Merge branch 'jc/maint-pull-docfix' into maint
[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 #include "refs.h"
15
16 static int debug;
17
18 struct helper_data {
19         const char *name;
20         struct child_process *helper;
21         FILE *out;
22         unsigned fetch : 1,
23                 import : 1,
24                 bidi_import : 1,
25                 export : 1,
26                 option : 1,
27                 push : 1,
28                 connect : 1,
29                 signed_tags : 1,
30                 check_connectivity : 1,
31                 no_disconnect_req : 1,
32                 no_private_update : 1;
33         char *export_marks;
34         char *import_marks;
35         /* These go from remote name (as in "list") to private name */
36         struct refspec *refspecs;
37         int refspec_nr;
38         /* Transport options for fetch-pack/send-pack (should one of
39          * those be invoked).
40          */
41         struct git_transport_options transport_options;
42 };
43
44 static void sendline(struct helper_data *helper, struct strbuf *buffer)
45 {
46         if (debug)
47                 fprintf(stderr, "Debug: Remote helper: -> %s", buffer->buf);
48         if (write_in_full(helper->helper->in, buffer->buf, buffer->len)
49                 != buffer->len)
50                 die_errno("Full write to remote helper failed");
51 }
52
53 static int recvline_fh(FILE *helper, struct strbuf *buffer, const char *name)
54 {
55         strbuf_reset(buffer);
56         if (debug)
57                 fprintf(stderr, "Debug: Remote helper: Waiting...\n");
58         if (strbuf_getline(buffer, helper, '\n') == EOF) {
59                 if (debug)
60                         fprintf(stderr, "Debug: Remote helper quit.\n");
61                 exit(128);
62         }
63
64         if (debug)
65                 fprintf(stderr, "Debug: Remote helper: <- %s\n", buffer->buf);
66         return 0;
67 }
68
69 static int recvline(struct helper_data *helper, struct strbuf *buffer)
70 {
71         return recvline_fh(helper->out, buffer, helper->name);
72 }
73
74 static void xchgline(struct helper_data *helper, struct strbuf *buffer)
75 {
76         sendline(helper, buffer);
77         recvline(helper, buffer);
78 }
79
80 static void write_constant(int fd, const char *str)
81 {
82         if (debug)
83                 fprintf(stderr, "Debug: Remote helper: -> %s", str);
84         if (write_in_full(fd, str, strlen(str)) != strlen(str))
85                 die_errno("Full write to remote helper failed");
86 }
87
88 static const char *remove_ext_force(const char *url)
89 {
90         if (url) {
91                 const char *colon = strchr(url, ':');
92                 if (colon && colon[1] == ':')
93                         return colon + 2;
94         }
95         return url;
96 }
97
98 static void do_take_over(struct transport *transport)
99 {
100         struct helper_data *data;
101         data = (struct helper_data *)transport->data;
102         transport_take_over(transport, data->helper);
103         fclose(data->out);
104         free(data);
105 }
106
107 static struct child_process *get_helper(struct transport *transport)
108 {
109         struct helper_data *data = transport->data;
110         struct argv_array argv = ARGV_ARRAY_INIT;
111         struct strbuf buf = STRBUF_INIT;
112         struct child_process *helper;
113         const char **refspecs = NULL;
114         int refspec_nr = 0;
115         int refspec_alloc = 0;
116         int duped;
117         int code;
118         char git_dir_buf[sizeof(GIT_DIR_ENVIRONMENT) + PATH_MAX + 1];
119         const char *helper_env[] = {
120                 git_dir_buf,
121                 NULL
122         };
123
124
125         if (data->helper)
126                 return data->helper;
127
128         helper = xcalloc(1, sizeof(*helper));
129         helper->in = -1;
130         helper->out = -1;
131         helper->err = 0;
132         argv_array_pushf(&argv, "git-remote-%s", data->name);
133         argv_array_push(&argv, transport->remote->name);
134         argv_array_push(&argv, remove_ext_force(transport->url));
135         helper->argv = argv_array_detach(&argv, NULL);
136         helper->git_cmd = 0;
137         helper->silent_exec_failure = 1;
138
139         snprintf(git_dir_buf, sizeof(git_dir_buf), "%s=%s", GIT_DIR_ENVIRONMENT, get_git_dir());
140         helper->env = helper_env;
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
151         /*
152          * Open the output as FILE* so strbuf_getline() can be used.
153          * Do this with duped fd because fclose() will close the fd,
154          * and stuff like taking over will require the fd to remain.
