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 	enum gotd_procid proc_id;
66 } gotd_session;
67 
68 static struct gotd_session_client {
69 	enum gotd_session_state		 state;
70 	int				 is_writing;
71 	struct gotd_client_capability	*capabilities;
72 	size_t				 ncapa_alloc;
73 	size_t				 ncapabilities;
74 	uint32_t			 id;
75 	int				 fd;
76 	int				 delta_cache_fd;
77 	struct gotd_imsgev		 iev;
78 	struct gotd_imsgev		 repo_child_iev;
79 	struct event			 tmo;
80 	uid_t				 euid;
81 	gid_t				 egid;
82 	char				*packfile_path;
83 	char				*packidx_path;
84 	int				 nref_updates;
85 	int				 accept_flush_pkt;
86 	int				 flush_disconnect;
87 } gotd_session_client;
88 
89 void gotd_session_sighdlr(int sig, short event, void *arg);
90 static void gotd_session_shutdown(void);
91 
92 static void
93 disconnect(struct gotd_session_client *client)
94 {
95 	log_debug("uid %d: disconnecting", client->euid);
96 
97 	if (gotd_imsg_compose_event(&gotd_session.parent_iev,
98 	    GOTD_IMSG_DISCONNECT, gotd_session.proc_id, -1, NULL, 0) == -1)
99 		log_warn("imsg compose DISCONNECT");
100 
101 	imsg_clear(&client->repo_child_iev.ibuf);
102 	event_del(&client->repo_child_iev.ev);
103 	evtimer_del(&client->tmo);
104 	close(client->fd);
105 	if (client->delta_cache_fd != -1)
106 		close(client->delta_cache_fd);
107 	if (client->packfile_path) {
108 		if (unlink(client->packfile_path) == -1 && errno != ENOENT)
109 			log_warn("unlink %s: ", client->packfile_path);
110 		free(client->packfile_path);
111 	}
112 	if (client->packidx_path) {
113 		if (unlink(client->packidx_path) == -1 && errno != ENOENT)
114 			log_warn("unlink %s: ", client->packidx_path);
115 		free(client->packidx_path);
116 	}
117 	free(client->capabilities);
118 
119 	gotd_session_shutdown();
120 }
121 
122 static void
123 disconnect_on_error(struct gotd_session_client *client,
124     const struct got_error *err)
125 {
126 	struct imsgbuf ibuf;
127 
128 	if (err->code != GOT_ERR_EOF) {
129 		log_warnx("uid %d: %s", client->euid, err->msg);
130 		imsg_init(&ibuf, client->fd);
131 		gotd_imsg_send_error(&ibuf, 0, gotd_session.proc_id, err);
132 		imsg_clear(&ibuf);
133 	}
134 
135 	disconnect(client);
136 }
137 
138 static void
139 gotd_request_timeout(int fd, short events, void *arg)
140 {
141 	struct gotd_session_client *client = arg;
142 
143 	log_debug("disconnecting uid %d due to timeout", client->euid);
144 	disconnect(client);
145 }
146 
147 void
148 gotd_session_sighdlr(int sig, short event, void *arg)
149 {
150 	/*
151 	 * Normal signal handler rules don't apply because libevent
152 	 * decouples for us.
153 	 */
154 
155 	switch (sig) {
156 	case SIGHUP:
157 		log_info("%s: ignoring SIGHUP", __func__);
158 		break;
159 	case SIGUSR1:
160 		log_info("%s: ignoring SIGUSR1", __func__);
161 		break;
162 	case SIGTERM:
163 	case SIGINT:
164 		gotd_session_shutdown();
165 		/* NOTREACHED */
166 		break;
167 	default:
168 		fatalx("unexpected signal");
169 	}
170 }
171 
172 static const struct got_error *
173 recv_packfile_done(uint32_t *client_id, struct imsg *imsg)
174 {
175 	struct gotd_imsg_packfile_done idone;
176 	size_t datalen;
177 
178 	log_debug("packfile-done received");
179 
180 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
181 	if (datalen != sizeof(idone))
182 		return got_error(GOT_ERR_PRIVSEP_LEN);
183 	memcpy(&idone, imsg->data, sizeof(idone));
184 
185 	*client_id = idone.client_id;
186 	return NULL;
187 }
188 
189 static const struct got_error *
190 recv_packfile_install(uint32_t *client_id, struct imsg *imsg)
191 {
192 	struct gotd_imsg_packfile_install inst;
193 	size_t datalen;
194 
195 	log_debug("packfile-install received");
196 
197 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
