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Date:: Fri Jun 16 08:58:13 2023 UTC
Message:: make gotd show relevant commit hashes in error message if ref-updates collide
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1 /*
2  * Copyright (c) 2022, 2023 Stefan Sperling <stsp@openbsd.org>
3  *
4  * Permission to use, copy, modify, and distribute this software for any
5  * purpose with or without fee is hereby granted, provided that the above
6  * copyright notice and this permission notice appear in all copies.
7  *
8  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15  */
16 
17 #include <sys/types.h>
18 #include <sys/queue.h>
19 #include <sys/tree.h>
20 #include <sys/socket.h>
21 #include <sys/stat.h>
22 #include <sys/uio.h>
23 
24 #include <errno.h>
25 #include <event.h>
26 #include <limits.h>
27 #include <sha1.h>
28 #include <sha2.h>
29 #include <signal.h>
30 #include <stdint.h>
31 #include <stdio.h>
32 #include <stdlib.h>
33 #include <string.h>
34 #include <imsg.h>
35 #include <unistd.h>
36 
37 #include "got_error.h"
38 #include "got_repository.h"
39 #include "got_object.h"
40 #include "got_path.h"
41 #include "got_reference.h"
42 #include "got_opentemp.h"
43 
44 #include "got_lib_hash.h"
45 #include "got_lib_delta.h"
46 #include "got_lib_object.h"
47 #include "got_lib_object_cache.h"
48 #include "got_lib_pack.h"
49 #include "got_lib_repository.h"
50 #include "got_lib_gitproto.h"
51 
52 #include "gotd.h"
53 #include "log.h"
54 #include "session.h"
55 
56 
57 static struct gotd_session {
58 	pid_t pid;
59 	const char *title;
60 	struct got_repository *repo;
61 	int *pack_fds;
62 	int *temp_fds;
63 	struct gotd_imsgev parent_iev;
64 	struct timeval request_timeout;
65 } gotd_session;
66 
67 static struct gotd_session_client {
68 	enum gotd_session_state		 state;
69 	int				 is_writing;
70 	struct gotd_client_capability	*capabilities;
71 	size_t				 ncapa_alloc;
72 	size_t				 ncapabilities;
73 	uint32_t			 id;
74 	int				 fd;
75 	int				 delta_cache_fd;
76 	struct gotd_imsgev		 iev;
77 	struct gotd_imsgev		 repo_child_iev;
78 	struct event			 tmo;
79 	uid_t				 euid;
80 	gid_t				 egid;
81 	char				*packfile_path;
82 	char				*packidx_path;
83 	int				 nref_updates;
84 	int				 accept_flush_pkt;
85 } gotd_session_client;
86 
87 void gotd_session_sighdlr(int sig, short event, void *arg);
88 static void gotd_session_shutdown(void);
89 
90 static void
91 disconnect(struct gotd_session_client *client)
92 {
93 	log_debug("uid %d: disconnecting", client->euid);
94 
95 	if (gotd_imsg_compose_event(&gotd_session.parent_iev,
96 	    GOTD_IMSG_DISCONNECT, PROC_SESSION, -1, NULL, 0) == -1)
97 		log_warn("imsg compose DISCONNECT");
98 
99 	imsg_clear(&client->repo_child_iev.ibuf);
100 	event_del(&client->repo_child_iev.ev);
101 	evtimer_del(&client->tmo);
102 	close(client->fd);
103 	if (client->delta_cache_fd != -1)
104 		close(client->delta_cache_fd);
105 	if (client->packfile_path) {
106 		if (unlink(client->packfile_path) == -1 && errno != ENOENT)
107 			log_warn("unlink %s: ", client->packfile_path);
108 		free(client->packfile_path);
109 	}
110 	if (client->packidx_path) {
111 		if (unlink(client->packidx_path) == -1 && errno != ENOENT)
112 			log_warn("unlink %s: ", client->packidx_path);
113 		free(client->packidx_path);
114 	}
115 	free(client->capabilities);
116 
117 	gotd_session_shutdown();
118 }
119 
120 static void
121 disconnect_on_error(struct gotd_session_client *client,
122     const struct got_error *err)
123 {
124 	struct imsgbuf ibuf;
125 
126 	log_warnx("uid %d: %s", client->euid, err->msg);
127 	if (err->code != GOT_ERR_EOF) {
128 		imsg_init(&ibuf, client->fd);
129 		gotd_imsg_send_error(&ibuf, 0, PROC_SESSION, err);
130 		imsg_clear(&ibuf);
131 	}
132 
133 	disconnect(client);
134 }
135 
136 static void
137 gotd_request_timeout(int fd, short events, void *arg)
138 {
139 	struct gotd_session_client *client = arg;
140 
141 	log_debug("disconnecting uid %d due to timeout", client->euid);
142 	disconnect(client);
143 }
144 
145 void
146 gotd_session_sighdlr(int sig, short event, void *arg)
147 {
148 	/*
149 	 * Normal signal handler rules don't apply because libevent
150 	 * decouples for us.
151 	 */
152 
153 	switch (sig) {
154 	case SIGHUP:
155 		log_info("%s: ignoring SIGHUP", __func__);
156 		break;
157 	case SIGUSR1:
158 		log_info("%s: ignoring SIGUSR1", __func__);
159 		break;
160 	case SIGTERM:
161 	case SIGINT:
162 		gotd_session_shutdown();
163 		/* NOTREACHED */
164 		break;
165 	default:
166 		fatalx("unexpected signal");
167 	}
168 }
169 
170 static const struct got_error *
171 recv_packfile_done(uint32_t *client_id, struct imsg *imsg)
172 {
173 	struct gotd_imsg_packfile_done idone;
174 	size_t datalen;
175 
176 	log_debug("packfile-done received");
177 
178 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
179 	if (datalen != sizeof(idone))
180 		return got_error(GOT_ERR_PRIVSEP_LEN);
181 	memcpy(&idone, imsg->data, sizeof(idone));
182 
183 	*client_id = idone.client_id;
184 	return NULL;
185 }
186 
187 static const struct got_error *
188 recv_packfile_install(uint32_t *client_id, struct imsg *imsg)
189 {
190 	struct gotd_imsg_packfile_install inst;
191 	size_t datalen;
192 
193 	log_debug("packfile-install received");
194 
195 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
196 	if (datalen != sizeof(inst))
197 		return got_error(GOT_ERR_PRIVSEP_LEN);
198 	memcpy(&inst, imsg->data, sizeof(inst));
199 
200 	*client_id = inst.client_id;
201 	return NULL;
202 }
203 
204 static const struct got_error *
205 recv_ref_updates_start(uint32_t *client_id, struct imsg *imsg)
206 {
207 	struct gotd_imsg_ref_updates_start istart;
208 	size_t datalen;
209 
210 	log_debug("ref-updates-start received");
211 
212 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
213 	if (datalen != sizeof(istart))
214 		return got_error(GOT_ERR_PRIVSEP_LEN);
215 	memcpy(&istart, imsg->data, sizeof(istart));
216 
217 	*client_id = istart.client_id;
218 	return NULL;
219 }
220 
221 static const struct got_error *