155          */
156         duped = dup(helper->out);
157         if (duped < 0)
158                 die_errno("Can't dup helper output fd");
159         data->out = xfdopen(duped, "r");
160
161         write_constant(helper->in, "capabilities\n");
162
163         while (1) {
164                 const char *capname;
165                 int mandatory = 0;
166                 recvline(data, &buf);
167
168                 if (!*buf.buf)
169                         break;
170
171                 if (*buf.buf == '*') {
172                         capname = buf.buf + 1;
173                         mandatory = 1;
174                 } else
175                         capname = buf.buf;
176
177                 if (debug)
178                         fprintf(stderr, "Debug: Got cap %s\n", capname);
179                 if (!strcmp(capname, "fetch"))
180                         data->fetch = 1;
181                 else if (!strcmp(capname, "option"))
182                         data->option = 1;
183                 else if (!strcmp(capname, "push"))
184                         data->push = 1;
185                 else if (!strcmp(capname, "import"))
186                         data->import = 1;
187                 else if (!strcmp(capname, "bidi-import"))
188                         data->bidi_import = 1;
189                 else if (!strcmp(capname, "export"))
190                         data->export = 1;
191                 else if (!strcmp(capname, "check-connectivity"))
192                         data->check_connectivity = 1;
193                 else if (!data->refspecs && !prefixcmp(capname, "refspec ")) {
194                         ALLOC_GROW(refspecs,
195                                    refspec_nr + 1,
196                                    refspec_alloc);
197                         refspecs[refspec_nr++] = xstrdup(capname + strlen("refspec "));
198                 } else if (!strcmp(capname, "connect")) {
199                         data->connect = 1;
200                 } else if (!strcmp(capname, "signed-tags")) {
201                         data->signed_tags = 1;
202                 } else if (!prefixcmp(capname, "export-marks ")) {
203                         struct strbuf arg = STRBUF_INIT;
204                         strbuf_addstr(&arg, "--export-marks=");
205                         strbuf_addstr(&arg, capname + strlen("export-marks "));
206                         data->export_marks = strbuf_detach(&arg, NULL);
207                 } else if (!prefixcmp(capname, "import-marks")) {
208                         struct strbuf arg = STRBUF_INIT;
209                         strbuf_addstr(&arg, "--import-marks=");
210                         strbuf_addstr(&arg, capname + strlen("import-marks "));
211                         data->import_marks = strbuf_detach(&arg, NULL);
212                 } else if (!prefixcmp(capname, "no-private-update")) {
213                         data->no_private_update = 1;
214                 } else if (mandatory) {
215                         die("Unknown mandatory capability %s. This remote "
216                             "helper probably needs newer version of Git.",
217                             capname);
218                 }
219         }
220         if (refspecs) {
221                 int i;
222                 data->refspec_nr = refspec_nr;
223                 data->refspecs = parse_fetch_refspec(refspec_nr, refspecs);
224                 for (i = 0; i < refspec_nr; i++)
225                         free((char *)refspecs[i]);
226                 free(refspecs);
227         } else if (data->import || data->bidi_import || data->export) {
228                 warning("This remote helper should implement refspec capability.");
229         }
230         strbuf_release(&buf);
231         if (debug)
232                 fprintf(stderr, "Debug: Capabilities complete.\n");
233         return data->helper;
234 }
235
236 static int disconnect_helper(struct transport *transport)
237 {
238         struct helper_data *data = transport->data;
239         int res = 0;
240
241         if (data->helper) {
242                 if (debug)
243                         fprintf(stderr, "Debug: Disconnecting.\n");
244                 if (!data->no_disconnect_req) {
245                         /*
246                          * Ignore write errors; there's nothing we can do,
247                          * since we're about to close the pipe anyway. And the
248                          * most likely error is EPIPE due to the helper dying
249                          * to report an error itself.
250                          */
251                         sigchain_push(SIGPIPE, SIG_IGN);
252                         xwrite(data->helper->in, "\n", 1);
253                         sigchain_pop(SIGPIPE);
254                 }
255                 close(data->helper->in);
256                 close(data->helper->out);
257                 fclose(data->out);
258                 res = finish_command(data->helper);
259                 argv_array_free_detached(data->helper->argv);
260                 free(data->helper);
261                 data->helper = NULL;
262         }
263         return res;
264 }
265
266 static const char *unsupported_options[] = {
267         TRANS_OPT_UPLOADPACK,
268         TRANS_OPT_RECEIVEPACK,
269         TRANS_OPT_THIN,
270         TRANS_OPT_KEEP
271         };
272
273 static const char *boolean_options[] = {
274         TRANS_OPT_THIN,
275         TRANS_OPT_KEEP,
276         TRANS_OPT_FOLLOWTAGS
277         };
278
279 static int set_helper_option(struct transport *transport,
280                           const char *name, const char *value)
281 {
282         struct helper_data *data = transport->data;
283         struct strbuf buf = STRBUF_INIT;
284         int i, ret, is_bool = 0;
285
286         get_helper(transport);
287
288         if (!data->option)
289                 return 1;
290
291         for (i = 0; i < ARRAY_SIZE(unsupported_options); i++) {
292                 if (!strcmp(name, unsupported_options[i]))
293                         return 1;
294         }
295
296         for (i = 0; i < ARRAY_SIZE(boolean_options); i++) {
297                 if (!strcmp(name, boolean_options[i])) {
298                         is_bool = 1;
299                         break;
300                 }
301         }
302
303         strbuf_addf(&buf, "option %s ", name);
304         if (is_bool)
305                 strbuf_addstr(&buf, value ? "true" : "false");
306         else
307                 quote_c_style(value, &buf, NULL, 0);
308         strbuf_addch(&buf, '\n');
309
310         xchgline(data, &buf);
311
312         if (!strcmp(buf.buf, "ok"))
313                 ret = 0;
314         else if (!prefixcmp(buf.buf, "error")) {
315                 ret = -1;
316         } else if (!strcmp(buf.buf, "unsupported"))
317                 ret = 1;
318         else {
319                 warning("%s unexpectedly said: '%s'", data->name, buf.buf);
320                 ret = 1;
321         }
322         strbuf_release(&buf);
323         return ret;
324 }
325
326 static void standard_options(struct transport *t)
