Merge branch 'jk/merge-tree-added-identically'
[git] / 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 "quote.h"
9 #include "remote.h"
10 #include "string-list.h"
11 #include "thread-utils.h"
12 #include "sigchain.h"
13 #include "argv-array.h"
14
15 static int debug;
16
17 struct helper_data {
18         const char *name;
19         struct child_process *helper;
20         FILE *out;
21         unsigned fetch : 1,
22                 import : 1,
23                 bidi_import : 1,
24                 export : 1,
25                 option : 1,
26                 push : 1,
27                 connect : 1,
28                 signed_tags : 1,
29                 no_disconnect_req : 1;
30         char *export_marks;
31         char *import_marks;
32         /* These go from remote name (as in "list") to private name */
33         struct refspec *refspecs;
34         int refspec_nr;
35         /* Transport options for fetch-pack/send-pack (should one of
36          * those be invoked).
37          */
38         struct git_transport_options transport_options;
39 };
40
41 static void sendline(struct helper_data *helper, struct strbuf *buffer)
42 {
43         if (debug)
44                 fprintf(stderr, "Debug: Remote helper: -> %s", buffer->buf);
45         if (write_in_full(helper->helper->in, buffer->buf, buffer->len)
46                 != buffer->len)
47                 die_errno("Full write to remote helper failed");
48 }
49
50 static int recvline_fh(FILE *helper, struct strbuf *buffer)
51 {
52         strbuf_reset(buffer);
53         if (debug)
54                 fprintf(stderr, "Debug: Remote helper: Waiting...\n");
55         if (strbuf_getline(buffer, helper, '\n') == EOF) {
56                 if (debug)
57                         fprintf(stderr, "Debug: Remote helper quit.\n");
58                 exit(128);
59         }
60
61         if (debug)
62                 fprintf(stderr, "Debug: Remote helper: <- %s\n", buffer->buf);
63         return 0;
64 }
65
66 static int recvline(struct helper_data *helper, struct strbuf *buffer)
67 {
68         return recvline_fh(helper->out, buffer);
69 }
70
71 static void xchgline(struct helper_data *helper, struct strbuf *buffer)
72 {
73         sendline(helper, buffer);
74         recvline(helper, buffer);
75 }
76
77 static void write_constant(int fd, const char *str)
78 {
79         if (debug)
80                 fprintf(stderr, "Debug: Remote helper: -> %s", str);
81         if (write_in_full(fd, str, strlen(str)) != strlen(str))
82                 die_errno("Full write to remote helper failed");
83 }
84
85 static const char *remove_ext_force(const char *url)
86 {
87         if (url) {
88                 const char *colon = strchr(url, ':');
89                 if (colon && colon[1] == ':')
90                         return colon + 2;
91         }
92         return url;
93 }
94
95 static void do_take_over(struct transport *transport)
96 {
97         struct helper_data *data;
98         data = (struct helper_data *)transport->data;
99         transport_take_over(transport, data->helper);
100         fclose(data->out);
101         free(data);
102 }
103
104 static struct child_process *get_helper(struct transport *transport)
105 {
106         struct helper_data *data = transport->data;
107         struct argv_array argv = ARGV_ARRAY_INIT;
108         struct strbuf buf = STRBUF_INIT;
109         struct child_process *helper;
110         const char **refspecs = NULL;
111         int refspec_nr = 0;
112         int refspec_alloc = 0;
113         int duped;
114         int code;
115         char git_dir_buf[sizeof(GIT_DIR_ENVIRONMENT) + PATH_MAX + 1];
116         const char *helper_env[] = {
117                 git_dir_buf,
118                 NULL
119         };
120
121
122         if (data->helper)
123                 return data->helper;
124
125         helper = xcalloc(1, sizeof(*helper));
126         helper->in = -1;
127         helper->out = -1;
128         helper->err = 0;
129         argv_array_pushf(&argv, "git-remote-%s", data->name);
130         argv_array_push(&argv, transport->remote->name);
131         argv_array_push(&argv, remove_ext_force(transport->url));
132         helper->argv = argv_array_detach(&argv, NULL);
133         helper->git_cmd = 0;
134         helper->silent_exec_failure = 1;
135
136         snprintf(git_dir_buf, sizeof(git_dir_buf), "%s=%s", GIT_DIR_ENVIRONMENT, get_git_dir());
137         helper->env = helper_env;
138
139         code = start_command(helper);
140         if (code < 0 && errno == ENOENT)
141                 die("Unable to find remote helper for '%s'", data->name);
142         else if (code != 0)
143                 exit(code);
144
145         data->helper = helper;
146         data->no_disconnect_req = 0;
147
148         /*
149          * Open the output as FILE* so strbuf_getline() can be used.
150          * Do this with duped fd because fclose() will close the fd,
151          * and stuff like taking over will require the fd to remain.
