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_write.h"
55 
56 struct gotd_session_notif {
57 	STAILQ_ENTRY(gotd_session_notif) entry;
58 	int fd;
59 	enum gotd_notification_action action;
60 	char *refname;
61 	struct got_object_id old_id;
62 	struct got_object_id new_id;
63 };
64 STAILQ_HEAD(gotd_session_notifications, gotd_session_notif) notifications;
65 
66 enum gotd_session_write_state {
67 	GOTD_STATE_EXPECT_LIST_REFS,
68 	GOTD_STATE_EXPECT_CAPABILITIES,
69 	GOTD_STATE_EXPECT_REF_UPDATE,
70 	GOTD_STATE_EXPECT_MORE_REF_UPDATES,
71 	GOTD_STATE_EXPECT_PACKFILE,
72 	GOTD_STATE_NOTIFY,
73 };
74 
75 static struct gotd_session_write {
76 	pid_t pid;
77 	const char *title;
78 	struct got_repository *repo;
79 	struct gotd_repo *repo_cfg;
80 	int *pack_fds;
81 	int *temp_fds;
82 	struct gotd_imsgev parent_iev;
83 	struct gotd_imsgev notifier_iev;
84 	struct timeval request_timeout;
85 	enum gotd_session_write_state state;
86 	struct gotd_imsgev repo_child_iev;
87 } gotd_session;
88 
89 static struct gotd_session_client {
90 	struct gotd_client_capability	*capabilities;
91 	size_t				 ncapa_alloc;
92 	size_t				 ncapabilities;
93 	uint32_t			 id;
94 	int				 fd;
95 	int				 delta_cache_fd;
96 	struct gotd_imsgev		 iev;
97 	struct event			 tmo;
98 	uid_t				 euid;
99 	gid_t				 egid;
100 	char				*username;
101 	char				*packfile_path;
102 	char				*packidx_path;
103 	int				 nref_updates;
104 	int				 accept_flush_pkt;
105 	int				 flush_disconnect;
106 } gotd_session_client;
107 
108 static void session_write_shutdown(void);
109 
110 static void
111 disconnect(struct gotd_session_client *client)
112 {
113 	log_debug("uid %d: disconnecting", client->euid);
114 
115 	if (gotd_imsg_compose_event(&gotd_session.parent_iev,
116 	    GOTD_IMSG_DISCONNECT, PROC_SESSION_WRITE, -1, NULL, 0) == -1)
117 		log_warn("imsg compose DISCONNECT");
118 
119 	imsg_clear(&gotd_session.repo_child_iev.ibuf);
120 	event_del(&gotd_session.repo_child_iev.ev);
121 	evtimer_del(&client->tmo);
122 	close(client->fd);
123 	if (client->delta_cache_fd != -1)
124 		close(client->delta_cache_fd);
125 	if (client->packfile_path) {
126 		if (unlink(client->packfile_path) == -1 && errno != ENOENT)
127 			log_warn("unlink %s: ", client->packfile_path);
128 		free(client->packfile_path);
129 	}
130 	if (client->packidx_path) {
131 		if (unlink(client->packidx_path) == -1 && errno != ENOENT)
132 			log_warn("unlink %s: ", client->packidx_path);
133 		free(client->packidx_path);
134 	}
135 	free(client->capabilities);
136 
137 	session_write_shutdown();
138 }
139 
140 static void
141 disconnect_on_error(struct gotd_session_client *client,
142     const struct got_error *err)
143 {
144 	struct imsgbuf ibuf;
145 
146 	if (err->code != GOT_ERR_EOF) {
147 		log_warnx("uid %d: %s", client->euid, err->msg);
148 		imsg_init(&ibuf, client->fd);
149 		gotd_imsg_send_error(&ibuf, 0, PROC_SESSION_WRITE, err);
150 		imsg_clear(&ibuf);
151 	}
152 
153 	disconnect(client);
154 }
155 
156 static void
157 gotd_request_timeout(int fd, short events, void *arg)
158 {
159 	struct gotd_session_client *client = arg;
160 
161 	log_warnx("disconnecting uid %d due to timeout", client->euid);
162 	disconnect(client);
163 }
164 
165 static void
166 session_write_sighdlr(int sig, short event, void *arg)
167 {
168 	/*
169 	 * Normal signal handler rules don't apply because libevent
170 	 * decouples for us.
171 	 */
172 
173 	switch (sig) {
174 	case SIGHUP:
175 		log_info("%s: ignoring SIGHUP", __func__);
176 		break;
177 	case SIGUSR1:
178 		log_info("%s: ignoring SIGUSR1", __func__);
179 		break;
180 	case SIGTERM:
181 	case SIGINT:
182 		session_write_shutdown();
183 		/* NOTREACHED */
184 		break;
185 	default:
186 		fatalx("unexpected signal");
187 	}
188 }
189 
190 static const struct got_error *
191 recv_packfile_install(struct imsg *imsg)
192 {
193 	struct gotd_imsg_packfile_install inst;
194 	size_t datalen;
195 
196 	log_debug("packfile-install received");
197 
198 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
199 	if (datalen != sizeof(inst))
200 		return got_error(GOT_ERR_PRIVSEP_LEN);
201 	memcpy(&inst, imsg->data, sizeof(inst));
202 
203 	return NULL;
204 }
205 
206 static const struct got_error *
207 recv_ref_updates_start(struct imsg *imsg)
208 {
209 	struct gotd_imsg_ref_updates_start istart;
210 	size_t datalen;
211 
212 	log_debug("ref-updates-start received");
213 
214 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
215 	if (datalen != sizeof(istart))
216 		return got_error(GOT_ERR_PRIVSEP_LEN);
217 	memcpy(&istart, imsg->data, sizeof(istart));
218 
219 	return NULL;
220 }
221 
222 static const struct got_error *
223 recv_ref_update(struct imsg *imsg)
224 {
225 	struct gotd_imsg_ref_update iref;
226 	size_t datalen;
227 
228 	log_debug("ref-update received");
229 
230 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
231 	if (datalen < sizeof(iref))
232 		return got_error(GOT_ERR_PRIVSEP_LEN);
233 	memcpy(&iref, imsg->data, sizeof(iref));
234 
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 	memcpy(iok.old_id, iref->old_id, SHA1_DIGEST_LENGTH);
249 	memcpy(iok.new_id, iref->new_id, SHA1_DIGEST_LENGTH);
250 	iok.name_len = strlen(refname);
251 
252 	len = sizeof(iok) + iok.name_len;
253 	wbuf = imsg_create(&iev->ibuf, GOTD_IMSG_REF_UPDATE_OK,
254 	    PROC_SESSION_WRITE, gotd_session.pid, len);
255 	if (wbuf == NULL)
256 		return got_error_from_errno("imsg_create REF_UPDATE_OK");
257 
258 	if (imsg_add(wbuf, &iok, sizeof(iok)) == -1)
259 		return got_error_from_errno("imsg_add REF_UPDATE_OK");
260 	if (imsg_add(wbuf, refname, iok.name_len) == -1)
261 		return got_error_from_errno("imsg_add REF_UPDATE_OK");
262 
263 	imsg_close(&iev->ibuf, wbuf);
264 	gotd_imsg_event_add(iev);
265 	return NULL;
266 }
267 
268 static void
269 send_refs_updated(struct gotd_session_client *client)
270 {
271 	if (gotd_imsg_compose_event(&client->iev, GOTD_IMSG_REFS_UPDATED,
272 	    PROC_SESSION_WRITE, -1, NULL, 0) == -1)
273 		log_warn("imsg compose REFS_UPDATED");
274 }
275 
276 static const struct got_error *
277 send_ref_update_ng(struct gotd_session_client *client,
278     struct gotd_imsg_ref_update *iref, const char *refname,
279     const char *reason)
280 {
281 	const struct got_error *ng_err;
282 	struct gotd_imsg_ref_update_ng ing;
283 	struct gotd_imsgev *iev = &client->iev;
284 	struct ibuf *wbuf;