327 {
328         char buf[16];
329         int n;
330         int v = t->verbose;
331
332         set_helper_option(t, "progress", t->progress ? "true" : "false");
333
334         n = snprintf(buf, sizeof(buf), "%d", v + 1);
335         if (n >= sizeof(buf))
336                 die("impossibly large verbosity value");
337         set_helper_option(t, "verbosity", buf);
338 }
339
340 static int release_helper(struct transport *transport)
341 {
342         int res = 0;
343         struct helper_data *data = transport->data;
344         free_refspec(data->refspec_nr, data->refspecs);
345         data->refspecs = NULL;
346         res = disconnect_helper(transport);
347         free(transport->data);
348         return res;
349 }
350
351 static int fetch_with_fetch(struct transport *transport,
352                             int nr_heads, struct ref **to_fetch)
353 {
354         struct helper_data *data = transport->data;
355         int i;
356         struct strbuf buf = STRBUF_INIT;
357
358         standard_options(transport);
359         if (data->check_connectivity &&
360             data->transport_options.check_self_contained_and_connected)
361                 set_helper_option(transport, "check-connectivity", "true");
362
363         for (i = 0; i < nr_heads; i++) {
364                 const struct ref *posn = to_fetch[i];
365                 if (posn->status & REF_STATUS_UPTODATE)
366                         continue;
367
368                 strbuf_addf(&buf, "fetch %s %s\n",
369                             sha1_to_hex(posn->old_sha1), posn->name);
370         }
371
372         strbuf_addch(&buf, '\n');
373         sendline(data, &buf);
374
375         while (1) {
376                 recvline(data, &buf);
377
378                 if (!prefixcmp(buf.buf, "lock ")) {
379                         const char *name = buf.buf + 5;
380                         if (transport->pack_lockfile)
381                                 warning("%s also locked %s", data->name, name);
382                         else
383                                 transport->pack_lockfile = xstrdup(name);
384                 }
385                 else if (data->check_connectivity &&
386                          data->transport_options.check_self_contained_and_connected &&
387                          !strcmp(buf.buf, "connectivity-ok"))
388                         data->transport_options.self_contained_and_connected = 1;
389                 else if (!buf.len)
390                         break;
391                 else
392                         warning("%s unexpectedly said: '%s'", data->name, buf.buf);
393         }
394         strbuf_release(&buf);
395         return 0;
396 }
397
398 static int get_importer(struct transport *transport, struct child_process *fastimport)
399 {
400         struct child_process *helper = get_helper(transport);
401         struct helper_data *data = transport->data;
402         struct argv_array argv = ARGV_ARRAY_INIT;
403         int cat_blob_fd, code;
404         memset(fastimport, 0, sizeof(*fastimport));
405         fastimport->in = helper->out;
406         argv_array_push(&argv, "fast-import");
407         argv_array_push(&argv, debug ? "--stats" : "--quiet");
408
409         if (data->bidi_import) {
410                 cat_blob_fd = xdup(helper->in);
411                 argv_array_pushf(&argv, "--cat-blob-fd=%d", cat_blob_fd);
412         }
413         fastimport->argv = argv.argv;
414         fastimport->git_cmd = 1;
415
416         code = start_command(fastimport);
417         return code;
418 }
419
420 static int get_exporter(struct transport *transport,
421                         struct child_process *fastexport,
422                         struct string_list *revlist_args)
423 {
424         struct helper_data *data = transport->data;
425         struct child_process *helper = get_helper(transport);
426         int argc = 0, i;
427         memset(fastexport, 0, sizeof(*fastexport));
428
429         /* we need to duplicate helper->in because we want to use it after
430          * fastexport is done with it. */
431         fastexport->out = dup(helper->in);
432         fastexport->argv = xcalloc(6 + revlist_args->nr, sizeof(*fastexport->argv));
433         fastexport->argv[argc++] = "fast-export";
434         fastexport->argv[argc++] = "--use-done-feature";
435         fastexport->argv[argc++] = data->signed_tags ?
436                 "--signed-tags=verbatim" : "--signed-tags=warn-strip";
437         if (data->export_marks)
438                 fastexport->argv[argc++] = data->export_marks;
439         if (data->import_marks)
440                 fastexport->argv[argc++] = data->import_marks;
441
442         for (i = 0; i < revlist_args->nr; i++)
443                 fastexport->argv[argc++] = revlist_args->items[i].string;
444
445         fastexport->git_cmd = 1;
446         return start_command(fastexport);
447 }
448
449 static int fetch_with_import(struct transport *transport,
450                              int nr_heads, struct ref **to_fetch)
451 {
452         struct child_process fastimport;
453         struct helper_data *data = transport->data;
454         int i;
455         struct ref *posn;
456         struct strbuf buf = STRBUF_INIT;
457
458         get_helper(transport);
459
460         if (get_importer(transport, &fastimport))
461                 die("Couldn't run fast-import");
462
463         for (i = 0; i < nr_heads; i++) {
464                 posn = to_fetch[i];
465                 if (posn->status & REF_STATUS_UPTODATE)
466                         continue;
467
468                 strbuf_addf(&buf, "import %s\n", posn->name);
469                 sendline(data, &buf);
470                 strbuf_reset(&buf);
471         }
472
473         write_constant(data->helper->in, "\n");
474         /*
475          * remote-helpers that advertise the bidi-import capability are required to
476          * buffer the complete batch of import commands until this newline before
477          * sending data to fast-import.
478          * These helpers read back data from fast-import on their stdin, which could
479          * be mixed with import commands, otherwise.
480          */
481
482         if (finish_command(&fastimport))
483                 die("Error while running fast-import");
484         argv_array_free_detached(fastimport.argv);
485
486         /*
487          * The fast-import stream of a remote helper that advertises
488          * the "refspec" capability writes to the refs named after the
489          * right hand side of the first refspec matching each ref we
490          * were fetching.
491          *
492          * (If no "refspec" capability was specified, for historical
493          * reasons we default to the equivalent of *:*.)
494          *
495          * Store the result in to_fetch[i].old_sha1.  Callers such
496          * as "git fetch" can use the value to write feedback to the
497          * terminal, populate FETCH_HEAD, and determine what new value
498          * should be written to peer_ref if the update is a
499          * fast-forward or this is a forced update.