198 	if (datalen != sizeof(inst))
199 		return got_error(GOT_ERR_PRIVSEP_LEN);
200 	memcpy(&inst, imsg->data, sizeof(inst));
201 
202 	*client_id = inst.client_id;
203 	return NULL;
204 }
205 
206 static const struct got_error *
207 recv_ref_updates_start(uint32_t *client_id, 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 	*client_id = istart.client_id;
220 	return NULL;
221 }
222 
223 static const struct got_error *
224 recv_ref_update(uint32_t *client_id, struct imsg *imsg)
225 {
226 	struct gotd_imsg_ref_update iref;
227 	size_t datalen;
228 
229 	log_debug("ref-update received");
230 
231 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
232 	if (datalen < sizeof(iref))
233 		return got_error(GOT_ERR_PRIVSEP_LEN);
234 	memcpy(&iref, imsg->data, sizeof(iref));
235 
236 	*client_id = iref.client_id;
237 	return NULL;
238 }
239 
240 static const struct got_error *
241 send_ref_update_ok(struct gotd_session_client *client,
242     struct gotd_imsg_ref_update *iref, const char *refname)
243 {
244 	struct gotd_imsg_ref_update_ok iok;
245 	struct gotd_imsgev *iev = &client->iev;
246 	struct ibuf *wbuf;
247 	size_t len;
248 
249 	memset(&iok, 0, sizeof(iok));
250 	iok.client_id = client->id;
251 	memcpy(iok.old_id, iref->old_id, SHA1_DIGEST_LENGTH);
252 	memcpy(iok.new_id, iref->new_id, SHA1_DIGEST_LENGTH);
253 	iok.name_len = strlen(refname);
254 
255 	len = sizeof(iok) + iok.name_len;
256 	wbuf = imsg_create(&iev->ibuf, GOTD_IMSG_REF_UPDATE_OK,
257 	    gotd_session.proc_id, gotd_session.pid, len);
258 	if (wbuf == NULL)
259 		return got_error_from_errno("imsg_create REF_UPDATE_OK");
260 
261 	if (imsg_add(wbuf, &iok, sizeof(iok)) == -1)
262 		return got_error_from_errno("imsg_add REF_UPDATE_OK");
263 	if (imsg_add(wbuf, refname, iok.name_len) == -1)
264 		return got_error_from_errno("imsg_add REF_UPDATE_OK");
265 
266 	imsg_close(&iev->ibuf, wbuf);
267 	gotd_imsg_event_add(iev);
268 	return NULL;
269 }
270 
271 static void
272 send_refs_updated(struct gotd_session_client *client)
273 {
274 	if (gotd_imsg_compose_event(&client->iev, GOTD_IMSG_REFS_UPDATED,
275 	    gotd_session.proc_id, -1, NULL, 0) == -1)
276 		log_warn("imsg compose REFS_UPDATED");
277 }
278 
279 static const struct got_error *
280 send_ref_update_ng(struct gotd_session_client *client,
281     struct gotd_imsg_ref_update *iref, const char *refname,
282     const char *reason)
283 {
284 	const struct got_error *ng_err;
285 	struct gotd_imsg_ref_update_ng ing;
286 	struct gotd_imsgev *iev = &client->iev;
287 	struct ibuf *wbuf;
288 	size_t len;
289 
290 	memset(&ing, 0, sizeof(ing));
291 	ing.client_id = client->id;
292 	memcpy(ing.old_id, iref->old_id, SHA1_DIGEST_LENGTH);
293 	memcpy(ing.new_id, iref->new_id, SHA1_DIGEST_LENGTH);
294 	ing.name_len = strlen(refname);
295 
296 	ng_err = got_error_fmt(GOT_ERR_REF_BUSY, "%s", reason);
297 	ing.reason_len = strlen(ng_err->msg);
298 
299 	len = sizeof(ing) + ing.name_len + ing.reason_len;
300 	wbuf = imsg_create(&iev->ibuf, GOTD_IMSG_REF_UPDATE_NG,
301 	    gotd_session.proc_id, gotd_session.pid, len);
302 	if (wbuf == NULL)
303 		return got_error_from_errno("imsg_create REF_UPDATE_NG");
304 
305 	if (imsg_add(wbuf, &ing, sizeof(ing)) == -1)
306 		return got_error_from_errno("imsg_add REF_UPDATE_NG");
307 	if (imsg_add(wbuf, refname, ing.name_len) == -1)
308 		return got_error_from_errno("imsg_add REF_UPDATE_NG");
309 	if (imsg_add(wbuf, ng_err->msg, ing.reason_len) == -1)
310 		return got_error_from_errno("imsg_add REF_UPDATE_NG");
311 
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 	/* Ensure we re-read the pack index list upon next access. */
371 	gotd_session.repo->pack_path_mtime.tv_sec = 0;
372 	gotd_session.repo->pack_path_mtime.tv_nsec = 0;