285 	size_t len;
286 
287 	memset(&ing, 0, sizeof(ing));
288 	memcpy(ing.old_id, iref->old_id, SHA1_DIGEST_LENGTH);
289 	memcpy(ing.new_id, iref->new_id, SHA1_DIGEST_LENGTH);
290 	ing.name_len = strlen(refname);
291 
292 	ng_err = got_error_fmt(GOT_ERR_REF_BUSY, "%s", reason);
293 	ing.reason_len = strlen(ng_err->msg);
294 
295 	len = sizeof(ing) + ing.name_len + ing.reason_len;
296 	wbuf = imsg_create(&iev->ibuf, GOTD_IMSG_REF_UPDATE_NG,
297 	    PROC_SESSION_WRITE, gotd_session.pid, len);
298 	if (wbuf == NULL)
299 		return got_error_from_errno("imsg_create REF_UPDATE_NG");
300 
301 	if (imsg_add(wbuf, &ing, sizeof(ing)) == -1)
302 		return got_error_from_errno("imsg_add REF_UPDATE_NG");
303 	if (imsg_add(wbuf, refname, ing.name_len) == -1)
304 		return got_error_from_errno("imsg_add REF_UPDATE_NG");
305 	if (imsg_add(wbuf, ng_err->msg, ing.reason_len) == -1)
306 		return got_error_from_errno("imsg_add REF_UPDATE_NG");
307 
308 	imsg_close(&iev->ibuf, wbuf);
309 	gotd_imsg_event_add(iev);
310 	return NULL;
311 }
312 
313 static const struct got_error *
314 install_pack(struct gotd_session_client *client, const char *repo_path,
315     struct imsg *imsg)
316 {
317 	const struct got_error *err = NULL;
318 	struct gotd_imsg_packfile_install inst;
319 	char hex[SHA1_DIGEST_STRING_LENGTH];
320 	size_t datalen;
321 	char *packfile_path = NULL, *packidx_path = NULL;
322 
323 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
324 	if (datalen != sizeof(inst))
325 		return got_error(GOT_ERR_PRIVSEP_LEN);
326 	memcpy(&inst, imsg->data, sizeof(inst));
327 
328 	if (client->packfile_path == NULL)
329 		return got_error_msg(GOT_ERR_BAD_REQUEST,
330 		    "client has no pack file");
331 	if (client->packidx_path == NULL)
332 		return got_error_msg(GOT_ERR_BAD_REQUEST,
333 		    "client has no pack file index");
334 
335 	if (got_sha1_digest_to_str(inst.pack_sha1, hex, sizeof(hex)) == NULL)
336 		return got_error_msg(GOT_ERR_NO_SPACE,
337 		    "could not convert pack file SHA1 to hex");
338 
339 	if (asprintf(&packfile_path, "/%s/%s/pack-%s.pack",
340 	    repo_path, GOT_OBJECTS_PACK_DIR, hex) == -1) {
341 		err = got_error_from_errno("asprintf");
342 		goto done;
343 	}
344 
345 	if (asprintf(&packidx_path, "/%s/%s/pack-%s.idx",
346 	    repo_path, GOT_OBJECTS_PACK_DIR, hex) == -1) {
347 		err = got_error_from_errno("asprintf");
348 		goto done;
349 	}
350 
351 	if (rename(client->packfile_path, packfile_path) == -1) {
352 		err = got_error_from_errno3("rename", client->packfile_path,
353 		    packfile_path);
354 		goto done;
355 	}
356 
357 	free(client->packfile_path);
358 	client->packfile_path = NULL;
359 
360 	if (rename(client->packidx_path, packidx_path) == -1) {
361 		err = got_error_from_errno3("rename", client->packidx_path,
362 		    packidx_path);
363 		goto done;
364 	}
365 
366 	/* Ensure we re-read the pack index list upon next access. */
367 	gotd_session.repo->pack_path_mtime.tv_sec = 0;
368 	gotd_session.repo->pack_path_mtime.tv_nsec = 0;
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 validate_namespace(const char *namespace)
401 {
402 	size_t len = strlen(namespace);
403 
404 	if (len < 5 || strncmp("refs/", namespace, 5) != 0 ||
405 	    namespace[len - 1] != '/') {
406 		return got_error_fmt(GOT_ERR_BAD_REF_NAME,
407 		    "reference namespace '%s'", namespace);
408 	}
409 
410 	return NULL;
411 }
412 
413 static const struct got_error *
414 queue_notification(struct got_object_id *old_id, struct got_object_id *new_id,
415     struct got_repository *repo, struct got_reference *ref)
416 {
417 	const struct got_error *err = NULL;
418 	struct gotd_repo *repo_cfg = gotd_session.repo_cfg;
419 	struct gotd_imsgev *iev = &gotd_session.repo_child_iev;
420 	struct got_pathlist_entry *pe;
421 	struct gotd_session_notif *notif;
422 
423 	if (iev->ibuf.fd == -1 ||
424 	    STAILQ_EMPTY(&repo_cfg->notification_targets))
425 		return NULL; /* notifications unused */
426 
427 	TAILQ_FOREACH(pe, &repo_cfg->notification_refs, entry) {
428 		const char *refname = pe->path;
429 		if (strcmp(got_ref_get_name(ref), refname) == 0)
430 			break;
431 	}
432 	if (pe == NULL) {
433 		TAILQ_FOREACH(pe, &repo_cfg->notification_ref_namespaces,
434 		    entry) {
435 			const char *namespace = pe->path;
436 
437 			err = validate_namespace(namespace);
438 			if (err)
439 				return err;
440 			if (strncmp(namespace, got_ref_get_name(ref),
441 			    strlen(namespace)) == 0)
442 				break;
443 		}
444 	}
445 
446 	/*
447 	 * If a branch or a reference namespace was specified in the
448 	 * configuration file then only send notifications if a match
449 	 * was found.
450 	 */
451 	if (pe == NULL && (!TAILQ_EMPTY(&repo_cfg->notification_refs) ||
452 	    !TAILQ_EMPTY(&repo_cfg->notification_ref_namespaces)))
453 		return NULL;
454 
455 	notif = calloc(1, sizeof(*notif));
456 	if (notif == NULL)
457 		return got_error_from_errno("calloc");
458 
459 	notif->fd = -1;
460 
461 	if (old_id == NULL)
462 		notif->action = GOTD_NOTIF_ACTION_CREATED;
463 	else if (new_id == NULL)
464 		notif->action = GOTD_NOTIF_ACTION_REMOVED;
465 	else
466 		notif->action = GOTD_NOTIF_ACTION_CHANGED;
467 
468 	if (old_id != NULL)
469 		memcpy(&notif->old_id, old_id, sizeof(notif->old_id));
470 	if (new_id != NULL)
471 		memcpy(&notif->new_id, new_id, sizeof(notif->new_id));
472 
473 	notif->refname = strdup(got_ref_get_name(ref));
474 	if (notif->refname == NULL) {
475 		err = got_error_from_errno("strdup");
476 		goto done;
477 	}
478 
479 	STAILQ_INSERT_TAIL(&notifications, notif, entry);
480 done:
481 	if (err && notif) {
482 		free(notif->refname);
483 		free(notif);
484 	}
485 	return err;
486 }
487 
488 /* Forward notification content to the NOTIFY process. */
489 static const struct got_error *
490 forward_notification(struct gotd_session_client *client, struct imsg *imsg)
491 {
492 	const struct got_error *err = NULL;
493 	struct gotd_imsgev *iev = &gotd_session.notifier_iev;
494 	struct gotd_session_notif *notif;
495 	struct gotd_imsg_notification_content icontent;
496 	char *refname = NULL, *id_str = NULL;
497 	size_t datalen;
498 	struct gotd_imsg_notify inotify;
499 	const char *action;
500 	struct ibuf *wbuf;
501 
502 	memset(&inotify, 0, sizeof(inotify));
503 
504 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
505 	if (datalen < sizeof(icontent))