500          */
501         for (i = 0; i < nr_heads; i++) {
502                 char *private;
503                 posn = to_fetch[i];
504                 if (posn->status & REF_STATUS_UPTODATE)
505                         continue;
506                 if (data->refspecs)
507                         private = apply_refspecs(data->refspecs, data->refspec_nr, posn->name);
508                 else
509                         private = xstrdup(posn->name);
510                 if (private) {
511                         read_ref(private, posn->old_sha1);
512                         free(private);
513                 }
514         }
515         strbuf_release(&buf);
516         return 0;
517 }
518
519 static int process_connect_service(struct transport *transport,
520                                    const char *name, const char *exec)
521 {
522         struct helper_data *data = transport->data;
523         struct strbuf cmdbuf = STRBUF_INIT;
524         struct child_process *helper;
525         int r, duped, ret = 0;
526         FILE *input;
527
528         helper = get_helper(transport);
529
530         /*
531          * Yes, dup the pipe another time, as we need unbuffered version
532          * of input pipe as FILE*. fclose() closes the underlying fd and
533          * stream buffering only can be changed before first I/O operation
534          * on it.
535          */
536         duped = dup(helper->out);
537         if (duped < 0)
538                 die_errno("Can't dup helper output fd");
539         input = xfdopen(duped, "r");
540         setvbuf(input, NULL, _IONBF, 0);
541
542         /*
543          * Handle --upload-pack and friends. This is fire and forget...
544          * just warn if it fails.
545          */
546         if (strcmp(name, exec)) {
547                 r = set_helper_option(transport, "servpath", exec);
548                 if (r > 0)
549                         warning("Setting remote service path not supported by protocol.");
550                 else if (r < 0)
551                         warning("Invalid remote service path.");
552         }
553
554         if (data->connect)
555                 strbuf_addf(&cmdbuf, "connect %s\n", name);
556         else
557                 goto exit;
558
559         sendline(data, &cmdbuf);
560         recvline_fh(input, &cmdbuf, name);
561         if (!strcmp(cmdbuf.buf, "")) {
562                 data->no_disconnect_req = 1;
563                 if (debug)
564                         fprintf(stderr, "Debug: Smart transport connection "
565                                 "ready.\n");
566                 ret = 1;
567         } else if (!strcmp(cmdbuf.buf, "fallback")) {
568                 if (debug)
569                         fprintf(stderr, "Debug: Falling back to dumb "
570                                 "transport.\n");
571         } else
572                 die("Unknown response to connect: %s",
573                         cmdbuf.buf);
574
575 exit:
576         fclose(input);
577         return ret;
578 }
579
580 static int process_connect(struct transport *transport,
581                                      int for_push)
582 {
583         struct helper_data *data = transport->data;
584         const char *name;
585         const char *exec;
586
587         name = for_push ? "git-receive-pack" : "git-upload-pack";
588         if (for_push)
589                 exec = data->transport_options.receivepack;
590         else
591                 exec = data->transport_options.uploadpack;
592
593         return process_connect_service(transport, name, exec);
594 }
595
596 static int connect_helper(struct transport *transport, const char *name,
597                    const char *exec, int fd[2])
598 {
599         struct helper_data *data = transport->data;
600
601         /* Get_helper so connect is inited. */
602         get_helper(transport);
603         if (!data->connect)
604                 die("Operation not supported by protocol.");
605
606         if (!process_connect_service(transport, name, exec))
607                 die("Can't connect to subservice %s.", name);
608
609         fd[0] = data->helper->out;
610         fd[1] = data->helper->in;
611         return 0;
612 }
613
614 static int fetch(struct transport *transport,
615                  int nr_heads, struct ref **to_fetch)
616 {
617         struct helper_data *data = transport->data;
618         int i, count;
619
620         if (process_connect(transport, 0)) {
621                 do_take_over(transport);
622                 return transport->fetch(transport, nr_heads, to_fetch);
623         }
624
625         count = 0;
626         for (i = 0; i < nr_heads; i++)
627                 if (!(to_fetch[i]->status & REF_STATUS_UPTODATE))
628                         count++;
629
630         if (!count)
631                 return 0;
632
633         if (data->fetch)
634                 return fetch_with_fetch(transport, nr_heads, to_fetch);
635
636         if (data->import)
637                 return fetch_with_import(transport, nr_heads, to_fetch);
638
639         return -1;
640 }
641
642 static int push_update_ref_status(struct strbuf *buf,
643                                    struct ref **ref,
644                                    struct ref *remote_refs)
645 {
646         char *refname, *msg;
647         int status;
648
649         if (!prefixcmp(buf->buf, "ok ")) {
650                 status = REF_STATUS_OK;
651                 refname = buf->buf + 3;
652         } else if (!prefixcmp(buf->buf, "error ")) {
653                 status = REF_STATUS_REMOTE_REJECT;
654                 refname = buf->buf + 6;
655         } else
656                 die("expected ok/error, helper said '%s'", buf->buf);
657
658         msg = strchr(refname, ' ');
659         if (msg) {
660                 struct strbuf msg_buf = STRBUF_INIT;
661                 const char *end;
662
663                 *msg++ = '\0';
664                 if (!unquote_c_style(&msg_buf, msg, &end))
665                         msg = strbuf_detach(&msg_buf, NULL);
666                 else
667                         msg = xstrdup(msg);
668                 strbuf_release(&msg_buf);
669
670                 if (!strcmp(msg, "no match")) {
671                         status = REF_STATUS_NONE;
672                         free(msg);
673                         msg = NULL;
674                 }
675                 else if (!strcmp(msg, "up to date")) {
676                         status = REF_STATUS_UPTODATE;
677                         free(msg);
678                         msg = NULL;
679                 }
680                 else if (!strcmp(msg, "non-fast forward")) {
681                         status = REF_STATUS_REJECT_NONFASTFORWARD;
682                         free(msg);
683                         msg = NULL;
684                 }
685                 else if (!strcmp(msg, "already exists")) {
686                         status = REF_STATUS_REJECT_ALREADY_EXISTS;
687                         free(msg);
688                         msg = NULL;
689                 }
690                 else if (!strcmp(msg, "fetch first")) {
691                         status = REF_STATUS_REJECT_FETCH_FIRST;
692                         free(msg);
693                         msg = NULL;
694                 }
695                 else if (!strcmp(msg, "needs force")) {
696                         status = REF_STATUS_REJECT_NEEDS_FORCE;
697                         free(msg);
698                         msg = NULL;
699                 }
700                 else if (!strcmp(msg, "stale info")) {
701                         status = REF_STATUS_REJECT_STALE;
702                         free(msg);
703                         msg = NULL;
704                 }
705         }
706
707         if (*ref)
708                 *ref = find_ref_by_name(*ref, refname);
709         if (!*ref)
710                 *ref = find_ref_by_name(remote_refs, refname);
711         if (!*ref) {
712                 warning("helper reported unexpected status of %s", refname);
713                 return 1;
714         }
715
716         if ((*ref)->status != REF_STATUS_NONE) {
717                 /*
718                  * Earlier, the ref was marked not to be pushed, so ignore the ref
719                  * status reported by the remote helper if the latter is 'no match'.