152          */
153         duped = dup(helper->out);
154         if (duped < 0)
155                 die_errno("Can't dup helper output fd");
156         data->out = xfdopen(duped, "r");
157
158         write_constant(helper->in, "capabilities\n");
159
160         while (1) {
161                 const char *capname;
162                 int mandatory = 0;
163                 recvline(data, &buf);
164
165                 if (!*buf.buf)
166                         break;
167
168                 if (*buf.buf == '*') {
169                         capname = buf.buf + 1;
170                         mandatory = 1;
171                 } else
172                         capname = buf.buf;
173
174                 if (debug)
175                         fprintf(stderr, "Debug: Got cap %s\n", capname);
176                 if (!strcmp(capname, "fetch"))
177                         data->fetch = 1;
178                 else if (!strcmp(capname, "option"))
179                         data->option = 1;
180                 else if (!strcmp(capname, "push"))
181                         data->push = 1;
182                 else if (!strcmp(capname, "import"))
183                         data->import = 1;
184                 else if (!strcmp(capname, "bidi-import"))
185                         data->bidi_import = 1;
186                 else if (!strcmp(capname, "export"))
187                         data->export = 1;
188                 else if (!data->refspecs && !prefixcmp(capname, "refspec ")) {
189                         ALLOC_GROW(refspecs,
190                                    refspec_nr + 1,
191                                    refspec_alloc);
192                         refspecs[refspec_nr++] = xstrdup(capname + strlen("refspec "));
193                 } else if (!strcmp(capname, "connect")) {
194                         data->connect = 1;
195                 } else if (!strcmp(capname, "signed-tags")) {
196                         data->signed_tags = 1;
197                 } else if (!prefixcmp(capname, "export-marks ")) {
198                         struct strbuf arg = STRBUF_INIT;
199                         strbuf_addstr(&arg, "--export-marks=");
200                         strbuf_addstr(&arg, capname + strlen("export-marks "));
201                         data->export_marks = strbuf_detach(&arg, NULL);
202                 } else if (!prefixcmp(capname, "import-marks")) {
203                         struct strbuf arg = STRBUF_INIT;
204                         strbuf_addstr(&arg, "--import-marks=");
205                         strbuf_addstr(&arg, capname + strlen("import-marks "));
206                         data->import_marks = strbuf_detach(&arg, NULL);
207                 } else if (mandatory) {
208                         die("Unknown mandatory capability %s. This remote "
209                             "helper probably needs newer version of Git.",
210                             capname);
211                 }
212         }
213         if (refspecs) {
214                 int i;
215                 data->refspec_nr = refspec_nr;
216                 data->refspecs = parse_fetch_refspec(refspec_nr, refspecs);
217                 for (i = 0; i < refspec_nr; i++) {
218                         free((char *)refspecs[i]);
219                 }
220                 free(refspecs);
221         }
222         strbuf_release(&buf);
223         if (debug)
224                 fprintf(stderr, "Debug: Capabilities complete.\n");
225         return data->helper;
226 }
227
228 static int disconnect_helper(struct transport *transport)
229 {
230         struct helper_data *data = transport->data;
231         int res = 0;
232
233         if (data->helper) {
234                 if (debug)
235                         fprintf(stderr, "Debug: Disconnecting.\n");
236                 if (!data->no_disconnect_req) {
237                         /*
238                          * Ignore write errors; there's nothing we can do,
239                          * since we're about to close the pipe anyway. And the
240                          * most likely error is EPIPE due to the helper dying
241                          * to report an error itself.
242                          */
243                         sigchain_push(SIGPIPE, SIG_IGN);
244                         xwrite(data->helper->in, "\n", 1);
245                         sigchain_pop(SIGPIPE);
246                 }
247                 close(data->helper->in);
248                 close(data->helper->out);
249                 fclose(data->out);
250                 res = finish_command(data->helper);
251                 argv_array_free_detached(data->helper->argv);
252                 free(data->helper);
253                 data->helper = NULL;
254         }
255         return res;
256 }
257
258 static const char *unsupported_options[] = {
259         TRANS_OPT_UPLOADPACK,
260         TRANS_OPT_RECEIVEPACK,
261         TRANS_OPT_THIN,
262         TRANS_OPT_KEEP
263         };
264 static const char *boolean_options[] = {
265         TRANS_OPT_THIN,
266         TRANS_OPT_KEEP,
267         TRANS_OPT_FOLLOWTAGS
268         };
269
270 static int set_helper_option(struct transport *transport,
271                           const char *name, const char *value)
272 {
273         struct helper_data *data = transport->data;
274         struct strbuf buf = STRBUF_INIT;
275         int i, ret, is_bool = 0;
276
277         get_helper(transport);
278
279         if (!data->option)
280                 return 1;
281
282         for (i = 0; i < ARRAY_SIZE(unsupported_options); i++) {
283                 if (!strcmp(name, unsupported_options[i]))
284                         return 1;
285         }
286
287         for (i = 0; i < ARRAY_SIZE(boolean_options); i++) {
288                 if (!strcmp(name, boolean_options[i])) {
289                         is_bool = 1;
290                         break;
291                 }
292         }
293
294         strbuf_addf(&buf, "option %s ", name);
295         if (is_bool)
296                 strbuf_addstr(&buf, value ? "true" : "false");
297         else
298                 quote_c_style(value, &buf, NULL, 0);
299         strbuf_addch(&buf, '\n');
300
301         xchgline(data, &buf);
302
303         if (!strcmp(buf.buf, "ok"))
304                 ret = 0;
305         else if (!prefixcmp(buf.buf, "error")) {
306                 ret = -1;
307         } else if (!strcmp(buf.buf, "unsupported"))
308                 ret = 1;
309         else {