373 
374 	free(client->packidx_path);
375 	client->packidx_path = NULL;
376 done:
377 	free(packfile_path);
378 	free(packidx_path);
379 	return err;
380 }
381 
382 static const struct got_error *
383 begin_ref_updates(struct gotd_session_client *client, struct imsg *imsg)
384 {
385 	struct gotd_imsg_ref_updates_start istart;
386 	size_t datalen;
387 
388 	if (client->nref_updates != -1)
389 		return got_error(GOT_ERR_PRIVSEP_MSG);
390 
391 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
392 	if (datalen != sizeof(istart))
393 		return got_error(GOT_ERR_PRIVSEP_LEN);
394 	memcpy(&istart, imsg->data, sizeof(istart));
395 
396 	if (istart.nref_updates <= 0)
397 		return got_error(GOT_ERR_PRIVSEP_MSG);
398 
399 	client->nref_updates = istart.nref_updates;
400 	return NULL;
401 }
402 
403 static const struct got_error *
404 update_ref(int *shut, struct gotd_session_client *client,
405     const char *repo_path, struct imsg *imsg)
406 {
407 	const struct got_error *err = NULL;
408 	struct got_repository *repo = gotd_session.repo;
409 	struct got_reference *ref = NULL;
410 	struct gotd_imsg_ref_update iref;
411 	struct got_object_id old_id, new_id;
412 	struct got_object_id *id = NULL;
413 	char *refname = NULL;
414 	size_t datalen;
415 	int locked = 0;
416 	char hex1[SHA1_DIGEST_STRING_LENGTH];
417 	char hex2[SHA1_DIGEST_STRING_LENGTH];
418 
419 	log_debug("update-ref from uid %d", client->euid);
420 
421 	if (client->nref_updates <= 0)
422 		return got_error(GOT_ERR_PRIVSEP_MSG);
423 
424 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
425 	if (datalen < sizeof(iref))
426 		return got_error(GOT_ERR_PRIVSEP_LEN);
427 	memcpy(&iref, imsg->data, sizeof(iref));
428 	if (datalen != sizeof(iref) + iref.name_len)
429 		return got_error(GOT_ERR_PRIVSEP_LEN);
430 	refname = strndup(imsg->data + sizeof(iref), iref.name_len);
431 	if (refname == NULL)
432 		return got_error_from_errno("strndup");
433 
434 	log_debug("updating ref %s for uid %d", refname, client->euid);
435 
436 	memcpy(old_id.sha1, iref.old_id, SHA1_DIGEST_LENGTH);
437 	memcpy(new_id.sha1, iref.new_id, SHA1_DIGEST_LENGTH);
438 	err = got_repo_find_object_id(iref.delete_ref ? &old_id : &new_id,
439 	    repo);
440 	if (err)
441 		goto done;
442 
443 	if (iref.ref_is_new) {
444 		err = got_ref_open(&ref, repo, refname, 0);
445 		if (err) {
446 			if (err->code != GOT_ERR_NOT_REF)
447 				goto done;
448 			err = got_ref_alloc(&ref, refname, &new_id);
449 			if (err)
450 				goto done;
451 			err = got_ref_write(ref, repo); /* will lock/unlock */
452 			if (err)
453 				goto done;
454 		} else {
455 			err = got_ref_resolve(&id, repo, ref);
456 			if (err)
457 				goto done;
458 			got_object_id_hex(&new_id, hex1, sizeof(hex1));
459 			got_object_id_hex(id, hex2, sizeof(hex2));
460 			err = got_error_fmt(GOT_ERR_REF_BUSY,
461 			    "Addition %s: %s failed; %s: %s has been "
462 			    "created by someone else while transaction "
463 			    "was in progress",
464 			    got_ref_get_name(ref), hex1,
465 			    got_ref_get_name(ref), hex2);
466 			goto done;
467 		}
468 	} else if (iref.delete_ref) {
469 		err = got_ref_open(&ref, repo, refname, 1 /* lock */);
470 		if (err)
471 			goto done;
472 		locked = 1;
473 
474 		err = got_ref_resolve(&id, repo, ref);
475 		if (err)
476 			goto done;
477 
478 		if (got_object_id_cmp(id, &old_id) != 0) {
479 			got_object_id_hex(&old_id, hex1, sizeof(hex1));
480 			got_object_id_hex(id, hex2, sizeof(hex2));
481 			err = got_error_fmt(GOT_ERR_REF_BUSY,
482 			    "Deletion %s: %s failed; %s: %s has been "
483 			    "created by someone else while transaction "
484 			    "was in progress",
485 			    got_ref_get_name(ref), hex1,
486 			    got_ref_get_name(ref), hex2);