506 		return got_error(GOT_ERR_PRIVSEP_LEN);
507 	memcpy(&icontent, imsg->data, sizeof(icontent));
508 	if (datalen != sizeof(icontent) + icontent.refname_len)
509 		return got_error(GOT_ERR_PRIVSEP_LEN);
510 	refname = strndup(imsg->data + sizeof(icontent), icontent.refname_len);
511 	if (refname == NULL)
512 		return got_error_from_errno("strndup");
513 
514 	notif = STAILQ_FIRST(&notifications);
515 	if (notif == NULL)
516 		return got_error(GOT_ERR_PRIVSEP_MSG);
517 
518 	STAILQ_REMOVE(&notifications, notif, gotd_session_notif, entry);
519 
520 	if (notif->action != icontent.action || notif->fd == -1 ||
521 	    strcmp(notif->refname, refname) != 0) {
522 		err = got_error(GOT_ERR_PRIVSEP_MSG);
523 		goto done;
524 	}
525 	if (notif->action == GOTD_NOTIF_ACTION_CREATED) {
526 		if (memcmp(notif->new_id.sha1, icontent.new_id,
527 		    SHA1_DIGEST_LENGTH) != 0) {
528 			err = got_error_msg(GOT_ERR_PRIVSEP_MSG,
529 			    "received notification content for unknown event");
530 			goto done;
531 		}
532 	} else if (notif->action == GOTD_NOTIF_ACTION_REMOVED) {
533 		if (memcmp(notif->old_id.sha1, icontent.old_id,
534 		    SHA1_DIGEST_LENGTH) != 0) {
535 			err = got_error_msg(GOT_ERR_PRIVSEP_MSG,
536 			    "received notification content for unknown event");
537 			goto done;
538 		}
539 	} else if (memcmp(notif->old_id.sha1, icontent.old_id,
540 	    SHA1_DIGEST_LENGTH) != 0 ||
541 	    memcmp(notif->new_id.sha1, icontent.new_id,
542 	    SHA1_DIGEST_LENGTH) != 0) {
543 		err = got_error_msg(GOT_ERR_PRIVSEP_MSG,
544 		    "received notification content for unknown event");
545 		goto done;
546 	}
547 
548 	switch (notif->action) {
549 	case GOTD_NOTIF_ACTION_CREATED:
550 		action = "created";
551 		err = got_object_id_str(&id_str, &notif->new_id);
552 		if (err)
553 			goto done;
554 		break;
555 	case GOTD_NOTIF_ACTION_REMOVED:
556 		action = "removed";
557 		err = got_object_id_str(&id_str, &notif->old_id);
558 		if (err)
559 			goto done;
560 		break;
561 	case GOTD_NOTIF_ACTION_CHANGED:
562 		action = "changed";
563 		err = got_object_id_str(&id_str, &notif->new_id);
564 		if (err)
565 			goto done;
566 		break;
567 	default:
568 		err = got_error(GOT_ERR_PRIVSEP_MSG);
569 		goto done;
570 	}
571 
572 	strlcpy(inotify.repo_name, gotd_session.repo_cfg->name,
573 	    sizeof(inotify.repo_name));
574 
575 	snprintf(inotify.subject_line, sizeof(inotify.subject_line),
576 	    "%s: %s %s %s: %.12s", gotd_session.repo_cfg->name,
577 	    client->username, action, notif->refname, id_str);
578 
579 	inotify.username_len = strlen(client->username);
580 	wbuf = imsg_create(&iev->ibuf, GOTD_IMSG_NOTIFY,
581 	    PROC_SESSION_WRITE, gotd_session.pid,
582 	    sizeof(inotify) + inotify.username_len);
583 	if (wbuf == NULL) {
584 		err = got_error_from_errno("imsg_create NOTIFY");
585 		goto done;
586 	}
587 	if (imsg_add(wbuf, &inotify, sizeof(inotify)) == -1) {
588 		err = got_error_from_errno("imsg_add NOTIFY");
589 		goto done;
590 	}
591 	if (imsg_add(wbuf, client->username, inotify.username_len) == -1) {
592 		err = got_error_from_errno("imsg_add NOTIFY");
593 		goto done;
594 	}
595 
596 	ibuf_fd_set(wbuf, notif->fd);
597 	notif->fd = -1;
598 
599 	imsg_close(&iev->ibuf, wbuf);
600 	gotd_imsg_event_add(iev);
601 done:
602 	if (notif->fd != -1)
603 		close(notif->fd);
604 	free(notif);
605 	free(refname);
606 	free(id_str);
607 	return err;
608 }
609 
610 /* Request notification content from REPO_WRITE process. */
611 static const struct got_error *
612 request_notification(struct gotd_session_notif *notif)
613 {
614 	const struct got_error *err = NULL;
615 	struct gotd_imsgev *iev = &gotd_session.repo_child_iev;
616 	struct gotd_imsg_notification_content icontent;
617 	struct ibuf *wbuf;
618 	size_t len;
619 	int fd;
620 
621 	fd = got_opentempfd();
622 	if (fd == -1)
623 		return got_error_from_errno("got_opentemp");
624 
625 	memset(&icontent, 0, sizeof(icontent));
626 
627 	icontent.action = notif->action;
628 	memcpy(&icontent.old_id, &notif->old_id, sizeof(notif->old_id));
629 	memcpy(&icontent.new_id, &notif->new_id, sizeof(notif->new_id));
630 	icontent.refname_len = strlen(notif->refname);
631 
632 	len = sizeof(icontent) + icontent.refname_len;
633 	wbuf = imsg_create(&iev->ibuf, GOTD_IMSG_NOTIFY,
634 	    PROC_SESSION_WRITE, gotd_session.pid, len);
635 	if (wbuf == NULL) {
636 		err = got_error_from_errno("imsg_create NOTIFY");
637 		goto done;
638 	}
639 	if (imsg_add(wbuf, &icontent, sizeof(icontent)) == -1) {
640 		err = got_error_from_errno("imsg_add NOTIFY");
641 		goto done;
642 	}
643 	if (imsg_add(wbuf, notif->refname, icontent.refname_len) == -1) {
644 		err = got_error_from_errno("imsg_add NOTIFY");
645 		goto done;
646 	}
647 
648 	notif->fd = dup(fd);
649 	if (notif->fd == -1) {
650 		err = got_error_from_errno("dup");
651 		goto done;
652 	}
653 
654 	ibuf_fd_set(wbuf, fd);
655 	fd = -1;
656 
657 	imsg_close(&iev->ibuf, wbuf);
658 	gotd_imsg_event_add(iev);
659 done:
660 	if (err && fd != -1)
661 		close(fd);
662 	return err;
663 }
664 
665 static const struct got_error *
666 update_ref(int *shut, struct gotd_session_client *client,
667     const char *repo_path, struct imsg *imsg)
668 {
669 	const struct got_error *err = NULL;
670 	struct got_repository *repo = gotd_session.repo;
671 	struct got_reference *ref = NULL;
672 	struct gotd_imsg_ref_update iref;
673 	struct got_object_id old_id, new_id;
674 	struct gotd_session_notif *notif;
675 	struct got_object_id *id = NULL;
676 	char *refname = NULL;
677 	size_t datalen;
678 	int locked = 0;
679 	char hex1[SHA1_DIGEST_STRING_LENGTH];
680 	char hex2[SHA1_DIGEST_STRING_LENGTH];
681 
682 	log_debug("update-ref from uid %d", client->euid);
683 
684 	if (client->nref_updates <= 0)
685 		return got_error(GOT_ERR_PRIVSEP_MSG);
686 
687 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
688 	if (datalen < sizeof(iref))
689 		return got_error(GOT_ERR_PRIVSEP_LEN);
690 	memcpy(&iref, imsg->data, sizeof(iref));
691 	if (datalen != sizeof(iref) + iref.name_len)
692 		return got_error(GOT_ERR_PRIVSEP_LEN);
693 	refname = strndup(imsg->data + sizeof(iref), iref.name_len);
694 	if (refname == NULL)
695 		return got_error_from_errno("strndup");
696 
697 	log_debug("updating ref %s for uid %d", refname, client->euid);
698 
699 	memcpy(old_id.sha1, iref.old_id, SHA1_DIGEST_LENGTH);