310                 warning("%s unexpectedly said: '%s'", data->name, buf.buf);
311                 ret = 1;
312         }
313         strbuf_release(&buf);
314         return ret;
315 }
316
317 static void standard_options(struct transport *t)
318 {
319         char buf[16];
320         int n;
321         int v = t->verbose;
322
323         set_helper_option(t, "progress", t->progress ? "true" : "false");
324
325         n = snprintf(buf, sizeof(buf), "%d", v + 1);
326         if (n >= sizeof(buf))
327                 die("impossibly large verbosity value");
328         set_helper_option(t, "verbosity", buf);
329 }
330
331 static int release_helper(struct transport *transport)
332 {
333         int res = 0;
334         struct helper_data *data = transport->data;
335         free_refspec(data->refspec_nr, data->refspecs);
336         data->refspecs = NULL;
337         res = disconnect_helper(transport);
338         free(transport->data);
339         return res;
340 }
341
342 static int fetch_with_fetch(struct transport *transport,
343                             int nr_heads, struct ref **to_fetch)
344 {
345         struct helper_data *data = transport->data;
346         int i;
347         struct strbuf buf = STRBUF_INIT;
348
349         standard_options(transport);
350
351         for (i = 0; i < nr_heads; i++) {
352                 const struct ref *posn = to_fetch[i];
353                 if (posn->status & REF_STATUS_UPTODATE)
354                         continue;
355
356                 strbuf_addf(&buf, "fetch %s %s\n",
357                             sha1_to_hex(posn->old_sha1), posn->name);
358         }
359
360         strbuf_addch(&buf, '\n');
361         sendline(data, &buf);
362
363         while (1) {
364                 recvline(data, &buf);
365
366                 if (!prefixcmp(buf.buf, "lock ")) {
367                         const char *name = buf.buf + 5;
368                         if (transport->pack_lockfile)
369                                 warning("%s also locked %s", data->name, name);
370                         else
371                                 transport->pack_lockfile = xstrdup(name);
372                 }
373                 else if (!buf.len)
374                         break;
375                 else
376                         warning("%s unexpectedly said: '%s'", data->name, buf.buf);
377         }
378         strbuf_release(&buf);
379         return 0;
380 }
381
382 static int get_importer(struct transport *transport, struct child_process *fastimport)
383 {
384         struct child_process *helper = get_helper(transport);
385         struct helper_data *data = transport->data;
386         struct argv_array argv = ARGV_ARRAY_INIT;
387         int cat_blob_fd, code;
388         memset(fastimport, 0, sizeof(*fastimport));
389         fastimport->in = helper->out;
390         argv_array_push(&argv, "fast-import");
391         argv_array_push(&argv, debug ? "--stats" : "--quiet");
392
393         if (data->bidi_import) {
394                 cat_blob_fd = xdup(helper->in);
395                 argv_array_pushf(&argv, "--cat-blob-fd=%d", cat_blob_fd);
396         }
397         fastimport->argv = argv.argv;
398         fastimport->git_cmd = 1;
399
400         code = start_command(fastimport);
401         return code;
402 }
403
404 static int get_exporter(struct transport *transport,
405                         struct child_process *fastexport,
406                         struct string_list *revlist_args)
407 {
408         struct helper_data *data = transport->data;
409         struct child_process *helper = get_helper(transport);
410         int argc = 0, i;
411         memset(fastexport, 0, sizeof(*fastexport));
412
413         /* we need to duplicate helper->in because we want to use it after
414          * fastexport is done with it. */
415         fastexport->out = dup(helper->in);
416         fastexport->argv = xcalloc(6 + revlist_args->nr, sizeof(*fastexport->argv));
417         fastexport->argv[argc++] = "fast-export";
418         fastexport->argv[argc++] = "--use-done-feature";
419         fastexport->argv[argc++] = data->signed_tags ?
420                 "--signed-tags=verbatim" : "--signed-tags=warn-strip";
421         if (data->export_marks)
422                 fastexport->argv[argc++] = data->export_marks;
423         if (data->import_marks)
424                 fastexport->argv[argc++] = data->import_marks;
425
426         for (i = 0; i < revlist_args->nr; i++)
427                 fastexport->argv[argc++] = revlist_args->items[i].string;
428
429         fastexport->git_cmd = 1;
430         return start_command(fastexport);
431 }
432
433 static int fetch_with_import(struct transport *transport,
434                              int nr_heads, struct ref **to_fetch)
435 {
436         struct child_process fastimport;
437         struct helper_data *data = transport->data;
438         int i;
439         struct ref *posn;
440         struct strbuf buf = STRBUF_INIT;
441
442         get_helper(transport);
443
444         if (get_importer(transport, &fastimport))
445                 die("Couldn't run fast-import");
446
447         for (i = 0; i < nr_heads; i++) {
448                 posn = to_fetch[i];
449                 if (posn->status & REF_STATUS_UPTODATE)
450                         continue;
451
452                 strbuf_addf(&buf, "import %s\n", posn->name);
453                 sendline(data, &buf);
454                 strbuf_reset(&buf);
455         }
456
457         write_constant(data->helper->in, "\n");
458         /*
459          * remote-helpers that advertise the bidi-import capability are required to
460          * buffer the complete batch of import commands until this newline before
461          * sending data to fast-import.
462          * These helpers read back data from fast-import on their stdin, which could
463          * be mixed with import commands, otherwise.
464          */
465
466         if (finish_command(&fastimport))
467                 die("Error while running fast-import");
468         argv_array_free_detached(fastimport.argv);
469
470         /*
471          * The fast-import stream of a remote helper that advertises
472          * the "refspec" capability writes to the refs named after the
473          * right hand side of the first refspec matching each ref we
474          * were fetching.
475          *
476          * (If no "refspec" capability was specified, for historical
477          * reasons we default to *:*.)