222 recv_ref_update(uint32_t *client_id, struct imsg *imsg)
223 {
224 	struct gotd_imsg_ref_update iref;
225 	size_t datalen;
226 
227 	log_debug("ref-update received");
228 
229 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
230 	if (datalen < sizeof(iref))
231 		return got_error(GOT_ERR_PRIVSEP_LEN);
232 	memcpy(&iref, imsg->data, sizeof(iref));
233 
234 	*client_id = iref.client_id;
235 	return NULL;
236 }
237 
238 static const struct got_error *
239 send_ref_update_ok(struct gotd_session_client *client,
240     struct gotd_imsg_ref_update *iref, const char *refname)
241 {
242 	struct gotd_imsg_ref_update_ok iok;
243 	struct gotd_imsgev *iev = &client->iev;
244 	struct ibuf *wbuf;
245 	size_t len;
246 
247 	memset(&iok, 0, sizeof(iok));
248 	iok.client_id = client->id;
249 	memcpy(iok.old_id, iref->old_id, SHA1_DIGEST_LENGTH);
250 	memcpy(iok.new_id, iref->new_id, SHA1_DIGEST_LENGTH);
251 	iok.name_len = strlen(refname);
252 
253 	len = sizeof(iok) + iok.name_len;
254 	wbuf = imsg_create(&iev->ibuf, GOTD_IMSG_REF_UPDATE_OK,
255 	    PROC_SESSION, gotd_session.pid, len);
256 	if (wbuf == NULL)
257 		return got_error_from_errno("imsg_create REF_UPDATE_OK");
258 
259 	if (imsg_add(wbuf, &iok, sizeof(iok)) == -1)
260 		return got_error_from_errno("imsg_add REF_UPDATE_OK");
261 	if (imsg_add(wbuf, refname, iok.name_len) == -1)
262 		return got_error_from_errno("imsg_add REF_UPDATE_OK");
263 
264 	wbuf->fd = -1;
265 	imsg_close(&iev->ibuf, wbuf);
266 	gotd_imsg_event_add(iev);
267 	return NULL;
268 }
269 
270 static void
271 send_refs_updated(struct gotd_session_client *client)
272 {
273 	if (gotd_imsg_compose_event(&client->iev, GOTD_IMSG_REFS_UPDATED,
274 	    PROC_SESSION, -1, NULL, 0) == -1)
275 		log_warn("imsg compose REFS_UPDATED");
276 }
277 
278 static const struct got_error *
279 send_ref_update_ng(struct gotd_session_client *client,
280     struct gotd_imsg_ref_update *iref, const char *refname,
281     const char *reason)
282 {
283 	const struct got_error *ng_err;
284 	struct gotd_imsg_ref_update_ng ing;
285 	struct gotd_imsgev *iev = &client->iev;
286 	struct ibuf *wbuf;
287 	size_t len;
288 
289 	memset(&ing, 0, sizeof(ing));
290 	ing.client_id = client->id;
291 	memcpy(ing.old_id, iref->old_id, SHA1_DIGEST_LENGTH);
292 	memcpy(ing.new_id, iref->new_id, SHA1_DIGEST_LENGTH);
293 	ing.name_len = strlen(refname);
294 
295 	ng_err = got_error_fmt(GOT_ERR_REF_BUSY, "%s", reason);
296 	ing.reason_len = strlen(ng_err->msg);
297 
298 	len = sizeof(ing) + ing.name_len + ing.reason_len;
299 	wbuf = imsg_create(&iev->ibuf, GOTD_IMSG_REF_UPDATE_NG,
300 	    PROC_SESSION, gotd_session.pid, len);
301 	if (wbuf == NULL)
302 		return got_error_from_errno("imsg_create REF_UPDATE_NG");
303 
304 	if (imsg_add(wbuf, &ing, sizeof(ing)) == -1)
305 		return got_error_from_errno("imsg_add REF_UPDATE_NG");
306 	if (imsg_add(wbuf, refname, ing.name_len) == -1)
307 		return got_error_from_errno("imsg_add REF_UPDATE_NG");
308 	if (imsg_add(wbuf, ng_err->msg, ing.reason_len) == -1)
309 		return got_error_from_errno("imsg_add REF_UPDATE_NG");
310 
311 	wbuf->fd = -1;
312 	imsg_close(&iev->ibuf, wbuf);
313 	gotd_imsg_event_add(iev);
314 	return NULL;
315 }
316 
317 static const struct got_error *
318 install_pack(struct gotd_session_client *client, const char *repo_path,
319     struct imsg *imsg)
320 {
321 	const struct got_error *err = NULL;
322 	struct gotd_imsg_packfile_install inst;
323 	char hex[SHA1_DIGEST_STRING_LENGTH];
324 	size_t datalen;
325 	char *packfile_path = NULL, *packidx_path = NULL;
326 
327 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
328 	if (datalen != sizeof(inst))
329 		return got_error(GOT_ERR_PRIVSEP_LEN);
330 	memcpy(&inst, imsg->data, sizeof(inst));
331 
332 	if (client->packfile_path == NULL)
333 		return got_error_msg(GOT_ERR_BAD_REQUEST,
334 		    "client has no pack file");
335 	if (client->packidx_path == NULL)
336 		return got_error_msg(GOT_ERR_BAD_REQUEST,
337 		    "client has no pack file index");
338 
339 	if (got_sha1_digest_to_str(inst.pack_sha1, hex, sizeof(hex)) == NULL)
340 		return got_error_msg(GOT_ERR_NO_SPACE,
341 		    "could not convert pack file SHA1 to hex");
342 
343 	if (asprintf(&packfile_path, "/%s/%s/pack-%s.pack",
344 	    repo_path, GOT_OBJECTS_PACK_DIR, hex) == -1) {
345 		err = got_error_from_errno("asprintf");
346 		goto done;
347 	}
348 
349 	if (asprintf(&packidx_path, "/%s/%s/pack-%s.idx",
350 	    repo_path, GOT_OBJECTS_PACK_DIR, hex) == -1) {
351 		err = got_error_from_errno("asprintf");
352 		goto done;
353 	}
354 
355 	if (rename(client->packfile_path, packfile_path) == -1) {
356 		err = got_error_from_errno3("rename", client->packfile_path,
357 		    packfile_path);
358 		goto done;
359 	}
360 
361 	free(client->packfile_path);
362 	client->packfile_path = NULL;
363 
364 	if (rename(client->packidx_path, packidx_path) == -1) {
365 		err = got_error_from_errno3("rename", client->packidx_path,
366 		    packidx_path);
367 		goto done;
368 	}
369 
370 	free(client->packidx_path);
371 	client->packidx_path = NULL;
372 done:
373 	free(packfile_path);
374 	free(packidx_path);
375 	return err;
376 }
377 
378 static const struct got_error *
379 begin_ref_updates(struct gotd_session_client *client, struct imsg *imsg)
380 {
381 	struct gotd_imsg_ref_updates_start istart;
382 	size_t datalen;
383 
384 	if (client->nref_updates != -1)
385 		return got_error(GOT_ERR_PRIVSEP_MSG);
386 
387 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
388 	if (datalen != sizeof(istart))
389 		return got_error(GOT_ERR_PRIVSEP_LEN);
390 	memcpy(&istart, imsg->data, sizeof(istart));
391 
392 	if (istart.nref_updates <= 0)
393 		return got_error(GOT_ERR_PRIVSEP_MSG);
394 
395 	client->nref_updates = istart.nref_updates;
396 	return NULL;
397 }
398 
399 static const struct got_error *
400 update_ref(int *shut, struct gotd_session_client *client,
401     const char *repo_path, struct imsg *imsg)
402 {
403 	const struct got_error *err = NULL;
404 	struct got_repository *repo = NULL;
405 	struct got_reference *ref = NULL;
406 	struct gotd_imsg_ref_update iref;