487 			goto done;
488 		}
489 
490 		err = got_ref_delete(ref, repo);
491 		if (err)
492 			goto done;
493 
494 		free(id);
495 		id = NULL;
496 	} else {
497 		err = got_ref_open(&ref, repo, refname, 1 /* lock */);
498 		if (err)
499 			goto done;
500 		locked = 1;
501 
502 		err = got_ref_resolve(&id, repo, ref);
503 		if (err)
504 			goto done;
505 
506 		if (got_object_id_cmp(id, &old_id) != 0) {
507 			got_object_id_hex(&old_id, hex1, sizeof(hex1));
508 			got_object_id_hex(id, hex2, sizeof(hex2));
509 			err = got_error_fmt(GOT_ERR_REF_BUSY,
510 			    "Update %s: %s failed; %s: %s has been "
511 			    "created by someone else while transaction "
512 			    "was in progress",
513 			    got_ref_get_name(ref), hex1,
514 			    got_ref_get_name(ref), hex2);
515 			goto done;
516 		}
517 
518 		if (got_object_id_cmp(&new_id, &old_id) != 0) {
519 			err = got_ref_change_ref(ref, &new_id);
520 			if (err)
521 				goto done;
522 
523 			err = got_ref_write(ref, repo);
524 			if (err)
525 				goto done;
526 		}
527 
528 		free(id);
529 		id = NULL;
530 	}
531 done:
532 	if (err) {
533 		if (err->code == GOT_ERR_LOCKFILE_TIMEOUT) {
534 			err = got_error_fmt(GOT_ERR_LOCKFILE_TIMEOUT,
535 			    "could not acquire exclusive file lock for %s",
536 			    refname);
537 		}
538 		send_ref_update_ng(client, &iref, refname, err->msg);
539 	} else
540 		send_ref_update_ok(client, &iref, refname);
541 
542 	if (client->nref_updates > 0) {
543 		client->nref_updates--;
544 		if (client->nref_updates == 0) {
545 			send_refs_updated(client);
546 			client->flush_disconnect = 1;
547 		}
548 
549 	}
550 	if (locked) {
551 		const struct got_error *unlock_err;
552 		unlock_err = got_ref_unlock(ref);
553 		if (unlock_err && err == NULL)
554 			err = unlock_err;
555 	}
556 	if (ref)
557 		got_ref_close(ref);
558 	free(refname);
559 	free(id);
560 	return err;
561 }
562 
563 static void
564 session_dispatch_repo_child(int fd, short event, void *arg)
565 {
566 	struct gotd_imsgev *iev = arg;
567 	struct imsgbuf *ibuf = &iev->ibuf;
568 	struct gotd_session_client *client = &gotd_session_client;
569 	ssize_t n;
570 	int shut = 0;
571 	struct imsg imsg;
572 
573 	if (event & EV_READ) {
574 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
575 			fatal("imsg_read error");
576 		if (n == 0) {
577 			/* Connection closed. */
578 			shut = 1;
579 			goto done;
580 		}
581 	}
582 
583 	if (event & EV_WRITE) {
584 		n = msgbuf_write(&ibuf->w);
585 		if (n == -1 && errno != EAGAIN)
586 			fatal("msgbuf_write");
587 		if (n == 0) {
588 			/* Connection closed. */
589 			shut = 1;
590 			goto done;
591 		}
592 	}
593 
594 	for (;;) {
595 		const struct got_error *err = NULL;
596 		uint32_t client_id = 0;
597 		int do_disconnect = 0;
598 		int do_ref_updates = 0, do_ref_update = 0;
599 		int do_packfile_install = 0;
600 
601 		if ((n = imsg_get(ibuf, &imsg)) == -1)
602 			fatal("%s: imsg_get error", __func__);
603 		if (n == 0)	/* No more messages. */
604 			break;
605 
606 		switch (imsg.hdr.type) {
607 		case GOTD_IMSG_ERROR:
608 			do_disconnect = 1;
609 			err = gotd_imsg_recv_error(&client_id, &imsg);
610 			break;
611 		case GOTD_IMSG_PACKFILE_DONE:
612 			do_disconnect = 1;
613 			err = recv_packfile_done(&client_id, &imsg);
614 			break;
615 		case GOTD_IMSG_PACKFILE_INSTALL:
616 			err = recv_packfile_install(&client_id, &imsg);
617 			if (err == NULL)
618 				do_packfile_install = 1;
619 			break;
620 		case GOTD_IMSG_REF_UPDATES_START:
621 			err = recv_ref_updates_start(&client_id, &imsg);
622 			if (err == NULL)
623 				do_ref_updates = 1;
624 			break;
625 		case GOTD_IMSG_REF_UPDATE:
626 			err = recv_ref_update(&client_id, &imsg);
627 			if (err == NULL)
628 				do_ref_update = 1;
629 			break;