700 	memcpy(new_id.sha1, iref.new_id, SHA1_DIGEST_LENGTH);
701 	err = got_repo_find_object_id(iref.delete_ref ? &old_id : &new_id,
702 	    repo);
703 	if (err)
704 		goto done;
705 
706 	if (iref.ref_is_new) {
707 		err = got_ref_open(&ref, repo, refname, 0);
708 		if (err) {
709 			if (err->code != GOT_ERR_NOT_REF)
710 				goto done;
711 			err = got_ref_alloc(&ref, refname, &new_id);
712 			if (err)
713 				goto done;
714 			err = got_ref_write(ref, repo); /* will lock/unlock */
715 			if (err)
716 				goto done;
717 			err = queue_notification(NULL, &new_id, repo, ref);
718 			if (err)
719 				goto done;
720 		} else {
721 			err = got_ref_resolve(&id, repo, ref);
722 			if (err)
723 				goto done;
724 			got_object_id_hex(&new_id, hex1, sizeof(hex1));
725 			got_object_id_hex(id, hex2, sizeof(hex2));
726 			err = got_error_fmt(GOT_ERR_REF_BUSY,
727 			    "Addition %s: %s failed; %s: %s has been "
728 			    "created by someone else while transaction "
729 			    "was in progress",
730 			    got_ref_get_name(ref), hex1,
731 			    got_ref_get_name(ref), hex2);
732 			goto done;
733 		}
734 	} else if (iref.delete_ref) {
735 		err = got_ref_open(&ref, repo, refname, 1 /* lock */);
736 		if (err)
737 			goto done;
738 		locked = 1;
739 
740 		err = got_ref_resolve(&id, repo, ref);
741 		if (err)
742 			goto done;
743 
744 		if (got_object_id_cmp(id, &old_id) != 0) {
745 			got_object_id_hex(&old_id, hex1, sizeof(hex1));
746 			got_object_id_hex(id, hex2, sizeof(hex2));
747 			err = got_error_fmt(GOT_ERR_REF_BUSY,
748 			    "Deletion %s: %s failed; %s: %s has been "
749 			    "created by someone else while transaction "
750 			    "was in progress",
751 			    got_ref_get_name(ref), hex1,
752 			    got_ref_get_name(ref), hex2);
753 			goto done;
754 		}
755 
756 		err = got_ref_delete(ref, repo);
757 		if (err)
758 			goto done;
759 		err = queue_notification(&old_id, NULL, repo, ref);
760 		if (err)
761 			goto done;
762 		free(id);
763 		id = NULL;
764 	} else {
765 		err = got_ref_open(&ref, repo, refname, 1 /* lock */);
766 		if (err)
767 			goto done;
768 		locked = 1;
769 
770 		err = got_ref_resolve(&id, repo, ref);
771 		if (err)
772 			goto done;
773 
774 		if (got_object_id_cmp(id, &old_id) != 0) {
775 			got_object_id_hex(&old_id, hex1, sizeof(hex1));
776 			got_object_id_hex(id, hex2, sizeof(hex2));
777 			err = got_error_fmt(GOT_ERR_REF_BUSY,
778 			    "Update %s: %s failed; %s: %s has been "
779 			    "created by someone else while transaction "
780 			    "was in progress",
781 			    got_ref_get_name(ref), hex1,
782 			    got_ref_get_name(ref), hex2);
783 			goto done;
784 		}
785 
786 		if (got_object_id_cmp(&new_id, &old_id) != 0) {
787 			err = got_ref_change_ref(ref, &new_id);
788 			if (err)
789 				goto done;
790 			err = got_ref_write(ref, repo);
791 			if (err)
792 				goto done;
793 			err = queue_notification(&old_id, &new_id, repo, ref);
794 			if (err)
795 				goto done;
796 		}
797 
798 		free(id);
799 		id = NULL;
800 	}
801 done:
802 	if (err) {
803 		if (err->code == GOT_ERR_LOCKFILE_TIMEOUT) {
804 			err = got_error_fmt(GOT_ERR_LOCKFILE_TIMEOUT,
805 			    "could not acquire exclusive file lock for %s",
806 			    refname);
807 		}
808 		send_ref_update_ng(client, &iref, refname, err->msg);
809 	} else
810 		send_ref_update_ok(client, &iref, refname);
811 
812 	if (client->nref_updates > 0) {
813 		client->nref_updates--;
814 		if (client->nref_updates == 0) {
815 			send_refs_updated(client);
816 			notif = STAILQ_FIRST(&notifications);
817 			if (notif) {
818 				gotd_session.state = GOTD_STATE_NOTIFY;
819 				err = request_notification(notif);
820 				if (err) {
821 					log_warn("could not send notification: "
822 					    "%s", err->msg);
823 					client->flush_disconnect = 1;
824 				}
825 			} else
826 				client->flush_disconnect = 1;
827 		}
828 
829 	}
830 	if (locked) {
831 		const struct got_error *unlock_err;
832 		unlock_err = got_ref_unlock(ref);
833 		if (unlock_err && err == NULL)
834 			err = unlock_err;
835 	}
836 	if (ref)
837 		got_ref_close(ref);
838 	free(refname);
839 	free(id);
840 	return err;
841 }
842 
843 static const struct got_error *
844 recv_notification_content(struct imsg *imsg)
845 {
846 	struct gotd_imsg_notification_content inotif;
847 	size_t datalen;
848 
849 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
850 	if (datalen < sizeof(inotif))
851 		return got_error(GOT_ERR_PRIVSEP_LEN);
852 	memcpy(&inotif, imsg->data, sizeof(inotif));
853 
854 	return NULL;
855 }
856 
857 static void
858 session_dispatch_repo_child(int fd, short event, void *arg)
859 {
860 	struct gotd_imsgev *iev = arg;
861 	struct imsgbuf *ibuf = &iev->ibuf;
862 	struct gotd_session_client *client = &gotd_session_client;
863 	ssize_t n;
864 	int shut = 0;
865 	struct imsg imsg;
866 
867 	if (event & EV_READ) {
868 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
869 			fatal("imsg_read error");
870 		if (n == 0) {
871 			/* Connection closed. */
872 			shut = 1;
873 			goto done;
874 		}
875 	}
876 
877 	if (event & EV_WRITE) {
878 		n = msgbuf_write(&ibuf->w);
879 		if (n == -1 && errno != EAGAIN)
880 			fatal("msgbuf_write");
881 		if (n == 0) {
882 			/* Connection closed. */
883 			shut = 1;
884 			goto done;
885 		}
886 	}
887 
888 	for (;;) {
889 		const struct got_error *err = NULL;
890 		uint32_t client_id = 0;
891 		int do_disconnect = 0;
892 		int do_ref_updates = 0, do_ref_update = 0;
893 		int do_packfile_install = 0, do_notify = 0;
894 
895 		if ((n = imsg_get(ibuf, &imsg)) == -1)
896 			fatal("%s: imsg_get error", __func__);
897 		if (n == 0)	/* No more messages. */
898 			break;
899 
900 		switch (imsg.hdr.type) {
901 		case GOTD_IMSG_ERROR:
902 			do_disconnect = 1;
903 			err = gotd_imsg_recv_error(&client_id, &imsg);
904 			break;
905 		case GOTD_IMSG_PACKFILE_INSTALL:
906 			err = recv_packfile_install(&imsg);
907 			if (err == NULL)
908 				do_packfile_install = 1;
909 			break;
910 		case GOTD_IMSG_REF_UPDATES_START:
911 			err = recv_ref_updates_start(&imsg);
912 			if (err == NULL)
913 				do_ref_updates = 1;
914 			break;
915 		case GOTD_IMSG_REF_UPDATE:
916 			err = recv_ref_update(&imsg);
917 			if (err == NULL)
918 				do_ref_update = 1;
919 			break;
920 		case GOTD_IMSG_NOTIFY:
921 			err = recv_notification_content(&imsg);
922 			if (err == NULL)
923 				do_notify = 1;
924 			break;
925 		default:
926 			log_debug("unexpected imsg %d", imsg.hdr.type);
927 			break;
928 		}
929 
930 		if (do_disconnect || err) {
931 			if (err)
932 				disconnect_on_error(client, err);
933 			else
934 				disconnect(client);
935 		} else {
936 			struct gotd_session_notif *notif;
937 
938 			if (do_packfile_install)
939 				err = install_pack(client,
940 				    gotd_session.repo->path, &imsg);
941 			else if (do_ref_updates)
942 				err = begin_ref_updates(client, &imsg);
943 			else if (do_ref_update)
944 				err = update_ref(&shut, client,
945 				    gotd_session.repo->path, &imsg);
946 			else if (do_notify)
947 				err = forward_notification(client, &imsg);
948 			if (err)
949 				log_warnx("uid %d: %s", client->euid, err->msg);
950 
951 			notif = STAILQ_FIRST(&notifications);
952 			if (notif && do_notify) {
953 				/* Request content for next notification. */
954 				err = request_notification(notif);
955 				if (err) {
956 					log_warn("could not send notification: "
957 					    "%s", err->msg);
958 					shut = 1;
959 				}
960 			}
961 		}
962 		imsg_free(&imsg);
963 	}
964 done:
965 	if (!shut) {
966 		gotd_imsg_event_add(iev);
967 	} else {
968 		/* This pipe is dead. Remove its event handler */
969 		event_del(&iev->ev);
970 		event_loopexit(NULL);
971 	}
972 }
973 
974 static const struct got_error *
975 recv_capabilities(struct gotd_session_client *client, struct imsg *imsg)
976 {
977 	struct gotd_imsg_capabilities icapas;
978 	size_t datalen;
979 
980 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
981 	if (datalen != sizeof(icapas))
982 		return got_error(GOT_ERR_PRIVSEP_LEN);
983 	memcpy(&icapas, imsg->data, sizeof(icapas));
984 
985 	client->ncapa_alloc = icapas.ncapabilities;
986 	client->capabilities = calloc(client->ncapa_alloc,
987 	    sizeof(*client->capabilities));
988 	if (client->capabilities == NULL) {
989 		client->ncapa_alloc = 0;
990 		return got_error_from_errno("calloc");
991 	}
992 
993 	log_debug("expecting %zu capabilities from uid %d",
994 	    client->ncapa_alloc, client->euid);
995 	return NULL;
996 }
997 
998 static const struct got_error *
999 recv_capability(struct gotd_session_client *client, struct imsg *imsg)
1000 {
1001 	struct gotd_imsg_capability icapa;
1002 	struct gotd_client_capability *capa;
1003 	size_t datalen;
1004 	char *key, *value = NULL;
1005 
1006 	if (client->capabilities == NULL ||
1007 	    client->ncapabilities >= client->ncapa_alloc) {
1008 		return got_error_msg(GOT_ERR_BAD_REQUEST,
1009 		    "unexpected capability received");
1010 	}
1011 
1012 	memset(&icapa, 0, sizeof(icapa));
1013 
1014 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1015 	if (datalen < sizeof(icapa))
1016 		return got_error(GOT_ERR_PRIVSEP_LEN);
1017 	memcpy(&icapa, imsg->data, sizeof(icapa));
1018 
1019 	if (datalen != sizeof(icapa) + icapa.key_len + icapa.value_len)
1020 		return got_error(GOT_ERR_PRIVSEP_LEN);
1021 
1022 	key = strndup(imsg->data + sizeof(icapa), icapa.key_len);
1023 	if (key == NULL)
1024 		return got_error_from_errno("strndup");
1025 	if (icapa.value_len > 0) {
1026 		value = strndup(imsg->data + sizeof(icapa) + icapa.key_len,
1027 		    icapa.value_len);
1028 		if (value == NULL) {
1029 			free(key);
1030 			return got_error_from_errno("strndup");
1031 		}
1032 	}
1033 
1034 	capa = &client->capabilities[client->ncapabilities++];
1035 	capa->key = key;
1036 	capa->value = value;
1037 
1038 	if (value)
1039 		log_debug("uid %d: capability %s=%s", client->euid, key, value);
1040 	else
1041 		log_debug("uid %d: capability %s", client->euid, key);
1042 
1043 	return NULL;
1044 }
1045 
1046 static const struct got_error *
1047 forward_ref_update(struct gotd_session_client *client, struct imsg *imsg)
1048 {
1049 	const struct got_error *err = NULL;
1050 	struct gotd_imsg_ref_update ireq;
1051 	struct gotd_imsg_ref_update *iref = NULL;
1052 	size_t datalen;
1053 
1054 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1055 	if (datalen < sizeof(ireq))
1056 		return got_error(GOT_ERR_PRIVSEP_LEN);
1057 	memcpy(&ireq, imsg->data, sizeof(ireq));
1058 	if (datalen != sizeof(ireq) + ireq.name_len)
1059 		return got_error(GOT_ERR_PRIVSEP_LEN);
1060 
1061 	iref = malloc(datalen);
1062 	if (iref == NULL)
1063 		return got_error_from_errno("malloc");
1064 	memcpy(iref, imsg->data, datalen);
1065 
1066 	if (gotd_imsg_compose_event(&gotd_session.repo_child_iev,
1067 	    GOTD_IMSG_REF_UPDATE, PROC_SESSION_WRITE, -1,
1068 	    iref, datalen) == -1)
1069 		err = got_error_from_errno("imsg compose REF_UPDATE");
1070 	free(iref);
1071 	return err;
1072 }
1073 
1074 static int
1075 client_has_capability(struct gotd_session_client *client, const char *capastr)
1076 {
1077 	struct gotd_client_capability *capa;
1078 	size_t i;
1079 
1080 	if (client->ncapabilities == 0)
1081 		return 0;
1082 
1083 	for (i = 0; i < client->ncapabilities; i++) {
1084 		capa = &client->capabilities[i];
1085 		if (strcmp(capa->key, capastr) == 0)
1086 			return 1;
1087 	}
1088 
1089 	return 0;
1090 }
1091 
1092 static const struct got_error *
1093 recv_packfile(struct gotd_session_client *client)
1094 {
1095 	const struct got_error *err = NULL;
1096 	struct gotd_imsg_recv_packfile ipack;
1097 	char *basepath = NULL, *pack_path = NULL, *idx_path = NULL;
1098 	int packfd = -1, idxfd = -1;
1099 	int pipe[2] = { -1, -1 };
1100 
1101 	if (client->packfile_path) {
1102 		return got_error_fmt(GOT_ERR_PRIVSEP_MSG,
1103 		    "uid %d already has a pack file", client->euid);
1104 	}
1105 
1106 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pipe) == -1)
1107 		return got_error_from_errno("socketpair");
1108 
1109 	/* Send pack pipe end 0 to repo child process. */
1110 	if (gotd_imsg_compose_event(&gotd_session.repo_child_iev,
1111 	    GOTD_IMSG_PACKFILE_PIPE, PROC_SESSION_WRITE, pipe[0],
1112 	        NULL, 0) == -1) {
1113 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
1114 		pipe[0] = -1;
1115 		goto done;
1116 	}
1117 	pipe[0] = -1;
1118 
1119 	/* Send pack pipe end 1 to gotsh(1) (expects just an fd, no data). */
1120 	if (gotd_imsg_compose_event(&client->iev,
1121 	    GOTD_IMSG_PACKFILE_PIPE, PROC_SESSION_WRITE, pipe[1],
1122 	    NULL, 0) == -1)
1123 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
1124 	pipe[1] = -1;
1125 
1126 	if (asprintf(&basepath, "%s/%s/receiving-from-uid-%d.pack",