407 	struct got_object_id old_id, new_id;
408 	struct got_object_id *id = NULL;
409 	struct got_object *obj = NULL;
410 	char *refname = NULL;
411 	size_t datalen;
412 	int locked = 0;
413 	char hex1[SHA1_DIGEST_STRING_LENGTH];
414 	char hex2[SHA1_DIGEST_STRING_LENGTH];
415 
416 	log_debug("update-ref from uid %d", client->euid);
417 
418 	if (client->nref_updates <= 0)
419 		return got_error(GOT_ERR_PRIVSEP_MSG);
420 
421 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
422 	if (datalen < sizeof(iref))
423 		return got_error(GOT_ERR_PRIVSEP_LEN);
424 	memcpy(&iref, imsg->data, sizeof(iref));
425 	if (datalen != sizeof(iref) + iref.name_len)
426 		return got_error(GOT_ERR_PRIVSEP_LEN);
427 	refname = strndup(imsg->data + sizeof(iref), iref.name_len);
428 	if (refname == NULL)
429 		return got_error_from_errno("strndup");
430 
431 	log_debug("updating ref %s for uid %d", refname, client->euid);
432 
433 	err = got_repo_open(&repo, repo_path, NULL, NULL);
434 	if (err)
435 		goto done;
436 
437 	memcpy(old_id.sha1, iref.old_id, SHA1_DIGEST_LENGTH);
438 	memcpy(new_id.sha1, iref.new_id, SHA1_DIGEST_LENGTH);
439 	err = got_object_open(&obj, repo,
440 	    iref.delete_ref ? &old_id : &new_id);
441 	if (err)
442 		goto done;
443 
444 	if (iref.ref_is_new) {
445 		err = got_ref_open(&ref, repo, refname, 0);
446 		if (err) {
447 			if (err->code != GOT_ERR_NOT_REF)
448 				goto done;
449 			err = got_ref_alloc(&ref, refname, &new_id);
450 			if (err)
451 				goto done;
452 			err = got_ref_write(ref, repo); /* will lock/unlock */
453 			if (err)
454 				goto done;
455 		} else {
456 			err = got_ref_resolve(&id, repo, ref);
457 			if (err)
458 				goto done;
459 			got_object_id_hex(&new_id, hex1, sizeof(hex1));
460 			got_object_id_hex(id, hex2, sizeof(hex2));
461 			err = got_error_fmt(GOT_ERR_REF_BUSY,
462 			    "Addition %s: %s failed; %s: %s has been "
463 			    "created by someone else while transaction "
464 			    "was in progress",
465 			    got_ref_get_name(ref), hex1,
466 			    got_ref_get_name(ref), hex2);
467 			goto done;
468 		}
469 	} else if (iref.delete_ref) {
470 		err = got_ref_open(&ref, repo, refname, 1 /* lock */);
471 		if (err)
472 			goto done;
473 		locked = 1;
474 
475 		err = got_ref_resolve(&id, repo, ref);
476 		if (err)
477 			goto done;
478 
479 		if (got_object_id_cmp(id, &old_id) != 0) {
480 			got_object_id_hex(&old_id, hex1, sizeof(hex1));
481 			got_object_id_hex(id, hex2, sizeof(hex2));
482 			err = got_error_fmt(GOT_ERR_REF_BUSY,
483 			    "Deletion %s: %s failed; %s: %s has been "
484 			    "created by someone else while transaction "
485 			    "was in progress",
486 			    got_ref_get_name(ref), hex1,
487 			    got_ref_get_name(ref), hex2);
488 			goto done;
489 		}
490 
491 		err = got_ref_delete(ref, repo);
492 		if (err)
493 			goto done;
494 
495 		free(id);
496 		id = NULL;
497 	} else {
498 		err = got_ref_open(&ref, repo, refname, 1 /* lock */);
499 		if (err)
500 			goto done;
501 		locked = 1;
502 
503 		err = got_ref_resolve(&id, repo, ref);
504 		if (err)
505 			goto done;
506 
507 		if (got_object_id_cmp(id, &old_id) != 0) {
508 			got_object_id_hex(&old_id, hex1, sizeof(hex1));
509 			got_object_id_hex(id, hex2, sizeof(hex2));
510 			err = got_error_fmt(GOT_ERR_REF_BUSY,
511 			    "Update %s: %s failed; %s: %s has been "
512 			    "created by someone else while transaction "
513 			    "was in progress",
514 			    got_ref_get_name(ref), hex1,
515 			    got_ref_get_name(ref), hex2);
516 			goto done;
517 		}
518 
519 		if (got_object_id_cmp(&new_id, &old_id) != 0) {
520 			err = got_ref_change_ref(ref, &new_id);
521 			if (err)
522 				goto done;
523 
524 			err = got_ref_write(ref, repo);
525 			if (err)
526 				goto done;
527 		}
528 
529 		free(id);
530 		id = NULL;
531 	}
532 done:
533 	if (err) {
534 		if (err->code == GOT_ERR_LOCKFILE_TIMEOUT) {
535 			err = got_error_fmt(GOT_ERR_LOCKFILE_TIMEOUT,
536 			    "could not acquire exclusive file lock for %s",
537 			    refname);
538 		}
539 		send_ref_update_ng(client, &iref, refname, err->msg);
540 	} else
541 		send_ref_update_ok(client, &iref, refname);
542 
543 	if (client->nref_updates > 0) {
544 		client->nref_updates--;
545 		if (client->nref_updates == 0) {
546 			send_refs_updated(client);
547 			*shut = 1;
548 		}
549 
550 	}
551 	if (locked) {
552 		const struct got_error *unlock_err;
553 		unlock_err = got_ref_unlock(ref);
554 		if (unlock_err && err == NULL)
555 			err = unlock_err;
556 	}
557 	if (ref)
558 		got_ref_close(ref);
559 	if (obj)
560 		got_object_close(obj);
561 	if (repo)
562 		got_repo_close(repo);
563 	free(refname);
564 	free(id);
565 	return err;
566 }
567 
568 static void
569 session_dispatch_repo_child(int fd, short event, void *arg)
570 {
571 	struct gotd_imsgev *iev = arg;
572 	struct imsgbuf *ibuf = &iev->ibuf;
573 	struct gotd_session_client *client = &gotd_session_client;
574 	ssize_t n;
575 	int shut = 0;
576 	struct imsg imsg;
577 
578 	if (event & EV_READ) {
579 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
580 			fatal("imsg_read error");
581 		if (n == 0) {
582 			/* Connection closed. */
583 			shut = 1;
584 			goto done;
585 		}
586 	}
587 
588 	if (event & EV_WRITE) {
589 		n = msgbuf_write(&ibuf->w);
590 		if (n == -1 && errno != EAGAIN)
591 			fatal("msgbuf_write");
592 		if (n == 0) {
593 			/* Connection closed. */
594 			shut = 1;
595 			goto done;
596 		}
597 	}
598 
599 	for (;;) {
600 		const struct got_error *err = NULL;
601 		uint32_t client_id = 0;
602 		int do_disconnect = 0;
603 		int do_ref_updates = 0, do_ref_update = 0;
604 		int do_packfile_install = 0;
605 
606 		if ((n = imsg_get(ibuf, &imsg)) == -1)
607 			fatal("%s: imsg_get error", __func__);
608 		if (n == 0)	/* No more messages. */
609 			break;
610 
611 		switch (imsg.hdr.type) {
612 		case GOTD_IMSG_ERROR:
613 			do_disconnect = 1;
614 			err = gotd_imsg_recv_error(&client_id, &imsg);
615 			break;
616 		case GOTD_IMSG_PACKFILE_DONE:
617 			do_disconnect = 1;
618 			err = recv_packfile_done(&client_id, &imsg);
