg_thread;
1360         int err;
1361         int ret = 0;
1362         err = pthread_create(&gtp_thread, NULL, udt_copy_task_routine,
1363                 &s->gtp);
1364         if (err)
1365                 die(_("can't start thread for copying data: %s"), strerror(err));
1366         err = pthread_create(&ptg_thread, NULL, udt_copy_task_routine,
1367                 &s->ptg);
1368         if (err)
1369                 die(_("can't start thread for copying data: %s"), strerror(err));
1370
1371         ret |= tloop_join(gtp_thread, "Git to program copy");
1372         ret |= tloop_join(ptg_thread, "Program to git copy");
1373         return ret;
1374 }
1375 #else
1376
1377 /* Close the source and target (for writing) for transfer. */
1378 static void udt_kill_transfer(struct unidirectional_transfer *t)
1379 {
1380         t->state = SSTATE_FINISHED;
1381         /*
1382          * Socket read end left open isn't a disaster if nobody
1383          * attempts to read from it (mingw compat headers do not
1384          * have SHUT_RD)...
1385          *
1386          * We can't fully close the socket since otherwise gtp
1387          * task would first close the socket it sends data to
1388          * while closing the ptg file descriptors.
1389          */
1390         if (!t->src_is_sock)
1391                 close(t->src);
1392         if (t->dest_is_sock)
1393                 shutdown(t->dest, SHUT_WR);
1394         else
1395                 close(t->dest);
1396 }
1397
1398 /*
1399  * Join process, with appropriate errors on failure. Name is name for the
1400  * process (for error messages). Returns 0 on success, 1 on failure.
1401  */
1402 static int tloop_join(pid_t pid, const char *name)
1403 {
1404         int tret;
1405         if (waitpid(pid, &tret, 0) < 0) {
1406                 error_errno(_("%s process failed to wait"), name);
1407                 return 1;
1408         }
1409         if (!WIFEXITED(tret) || WEXITSTATUS(tret)) {
1410                 error(_("%s process failed"), name);
1411                 return 1;
1412         }
1413         return 0;
1414 }
1415
1416 /*
1417  * Spawn the transfer tasks and then wait for them. Returns 0 on success,
1418  * -1 on failure.
1419  */
1420 static int tloop_spawnwait_tasks(struct bidirectional_transfer_state *s)
1421 {
1422         pid_t pid1, pid2;
1423         int ret = 0;
1424
1425         /* Fork thread #1: git to program. */
1426         pid1 = fork();
1427         if (pid1 < 0)
1428                 die_errno(_("can't start thread for copying data"));
1429         else if (pid1 == 0) {
1430                 udt_kill_transfer(&s->ptg);
1431                 exit(udt_copy_task_routine(&s->gtp) ? 0 : 1);
1432         }
1433
1434         /* Fork thread #2: program to git. */
1435         pid2 = fork();
1436         if (pid2 < 0)
1437                 die_errno(_("can't start thread for copying data"));
1438         else if (pid2 == 0) {
1439                 udt_kill_transfer(&s->gtp);
1440                 exit(udt_copy_task_routine(&s->ptg) ? 0 : 1);
1441         }
1442
1443         /*
1444          * Close both streams in parent as to not interfere with
1445          * end of file detection and wait for both tasks to finish.
1446          */
1447         udt_kill_transfer(&s->gtp);
1448         udt_kill_transfer(&s->ptg);
1449         ret |= tloop_join(pid1, "Git to program copy");
1450         ret |= tloop_join(pid2, "Program to git copy");
1451         return ret;
1452 }
1453 #endif
1454
1455 /*
1456  * Copies data from stdin to output and from input to stdout simultaneously.
1457  * Additionally filtering through given filter. If filter is NULL, uses
1458  * identity filter.
1459  */
1460 int bidirectional_transfer_loop(int input, int output)
1461 {
1462         struct bidirectional_transfer_state state;
1463
1464         /* Fill the state fields. */
1465         state.ptg.src = input;
1466         state.ptg.dest = 1;
1467         state.ptg.src_is_sock = (input == output);
1468         state.ptg.dest_is_sock = 0;
1469         state.ptg.state = SSTATE_TRANSFERRING;
1470         state.ptg.bufuse = 0;
1471         state.ptg.src_name = "remote input";
1472         state.ptg.dest_name = "stdout";
1473
1474         state.gtp.src = 0;
1475         state.gtp.dest = output;
1476         state.gtp.src_is_sock = 0;
1477         state.gtp.dest_is_sock = (input == output);
1478         state.gtp.state = SSTATE_TRANSFERRING;
1479         state.gtp.bufuse = 0;
1480         state.gtp.src_name = "stdin";
1481         state.gtp.dest_name = "remote output";
1482
1483         return tloop_spawnwait_tasks(&state);
1484 }