478          *
479          * Store the result in to_fetch[i].old_sha1.  Callers such
480          * as "git fetch" can use the value to write feedback to the
481          * terminal, populate FETCH_HEAD, and determine what new value
482          * should be written to peer_ref if the update is a
483          * fast-forward or this is a forced update.
484          */
485         for (i = 0; i < nr_heads; i++) {
486                 char *private;
487                 posn = to_fetch[i];
488                 if (posn->status & REF_STATUS_UPTODATE)
489                         continue;
490                 if (data->refspecs)
491                         private = apply_refspecs(data->refspecs, data->refspec_nr, posn->name);
492                 else
493                         private = xstrdup(posn->name);
494                 if (private) {
495                         read_ref(private, posn->old_sha1);
496                         free(private);
497                 }
498         }
499         strbuf_release(&buf);
500         return 0;
501 }
502
503 static int process_connect_service(struct transport *transport,
504                                    const char *name, const char *exec)
505 {
506         struct helper_data *data = transport->data;
507         struct strbuf cmdbuf = STRBUF_INIT;
508         struct child_process *helper;
509         int r, duped, ret = 0;
510         FILE *input;
511
512         helper = get_helper(transport);
513
514         /*
515          * Yes, dup the pipe another time, as we need unbuffered version
516          * of input pipe as FILE*. fclose() closes the underlying fd and
517          * stream buffering only can be changed before first I/O operation
518          * on it.
519          */
520         duped = dup(helper->out);
521         if (duped < 0)
522                 die_errno("Can't dup helper output fd");
523         input = xfdopen(duped, "r");
524         setvbuf(input, NULL, _IONBF, 0);
525
526         /*
527          * Handle --upload-pack and friends. This is fire and forget...
528          * just warn if it fails.
529          */
530         if (strcmp(name, exec)) {
531                 r = set_helper_option(transport, "servpath", exec);
532                 if (r > 0)
533                         warning("Setting remote service path not supported by protocol.");
534                 else if (r < 0)
535                         warning("Invalid remote service path.");
536         }
537
538         if (data->connect)
539                 strbuf_addf(&cmdbuf, "connect %s\n", name);
540         else
541                 goto exit;
542
543         sendline(data, &cmdbuf);
544         recvline_fh(input, &cmdbuf);
545         if (!strcmp(cmdbuf.buf, "")) {
546                 data->no_disconnect_req = 1;
547                 if (debug)
548                         fprintf(stderr, "Debug: Smart transport connection "
549                                 "ready.\n");
550                 ret = 1;
551         } else if (!strcmp(cmdbuf.buf, "fallback")) {
552                 if (debug)
553                         fprintf(stderr, "Debug: Falling back to dumb "
554                                 "transport.\n");
555         } else
556                 die("Unknown response to connect: %s",
557                         cmdbuf.buf);
558
559 exit:
560         fclose(input);
561         return ret;
562 }
563
564 static int process_connect(struct transport *transport,
565                                      int for_push)
566 {
567         struct helper_data *data = transport->data;
568         const char *name;
569         const char *exec;
570
571         name = for_push ? "git-receive-pack" : "git-upload-pack";
572         if (for_push)
573                 exec = data->transport_options.receivepack;
574         else
575                 exec = data->transport_options.uploadpack;
576
577         return process_connect_service(transport, name, exec);
578 }
579
580 static int connect_helper(struct transport *transport, const char *name,
581                    const char *exec, int fd[2])
582 {
583         struct helper_data *data = transport->data;
584
585         /* Get_helper so connect is inited. */
586         get_helper(transport);
587         if (!data->connect)
588                 die("Operation not supported by protocol.");
589
590         if (!process_connect_service(transport, name, exec))
591                 die("Can't connect to subservice %s.", name);
592
593         fd[0] = data->helper->out;
594         fd[1] = data->helper->in;
595         return 0;
596 }
597
598 static int fetch(struct transport *transport,
599                  int nr_heads, struct ref **to_fetch)
600 {
601         struct helper_data *data = transport->data;
602         int i, count;
603
604         if (process_connect(transport, 0)) {
605                 do_take_over(transport);
606                 return transport->fetch(transport, nr_heads, to_fetch);
607         }
608
609         count = 0;
610         for (i = 0; i < nr_heads; i++)
611                 if (!(to_fetch[i]->status & REF_STATUS_UPTODATE))
612                         count++;
613
614         if (!count)
615                 return 0;
616
617         if (data->fetch)
618                 return fetch_with_fetch(transport, nr_heads, to_fetch);
619
620         if (data->import)
621                 return fetch_with_import(transport, nr_heads, to_fetch);
622
623         return -1;
624 }
625
626 static void push_update_ref_status(struct strbuf *buf,
627                                    struct ref **ref,
628                                    struct ref *remote_refs)
629 {
630         char *refname, *msg;
631         int status;
632
633         if (!prefixcmp(buf->buf, "ok ")) {
634                 status = REF_STATUS_OK;
635                 refname = buf->buf + 3;
636         } else if (!prefixcmp(buf->buf, "error ")) {
637                 status = REF_STATUS_REMOTE_REJECT;
638                 refname = buf->buf + 6;
639         } else
640                 die("expected ok/error, helper said '%s'", buf->buf);
641
642         msg = strchr(refname, ' ');
643         if (msg) {
644                 struct strbuf msg_buf = STRBUF_INIT;