619 			break;
620 		case GOTD_IMSG_PACKFILE_INSTALL:
621 			err = recv_packfile_install(&client_id, &imsg);
622 			if (err == NULL)
623 				do_packfile_install = 1;
624 			break;
625 		case GOTD_IMSG_REF_UPDATES_START:
626 			err = recv_ref_updates_start(&client_id, &imsg);
627 			if (err == NULL)
628 				do_ref_updates = 1;
629 			break;
630 		case GOTD_IMSG_REF_UPDATE:
631 			err = recv_ref_update(&client_id, &imsg);
632 			if (err == NULL)
633 				do_ref_update = 1;
634 			break;
635 		default:
636 			log_debug("unexpected imsg %d", imsg.hdr.type);
637 			break;
638 		}
639 
640 		if (do_disconnect) {
641 			if (err)
642 				disconnect_on_error(client, err);
643 			else
644 				disconnect(client);
645 		} else {
646 			if (do_packfile_install)
647 				err = install_pack(client,
648 				    gotd_session.repo->path, &imsg);
649 			else if (do_ref_updates)
650 				err = begin_ref_updates(client, &imsg);
651 			else if (do_ref_update)
652 				err = update_ref(&shut, client,
653 				    gotd_session.repo->path, &imsg);
654 			if (err)
655 				log_warnx("uid %d: %s", client->euid, err->msg);
656 		}
657 		imsg_free(&imsg);
658 	}
659 done:
660 	if (!shut) {
661 		gotd_imsg_event_add(iev);
662 	} else {
663 		/* This pipe is dead. Remove its event handler */
664 		event_del(&iev->ev);
665 		event_loopexit(NULL);
666 	}
667 }
668 
669 static const struct got_error *
670 recv_capabilities(struct gotd_session_client *client, struct imsg *imsg)
671 {
672 	struct gotd_imsg_capabilities icapas;
673 	size_t datalen;
674 
675 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
676 	if (datalen != sizeof(icapas))
677 		return got_error(GOT_ERR_PRIVSEP_LEN);
678 	memcpy(&icapas, imsg->data, sizeof(icapas));
679 
680 	client->ncapa_alloc = icapas.ncapabilities;
681 	client->capabilities = calloc(client->ncapa_alloc,
682 	    sizeof(*client->capabilities));
683 	if (client->capabilities == NULL) {
684 		client->ncapa_alloc = 0;
685 		return got_error_from_errno("calloc");
686 	}
687 
688 	log_debug("expecting %zu capabilities from uid %d",
689 	    client->ncapa_alloc, client->euid);
690 	return NULL;
691 }
692 
693 static const struct got_error *
694 recv_capability(struct gotd_session_client *client, struct imsg *imsg)
695 {
696 	struct gotd_imsg_capability icapa;
697 	struct gotd_client_capability *capa;
698 	size_t datalen;
699 	char *key, *value = NULL;
700 
701 	if (client->capabilities == NULL ||
702 	    client->ncapabilities >= client->ncapa_alloc) {
703 		return got_error_msg(GOT_ERR_BAD_REQUEST,
704 		    "unexpected capability received");
705 	}
706 
707 	memset(&icapa, 0, sizeof(icapa));
708 
709 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
710 	if (datalen < sizeof(icapa))
711 		return got_error(GOT_ERR_PRIVSEP_LEN);
712 	memcpy(&icapa, imsg->data, sizeof(icapa));
713 
714 	if (datalen != sizeof(icapa) + icapa.key_len + icapa.value_len)
715 		return got_error(GOT_ERR_PRIVSEP_LEN);
716 
717 	key = strndup(imsg->data + sizeof(icapa), icapa.key_len);
718 	if (key == NULL)
719 		return got_error_from_errno("strndup");
720 	if (icapa.value_len > 0) {
721 		value = strndup(imsg->data + sizeof(icapa) + icapa.key_len,
722 		    icapa.value_len);
723 		if (value == NULL) {
724 			free(key);
725 			return got_error_from_errno("strndup");
726 		}
727 	}
728 
729 	capa = &client->capabilities[client->ncapabilities++];
730 	capa->key = key;
731 	capa->value = value;
732 
733 	if (value)
734 		log_debug("uid %d: capability %s=%s", client->euid, key, value);
735 	else
736 		log_debug("uid %d: capability %s", client->euid, key);
737 
738 	return NULL;
739 }
740 
741 static const struct got_error *
742 ensure_client_is_reading(struct gotd_session_client *client)
743 {
744 	if (client->is_writing) {
745 		return got_error_fmt(GOT_ERR_BAD_PACKET,
746 		    "uid %d made a read-request but is not reading from "
747 		    "a repository", client->euid);
748 	}
749 
750 	return NULL;
751 }
752 
753 static const struct got_error *
754 ensure_client_is_writing(struct gotd_session_client *client)
755 {
756 	if (!client->is_writing) {
757 		return got_error_fmt(GOT_ERR_BAD_PACKET,
758 		    "uid %d made a write-request but is not writing to "
759 		    "a repository", client->euid);
760 	}
761 
762 	return NULL;
763 }
764 
765 static const struct got_error *
766 forward_want(struct gotd_session_client *client, struct imsg *imsg)
767 {
768 	struct gotd_imsg_want ireq;
769 	struct gotd_imsg_want iwant;
770 	size_t datalen;
771 
772 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
773 	if (datalen != sizeof(ireq))
774 		return got_error(GOT_ERR_PRIVSEP_LEN);
775 
776 	memcpy(&ireq, imsg->data, datalen);
777 
778 	memset(&iwant, 0, sizeof(iwant));
779 	memcpy(iwant.object_id, ireq.object_id, SHA1_DIGEST_LENGTH);
780 	iwant.client_id = client->id;
781 
782 	if (gotd_imsg_compose_event(&client->repo_child_iev, GOTD_IMSG_WANT,
783 	    PROC_SESSION, -1, &iwant, sizeof(iwant)) == -1)
784 		return got_error_from_errno("imsg compose WANT");
785 
786 	return NULL;
787 }
788 
789 static const struct got_error *
790 forward_ref_update(struct gotd_session_client *client, struct imsg *imsg)
791 {
792 	const struct got_error *err = NULL;
793 	struct gotd_imsg_ref_update ireq;
794 	struct gotd_imsg_ref_update *iref = NULL;
795 	size_t datalen;
796 
797 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
798 	if (datalen < sizeof(ireq))
799 		return got_error(GOT_ERR_PRIVSEP_LEN);
800 	memcpy(&ireq, imsg->data, sizeof(ireq));
801 	if (datalen != sizeof(ireq) + ireq.name_len)
802 		return got_error(GOT_ERR_PRIVSEP_LEN);
803 
804 	iref = malloc(datalen);
805 	if (iref == NULL)
806 		return got_error_from_errno("malloc");
807 	memcpy(iref, imsg->data, datalen);
808 
809 	iref->client_id = client->id;
810 	if (gotd_imsg_compose_event(&client->repo_child_iev,
811 	    GOTD_IMSG_REF_UPDATE, PROC_SESSION, -1, iref, datalen) == -1)
812 		err = got_error_from_errno("imsg compose REF_UPDATE");
813 	free(iref);
814 	return err;
815 }
816 
817 static const struct got_error *