630 		default:
631 			log_debug("unexpected imsg %d", imsg.hdr.type);
632 			break;
633 		}
634 
635 		if (do_disconnect) {
636 			if (err)
637 				disconnect_on_error(client, err);
638 			else
639 				disconnect(client);
640 		} else {
641 			if (do_packfile_install)
642 				err = install_pack(client,
643 				    gotd_session.repo->path, &imsg);
644 			else if (do_ref_updates)
645 				err = begin_ref_updates(client, &imsg);
646 			else if (do_ref_update)
647 				err = update_ref(&shut, client,
648 				    gotd_session.repo->path, &imsg);
649 			if (err)
650 				log_warnx("uid %d: %s", client->euid, err->msg);
651 		}
652 		imsg_free(&imsg);
653 	}
654 done:
655 	if (!shut) {
656 		gotd_imsg_event_add(iev);
657 	} else {
658 		/* This pipe is dead. Remove its event handler */
659 		event_del(&iev->ev);
660 		event_loopexit(NULL);
661 	}
662 }
663 
664 static const struct got_error *
665 recv_capabilities(struct gotd_session_client *client, struct imsg *imsg)
666 {
667 	struct gotd_imsg_capabilities icapas;
668 	size_t datalen;
669 
670 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
671 	if (datalen != sizeof(icapas))
672 		return got_error(GOT_ERR_PRIVSEP_LEN);
673 	memcpy(&icapas, imsg->data, sizeof(icapas));
674 
675 	client->ncapa_alloc = icapas.ncapabilities;
676 	client->capabilities = calloc(client->ncapa_alloc,
677 	    sizeof(*client->capabilities));
678 	if (client->capabilities == NULL) {
679 		client->ncapa_alloc = 0;
680 		return got_error_from_errno("calloc");
681 	}
682 
683 	log_debug("expecting %zu capabilities from uid %d",
684 	    client->ncapa_alloc, client->euid);
685 	return NULL;
686 }
687 
688 static const struct got_error *
689 recv_capability(struct gotd_session_client *client, struct imsg *imsg)
690 {
691 	struct gotd_imsg_capability icapa;
692 	struct gotd_client_capability *capa;
693 	size_t datalen;
694 	char *key, *value = NULL;
695 
696 	if (client->capabilities == NULL ||
697 	    client->ncapabilities >= client->ncapa_alloc) {
698 		return got_error_msg(GOT_ERR_BAD_REQUEST,
699 		    "unexpected capability received");
700 	}
701 
702 	memset(&icapa, 0, sizeof(icapa));
703 
704 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
705 	if (datalen < sizeof(icapa))
706 		return got_error(GOT_ERR_PRIVSEP_LEN);
707 	memcpy(&icapa, imsg->data, sizeof(icapa));
708 
709 	if (datalen != sizeof(icapa) + icapa.key_len + icapa.value_len)
710 		return got_error(GOT_ERR_PRIVSEP_LEN);
711 
712 	key = strndup(imsg->data + sizeof(icapa), icapa.key_len);
713 	if (key == NULL)
714 		return got_error_from_errno("strndup");
715 	if (icapa.value_len > 0) {
716 		value = strndup(imsg->data + sizeof(icapa) + icapa.key_len,
717 		    icapa.value_len);
718 		if (value == NULL) {
719 			free(key);
720 			return got_error_from_errno("strndup");
721 		}
722 	}
723 
724 	capa = &client->capabilities[client->ncapabilities++];
725 	capa->key = key;
726 	capa->value = value;
727 
728 	if (value)
729 		log_debug("uid %d: capability %s=%s", client->euid, key, value);
730 	else
731 		log_debug("uid %d: capability %s", client->euid, key);
732 
733 	return NULL;
734 }
735 
736 static const struct got_error *
737 ensure_client_is_reading(struct gotd_session_client *client)
738 {
739 	if (client->is_writing) {
740 		return got_error_fmt(GOT_ERR_BAD_PACKET,
741 		    "uid %d made a read-request but is not reading from "
742 		    "a repository", client->euid);
743 	}
744 
745 	return NULL;
746 }
747 
748 static const struct got_error *
749 ensure_client_is_writing(struct gotd_session_client *client)
750 {
751 	if (!client->is_writing) {
752 		return got_error_fmt(GOT_ERR_BAD_PACKET,
753 		    "uid %d made a write-request but is not writing to "
754 		    "a repository", client->euid);