720                  */
721                 if (status == REF_STATUS_NONE)
722                         return 1;
723         }
724
725         (*ref)->status = status;
726         (*ref)->remote_status = msg;
727         return !(status == REF_STATUS_OK);
728 }
729
730 static void push_update_refs_status(struct helper_data *data,
731                                     struct ref *remote_refs)
732 {
733         struct strbuf buf = STRBUF_INIT;
734         struct ref *ref = remote_refs;
735         for (;;) {
736                 char *private;
737
738                 recvline(data, &buf);
739                 if (!buf.len)
740                         break;
741
742                 if (push_update_ref_status(&buf, &ref, remote_refs))
743                         continue;
744
745                 if (!data->refspecs || data->no_private_update)
746                         continue;
747
748                 /* propagate back the update to the remote namespace */
749                 private = apply_refspecs(data->refspecs, data->refspec_nr, ref->name);
750                 if (!private)
751                         continue;
752                 update_ref("update by helper", private, ref->new_sha1, NULL, 0, 0);
753                 free(private);
754         }
755         strbuf_release(&buf);
756 }
757
758 static int push_refs_with_push(struct transport *transport,
759                                struct ref *remote_refs, int flags)
760 {
761         int force_all = flags & TRANSPORT_PUSH_FORCE;
762         int mirror = flags & TRANSPORT_PUSH_MIRROR;
763         struct helper_data *data = transport->data;
764         struct strbuf buf = STRBUF_INIT;
765         struct ref *ref;
766         struct string_list cas_options = STRING_LIST_INIT_DUP;
767         struct string_list_item *cas_option;
768
769         get_helper(transport);
770         if (!data->push)
771                 return 1;
772
773         for (ref = remote_refs; ref; ref = ref->next) {
774                 if (!ref->peer_ref && !mirror)
775                         continue;
776
777                 /* Check for statuses set by set_ref_status_for_push() */
778                 switch (ref->status) {
779                 case REF_STATUS_REJECT_NONFASTFORWARD:
780                 case REF_STATUS_REJECT_STALE:
781                 case REF_STATUS_REJECT_ALREADY_EXISTS:
782                 case REF_STATUS_UPTODATE:
783                         continue;
784                 default:
785                         ; /* do nothing */
786                 }
787
788                 if (force_all)
789                         ref->force = 1;
790
791                 strbuf_addstr(&buf, "push ");
792                 if (!ref->deletion) {
793                         if (ref->force)
794                                 strbuf_addch(&buf, '+');
795                         if (ref->peer_ref)
796                                 strbuf_addstr(&buf, ref->peer_ref->name);
797                         else
798                                 strbuf_addstr(&buf, sha1_to_hex(ref->new_sha1));
799                 }
800                 strbuf_addch(&buf, ':');
801                 strbuf_addstr(&buf, ref->name);
802                 strbuf_addch(&buf, '\n');
803
804                 /*
805                  * The "--force-with-lease" options without explicit
806                  * values to expect have already been expanded into
807                  * the ref->old_sha1_expect[] field; we can ignore
808                  * transport->smart_options->cas altogether and instead
809                  * can enumerate them from the refs.