818 forward_have(struct gotd_session_client *client, struct imsg *imsg)
819 {
820 	struct gotd_imsg_have ireq;
821 	struct gotd_imsg_have ihave;
822 	size_t datalen;
823 
824 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
825 	if (datalen != sizeof(ireq))
826 		return got_error(GOT_ERR_PRIVSEP_LEN);
827 
828 	memcpy(&ireq, imsg->data, datalen);
829 
830 	memset(&ihave, 0, sizeof(ihave));
831 	memcpy(ihave.object_id, ireq.object_id, SHA1_DIGEST_LENGTH);
832 	ihave.client_id = client->id;
833 
834 	if (gotd_imsg_compose_event(&client->repo_child_iev, GOTD_IMSG_HAVE,
835 	    PROC_SESSION, -1, &ihave, sizeof(ihave)) == -1)
836 		return got_error_from_errno("imsg compose HAVE");
837 
838 	return NULL;
839 }
840 
841 static int
842 client_has_capability(struct gotd_session_client *client, const char *capastr)
843 {
844 	struct gotd_client_capability *capa;
845 	size_t i;
846 
847 	if (client->ncapabilities == 0)
848 		return 0;
849 
850 	for (i = 0; i < client->ncapabilities; i++) {
851 		capa = &client->capabilities[i];
852 		if (strcmp(capa->key, capastr) == 0)
853 			return 1;
854 	}
855 
856 	return 0;
857 }
858 
859 static const struct got_error *
860 recv_packfile(struct gotd_session_client *client)
861 {
862 	const struct got_error *err = NULL;
863 	struct gotd_imsg_recv_packfile ipack;
864 	struct gotd_imsg_packfile_pipe ipipe;
865 	struct gotd_imsg_packidx_file ifile;
866 	char *basepath = NULL, *pack_path = NULL, *idx_path = NULL;
867 	int packfd = -1, idxfd = -1;
868 	int pipe[2] = { -1, -1 };
869 
870 	if (client->packfile_path) {
871 		return got_error_fmt(GOT_ERR_PRIVSEP_MSG,
872 		    "uid %d already has a pack file", client->euid);
873 	}
874 
875 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pipe) == -1)
876 		return got_error_from_errno("socketpair");
877 
878 	memset(&ipipe, 0, sizeof(ipipe));
879 	ipipe.client_id = client->id;
880 
881 	/* Send pack pipe end 0 to repo child process. */
882 	if (gotd_imsg_compose_event(&client->repo_child_iev,
883 	    GOTD_IMSG_PACKFILE_PIPE, PROC_SESSION, pipe[0],
884 	        &ipipe, sizeof(ipipe)) == -1) {
885 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
886 		pipe[0] = -1;
887 		goto done;
888 	}
889 	pipe[0] = -1;
890 
891 	/* Send pack pipe end 1 to gotsh(1) (expects just an fd, no data). */
892 	if (gotd_imsg_compose_event(&client->iev,
893 	    GOTD_IMSG_PACKFILE_PIPE, PROC_SESSION, pipe[1], NULL, 0) == -1)
894 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
895 	pipe[1] = -1;
896 
897 	if (asprintf(&basepath, "%s/%s/receiving-from-uid-%d.pack",
898 	    got_repo_get_path(gotd_session.repo), GOT_OBJECTS_PACK_DIR,
899 	    client->euid) == -1) {
900 		err = got_error_from_errno("asprintf");
901 		goto done;
902 	}
903 
904 	err = got_opentemp_named_fd(&pack_path, &packfd, basepath, "");
905 	if (err)
906 		goto done;
907 	if (fchmod(packfd, GOT_DEFAULT_PACK_MODE) == -1) {
908 		err = got_error_from_errno2("fchmod", pack_path);
909 		goto done;
910 	}
911 
912 	free(basepath);
913 	if (asprintf(&basepath, "%s/%s/receiving-from-uid-%d.idx",
914 	    got_repo_get_path(gotd_session.repo), GOT_OBJECTS_PACK_DIR,
915 	    client->euid) == -1) {
916 		err = got_error_from_errno("asprintf");
917 		basepath = NULL;
918 		goto done;
919 	}
920 	err = got_opentemp_named_fd(&idx_path, &idxfd, basepath, "");
921 	if (err)
922 		goto done;
923 	if (fchmod(idxfd, GOT_DEFAULT_PACK_MODE) == -1) {
924 		err = got_error_from_errno2("fchmod", idx_path);
925 		goto done;
926 	}
927 
928 	memset(&ifile, 0, sizeof(ifile));
929 	ifile.client_id = client->id;
930 	if (gotd_imsg_compose_event(&client->repo_child_iev,
931 	    GOTD_IMSG_PACKIDX_FILE, PROC_SESSION,
932 	    idxfd, &ifile, sizeof(ifile)) == -1) {
933 		err = got_error_from_errno("imsg compose PACKIDX_FILE");
934 		idxfd = -1;
935 		goto done;
936 	}
937 	idxfd = -1;
938 
939 	memset(&ipack, 0, sizeof(ipack));
940 	ipack.client_id = client->id;
941 	if (client_has_capability(client, GOT_CAPA_REPORT_STATUS))
942 		ipack.report_status = 1;
943 
944 	if (gotd_imsg_compose_event(&client->repo_child_iev,
945 	    GOTD_IMSG_RECV_PACKFILE, PROC_SESSION, packfd,
946 	    &ipack, sizeof(ipack)) == -1) {
947 		err = got_error_from_errno("imsg compose RECV_PACKFILE");
948 		packfd = -1;
949 		goto done;
950 	}
951 	packfd = -1;
952 
953 done:
954 	free(basepath);
955 	if (pipe[0] != -1 && close(pipe[0]) == -1 && err == NULL)
956 		err = got_error_from_errno("close");
957 	if (pipe[1] != -1 && close(pipe[1]) == -1 && err == NULL)
958 		err = got_error_from_errno("close");
959 	if (packfd != -1 && close(packfd) == -1 && err == NULL)
960 		err = got_error_from_errno("close");
961 	if (idxfd != -1 && close(idxfd) == -1 && err == NULL)
962 		err = got_error_from_errno("close");
963 	if (err) {
964 		free(pack_path);
965 		free(idx_path);
966 	} else {
967 		client->packfile_path = pack_path;
968 		client->packidx_path = idx_path;
969 	}
970 	return err;
971 }
972 
973 static const struct got_error *
974 send_packfile(struct gotd_session_client *client)
975 {
976 	const struct got_error *err = NULL;
977 	struct gotd_imsg_send_packfile ipack;
978 	struct gotd_imsg_packfile_pipe ipipe;
979 	int pipe[2];
980 
981 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pipe) == -1)
982 		return got_error_from_errno("socketpair");
983 
984 	memset(&ipack, 0, sizeof(ipack));
985 	memset(&ipipe, 0, sizeof(ipipe));
986 
987 	ipack.client_id = client->id;
988 	if (client_has_capability(client, GOT_CAPA_SIDE_BAND_64K))
989 		ipack.report_progress = 1;
990 
991 	client->delta_cache_fd = got_opentempfd();
992 	if (client->delta_cache_fd == -1)
993 		return got_error_from_errno("got_opentempfd");
994 
995 	if (gotd_imsg_compose_event(&client->repo_child_iev,
996 	    GOTD_IMSG_SEND_PACKFILE, PROC_GOTD, client->delta_cache_fd,
997 	    &ipack, sizeof(ipack)) == -1) {
998 		err = got_error_from_errno("imsg compose SEND_PACKFILE");
999 		close(pipe[0]);
1000 		close(pipe[1]);
1001 		return err;
1002 	}
1003 
1004 	ipipe.client_id = client->id;
1005 
1006 	/* Send pack pipe end 0 to repo child process. */