755 	}
756 
757 	return NULL;
758 }
759 
760 static const struct got_error *
761 forward_want(struct gotd_session_client *client, struct imsg *imsg)
762 {
763 	struct gotd_imsg_want ireq;
764 	struct gotd_imsg_want iwant;
765 	size_t datalen;
766 
767 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
768 	if (datalen != sizeof(ireq))
769 		return got_error(GOT_ERR_PRIVSEP_LEN);
770 
771 	memcpy(&ireq, imsg->data, datalen);
772 
773 	memset(&iwant, 0, sizeof(iwant));
774 	memcpy(iwant.object_id, ireq.object_id, SHA1_DIGEST_LENGTH);
775 	iwant.client_id = client->id;
776 
777 	if (gotd_imsg_compose_event(&client->repo_child_iev, GOTD_IMSG_WANT,
778 	    gotd_session.proc_id, -1, &iwant, sizeof(iwant)) == -1)
779 		return got_error_from_errno("imsg compose WANT");
780 
781 	return NULL;
782 }
783 
784 static const struct got_error *
785 forward_ref_update(struct gotd_session_client *client, struct imsg *imsg)
786 {
787 	const struct got_error *err = NULL;
788 	struct gotd_imsg_ref_update ireq;
789 	struct gotd_imsg_ref_update *iref = NULL;
790 	size_t datalen;
791 
792 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
793 	if (datalen < sizeof(ireq))
794 		return got_error(GOT_ERR_PRIVSEP_LEN);
795 	memcpy(&ireq, imsg->data, sizeof(ireq));
796 	if (datalen != sizeof(ireq) + ireq.name_len)
797 		return got_error(GOT_ERR_PRIVSEP_LEN);
798 
799 	iref = malloc(datalen);
800 	if (iref == NULL)
801 		return got_error_from_errno("malloc");
802 	memcpy(iref, imsg->data, datalen);
803 
804 	iref->client_id = client->id;
805 	if (gotd_imsg_compose_event(&client->repo_child_iev,
806 	    GOTD_IMSG_REF_UPDATE, gotd_session.proc_id, -1,
807 	    iref, datalen) == -1)
808 		err = got_error_from_errno("imsg compose REF_UPDATE");
809 	free(iref);
810 	return err;
811 }
812 
813 static const struct got_error *
814 forward_have(struct gotd_session_client *client, struct imsg *imsg)
815 {
816 	struct gotd_imsg_have ireq;
817 	struct gotd_imsg_have ihave;
818 	size_t datalen;
819 
820 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
821 	if (datalen != sizeof(ireq))
822 		return got_error(GOT_ERR_PRIVSEP_LEN);
823 
824 	memcpy(&ireq, imsg->data, datalen);
825 
826 	memset(&ihave, 0, sizeof(ihave));
827 	memcpy(ihave.object_id, ireq.object_id, SHA1_DIGEST_LENGTH);
828 	ihave.client_id = client->id;
829 
830 	if (gotd_imsg_compose_event(&client->repo_child_iev, GOTD_IMSG_HAVE,
831 	    gotd_session.proc_id, -1, &ihave, sizeof(ihave)) == -1)
832 		return got_error_from_errno("imsg compose HAVE");
833 
834 	return NULL;
835 }
836 
837 static int
838 client_has_capability(struct gotd_session_client *client, const char *capastr)
839 {
840 	struct gotd_client_capability *capa;
841 	size_t i;
842 
843 	if (client->ncapabilities == 0)
844 		return 0;
845 
846 	for (i = 0; i < client->ncapabilities; i++) {
847 		capa = &client->capabilities[i];
848 		if (strcmp(capa->key, capastr) == 0)
849 			return 1;
850 	}
851 
852 	return 0;
853 }
854 
855 static const struct got_error *
856 recv_packfile(struct gotd_session_client *client)
857 {
858 	const struct got_error *err = NULL;
859 	struct gotd_imsg_recv_packfile ipack;
860 	struct gotd_imsg_packfile_pipe ipipe;
861 	struct gotd_imsg_packidx_file ifile;
862 	char *basepath = NULL, *pack_path = NULL, *idx_path = NULL;
863 	int packfd = -1, idxfd = -1;
864 	int pipe[2] = { -1, -1 };
865 
866 	if (client->packfile_path) {
867 		return got_error_fmt(GOT_ERR_PRIVSEP_MSG,
868 		    "uid %d already has a pack file", client->euid);
869 	}
870 
871 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pipe) == -1)
872 		return got_error_from_errno("socketpair");
873 
874 	memset(&ipipe, 0, sizeof(ipipe));
875 	ipipe.client_id = client->id;
876 