810                  */
811                 if (ref->expect_old_sha1) {
812                         struct strbuf cas = STRBUF_INIT;
813                         strbuf_addf(&cas, "%s:%s",
814                                     ref->name, sha1_to_hex(ref->old_sha1_expect));
815                         string_list_append(&cas_options, strbuf_detach(&cas, NULL));
816                 }
817         }
818         if (buf.len == 0) {
819                 string_list_clear(&cas_options, 0);
820                 return 0;
821         }
822
823         standard_options(transport);
824         for_each_string_list_item(cas_option, &cas_options)
825                 set_helper_option(transport, "cas", cas_option->string);
826
827         if (flags & TRANSPORT_PUSH_DRY_RUN) {
828                 if (set_helper_option(transport, "dry-run", "true") != 0)
829                         die("helper %s does not support dry-run", data->name);
830         }
831
832         strbuf_addch(&buf, '\n');
833         sendline(data, &buf);
834         strbuf_release(&buf);
835
836         push_update_refs_status(data, remote_refs);
837         return 0;
838 }
839
840 static int push_refs_with_export(struct transport *transport,
841                 struct ref *remote_refs, int flags)
842 {
843         struct ref *ref;
844         struct child_process *helper, exporter;
845         struct helper_data *data = transport->data;
846         struct string_list revlist_args = STRING_LIST_INIT_NODUP;
847         struct strbuf buf = STRBUF_INIT;
848
849         if (!data->refspecs)
850                 die("remote-helper doesn't support push; refspec needed");
851
852         if (flags & TRANSPORT_PUSH_DRY_RUN) {
853                 if (set_helper_option(transport, "dry-run", "true") != 0)
854                         die("helper %s does not support dry-run", data->name);
855         }
856
857         helper = get_helper(transport);
858
859         write_constant(helper->in, "export\n");
860
861         strbuf_reset(&buf);
862
863         for (ref = remote_refs; ref; ref = ref->next) {
864                 char *private;
865                 unsigned char sha1[20];
866
867                 if (ref->deletion)
868                         die("remote-helpers do not support ref deletion");
869
870                 private = apply_refspecs(data->refspecs, data->refspec_nr, ref->name);
871                 if (private && !get_sha1(private, sha1)) {
872                         strbuf_addf(&buf, "^%s", private);
873                         string_list_append(&revlist_args, strbuf_detach(&buf, NULL));
874                         hashcpy(ref->old_sha1, sha1);
875                 }
876                 free(private);
877
878                 if (ref->deletion)
879                         die("remote-helpers do not support ref deletion");
880
881                 if (ref->peer_ref) {
882                         if (strcmp(ref->peer_ref->name, ref->name))
883                                 die("remote-helpers do not support old:new syntax");
884                         string_list_append(&revlist_args, ref->peer_ref->name);
885                 }
886         }
887
888         if (get_exporter(transport, &exporter, &revlist_args))
889                 die("Couldn't run fast-export");
890
891         if (finish_command(&exporter))
892                 die("Error while running fast-export");
893         push_update_refs_status(data, remote_refs);
894         return 0;
895 }
896
897 static int push_refs(struct transport *transport,
898                 struct ref *remote_refs, int flags)
899 {
900         struct helper_data *data = transport->data;
901
902         if (process_connect(transport, 1)) {
903                 do_take_over(transport);
904                 return transport->push_refs(transport, remote_refs, flags);
905         }
906
907         if (!remote_refs) {
908                 fprintf(stderr, "No refs in common and none specified; doing nothing.\n"
909                         "Perhaps you should specify a branch such as 'master'.\n");
910                 return 0;
911         }
912
913         if (data->push)
914                 return push_refs_with_push(transport, remote_refs, flags);
915
916         if (data->export)
917                 return push_refs_with_export(transport, remote_refs, flags);
918
919         return -1;
920 }
921
922
923 static int has_attribute(const char *attrs, const char *attr) {
924         int len;
925         if (!attrs)
926                 return 0;
927
928         len = strlen(attr);
929         for (;;) {
930                 const char *space = strchrnul(attrs, ' ');
931                 if (len == space - attrs && !strncmp(attrs, attr, len))
932                         return 1;
933                 if (!*space)
934                         return 0;
935                 attrs = space + 1;
936         }
937 }
938
939 static struct ref *get_refs_list(struct transport *transport, int for_push)
940 {
941         struct helper_data *data = transport->data;
942         struct child_process *helper;
943         struct ref *ret = NULL;
944         struct ref **tail = &ret;
945         struct ref *posn;
946         struct strbuf buf = STRBUF_INIT;
947
948         helper = get_helper(transport);
949
950         if (process_connect(transport, for_push)) {
951                 do_take_over(transport);
952                 return transport->get_refs_list(transport, for_push);
953         }
954
955         if (data->push && for_push)
956                 write_str_in_full(helper->in, "list for-push\n");
957         else
958                 write_str_in_full(helper->in, "list\n");
959
960         while (1) {
961                 char *eov, *eon;
962                 recvline(data, &buf);
963
964                 if (!*buf.buf)
965                         break;
966
967                 eov = strchr(buf.buf, ' ');
968                 if (!eov)
969                         die("Malformed response in ref list: %s", buf.buf);
970                 eon = strchr(eov + 1, ' ');
971                 *eov = '\0';
972                 if (eon)
973                         *eon = '\0';
974                 *tail = alloc_ref(eov + 1);
975                 if (buf.buf[0] == '@')
976                         (*tail)->symref = xstrdup(buf.buf + 1);
977                 else if (buf.buf[0] != '?')
978                         get_sha1_hex(buf.buf, (*tail)->old_sha1);
979                 if (eon) {
980                         if (has_attribute(eon + 1, "unchanged")) {
981                                 (*tail)->status |= REF_STATUS_UPTODATE;
982                                 read_ref((*tail)->name, (*tail)->old_sha1);
983                         }
984                 }
985                 tail = &((*tail)->next);
986         }
987         if (debug)
988                 fprintf(stderr, "Debug: Read ref listing.\n");
989         strbuf_release(&buf);
990
991         for (posn = ret; posn; posn = posn->next)
992                 resolve_remote_symref(posn, ret);
993
994         return ret;
995 }
996
997 int transport_helper_init(struct transport *transport, const char *name)
998 {
999         struct helper_data *data = xcalloc(sizeof(*data), 1);
1000         data->name = name;
1001
1002         if (getenv("GIT_TRANSPORT_HELPER_DEBUG"))
1003                 debug = 1;
1004
1005         transport->data = data;
1006         transport->set_option = set_helper_option;
1007         transport->get_refs_list = get_refs_list;
1008         transport->fetch = fetch;
1009         transport->push_refs = push_refs;
1010         transport->disconnect = release_helper;
1011         transport->connect = connect_helper;
1012         transport->smart_options = &(data->transport_options);
1013         return 0;
1014 }
1015
1016 /*
1017  * Linux pipes can buffer 65536 bytes at once (and most platforms can
1018  * buffer less), so attempt reads and writes with up to that size.
1019  */
1020 #define BUFFERSIZE 65536
1021 /* This should be enough to hold debugging message. */
1022 #define PBUFFERSIZE 8192
1023
1024 /* Print bidirectional transfer loop debug message. */
1025 __attribute__((format (printf, 1, 2)))
1026 static void transfer_debug(const char *fmt, ...)