1127 	    got_repo_get_path(gotd_session.repo), GOT_OBJECTS_PACK_DIR,
1128 	    client->euid) == -1) {
1129 		err = got_error_from_errno("asprintf");
1130 		goto done;
1131 	}
1132 
1133 	err = got_opentemp_named_fd(&pack_path, &packfd, basepath, "");
1134 	if (err)
1135 		goto done;
1136 	if (fchmod(packfd, GOT_DEFAULT_PACK_MODE) == -1) {
1137 		err = got_error_from_errno2("fchmod", pack_path);
1138 		goto done;
1139 	}
1140 
1141 	free(basepath);
1142 	if (asprintf(&basepath, "%s/%s/receiving-from-uid-%d.idx",
1143 	    got_repo_get_path(gotd_session.repo), GOT_OBJECTS_PACK_DIR,
1144 	    client->euid) == -1) {
1145 		err = got_error_from_errno("asprintf");
1146 		basepath = NULL;
1147 		goto done;
1148 	}
1149 	err = got_opentemp_named_fd(&idx_path, &idxfd, basepath, "");
1150 	if (err)
1151 		goto done;
1152 	if (fchmod(idxfd, GOT_DEFAULT_PACK_MODE) == -1) {
1153 		err = got_error_from_errno2("fchmod", idx_path);
1154 		goto done;
1155 	}
1156 
1157 	if (gotd_imsg_compose_event(&gotd_session.repo_child_iev,
1158 	    GOTD_IMSG_PACKIDX_FILE, PROC_SESSION_WRITE,
1159 	    idxfd, NULL, 0) == -1) {
1160 		err = got_error_from_errno("imsg compose PACKIDX_FILE");
1161 		idxfd = -1;
1162 		goto done;
1163 	}
1164 	idxfd = -1;
1165 
1166 	memset(&ipack, 0, sizeof(ipack));
1167 	if (client_has_capability(client, GOT_CAPA_REPORT_STATUS))
1168 		ipack.report_status = 1;
1169 
1170 	if (gotd_imsg_compose_event(&gotd_session.repo_child_iev,
1171 	    GOTD_IMSG_RECV_PACKFILE, PROC_SESSION_WRITE, packfd,
1172 	    &ipack, sizeof(ipack)) == -1) {
1173 		err = got_error_from_errno("imsg compose RECV_PACKFILE");
1174 		packfd = -1;
1175 		goto done;
1176 	}
1177 	packfd = -1;
1178 
1179 done:
1180 	free(basepath);
1181 	if (pipe[0] != -1 && close(pipe[0]) == -1 && err == NULL)
1182 		err = got_error_from_errno("close");
1183 	if (pipe[1] != -1 && close(pipe[1]) == -1 && err == NULL)
1184 		err = got_error_from_errno("close");
1185 	if (packfd != -1 && close(packfd) == -1 && err == NULL)
1186 		err = got_error_from_errno("close");
1187 	if (idxfd != -1 && close(idxfd) == -1 && err == NULL)
1188 		err = got_error_from_errno("close");
1189 	if (err) {
1190 		free(pack_path);
1191 		free(idx_path);
1192 	} else {
1193 		client->packfile_path = pack_path;
1194 		client->packidx_path = idx_path;
1195 	}
1196 	return err;
1197 }
1198 
1199 static void
1200 session_dispatch_client(int fd, short events, void *arg)
1201 {
1202 	struct gotd_imsgev *iev = arg;
1203 	struct imsgbuf *ibuf = &iev->ibuf;
1204 	struct gotd_session_client *client = &gotd_session_client;
1205 	const struct got_error *err = NULL;
1206 	struct imsg imsg;
1207 	ssize_t n;
1208 
1209 	if (events & EV_WRITE) {
1210 		while (ibuf->w.queued) {
1211 			n = msgbuf_write(&ibuf->w);
1212 			if (n == -1 && errno == EPIPE) {
1213 				/*
1214 				 * The client has closed its socket.
1215 				 * This can happen when Git clients are
1216 				 * done sending pack file data.
1217 				 */
1218 				msgbuf_clear(&ibuf->w);
1219 				continue;
1220 			} else if (n == -1 && errno != EAGAIN) {
1221 				err = got_error_from_errno("imsg_flush");
1222 				disconnect_on_error(client, err);
1223 				return;
1224 			}
1225 			if (n == 0) {
1226 				/* Connection closed. */
1227 				err = got_error(GOT_ERR_EOF);
1228 				disconnect_on_error(client, err);
1229 				return;
1230 			}
1231 		}
1232 
1233 		if (client->flush_disconnect) {
1234 			disconnect(client);
1235 			return;
1236 		}
1237 	}
1238 
1239 	if ((events & EV_READ) == 0)
1240 		return;
1241 
1242 	memset(&imsg, 0, sizeof(imsg));
1243 
1244 	while (err == NULL) {
1245 		err = gotd_imsg_recv(&imsg, ibuf, 0);
1246 		if (err) {
1247 			if (err->code == GOT_ERR_PRIVSEP_READ)
1248 				err = NULL;
1249 			else if (err->code == GOT_ERR_EOF &&
1250 			    gotd_session.state ==
1251 			    GOTD_STATE_EXPECT_CAPABILITIES) {
1252 				/*
1253 				 * The client has closed its socket before
1254 				 * sending its capability announcement.
1255 				 * This can happen when Git clients have
1256 				 * no ref-updates to send.
1257 				 */
1258 				disconnect_on_error(client, err);
1259 				return;
1260 			}
1261 			break;
1262 		}
1263 
1264 		evtimer_del(&client->tmo);
1265 
1266 		switch (imsg.hdr.type) {
1267 		case GOTD_IMSG_CAPABILITIES:
1268 			if (gotd_session.state !=
1269 			    GOTD_STATE_EXPECT_CAPABILITIES) {
1270 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1271 				    "unexpected capabilities received");
1272 				break;
1273 			}
1274 			log_debug("receiving capabilities from uid %d",
1275 			    client->euid);
1276 			err = recv_capabilities(client, &imsg);
1277 			break;
1278 		case GOTD_IMSG_CAPABILITY:
1279 			if (gotd_session.state != GOTD_STATE_EXPECT_CAPABILITIES) {
1280 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1281 				    "unexpected capability received");
1282 				break;
1283 			}
1284 			err = recv_capability(client, &imsg);
1285 			if (err || client->ncapabilities < client->ncapa_alloc)
1286 				break;
1287 			gotd_session.state = GOTD_STATE_EXPECT_REF_UPDATE;
1288 			client->accept_flush_pkt = 1;
1289 			log_debug("uid %d: expecting ref-update-lines",
1290 			    client->euid);
1291 			break;
1292 		case GOTD_IMSG_REF_UPDATE:
1293 			if (gotd_session.state != GOTD_STATE_EXPECT_REF_UPDATE &&
1294 			    gotd_session.state !=
1295 			    GOTD_STATE_EXPECT_MORE_REF_UPDATES) {
1296 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1297 				    "unexpected ref-update-line received");
1298 				break;
1299 			}
1300 			log_debug("received ref-update-line from uid %d",
1301 			    client->euid);
1302 			err = forward_ref_update(client, &imsg);
1303 			if (err)
1304 				break;
1305 			gotd_session.state = GOTD_STATE_EXPECT_MORE_REF_UPDATES;
1306 			client->accept_flush_pkt = 1;
1307 			break;
1308 		case GOTD_IMSG_FLUSH:
1309 			if (gotd_session.state !=
1310 			    GOTD_STATE_EXPECT_MORE_REF_UPDATES) {
1311 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1312 				    "unexpected flush-pkt received");
1313 				break;
1314 			}
1315 			if (!client->accept_flush_pkt) {
1316 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1317 				    "unexpected flush-pkt received");
1318 				break;
1319 			}
1320 
1321 			/*
1322 			 * Accept just one flush packet at a time.
1323 			 * Future client state transitions will set this flag
1324 			 * again if another flush packet is expected.