877 	/* Send pack pipe end 0 to repo child process. */
878 	if (gotd_imsg_compose_event(&client->repo_child_iev,
879 	    GOTD_IMSG_PACKFILE_PIPE, gotd_session.proc_id, pipe[0],
880 	        &ipipe, sizeof(ipipe)) == -1) {
881 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
882 		pipe[0] = -1;
883 		goto done;
884 	}
885 	pipe[0] = -1;
886 
887 	/* Send pack pipe end 1 to gotsh(1) (expects just an fd, no data). */
888 	if (gotd_imsg_compose_event(&client->iev,
889 	    GOTD_IMSG_PACKFILE_PIPE, gotd_session.proc_id, pipe[1],
890 	    NULL, 0) == -1)
891 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
892 	pipe[1] = -1;
893 
894 	if (asprintf(&basepath, "%s/%s/receiving-from-uid-%d.pack",
895 	    got_repo_get_path(gotd_session.repo), GOT_OBJECTS_PACK_DIR,
896 	    client->euid) == -1) {
897 		err = got_error_from_errno("asprintf");
898 		goto done;
899 	}
900 
901 	err = got_opentemp_named_fd(&pack_path, &packfd, basepath, "");
902 	if (err)
903 		goto done;
904 	if (fchmod(packfd, GOT_DEFAULT_PACK_MODE) == -1) {
905 		err = got_error_from_errno2("fchmod", pack_path);
906 		goto done;
907 	}
908 
909 	free(basepath);
910 	if (asprintf(&basepath, "%s/%s/receiving-from-uid-%d.idx",
911 	    got_repo_get_path(gotd_session.repo), GOT_OBJECTS_PACK_DIR,
912 	    client->euid) == -1) {
913 		err = got_error_from_errno("asprintf");
914 		basepath = NULL;
915 		goto done;
916 	}
917 	err = got_opentemp_named_fd(&idx_path, &idxfd, basepath, "");
918 	if (err)
919 		goto done;
920 	if (fchmod(idxfd, GOT_DEFAULT_PACK_MODE) == -1) {
921 		err = got_error_from_errno2("fchmod", idx_path);
922 		goto done;
923 	}
924 
925 	memset(&ifile, 0, sizeof(ifile));
926 	ifile.client_id = client->id;
927 	if (gotd_imsg_compose_event(&client->repo_child_iev,
928 	    GOTD_IMSG_PACKIDX_FILE, gotd_session.proc_id,
929 	    idxfd, &ifile, sizeof(ifile)) == -1) {
930 		err = got_error_from_errno("imsg compose PACKIDX_FILE");
931 		idxfd = -1;
932 		goto done;
933 	}
934 	idxfd = -1;
935 
936 	memset(&ipack, 0, sizeof(ipack));
937 	ipack.client_id = client->id;
938 	if (client_has_capability(client, GOT_CAPA_REPORT_STATUS))
939 		ipack.report_status = 1;
940 
941 	if (gotd_imsg_compose_event(&client->repo_child_iev,
942 	    GOTD_IMSG_RECV_PACKFILE, gotd_session.proc_id, packfd,
943 	    &ipack, sizeof(ipack)) == -1) {
944 		err = got_error_from_errno("imsg compose RECV_PACKFILE");
945 		packfd = -1;
946 		goto done;
947 	}
948 	packfd = -1;
949 
950 done:
951 	free(basepath);
952 	if (pipe[0] != -1 && close(pipe[0]) == -1 && err == NULL)
953 		err = got_error_from_errno("close");
954 	if (pipe[1] != -1 && close(pipe[1]) == -1 && err == NULL)
955 		err = got_error_from_errno("close");
956 	if (packfd != -1 && close(packfd) == -1 && err == NULL)
957 		err = got_error_from_errno("close");
958 	if (idxfd != -1 && close(idxfd) == -1 && err == NULL)
959 		err = got_error_from_errno("close");
960 	if (err) {
961 		free(pack_path);
962 		free(idx_path);
963 	} else {
964 		client->packfile_path = pack_path;
965 		client->packidx_path = idx_path;
966 	}
967 	return err;
968 }
969 
970 static const struct got_error *
971 send_packfile(struct gotd_session_client *client)
972 {
973 	const struct got_error *err = NULL;
974 	struct gotd_imsg_send_packfile ipack;
975 	struct gotd_imsg_packfile_pipe ipipe;
976 	int pipe[2];
977 
978 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pipe) == -1)
979 		return got_error_from_errno("socketpair");
980 
981 	memset(&ipack, 0, sizeof(ipack));
982 	memset(&ipipe, 0, sizeof(ipipe));
983 
984 	ipack.client_id = client->id;
985 	if (client_has_capability(client, GOT_CAPA_SIDE_BAND_64K))
986 		ipack.report_progress = 1;
987 
988 	client->delta_cache_fd = got_opentempfd();