645                 const char *end;
646
647                 *msg++ = '\0';
648                 if (!unquote_c_style(&msg_buf, msg, &end))
649                         msg = strbuf_detach(&msg_buf, NULL);
650                 else
651                         msg = xstrdup(msg);
652                 strbuf_release(&msg_buf);
653
654                 if (!strcmp(msg, "no match")) {
655                         status = REF_STATUS_NONE;
656                         free(msg);
657                         msg = NULL;
658                 }
659                 else if (!strcmp(msg, "up to date")) {
660                         status = REF_STATUS_UPTODATE;
661                         free(msg);
662                         msg = NULL;
663                 }
664                 else if (!strcmp(msg, "non-fast forward")) {
665                         status = REF_STATUS_REJECT_NONFASTFORWARD;
666                         free(msg);
667                         msg = NULL;
668                 }
669                 else if (!strcmp(msg, "already exists")) {
670                         status = REF_STATUS_REJECT_ALREADY_EXISTS;
671                         free(msg);
672                         msg = NULL;
673                 }
674                 else if (!strcmp(msg, "fetch first")) {
675                         status = REF_STATUS_REJECT_FETCH_FIRST;
676                         free(msg);
677                         msg = NULL;
678                 }
679                 else if (!strcmp(msg, "needs force")) {
680                         status = REF_STATUS_REJECT_NEEDS_FORCE;
681                         free(msg);
682                         msg = NULL;
683                 }
684         }
685
686         if (*ref)
687                 *ref = find_ref_by_name(*ref, refname);
688         if (!*ref)
689                 *ref = find_ref_by_name(remote_refs, refname);
690         if (!*ref) {
691                 warning("helper reported unexpected status of %s", refname);
692                 return;
693         }
694
695         if ((*ref)->status != REF_STATUS_NONE) {
696                 /*
697                  * Earlier, the ref was marked not to be pushed, so ignore the ref
698                  * status reported by the remote helper if the latter is 'no match'.
699                  */
700                 if (status == REF_STATUS_NONE)
701                         return;
702         }
703
704         (*ref)->status = status;
705         (*ref)->remote_status = msg;
706 }
707
708 static void push_update_refs_status(struct helper_data *data,
709                                     struct ref *remote_refs)
710 {
711         struct strbuf buf = STRBUF_INIT;
712         struct ref *ref = remote_refs;
713         for (;;) {
714                 recvline(data, &buf);
715                 if (!buf.len)
716                         break;
717
718                 push_update_ref_status(&buf, &ref, remote_refs);
719         }
720         strbuf_release(&buf);
721 }
722
723 static int push_refs_with_push(struct transport *transport,
724                 struct ref *remote_refs, int flags)
725 {
726         int force_all = flags & TRANSPORT_PUSH_FORCE;
727         int mirror = flags & TRANSPORT_PUSH_MIRROR;
728         struct helper_data *data = transport->data;
729         struct strbuf buf = STRBUF_INIT;
730         struct ref *ref;
731
732         get_helper(transport);
733         if (!data->push)
734                 return 1;
735
736         for (ref = remote_refs; ref; ref = ref->next) {
737                 if (!ref->peer_ref && !mirror)
738                         continue;
739
740                 /* Check for statuses set by set_ref_status_for_push() */
741                 switch (ref->status) {
742                 case REF_STATUS_REJECT_NONFASTFORWARD:
743                 case REF_STATUS_REJECT_ALREADY_EXISTS:
744                 case REF_STATUS_UPTODATE:
745                         continue;
746                 default:
747                         ; /* do nothing */
748                 }
749
750                 if (force_all)
751                         ref->force = 1;
752
753                 strbuf_addstr(&buf, "push ");
754                 if (!ref->deletion) {
755                         if (ref->force)
756                                 strbuf_addch(&buf, '+');
757                         if (ref->peer_ref)
758                                 strbuf_addstr(&buf, ref->peer_ref->name);
759                         else
760                                 strbuf_addstr(&buf, sha1_to_hex(ref->new_sha1));
761                 }
762                 strbuf_addch(&buf, ':');
763                 strbuf_addstr(&buf, ref->name);
764                 strbuf_addch(&buf, '\n');
765         }
766         if (buf.len == 0)
767                 return 0;
768
769         standard_options(transport);
770
771         if (flags & TRANSPORT_PUSH_DRY_RUN) {
772                 if (set_helper_option(transport, "dry-run", "true") != 0)
773                         die("helper %s does not support dry-run", data->name);
774         }
775
776         strbuf_addch(&buf, '\n');
777         sendline(data, &buf);
778         strbuf_release(&buf);
779
780         push_update_refs_status(data, remote_refs);
781         return 0;
782 }
783
784 static int push_refs_with_export(struct transport *transport,
785                 struct ref *remote_refs, int flags)
786 {
787         struct ref *ref;
788         struct child_process *helper, exporter;
789         struct helper_data *data = transport->data;
790         struct string_list revlist_args = STRING_LIST_INIT_NODUP;
791         struct strbuf buf = STRBUF_INIT;
792
793         helper = get_helper(transport);
794
795         write_constant(helper->in, "export\n");
796
797         strbuf_reset(&buf);
798
799         for (ref = remote_refs; ref; ref = ref->next) {
800                 char *private;
801                 unsigned char sha1[20];
802
803                 if (!data->refspecs)
804                         continue;
805                 private = apply_refspecs(data->refspecs, data->refspec_nr, ref->name);
806                 if (private && !get_sha1(private, sha1)) {
807                         strbuf_addf(&buf, "^%s", private);