1027 {
1028         va_list args;
1029         char msgbuf[PBUFFERSIZE];
1030         static int debug_enabled = -1;
1031
1032         if (debug_enabled < 0)
1033                 debug_enabled = getenv("GIT_TRANSLOOP_DEBUG") ? 1 : 0;
1034         if (!debug_enabled)
1035                 return;
1036
1037         va_start(args, fmt);
1038         vsnprintf(msgbuf, PBUFFERSIZE, fmt, args);
1039         va_end(args);
1040         fprintf(stderr, "Transfer loop debugging: %s\n", msgbuf);
1041 }
1042
1043 /* Stream state: More data may be coming in this direction. */
1044 #define SSTATE_TRANSFERING 0
1045 /*
1046  * Stream state: No more data coming in this direction, flushing rest of
1047  * data.
1048  */
1049 #define SSTATE_FLUSHING 1
1050 /* Stream state: Transfer in this direction finished. */
1051 #define SSTATE_FINISHED 2
1052
1053 #define STATE_NEEDS_READING(state) ((state) <= SSTATE_TRANSFERING)
1054 #define STATE_NEEDS_WRITING(state) ((state) <= SSTATE_FLUSHING)
1055 #define STATE_NEEDS_CLOSING(state) ((state) == SSTATE_FLUSHING)
1056
1057 /* Unidirectional transfer. */
1058 struct unidirectional_transfer {
1059         /* Source */
1060         int src;
1061         /* Destination */
1062         int dest;
1063         /* Is source socket? */
1064         int src_is_sock;
1065         /* Is destination socket? */
1066         int dest_is_sock;
1067         /* Transfer state (TRANSFERRING/FLUSHING/FINISHED) */
1068         int state;
1069         /* Buffer. */
1070         char buf[BUFFERSIZE];
1071         /* Buffer used. */
1072         size_t bufuse;
1073         /* Name of source. */
1074         const char *src_name;
1075         /* Name of destination. */
1076         const char *dest_name;
1077 };
1078
1079 /* Closes the target (for writing) if transfer has finished. */
1080 static void udt_close_if_finished(struct unidirectional_transfer *t)
1081 {
1082         if (STATE_NEEDS_CLOSING(t->state) && !t->bufuse) {
1083                 t->state = SSTATE_FINISHED;
1084                 if (t->dest_is_sock)
1085                         shutdown(t->dest, SHUT_WR);
1086                 else
1087                         close(t->dest);
1088                 transfer_debug("Closed %s.", t->dest_name);
1089         }
1090 }
1091
1092 /*
1093  * Tries to read read data from source into buffer. If buffer is full,
1094  * no data is read. Returns 0 on success, -1 on error.
1095  */
1096 static int udt_do_read(struct unidirectional_transfer *t)
1097 {
1098         ssize_t bytes;
1099
1100         if (t->bufuse == BUFFERSIZE)
1101                 return 0;       /* No space for more. */
1102
1103         transfer_debug("%s is readable", t->src_name);
1104         bytes = read(t->src, t->buf + t->bufuse, BUFFERSIZE - t->bufuse);
1105         if (bytes < 0 && errno != EWOULDBLOCK && errno != EAGAIN &&
1106                 errno != EINTR) {
1107                 error("read(%s) failed: %s", t->src_name, strerror(errno));
1108                 return -1;
1109         } else if (bytes == 0) {
1110                 transfer_debug("%s EOF (with %i bytes in buffer)",
1111                         t->src_name, (int)t->bufuse);
1112                 t->state = SSTATE_FLUSHING;
1113         } else if (bytes > 0) {
1114                 t->bufuse += bytes;
1115                 transfer_debug("Read %i bytes from %s (buffer now at %i)",
1116                         (int)bytes, t->src_name, (int)t->bufuse);
1117         }
1118         return 0;
1119 }
1120
1121 /* Tries to write data from buffer into destination. If buffer is empty,
1122  * no data is written. Returns 0 on success, -1 on error.
1123  */
1124 static int udt_do_write(struct unidirectional_transfer *t)
1125 {
1126         ssize_t bytes;
1127
1128         if (t->bufuse == 0)
1129                 return 0;       /* Nothing to write. */
1130
1131         transfer_debug("%s is writable", t->dest_name);
1132         bytes = write(t->dest, t->buf, t->bufuse);
1133         if (bytes < 0 && errno != EWOULDBLOCK && errno != EAGAIN &&
1134                 errno != EINTR) {
1135                 error("write(%s) failed: %s", t->dest_name, strerror(errno));
1136                 return -1;
1137         } else if (bytes > 0) {
1138                 t->bufuse -= bytes;
1139                 if (t->bufuse)
1140                         memmove(t->buf, t->buf + bytes, t->bufuse);
1141                 transfer_debug("Wrote %i bytes to %s (buffer now at %i)",
1142                         (int)bytes, t->dest_name, (int)t->bufuse);
1143         }
1144         return 0;
1145 }
1146
1147
1148 /* State of bidirectional transfer loop. */
1149 struct bidirectional_transfer_state {
1150         /* Direction from program to git. */
1151         struct unidirectional_transfer ptg;
1152         /* Direction from git to program. */
1153         struct unidirectional_transfer gtp;
1154 };
1155
1156 static void *udt_copy_task_routine(void *udt)
1157 {
1158         struct unidirectional_transfer *t = (struct unidirectional_transfer *)udt;
1159         while (t->state != SSTATE_FINISHED) {
1160                 if (STATE_NEEDS_READING(t->state))
1161                         if (udt_do_read(t))
1162                                 return NULL;
1163                 if (STATE_NEEDS_WRITING(t->state))
1164                         if (udt_do_write(t))
1165                                 return NULL;
1166                 if (STATE_NEEDS_CLOSING(t->state))
1167                         udt_close_if_finished(t);
1168         }
1169         return udt;     /* Just some non-NULL value. */
1170 }
1171
1172 #ifndef NO_PTHREADS
1173
1174 /*
1175  * Join thread, with appropriate errors on failure. Name is name for the
1176  * thread (for error messages). Returns 0 on success, 1 on failure.