1325 			 */
1326 			client->accept_flush_pkt = 0;
1327 
1328 			log_debug("received flush-pkt from uid %d",
1329 			    client->euid);
1330 			if (gotd_session.state ==
1331 			    GOTD_STATE_EXPECT_MORE_REF_UPDATES) {
1332 				gotd_session.state = GOTD_STATE_EXPECT_PACKFILE;
1333 				log_debug("uid %d: expecting packfile",
1334 				    client->euid);
1335 				err = recv_packfile(client);
1336 			} else {
1337 				/* should not happen, see above */
1338 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1339 				    "unexpected client state");
1340 				break;
1341 			}
1342 			break;
1343 		default:
1344 			log_debug("unexpected imsg %d", imsg.hdr.type);
1345 			err = got_error(GOT_ERR_PRIVSEP_MSG);
1346 			break;
1347 		}
1348 
1349 		imsg_free(&imsg);
1350 	}
1351 
1352 	if (err) {
1353 		if (err->code != GOT_ERR_EOF ||
1354 		    (gotd_session.state != GOTD_STATE_EXPECT_PACKFILE &&
1355 		    gotd_session.state != GOTD_STATE_NOTIFY))
1356 			disconnect_on_error(client, err);
1357 	} else {
1358 		gotd_imsg_event_add(iev);
1359 		evtimer_add(&client->tmo, &gotd_session.request_timeout);
1360 	}
1361 }
1362 
1363 static const struct got_error *
1364 list_refs_request(void)
1365 {
1366 	static const struct got_error *err;
1367 	struct gotd_session_client *client = &gotd_session_client;
1368 	struct gotd_imsgev *iev = &gotd_session.repo_child_iev;
1369 	int fd;
1370 
1371 	if (gotd_session.state != GOTD_STATE_EXPECT_LIST_REFS)
1372 		return got_error(GOT_ERR_PRIVSEP_MSG);
1373 
1374 	fd = dup(client->fd);
1375 	if (fd == -1)
1376 		return got_error_from_errno("dup");
1377 
1378 	if (gotd_imsg_compose_event(iev, GOTD_IMSG_LIST_REFS_INTERNAL,
1379 	    PROC_SESSION_WRITE, fd, NULL, 0) == -1) {
1380 		err = got_error_from_errno("imsg compose LIST_REFS_INTERNAL");
1381 		close(fd);
1382 		return err;
1383 	}
1384 
1385 	gotd_session.state = GOTD_STATE_EXPECT_CAPABILITIES;
1386 	log_debug("uid %d: expecting capabilities", client->euid);
1387 	return NULL;
1388 }
1389 
1390 static const struct got_error *
1391 recv_connect(struct imsg *imsg)
1392 {
1393 	struct gotd_session_client *client = &gotd_session_client;
1394 	struct gotd_imsg_connect iconnect;
1395 	size_t datalen;
1396 
1397 	if (gotd_session.state != GOTD_STATE_EXPECT_LIST_REFS)
1398 		return got_error(GOT_ERR_PRIVSEP_MSG);
1399 
1400 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1401 	if (datalen < sizeof(iconnect))
1402 		return got_error(GOT_ERR_PRIVSEP_LEN);
1403 	memcpy(&iconnect, imsg->data, sizeof(iconnect));
1404 	if (iconnect.username_len == 0 ||
1405 	    datalen != sizeof(iconnect) + iconnect.username_len)
1406 		return got_error(GOT_ERR_PRIVSEP_LEN);
1407 
1408 	client->euid = iconnect.euid;
1409 	client->egid = iconnect.egid;
1410 	client->fd = imsg_get_fd(imsg);
1411 	if (client->fd == -1)
1412 		return got_error(GOT_ERR_PRIVSEP_NO_FD);
1413 
1414 	client->username = strndup(imsg->data + sizeof(iconnect),
1415 	    iconnect.username_len);
1416 	if (client->username == NULL)
1417 		return got_error_from_errno("strndup");
1418 
1419 	imsg_init(&client->iev.ibuf, client->fd);
1420 	client->iev.handler = session_dispatch_client;
1421 	client->iev.events = EV_READ;
1422 	client->iev.handler_arg = NULL;
1423 	event_set(&client->iev.ev, client->iev.ibuf.fd, EV_READ,
1424 	    session_dispatch_client, &client->iev);
1425 	gotd_imsg_event_add(&client->iev);
1426 	evtimer_set(&client->tmo, gotd_request_timeout, client);
1427 	evtimer_add(&client->tmo, &gotd_session.request_timeout);
1428 
1429 	return NULL;
1430 }
1431 
1432 static void
1433 session_dispatch_notifier(int fd, short event, void *arg)
1434 {
1435 	const struct got_error *err;
1436 	struct gotd_session_client *client = &gotd_session_client;
1437 	struct gotd_imsgev *iev = arg;
1438 	struct imsgbuf *ibuf = &iev->ibuf;
1439 	ssize_t n;
1440 	int shut = 0;
1441 	struct imsg imsg;
1442 	struct gotd_session_notif *notif;
1443 
1444 	if (event & EV_READ) {
1445 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1446 			fatal("imsg_read error");
1447 		if (n == 0) {
1448 			/* Connection closed. */
1449 			shut = 1;
1450 			goto done;
1451 		}
1452 	}
1453 
1454 	if (event & EV_WRITE) {
1455 		n = msgbuf_write(&ibuf->w);
1456 		if (n == -1 && errno != EAGAIN)
1457 			fatal("msgbuf_write");
1458 		if (n == 0) {
1459 			/* Connection closed. */
1460 			shut = 1;
1461 			goto done;
1462 		}
1463 	}
1464 
1465 	for (;;) {
1466 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1467 			fatal("%s: imsg_get error", __func__);
1468 		if (n == 0)	/* No more messages. */
1469 			break;
1470 
1471 		switch (imsg.hdr.type) {
1472 		case GOTD_IMSG_NOTIFICATION_SENT:
1473 			if (gotd_session.state != GOTD_STATE_NOTIFY) {
1474 				log_warn("unexpected imsg %d", imsg.hdr.type);
1475 				break;
1476 			}
1477 			notif = STAILQ_FIRST(&notifications);
1478 			if (notif == NULL) {
1479 				disconnect(client);
1480 				break; /* NOTREACHED */
1481 			}
1482 			/* Request content for the next notification. */
1483 			err = request_notification(notif);
1484 			if (err) {
1485 				log_warn("could not send notification: %s",
1486 				    err->msg);
1487 				disconnect(client);
1488 			}
1489 			break;
1490 		default:
1491 			log_debug("unexpected imsg %d", imsg.hdr.type);
1492 			break;
1493 		}
1494 
1495 		imsg_free(&imsg);
1496 	}
1497 done:
1498 	if (!shut) {
1499 		gotd_imsg_event_add(iev);
1500 	} else {
1501 		/* This pipe is dead. Remove its event handler */
1502 		event_del(&iev->ev);
1503 		imsg_clear(&iev->ibuf);
1504 		imsg_init(&iev->ibuf, -1);
1505 	}
1506 }
1507 
1508 static const struct got_error *
1509 recv_notifier(struct imsg *imsg)
1510 {
1511 	struct gotd_imsgev *iev = &gotd_session.notifier_iev;
1512 	struct gotd_session_client *client = &gotd_session_client;
1513 	size_t datalen;
1514 	int fd;
1515 
1516 	if (gotd_session.state != GOTD_STATE_EXPECT_LIST_REFS)
1517 		return got_error(GOT_ERR_PRIVSEP_MSG);
1518 
1519 	/* We should already have received a pipe to the listener. */
1520 	if (client->fd == -1)
1521 		return got_error(GOT_ERR_PRIVSEP_MSG);
1522 
1523 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1524 	if (datalen != 0)
1525 		return got_error(GOT_ERR_PRIVSEP_LEN);
1526 
1527 	fd = imsg_get_fd(imsg);
1528 	if (fd == -1)
1529 		return NULL; /* notifications unused */
1530 
1531 	imsg_init(&iev->ibuf, fd);
1532 	iev->handler = session_dispatch_notifier;
1533 	iev->events = EV_READ;
1534 	iev->handler_arg = NULL;
1535 	event_set(&iev->ev, iev->ibuf.fd, EV_READ,
1536 	    session_dispatch_notifier, iev);
1537 	gotd_imsg_event_add(iev);
1538 
1539 	return NULL;
1540 }
1541 
1542 static const struct got_error *
1543 recv_repo_child(struct imsg *imsg)
1544 {
1545 	struct gotd_imsg_connect_repo_child ichild;
1546 	struct gotd_session_client *client = &gotd_session_client;
1547 	size_t datalen;