808                         string_list_append(&revlist_args, strbuf_detach(&buf, NULL));
809                         hashcpy(ref->old_sha1, sha1);
810                 }
811                 free(private);
812
813                 if (ref->deletion) {
814                         die("remote-helpers do not support ref deletion");
815                 }
816
817                 if (ref->peer_ref)
818                         string_list_append(&revlist_args, ref->peer_ref->name);
819
820         }
821
822         if (get_exporter(transport, &exporter, &revlist_args))
823                 die("Couldn't run fast-export");
824
825         if (finish_command(&exporter))
826                 die("Error while running fast-export");
827         push_update_refs_status(data, remote_refs);
828         return 0;
829 }
830
831 static int push_refs(struct transport *transport,
832                 struct ref *remote_refs, int flags)
833 {
834         struct helper_data *data = transport->data;
835
836         if (process_connect(transport, 1)) {
837                 do_take_over(transport);
838                 return transport->push_refs(transport, remote_refs, flags);
839         }
840
841         if (!remote_refs) {
842                 fprintf(stderr, "No refs in common and none specified; doing nothing.\n"
843                         "Perhaps you should specify a branch such as 'master'.\n");
844                 return 0;
845         }
846
847         if (data->push)
848                 return push_refs_with_push(transport, remote_refs, flags);
849
850         if (data->export)
851                 return push_refs_with_export(transport, remote_refs, flags);
852
853         return -1;
854 }
855
856
857 static int has_attribute(const char *attrs, const char *attr) {
858         int len;
859         if (!attrs)
860                 return 0;
861
862         len = strlen(attr);
863         for (;;) {
864                 const char *space = strchrnul(attrs, ' ');
865                 if (len == space - attrs && !strncmp(attrs, attr, len))
866                         return 1;
867                 if (!*space)
868                         return 0;
869                 attrs = space + 1;
870         }
871 }
872
873 static struct ref *get_refs_list(struct transport *transport, int for_push)
874 {
875         struct helper_data *data = transport->data;
876         struct child_process *helper;
877         struct ref *ret = NULL;
878         struct ref **tail = &ret;
879         struct ref *posn;
880         struct strbuf buf = STRBUF_INIT;
881
882         helper = get_helper(transport);
883
884         if (process_connect(transport, for_push)) {
885                 do_take_over(transport);
886                 return transport->get_refs_list(transport, for_push);
887         }
888
889         if (data->push && for_push)
890                 write_str_in_full(helper->in, "list for-push\n");
891         else
892                 write_str_in_full(helper->in, "list\n");
893
894         while (1) {
895                 char *eov, *eon;
896                 recvline(data, &buf);
897
898                 if (!*buf.buf)
899                         break;
900
901                 eov = strchr(buf.buf, ' ');
902                 if (!eov)
903                         die("Malformed response in ref list: %s", buf.buf);
904                 eon = strchr(eov + 1, ' ');
905                 *eov = '\0';
906                 if (eon)
907                         *eon = '\0';
908                 *tail = alloc_ref(eov + 1);
909                 if (buf.buf[0] == '@')
910                         (*tail)->symref = xstrdup(buf.buf + 1);
911                 else if (buf.buf[0] != '?')
912                         get_sha1_hex(buf.buf, (*tail)->old_sha1);
913                 if (eon) {
914                         if (has_attribute(eon + 1, "unchanged")) {
915                                 (*tail)->status |= REF_STATUS_UPTODATE;
916                                 read_ref((*tail)->name, (*tail)->old_sha1);
917                         }
918                 }
919                 tail = &((*tail)->next);
920         }
921         if (debug)
922                 fprintf(stderr, "Debug: Read ref listing.\n");
923         strbuf_release(&buf);
924
925         for (posn = ret; posn; posn = posn->next)
926                 resolve_remote_symref(posn, ret);
927
928         return ret;
929 }
930
931 int transport_helper_init(struct transport *transport, const char *name)
932 {
933         struct helper_data *data = xcalloc(sizeof(*data), 1);
934         data->name = name;
935
936         if (getenv("GIT_TRANSPORT_HELPER_DEBUG"))
937                 debug = 1;
938
939         transport->data = data;
940         transport->set_option = set_helper_option;
941         transport->get_refs_list = get_refs_list;
942         transport->fetch = fetch;
943         transport->push_refs = push_refs;
944         transport->disconnect = release_helper;
945         transport->connect = connect_helper;
946         transport->smart_options = &(data->transport_options);
947         return 0;
948 }
949
950 /*
951  * Linux pipes can buffer 65536 bytes at once (and most platforms can
952  * buffer less), so attempt reads and writes with up to that size.
953  */
954 #define BUFFERSIZE 65536
955 /* This should be enough to hold debugging message. */
956 #define PBUFFERSIZE 8192
957
958 /* Print bidirectional transfer loop debug message. */
959 static void transfer_debug(const char *fmt, ...)
960 {
961         va_list args;
962         char msgbuf[PBUFFERSIZE];
963         static int debug_enabled = -1;
964
965         if (debug_enabled < 0)
966                 debug_enabled = getenv("GIT_TRANSLOOP_DEBUG") ? 1 : 0;
967         if (!debug_enabled)
968                 return;
969
970         va_start(args, fmt);
971         vsnprintf(msgbuf, PBUFFERSIZE, fmt, args);
972         va_end(args);
973         fprintf(stderr, "Transfer loop debugging: %s\n", msgbuf);
974 }
975
976 /* Stream state: More data may be coming in this direction. */
977 #define SSTATE_TRANSFERING 0
978 /*
979  * Stream state: No more data coming in this direction, flushing rest of
980  * data.