1007 	if (gotd_imsg_compose_event(&client->repo_child_iev,
1008 	    GOTD_IMSG_PACKFILE_PIPE, PROC_GOTD,
1009 	    pipe[0], &ipipe, sizeof(ipipe)) == -1) {
1010 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
1011 		close(pipe[1]);
1012 		return err;
1013 	}
1014 
1015 	/* Send pack pipe end 1 to gotsh(1) (expects just an fd, no data). */
1016 	if (gotd_imsg_compose_event(&client->iev,
1017 	    GOTD_IMSG_PACKFILE_PIPE, PROC_GOTD, pipe[1], NULL, 0) == -1)
1018 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
1019 
1020 	return err;
1021 }
1022 
1023 static void
1024 session_dispatch_client(int fd, short events, void *arg)
1025 {
1026 	struct gotd_imsgev *iev = arg;
1027 	struct imsgbuf *ibuf = &iev->ibuf;
1028 	struct gotd_session_client *client = &gotd_session_client;
1029 	const struct got_error *err = NULL;
1030 	struct imsg imsg;
1031 	ssize_t n;
1032 
1033 	if (events & EV_WRITE) {
1034 		while (ibuf->w.queued) {
1035 			n = msgbuf_write(&ibuf->w);
1036 			if (n == -1 && errno == EPIPE) {
1037 				/*
1038 				 * The client has closed its socket.
1039 				 * This can happen when Git clients are
1040 				 * done sending pack file data.
1041 				 */
1042 				msgbuf_clear(&ibuf->w);
1043 				continue;
1044 			} else if (n == -1 && errno != EAGAIN) {
1045 				err = got_error_from_errno("imsg_flush");
1046 				disconnect_on_error(client, err);
1047 				return;
1048 			}
1049 			if (n == 0) {
1050 				/* Connection closed. */
1051 				err = got_error(GOT_ERR_EOF);
1052 				disconnect_on_error(client, err);
1053 				return;
1054 			}
1055 		}
1056 	}
1057 
1058 	if ((events & EV_READ) == 0)
1059 		return;
1060 
1061 	memset(&imsg, 0, sizeof(imsg));
1062 
1063 	while (err == NULL) {
1064 		err = gotd_imsg_recv(&imsg, ibuf, 0);
1065 		if (err) {
1066 			if (err->code == GOT_ERR_PRIVSEP_READ)
1067 				err = NULL;
1068 			else if (err->code == GOT_ERR_EOF &&
1069 			    client->state == GOTD_STATE_EXPECT_CAPABILITIES) {
1070 				/*
1071 				 * The client has closed its socket before
1072 				 * sending its capability announcement.
1073 				 * This can happen when Git clients have
1074 				 * no ref-updates to send.
1075 				 */
1076 				disconnect_on_error(client, err);
1077 				return;
1078 			}
1079 			break;
1080 		}
1081 
1082 		evtimer_del(&client->tmo);
1083 
1084 		switch (imsg.hdr.type) {
1085 		case GOTD_IMSG_CAPABILITIES:
1086 			if (client->state != GOTD_STATE_EXPECT_CAPABILITIES) {
1087 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1088 				    "unexpected capabilities received");
1089 				break;
1090 			}
1091 			log_debug("receiving capabilities from uid %d",
1092 			    client->euid);
1093 			err = recv_capabilities(client, &imsg);
1094 			break;
1095 		case GOTD_IMSG_CAPABILITY:
1096 			if (client->state != GOTD_STATE_EXPECT_CAPABILITIES) {
1097 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1098 				    "unexpected capability received");
1099 				break;
1100 			}
1101 			err = recv_capability(client, &imsg);
1102 			if (err || client->ncapabilities < client->ncapa_alloc)
1103 				break;
1104 			if (!client->is_writing) {
1105 				client->state = GOTD_STATE_EXPECT_WANT;
1106 				client->accept_flush_pkt = 1;
1107 				log_debug("uid %d: expecting want-lines",
1108 				    client->euid);
1109 			} else if (client->is_writing) {
1110 				client->state = GOTD_STATE_EXPECT_REF_UPDATE;
1111 				client->accept_flush_pkt = 1;
1112 				log_debug("uid %d: expecting ref-update-lines",
1113 				    client->euid);
1114 			} else
1115 				fatalx("client %d is both reading and writing",
1116 				    client->euid);
1117 			break;
1118 		case GOTD_IMSG_WANT:
1119 			if (client->state != GOTD_STATE_EXPECT_WANT) {
1120 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1121 				    "unexpected want-line received");
1122 				break;
1123 			}
1124 			log_debug("received want-line from uid %d",
1125 			    client->euid);
1126 			err = ensure_client_is_reading(client);
1127 			if (err)
1128 				break;
1129 			client->accept_flush_pkt = 1;
1130 			err = forward_want(client, &imsg);
1131 			break;
1132 		case GOTD_IMSG_REF_UPDATE:
1133 			if (client->state != GOTD_STATE_EXPECT_REF_UPDATE &&
1134 			    client->state !=
1135 			    GOTD_STATE_EXPECT_MORE_REF_UPDATES) {
1136 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1137 				    "unexpected ref-update-line received");
1138 				break;
1139 			}
1140 			log_debug("received ref-update-line from uid %d",
1141 			    client->euid);
1142 			err = ensure_client_is_writing(client);
1143 			if (err)
1144 				break;
1145 			err = forward_ref_update(client, &imsg);
1146 			if (err)
1147 				break;
1148 			client->state = GOTD_STATE_EXPECT_MORE_REF_UPDATES;
1149 			client->accept_flush_pkt = 1;
1150 			break;
1151 		case GOTD_IMSG_HAVE:
1152 			if (client->state != GOTD_STATE_EXPECT_HAVE) {
1153 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1154 				    "unexpected have-line received");
1155 				break;
1156 			}
1157 			log_debug("received have-line from uid %d",
1158 			    client->euid);
1159 			err = ensure_client_is_reading(client);
1160 			if (err)
1161 				break;
1162 			err = forward_have(client, &imsg);
1163 			if (err)
1164 				break;
1165 			client->accept_flush_pkt = 1;
1166 			break;
1167 		case GOTD_IMSG_FLUSH:
1168 			if (client->state == GOTD_STATE_EXPECT_WANT ||
1169 			    client->state == GOTD_STATE_EXPECT_HAVE) {
1170 				err = ensure_client_is_reading(client);
1171 				if (err)
1172 					break;
1173 			} else if (client->state ==
1174 			    GOTD_STATE_EXPECT_MORE_REF_UPDATES) {
1175 				err = ensure_client_is_writing(client);
1176 				if (err)
1177 					break;
1178 			} else if (client->state != GOTD_STATE_EXPECT_DONE) {
1179 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1180 				    "unexpected flush-pkt received");
1181 				break;
1182 			}
1183 			if (!client->accept_flush_pkt) {
1184 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1185 				    "unexpected flush-pkt received");
1186 				break;
1187 			}
1188 
1189 			/*
1190 			 * Accept just one flush packet at a time.