1177  */
1178 static int tloop_join(pthread_t thread, const char *name)
1179 {
1180         int err;
1181         void *tret;
1182         err = pthread_join(thread, &tret);
1183         if (!tret) {
1184                 error("%s thread failed", name);
1185                 return 1;
1186         }
1187         if (err) {
1188                 error("%s thread failed to join: %s", name, strerror(err));
1189                 return 1;
1190         }
1191         return 0;
1192 }
1193
1194 /*
1195  * Spawn the transfer tasks and then wait for them. Returns 0 on success,
1196  * -1 on failure.
1197  */
1198 static int tloop_spawnwait_tasks(struct bidirectional_transfer_state *s)
1199 {
1200         pthread_t gtp_thread;
1201         pthread_t ptg_thread;
1202         int err;
1203         int ret = 0;
1204         err = pthread_create(&gtp_thread, NULL, udt_copy_task_routine,
1205                 &s->gtp);
1206         if (err)
1207                 die("Can't start thread for copying data: %s", strerror(err));
1208         err = pthread_create(&ptg_thread, NULL, udt_copy_task_routine,
1209                 &s->ptg);
1210         if (err)
1211                 die("Can't start thread for copying data: %s", strerror(err));
1212
1213         ret |= tloop_join(gtp_thread, "Git to program copy");
1214         ret |= tloop_join(ptg_thread, "Program to git copy");
1215         return ret;
1216 }
1217 #else
1218
1219 /* Close the source and target (for writing) for transfer. */
1220 static void udt_kill_transfer(struct unidirectional_transfer *t)
1221 {
1222         t->state = SSTATE_FINISHED;
1223         /*
1224          * Socket read end left open isn't a disaster if nobody
1225          * attempts to read from it (mingw compat headers do not
1226          * have SHUT_RD)...
1227          *
1228          * We can't fully close the socket since otherwise gtp
1229          * task would first close the socket it sends data to
1230          * while closing the ptg file descriptors.
1231          */
1232         if (!t->src_is_sock)
1233                 close(t->src);
1234         if (t->dest_is_sock)
1235                 shutdown(t->dest, SHUT_WR);
1236         else
1237                 close(t->dest);
1238 }
1239
1240 /*
1241  * Join process, with appropriate errors on failure. Name is name for the
1242  * process (for error messages). Returns 0 on success, 1 on failure.
1243  */
1244 static int tloop_join(pid_t pid, const char *name)
1245 {
1246         int tret;
1247         if (waitpid(pid, &tret, 0) < 0) {
1248                 error("%s process failed to wait: %s", name, strerror(errno));
1249                 return 1;
1250         }
1251         if (!WIFEXITED(tret) || WEXITSTATUS(tret)) {
1252                 error("%s process failed", name);
1253                 return 1;
1254         }
1255         return 0;
1256 }
1257
1258 /*
1259  * Spawn the transfer tasks and then wait for them. Returns 0 on success,
1260  * -1 on failure.
1261  */
1262 static int tloop_spawnwait_tasks(struct bidirectional_transfer_state *s)
1263 {
1264         pid_t pid1, pid2;
1265         int ret = 0;
1266
1267         /* Fork thread #1: git to program. */
1268         pid1 = fork();
1269         if (pid1 < 0)
1270                 die_errno("Can't start thread for copying data");
1271         else if (pid1 == 0) {
1272                 udt_kill_transfer(&s->ptg);
1273                 exit(udt_copy_task_routine(&s->gtp) ? 0 : 1);
1274         }
1275
1276         /* Fork thread #2: program to git. */
1277         pid2 = fork();
1278         if (pid2 < 0)
1279                 die_errno("Can't start thread for copying data");
1280         else if (pid2 == 0) {
1281                 udt_kill_transfer(&s->gtp);
1282                 exit(udt_copy_task_routine(&s->ptg) ? 0 : 1);
1283         }
1284
1285         /*
1286          * Close both streams in parent as to not interfere with
1287          * end of file detection and wait for both tasks to finish.
1288          */
1289         udt_kill_transfer(&s->gtp);
1290         udt_kill_transfer(&s->ptg);
1291         ret |= tloop_join(pid1, "Git to program copy");
1292         ret |= tloop_join(pid2, "Program to git copy");
1293         return ret;
1294 }
1295 #endif
1296
1297 /*
1298  * Copies data from stdin to output and from input to stdout simultaneously.
1299  * Additionally filtering through given filter. If filter is NULL, uses
1300  * identity filter.
1301  */
1302 int bidirectional_transfer_loop(int input, int output)
1303 {
1304         struct bidirectional_transfer_state state;
1305
1306         /* Fill the state fields. */
1307         state.ptg.src = input;
1308         state.ptg.dest = 1;
1309         state.ptg.src_is_sock = (input == output);
1310         state.ptg.dest_is_sock = 0;
1311         state.ptg.state = SSTATE_TRANSFERING;
1312         state.ptg.bufuse = 0;
1313         state.ptg.src_name = "remote input";
1314         state.ptg.dest_name = "stdout";
1315
1316         state.gtp.src = 0;
1317         state.gtp.dest = output;
1318         state.gtp.src_is_sock = 0;
1319         state.gtp.dest_is_sock = (input == output);
1320         state.gtp.state = SSTATE_TRANSFERING;
1321         state.gtp.bufuse = 0;
1322         state.gtp.src_name = "stdin";
1323         state.gtp.dest_name = "remote output";
1324
1325         return tloop_spawnwait_tasks(&state);
1326 }