981  */
982 #define SSTATE_FLUSHING 1
983 /* Stream state: Transfer in this direction finished. */
984 #define SSTATE_FINISHED 2
985
986 #define STATE_NEEDS_READING(state) ((state) <= SSTATE_TRANSFERING)
987 #define STATE_NEEDS_WRITING(state) ((state) <= SSTATE_FLUSHING)
988 #define STATE_NEEDS_CLOSING(state) ((state) == SSTATE_FLUSHING)
989
990 /* Unidirectional transfer. */
991 struct unidirectional_transfer {
992         /* Source */
993         int src;
994         /* Destination */
995         int dest;
996         /* Is source socket? */
997         int src_is_sock;
998         /* Is destination socket? */
999         int dest_is_sock;
1000         /* Transfer state (TRANSFERRING/FLUSHING/FINISHED) */
1001         int state;
1002         /* Buffer. */
1003         char buf[BUFFERSIZE];
1004         /* Buffer used. */
1005         size_t bufuse;
1006         /* Name of source. */
1007         const char *src_name;
1008         /* Name of destination. */
1009         const char *dest_name;
1010 };
1011
1012 /* Closes the target (for writing) if transfer has finished. */
1013 static void udt_close_if_finished(struct unidirectional_transfer *t)
1014 {
1015         if (STATE_NEEDS_CLOSING(t->state) && !t->bufuse) {
1016                 t->state = SSTATE_FINISHED;
1017                 if (t->dest_is_sock)
1018                         shutdown(t->dest, SHUT_WR);
1019                 else
1020                         close(t->dest);
1021                 transfer_debug("Closed %s.", t->dest_name);
1022         }
1023 }
1024
1025 /*
1026  * Tries to read read data from source into buffer. If buffer is full,
1027  * no data is read. Returns 0 on success, -1 on error.
1028  */
1029 static int udt_do_read(struct unidirectional_transfer *t)
1030 {
1031         ssize_t bytes;
1032
1033         if (t->bufuse == BUFFERSIZE)
1034                 return 0;       /* No space for more. */
1035
1036         transfer_debug("%s is readable", t->src_name);
1037         bytes = read(t->src, t->buf + t->bufuse, BUFFERSIZE - t->bufuse);
1038         if (bytes < 0 && errno != EWOULDBLOCK && errno != EAGAIN &&
1039                 errno != EINTR) {
1040                 error("read(%s) failed: %s", t->src_name, strerror(errno));
1041                 return -1;
1042         } else if (bytes == 0) {
1043                 transfer_debug("%s EOF (with %i bytes in buffer)",
1044                         t->src_name, t->bufuse);
1045                 t->state = SSTATE_FLUSHING;
1046         } else if (bytes > 0) {
1047                 t->bufuse += bytes;
1048                 transfer_debug("Read %i bytes from %s (buffer now at %i)",
1049                         (int)bytes, t->src_name, (int)t->bufuse);
1050         }
1051         return 0;
1052 }
1053
1054 /* Tries to write data from buffer into destination. If buffer is empty,
1055  * no data is written. Returns 0 on success, -1 on error.
1056  */
1057 static int udt_do_write(struct unidirectional_transfer *t)
1058 {
1059         ssize_t bytes;
1060
1061         if (t->bufuse == 0)
1062                 return 0;       /* Nothing to write. */
1063
1064         transfer_debug("%s is writable", t->dest_name);
1065         bytes = write(t->dest, t->buf, t->bufuse);
1066         if (bytes < 0 && errno != EWOULDBLOCK && errno != EAGAIN &&
1067                 errno != EINTR) {
1068                 error("write(%s) failed: %s", t->dest_name, strerror(errno));
1069                 return -1;
1070         } else if (bytes > 0) {
1071                 t->bufuse -= bytes;
1072                 if (t->bufuse)
1073                         memmove(t->buf, t->buf + bytes, t->bufuse);
1074                 transfer_debug("Wrote %i bytes to %s (buffer now at %i)",
1075                         (int)bytes, t->dest_name, (int)t->bufuse);
1076         }
1077         return 0;
1078 }
1079
1080
1081 /* State of bidirectional transfer loop. */
1082 struct bidirectional_transfer_state {
1083         /* Direction from program to git. */
1084         struct unidirectional_transfer ptg;
1085         /* Direction from git to program. */
1086         struct unidirectional_transfer gtp;
1087 };
1088
1089 static void *udt_copy_task_routine(void *udt)
1090 {
1091         struct unidirectional_transfer *t = (struct unidirectional_transfer *)udt;
1092         while (t->state != SSTATE_FINISHED) {
1093                 if (STATE_NEEDS_READING(t->state))
1094                         if (udt_do_read(t))
1095                                 return NULL;
1096                 if (STATE_NEEDS_WRITING(t->state))
1097                         if (udt_do_write(t))
1098                                 return NULL;
1099                 if (STATE_NEEDS_CLOSING(t->state))
1100                         udt_close_if_finished(t);
1101         }
1102         return udt;     /* Just some non-NULL value. */
1103 }
1104
1105 #ifndef NO_PTHREADS
1106
1107 /*
1108  * Join thread, with apporiate errors on failure. Name is name for the
1109  * thread (for error messages). Returns 0 on success, 1 on failure.