1191 			 * Future client state transitions will set this flag
1192 			 * again if another flush packet is expected.
1193 			 */
1194 			client->accept_flush_pkt = 0;
1195 
1196 			log_debug("received flush-pkt from uid %d",
1197 			    client->euid);
1198 			if (client->state == GOTD_STATE_EXPECT_WANT) {
1199 				client->state = GOTD_STATE_EXPECT_HAVE;
1200 				log_debug("uid %d: expecting have-lines",
1201 				    client->euid);
1202 			} else if (client->state == GOTD_STATE_EXPECT_HAVE) {
1203 				client->state = GOTD_STATE_EXPECT_DONE;
1204 				client->accept_flush_pkt = 1;
1205 				log_debug("uid %d: expecting 'done'",
1206 				    client->euid);
1207 			} else if (client->state ==
1208 			    GOTD_STATE_EXPECT_MORE_REF_UPDATES) {
1209 				client->state = GOTD_STATE_EXPECT_PACKFILE;
1210 				log_debug("uid %d: expecting packfile",
1211 				    client->euid);
1212 				err = recv_packfile(client);
1213 			} else if (client->state != GOTD_STATE_EXPECT_DONE) {
1214 				/* should not happen, see above */
1215 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1216 				    "unexpected client state");
1217 				break;
1218 			}
1219 			break;
1220 		case GOTD_IMSG_DONE:
1221 			if (client->state != GOTD_STATE_EXPECT_HAVE &&
1222 			    client->state != GOTD_STATE_EXPECT_DONE) {
1223 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1224 				    "unexpected flush-pkt received");
1225 				break;
1226 			}
1227 			log_debug("received 'done' from uid %d", client->euid);
1228 			err = ensure_client_is_reading(client);
1229 			if (err)
1230 				break;
1231 			client->state = GOTD_STATE_DONE;
1232 			client->accept_flush_pkt = 1;
1233 			err = send_packfile(client);
1234 			break;
1235 		default:
1236 			log_debug("unexpected imsg %d", imsg.hdr.type);
1237 			err = got_error(GOT_ERR_PRIVSEP_MSG);
1238 			break;
1239 		}
1240 
1241 		imsg_free(&imsg);
1242 	}
1243 
1244 	if (err) {
1245 		if (err->code != GOT_ERR_EOF ||
1246 		    client->state != GOTD_STATE_EXPECT_PACKFILE)
1247 			disconnect_on_error(client, err);
1248 	} else {
1249 		gotd_imsg_event_add(iev);
1250 		evtimer_add(&client->tmo, &gotd_session.request_timeout);
1251 	}
1252 }
1253 
1254 static const struct got_error *
1255 list_refs_request(void)
1256 {
1257 	static const struct got_error *err;
1258 	struct gotd_session_client *client = &gotd_session_client;
1259 	struct gotd_imsgev *iev = &client->repo_child_iev;
1260 	struct gotd_imsg_list_refs_internal ilref;
1261 	int fd;
1262 
1263 	if (client->state != GOTD_STATE_EXPECT_LIST_REFS)
1264 		return got_error(GOT_ERR_PRIVSEP_MSG);
1265 
1266 	memset(&ilref, 0, sizeof(ilref));
1267 	ilref.client_id = client->id;
1268 
1269 	fd = dup(client->fd);
1270 	if (fd == -1)
1271 		return got_error_from_errno("dup");
1272 
1273 	if (gotd_imsg_compose_event(iev, GOTD_IMSG_LIST_REFS_INTERNAL,
1274 	    PROC_SESSION, fd, &ilref, sizeof(ilref)) == -1) {
1275 		err = got_error_from_errno("imsg compose LIST_REFS_INTERNAL");
1276 		close(fd);
1277 		return err;
1278 	}
1279 
1280 	client->state = GOTD_STATE_EXPECT_CAPABILITIES;
1281 	log_debug("uid %d: expecting capabilities", client->euid);
1282 	return NULL;
1283 }
1284 
1285 static const struct got_error *
1286 recv_connect(struct imsg *imsg)
1287 {
1288 	struct gotd_session_client *client = &gotd_session_client;
1289 	struct gotd_imsg_connect iconnect;
1290 	size_t datalen;
1291 
1292 	if (client->state != GOTD_STATE_EXPECT_LIST_REFS)
1293 		return got_error(GOT_ERR_PRIVSEP_MSG);
1294 
1295 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1296 	if (datalen != sizeof(iconnect))
1297 		return got_error(GOT_ERR_PRIVSEP_LEN);
1298 	memcpy(&iconnect, imsg->data, sizeof(iconnect));
1299 
1300 	if (imsg->fd == -1)
1301 		return got_error(GOT_ERR_PRIVSEP_NO_FD);
1302 
1303 	client->fd = imsg->fd;
1304 	client->euid = iconnect.euid;
1305 	client->egid = iconnect.egid;
1306 
1307 	imsg_init(&client->iev.ibuf, client->fd);
1308 	client->iev.handler = session_dispatch_client;
1309 	client->iev.events = EV_READ;
1310 	client->iev.handler_arg = NULL;
1311 	event_set(&client->iev.ev, client->iev.ibuf.fd, EV_READ,
1312 	    session_dispatch_client, &client->iev);
1313 	gotd_imsg_event_add(&client->iev);
1314 	evtimer_set(&client->tmo, gotd_request_timeout, client);
1315 
1316 	return NULL;
1317 }
1318 
1319 static const struct got_error *
1320 recv_repo_child(struct imsg *imsg)
1321 {
1322 	struct gotd_imsg_connect_repo_child ichild;
1323 	struct gotd_session_client *client = &gotd_session_client;
1324 	size_t datalen;
1325 
1326 	if (client->state != GOTD_STATE_EXPECT_LIST_REFS)
1327 		return got_error(GOT_ERR_PRIVSEP_MSG);
1328 
1329 	/* We should already have received a pipe to the listener. */
1330 	if (client->fd == -1)
1331 		return got_error(GOT_ERR_PRIVSEP_MSG);
1332 
1333 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1334 	if (datalen != sizeof(ichild))
1335 		return got_error(GOT_ERR_PRIVSEP_LEN);
1336 
1337 	memcpy(&ichild, imsg->data, sizeof(ichild));
1338 
1339 	client->id = ichild.client_id;
1340 	if (ichild.proc_id == PROC_REPO_WRITE)
1341 		client->is_writing = 1;
1342 	else if (ichild.proc_id == PROC_REPO_READ)
1343 		client->is_writing = 0;
1344 	else
1345 		return got_error_msg(GOT_ERR_PRIVSEP_MSG,
1346 		    "bad child process type");
1347 
1348 	if (imsg->fd == -1)
1349 		return got_error(GOT_ERR_PRIVSEP_NO_FD);
1350 