1548 	int fd;
1549 
1550 	if (gotd_session.state != GOTD_STATE_EXPECT_LIST_REFS)
1551 		return got_error(GOT_ERR_PRIVSEP_MSG);
1552 
1553 	/* We should already have received a pipe to the listener. */
1554 	if (client->fd == -1)
1555 		return got_error(GOT_ERR_PRIVSEP_MSG);
1556 
1557 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1558 	if (datalen != sizeof(ichild))
1559 		return got_error(GOT_ERR_PRIVSEP_LEN);
1560 
1561 	memcpy(&ichild, imsg->data, sizeof(ichild));
1562 
1563 	if (ichild.proc_id != PROC_REPO_WRITE)
1564 		return got_error_msg(GOT_ERR_PRIVSEP_MSG,
1565 		    "bad child process type");
1566 
1567 	fd = imsg_get_fd(imsg);
1568 	if (fd == -1)
1569 		return got_error(GOT_ERR_PRIVSEP_NO_FD);
1570 
1571 	imsg_init(&gotd_session.repo_child_iev.ibuf, fd);
1572 	gotd_session.repo_child_iev.handler = session_dispatch_repo_child;
1573 	gotd_session.repo_child_iev.events = EV_READ;
1574 	gotd_session.repo_child_iev.handler_arg = NULL;
1575 	event_set(&gotd_session.repo_child_iev.ev,
1576 	    gotd_session.repo_child_iev.ibuf.fd, EV_READ,
1577 	    session_dispatch_repo_child, &gotd_session.repo_child_iev);
1578 	gotd_imsg_event_add(&gotd_session.repo_child_iev);
1579 
1580 	/* The "recvfd" pledge promise is no longer needed. */
1581 	if (pledge("stdio rpath wpath cpath sendfd fattr flock", NULL) == -1)
1582 		fatal("pledge");
1583 
1584 	return NULL;
1585 }
1586 
1587 static void
1588 session_dispatch(int fd, short event, void *arg)
1589 {
1590 	struct gotd_imsgev *iev = arg;
1591 	struct imsgbuf *ibuf = &iev->ibuf;
1592 	struct gotd_session_client *client = &gotd_session_client;
1593 	ssize_t n;
1594 	int shut = 0;
1595 	struct imsg imsg;
1596 
1597 	if (event & EV_READ) {
1598 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1599 			fatal("imsg_read error");
1600 		if (n == 0) {
1601 			/* Connection closed. */
1602 			shut = 1;
1603 			goto done;
1604 		}
1605 	}
1606 
1607 	if (event & EV_WRITE) {
1608 		n = msgbuf_write(&ibuf->w);
1609 		if (n == -1 && errno != EAGAIN)
1610 			fatal("msgbuf_write");
1611 		if (n == 0) {
1612 			/* Connection closed. */
1613 			shut = 1;
1614 			goto done;
1615 		}
1616 	}
1617 
1618 	for (;;) {
1619 		const struct got_error *err = NULL;
1620 		uint32_t client_id = 0;
1621 		int do_disconnect = 0, do_list_refs = 0;
1622 
1623 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1624 			fatal("%s: imsg_get error", __func__);
1625 		if (n == 0)	/* No more messages. */
1626 			break;
1627 
1628 		switch (imsg.hdr.type) {
1629 		case GOTD_IMSG_ERROR:
1630 			do_disconnect = 1;
1631 			err = gotd_imsg_recv_error(&client_id, &imsg);
1632 			break;
1633 		case GOTD_IMSG_CONNECT:
1634 			err = recv_connect(&imsg);
1635 			break;
1636 		case GOTD_IMSG_DISCONNECT:
1637 			do_disconnect = 1;
1638 			break;
1639 		case GOTD_IMSG_CONNECT_NOTIFIER:
1640 			err = recv_notifier(&imsg);
1641 			break;
1642 		case GOTD_IMSG_CONNECT_REPO_CHILD:
1643 			err = recv_repo_child(&imsg);
1644 			if (err)
1645 				break;
1646 			do_list_refs = 1;
1647 			break;
1648 		default:
1649 			log_debug("unexpected imsg %d", imsg.hdr.type);
1650 			break;
1651 		}
1652 		imsg_free(&imsg);
1653 
1654 		if (do_disconnect) {
1655 			if (err)
1656 				disconnect_on_error(client, err);
1657 			else
1658 				disconnect(client);
1659 		} else if (do_list_refs)
1660 			err = list_refs_request();
1661 
1662 		if (err)
1663 			log_warnx("uid %d: %s", client->euid, err->msg);
1664 	}
1665 done:
1666 	if (!shut) {
1667 		gotd_imsg_event_add(iev);
1668 	} else {
1669 		/* This pipe is dead. Remove its event handler */
1670 		event_del(&iev->ev);
1671 		event_loopexit(NULL);
1672 	}
1673 }
1674 
1675 void
1676 session_write_main(const char *title, const char *repo_path,
1677     int *pack_fds, int *temp_fds, struct timeval *request_timeout,
1678     struct gotd_repo *repo_cfg)
1679 {
1680 	const struct got_error *err = NULL;
1681 	struct event evsigint, evsigterm, evsighup, evsigusr1;
1682 
1683 	STAILQ_INIT(&notifications);
1684 
1685 	gotd_session.title = title;
1686 	gotd_session.pid = getpid();
1687 	gotd_session.pack_fds = pack_fds;
1688 	gotd_session.temp_fds = temp_fds;
1689 	memcpy(&gotd_session.request_timeout, request_timeout,
1690 	    sizeof(gotd_session.request_timeout));
1691 	gotd_session.repo_cfg = repo_cfg;
1692 
1693 	imsg_init(&gotd_session.notifier_iev.ibuf, -1);
1694 
1695 	err = got_repo_open(&gotd_session.repo, repo_path, NULL, pack_fds);
1696 	if (err)
1697 		goto done;
1698 	if (!got_repo_is_bare(gotd_session.repo)) {
1699 		err = got_error_msg(GOT_ERR_NOT_GIT_REPO,
1700 		    "bare git repository required");
1701 		goto done;
1702 	}
1703 
1704 	got_repo_temp_fds_set(gotd_session.repo, temp_fds);
1705 
1706 	signal_set(&evsigint, SIGINT, session_write_sighdlr, NULL);
1707 	signal_set(&evsigterm, SIGTERM, session_write_sighdlr, NULL);
1708 	signal_set(&evsighup, SIGHUP, session_write_sighdlr, NULL);
1709 	signal_set(&evsigusr1, SIGUSR1, session_write_sighdlr, NULL);
1710 	signal(SIGPIPE, SIG_IGN);
1711 
1712 	signal_add(&evsigint, NULL);
1713 	signal_add(&evsigterm, NULL);
1714 	signal_add(&evsighup, NULL);
1715 	signal_add(&evsigusr1, NULL);
1716 
1717 	gotd_session.state = GOTD_STATE_EXPECT_LIST_REFS;
1718 
1719 	gotd_session_client.fd = -1;
1720 	gotd_session_client.nref_updates = -1;
1721 	gotd_session_client.delta_cache_fd = -1;
1722 	gotd_session_client.accept_flush_pkt = 1;
1723 
1724 	imsg_init(&gotd_session.parent_iev.ibuf, GOTD_FILENO_MSG_PIPE);
1725 	gotd_session.parent_iev.handler = session_dispatch;
1726 	gotd_session.parent_iev.events = EV_READ;
1727 	gotd_session.parent_iev.handler_arg = NULL;
1728 	event_set(&gotd_session.parent_iev.ev, gotd_session.parent_iev.ibuf.fd,
1729 	    EV_READ, session_dispatch, &gotd_session.parent_iev);
1730 	if (gotd_imsg_compose_event(&gotd_session.parent_iev,
1731 	    GOTD_IMSG_CLIENT_SESSION_READY, PROC_SESSION_WRITE,
1732 	    -1, NULL, 0) == -1) {
1733 		err = got_error_from_errno("imsg compose CLIENT_SESSION_READY");
1734 		goto done;
1735 	}
1736 
1737 	event_dispatch();
1738 done:
1739 	if (err)
1740 		log_warnx("%s: %s", title, err->msg);
1741 	session_write_shutdown();
1742 }
1743 
1744 static void
1745 session_write_shutdown(void)
1746 {
1747 	struct gotd_session_notif *notif;
1748 
1749 	log_debug("%s: shutting down", gotd_session.title);
1750 
1751 	while (!STAILQ_EMPTY(&notifications)) {
1752 		notif = STAILQ_FIRST(&notifications);
1753 		STAILQ_REMOVE_HEAD(&notifications, entry);
1754 		if (notif->fd != -1)
1755 			close(notif->fd);
1756 		free(notif->refname);
1757 		free(notif);
1758 	}
1759 
1760 	if (gotd_session.repo)
1761 		got_repo_close(gotd_session.repo);
1762 	got_repo_pack_fds_close(gotd_session.pack_fds);
1763 	got_repo_temp_fds_close(gotd_session.temp_fds);
1764 	free(gotd_session_client.username);
1765 	exit(0);
1766 }