1110  */
1111 static int tloop_join(pthread_t thread, const char *name)
1112 {
1113         int err;
1114         void *tret;
1115         err = pthread_join(thread, &tret);
1116         if (!tret) {
1117                 error("%s thread failed", name);
1118                 return 1;
1119         }
1120         if (err) {
1121                 error("%s thread failed to join: %s", name, strerror(err));
1122                 return 1;
1123         }
1124         return 0;
1125 }
1126
1127 /*
1128  * Spawn the transfer tasks and then wait for them. Returns 0 on success,
1129  * -1 on failure.
1130  */
1131 static int tloop_spawnwait_tasks(struct bidirectional_transfer_state *s)
1132 {
1133         pthread_t gtp_thread;
1134         pthread_t ptg_thread;
1135         int err;
1136         int ret = 0;
1137         err = pthread_create(&gtp_thread, NULL, udt_copy_task_routine,
1138                 &s->gtp);
1139         if (err)
1140                 die("Can't start thread for copying data: %s", strerror(err));
1141         err = pthread_create(&ptg_thread, NULL, udt_copy_task_routine,
1142                 &s->ptg);
1143         if (err)
1144                 die("Can't start thread for copying data: %s", strerror(err));
1145
1146         ret |= tloop_join(gtp_thread, "Git to program copy");
1147         ret |= tloop_join(ptg_thread, "Program to git copy");
1148         return ret;
1149 }
1150 #else
1151
1152 /* Close the source and target (for writing) for transfer. */
1153 static void udt_kill_transfer(struct unidirectional_transfer *t)
1154 {
1155         t->state = SSTATE_FINISHED;
1156         /*
1157          * Socket read end left open isn't a disaster if nobody
1158          * attempts to read from it (mingw compat headers do not
1159          * have SHUT_RD)...
1160          *
1161          * We can't fully close the socket since otherwise gtp
1162          * task would first close the socket it sends data to
1163          * while closing the ptg file descriptors.
1164          */
1165         if (!t->src_is_sock)
1166                 close(t->src);
1167         if (t->dest_is_sock)
1168                 shutdown(t->dest, SHUT_WR);
1169         else
1170                 close(t->dest);
1171 }
1172
1173 /*
1174  * Join process, with apporiate errors on failure. Name is name for the
1175  * process (for error messages). Returns 0 on success, 1 on failure.
1176  */
1177 static int tloop_join(pid_t pid, const char *name)
1178 {
1179         int tret;
1180         if (waitpid(pid, &tret, 0) < 0) {
1181                 error("%s process failed to wait: %s", name, strerror(errno));
1182                 return 1;
1183         }
1184         if (!WIFEXITED(tret) || WEXITSTATUS(tret)) {
1185                 error("%s process failed", name);
1186                 return 1;
1187         }
1188         return 0;
1189 }
1190
1191 /*
1192  * Spawn the transfer tasks and then wait for them. Returns 0 on success,
1193  * -1 on failure.
1194  */
1195 static int tloop_spawnwait_tasks(struct bidirectional_transfer_state *s)
1196 {
1197         pid_t pid1, pid2;
1198         int ret = 0;
1199
1200         /* Fork thread #1: git to program. */
1201         pid1 = fork();
1202         if (pid1 < 0)
1203                 die_errno("Can't start thread for copying data");
1204         else if (pid1 == 0) {
1205                 udt_kill_transfer(&s->ptg);
1206                 exit(udt_copy_task_routine(&s->gtp) ? 0 : 1);
1207         }
1208
1209         /* Fork thread #2: program to git. */
1210         pid2 = fork();
1211         if (pid2 < 0)
1212                 die_errno("Can't start thread for copying data");
1213         else if (pid2 == 0) {
1214                 udt_kill_transfer(&s->gtp);
1215                 exit(udt_copy_task_routine(&s->ptg) ? 0 : 1);
1216         }
1217
1218         /*
1219          * Close both streams in parent as to not interfere with
1220          * end of file detection and wait for both tasks to finish.
1221          */
1222         udt_kill_transfer(&s->gtp);
1223         udt_kill_transfer(&s->ptg);
1224         ret |= tloop_join(pid1, "Git to program copy");
1225         ret |= tloop_join(pid2, "Program to git copy");
1226         return ret;
1227 }
1228 #endif
1229
1230 /*
1231  * Copies data from stdin to output and from input to stdout simultaneously.
1232  * Additionally filtering through given filter. If filter is NULL, uses
1233  * identity filter.
1234  */
1235 int bidirectional_transfer_loop(int input, int output)
1236 {
1237         struct bidirectional_transfer_state state;
1238
1239         /* Fill the state fields. */
1240         state.ptg.src = input;
1241         state.ptg.dest = 1;
1242         state.ptg.src_is_sock = (input == output);
1243         state.ptg.dest_is_sock = 0;
1244         state.ptg.state = SSTATE_TRANSFERING;
1245         state.ptg.bufuse = 0;
1246         state.ptg.src_name = "remote input";
1247         state.ptg.dest_name = "stdout";
1248
1249         state.gtp.src = 0;
1250         state.gtp.dest = output;
1251         state.gtp.src_is_sock = 0;
1252         state.gtp.dest_is_sock = (input == output);
1253         state.gtp.state = SSTATE_TRANSFERING;
1254         state.gtp.bufuse = 0;
1255         state.gtp.src_name = "stdin";
1256         state.gtp.dest_name = "remote output";
1257
1258         return tloop_spawnwait_tasks(&state);
1259 }