1351 	imsg_init(&client->repo_child_iev.ibuf, imsg->fd);
1352 	client->repo_child_iev.handler = session_dispatch_repo_child;
1353 	client->repo_child_iev.events = EV_READ;
1354 	client->repo_child_iev.handler_arg = NULL;
1355 	event_set(&client->repo_child_iev.ev, client->repo_child_iev.ibuf.fd,
1356 	    EV_READ, session_dispatch_repo_child, &client->repo_child_iev);
1357 	gotd_imsg_event_add(&client->repo_child_iev);
1358 
1359 	/* The "recvfd" pledge promise is no longer needed. */
1360 	if (pledge("stdio rpath wpath cpath sendfd fattr flock", NULL) == -1)
1361 		fatal("pledge");
1362 
1363 	return NULL;
1364 }
1365 
1366 static void
1367 session_dispatch(int fd, short event, void *arg)
1368 {
1369 	struct gotd_imsgev *iev = arg;
1370 	struct imsgbuf *ibuf = &iev->ibuf;
1371 	struct gotd_session_client *client = &gotd_session_client;
1372 	ssize_t n;
1373 	int shut = 0;
1374 	struct imsg imsg;
1375 
1376 	if (event & EV_READ) {
1377 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1378 			fatal("imsg_read error");
1379 		if (n == 0) {
1380 			/* Connection closed. */
1381 			shut = 1;
1382 			goto done;
1383 		}
1384 	}
1385 
1386 	if (event & EV_WRITE) {
1387 		n = msgbuf_write(&ibuf->w);
1388 		if (n == -1 && errno != EAGAIN)
1389 			fatal("msgbuf_write");
1390 		if (n == 0) {
1391 			/* Connection closed. */
1392 			shut = 1;
1393 			goto done;
1394 		}
1395 	}
1396 
1397 	for (;;) {
1398 		const struct got_error *err = NULL;
1399 		uint32_t client_id = 0;
1400 		int do_disconnect = 0, do_list_refs = 0;
1401 
1402 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1403 			fatal("%s: imsg_get error", __func__);
1404 		if (n == 0)	/* No more messages. */
1405 			break;
1406 
1407 		switch (imsg.hdr.type) {
1408 		case GOTD_IMSG_ERROR:
1409 			do_disconnect = 1;
1410 			err = gotd_imsg_recv_error(&client_id, &imsg);
1411 			break;
1412 		case GOTD_IMSG_CONNECT:
1413 			err = recv_connect(&imsg);
1414 			break;
1415 		case GOTD_IMSG_DISCONNECT:
1416 			do_disconnect = 1;
1417 			break;
1418 		case GOTD_IMSG_CONNECT_REPO_CHILD:
1419 			err = recv_repo_child(&imsg);
1420 			if (err)
1421 				break;
1422 			do_list_refs = 1;
1423 			break;
1424 		default:
1425 			log_debug("unexpected imsg %d", imsg.hdr.type);
1426 			break;
1427 		}
1428 		imsg_free(&imsg);
1429 
1430 		if (do_disconnect) {
1431 			if (err)
1432 				disconnect_on_error(client, err);
1433 			else
1434 				disconnect(client);
1435 		} else if (do_list_refs)
1436 			err = list_refs_request();
1437 
1438 		if (err)
1439 			log_warnx("uid %d: %s", client->euid, err->msg);
1440 	}
1441 done:
1442 	if (!shut) {
1443 		gotd_imsg_event_add(iev);
1444 	} else {
1445 		/* This pipe is dead. Remove its event handler */
1446 		event_del(&iev->ev);
1447 		event_loopexit(NULL);
1448 	}
1449 }
1450 
1451 void
1452 session_main(const char *title, const char *repo_path,
1453     int *pack_fds, int *temp_fds, struct timeval *request_timeout)
1454 {
1455 	const struct got_error *err = NULL;
1456 	struct event evsigint, evsigterm, evsighup, evsigusr1;
1457 
1458 	gotd_session.title = title;
1459 	gotd_session.pid = getpid();
1460 	gotd_session.pack_fds = pack_fds;
1461 	gotd_session.temp_fds = temp_fds;
1462 	memcpy(&gotd_session.request_timeout, request_timeout,
1463 	    sizeof(gotd_session.request_timeout));
1464 
1465 	err = got_repo_open(&gotd_session.repo, repo_path, NULL, pack_fds);
1466 	if (err)
1467 		goto done;
1468 	if (!got_repo_is_bare(gotd_session.repo)) {
1469 		err = got_error_msg(GOT_ERR_NOT_GIT_REPO,
1470 		    "bare git repository required");
1471 		goto done;
1472 	}
1473 
1474 	got_repo_temp_fds_set(gotd_session.repo, temp_fds);
1475 
1476 	signal_set(&evsigint, SIGINT, gotd_session_sighdlr, NULL);
1477 	signal_set(&evsigterm, SIGTERM, gotd_session_sighdlr, NULL);
1478 	signal_set(&evsighup, SIGHUP, gotd_session_sighdlr, NULL);
1479 	signal_set(&evsigusr1, SIGUSR1, gotd_session_sighdlr, NULL);
1480 	signal(SIGPIPE, SIG_IGN);
1481 
1482 	signal_add(&evsigint, NULL);
1483 	signal_add(&evsigterm, NULL);
1484 	signal_add(&evsighup, NULL);
1485 	signal_add(&evsigusr1, NULL);
1486 
1487 	gotd_session_client.state = GOTD_STATE_EXPECT_LIST_REFS;
1488 	gotd_session_client.fd = -1;
1489 	gotd_session_client.nref_updates = -1;
1490 	gotd_session_client.delta_cache_fd = -1;
1491 	gotd_session_client.accept_flush_pkt = 1;
1492 
1493 	imsg_init(&gotd_session.parent_iev.ibuf, GOTD_FILENO_MSG_PIPE);
1494 	gotd_session.parent_iev.handler = session_dispatch;
1495 	gotd_session.parent_iev.events = EV_READ;
1496 	gotd_session.parent_iev.handler_arg = NULL;
1497 	event_set(&gotd_session.parent_iev.ev, gotd_session.parent_iev.ibuf.fd,
1498 	    EV_READ, session_dispatch, &gotd_session.parent_iev);
1499 	if (gotd_imsg_compose_event(&gotd_session.parent_iev,
1500 	    GOTD_IMSG_CLIENT_SESSION_READY, PROC_SESSION, -1, NULL, 0) == -1) {
1501 		err = got_error_from_errno("imsg compose CLIENT_SESSION_READY");
1502 		goto done;
1503 	}
1504 
1505 	event_dispatch();
1506 done:
1507 	if (err)
1508 		log_warnx("%s: %s", title, err->msg);
1509 	gotd_session_shutdown();
1510 }
1511 
1512 void
1513 gotd_session_shutdown(void)
1514 {
1515 	log_debug("shutting down");
1516 	if (gotd_session.repo)
1517 		got_repo_close(gotd_session.repo);
1518 	got_repo_pack_fds_close(gotd_session.pack_fds);
1519 	got_repo_temp_fds_close(gotd_session.temp_fds);
1520 	exit(0);
1521 }