989 	if (client->delta_cache_fd == -1)
990 		return got_error_from_errno("got_opentempfd");
991 
992 	if (gotd_imsg_compose_event(&client->repo_child_iev,
993 	    GOTD_IMSG_SEND_PACKFILE, PROC_GOTD, client->delta_cache_fd,
994 	    &ipack, sizeof(ipack)) == -1) {
995 		err = got_error_from_errno("imsg compose SEND_PACKFILE");
996 		close(pipe[0]);
997 		close(pipe[1]);
998 		return err;
999 	}
1000 
1001 	ipipe.client_id = client->id;
1002 
1003 	/* Send pack pipe end 0 to repo child process. */
1004 	if (gotd_imsg_compose_event(&client->repo_child_iev,
1005 	    GOTD_IMSG_PACKFILE_PIPE, PROC_GOTD,
1006 	    pipe[0], &ipipe, sizeof(ipipe)) == -1) {
1007 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
1008 		close(pipe[1]);
1009 		return err;
1010 	}
1011 
1012 	/* Send pack pipe end 1 to gotsh(1) (expects just an fd, no data). */
1013 	if (gotd_imsg_compose_event(&client->iev,
1014 	    GOTD_IMSG_PACKFILE_PIPE, PROC_GOTD, pipe[1], NULL, 0) == -1)
1015 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
1016 
1017 	return err;
1018 }
1019 
1020 static void
1021 session_dispatch_client(int fd, short events, void *arg)
1022 {
1023 	struct gotd_imsgev *iev = arg;
1024 	struct imsgbuf *ibuf = &iev->ibuf;
1025 	struct gotd_session_client *client = &gotd_session_client;
1026 	const struct got_error *err = NULL;
1027 	struct imsg imsg;
1028 	ssize_t n;
1029 
1030 	if (events & EV_WRITE) {
1031 		while (ibuf->w.queued) {
1032 			n = msgbuf_write(&ibuf->w);
1033 			if (n == -1 && errno == EPIPE) {
1034 				/*
1035 				 * The client has closed its socket.
1036 				 * This can happen when Git clients are
1037 				 * done sending pack file data.
1038 				 */
1039 				msgbuf_clear(&ibuf->w);
1040 				continue;
1041 			} else if (n == -1 && errno != EAGAIN) {
1042 				err = got_error_from_errno("imsg_flush");
1043 				disconnect_on_error(client, err);
1044 				return;
1045 			}
1046 			if (n == 0) {
1047 				/* Connection closed. */
1048 				err = got_error(GOT_ERR_EOF);
1049 				disconnect_on_error(client, err);
1050 				return;
1051 			}
1052 		}
1053 
1054 		if (client->flush_disconnect) {
1055 			disconnect(client);
1056 			return;
1057 		}
1058 	}
1059 
1060 	if ((events & EV_READ) == 0)
1061 		return;
1062 
1063 	memset(&imsg, 0, sizeof(imsg));
1064 
1065 	while (err == NULL) {
1066 		err = gotd_imsg_recv(&imsg, ibuf, 0);
1067 		if (err) {
1068 			if (err->code == GOT_ERR_PRIVSEP_READ)
1069 				err = NULL;
1070 			else if (err->code == GOT_ERR_EOF &&
1071 			    client->state == GOTD_STATE_EXPECT_CAPABILITIES) {
1072 				/*
1073 				 * The client has closed its socket before
1074 				 * sending its capability announcement.
1075 				 * This can happen when Git clients have
1076 				 * no ref-updates to send.
1077 				 */
1078 				disconnect_on_error(client, err);
1079 				return;
1080 			}
1081 			break;
1082 		}
1083 
1084 		evtimer_del(&client->tmo);
1085 
1086 		switch (imsg.hdr.type) {
1087 		case GOTD_IMSG_CAPABILITIES:
1088 			if (client->state != GOTD_STATE_EXPECT_CAPABILITIES) {
1089 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1090 				    "unexpected capabilities received");
1091 				break;
1092 			}
1093 			log_debug("receiving capabilities from uid %d",
1094 			    client->euid);
1095 			err = recv_capabilities(client, &imsg);
1096 			break;
1097 		case GOTD_IMSG_CAPABILITY:
1098 			if (client->state != GOTD_STATE_EXPECT_CAPABILITIES) {
1099 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1100 				    "unexpected capability received");
1101 				break;
1102 			}
1103 			err = recv_capability(client, &imsg);
1104 			if (err || client->ncapabilities < client->ncapa_alloc)
1105 				break;
1106 			if (!client->is_writing) {
1107 				client->state = GOTD_STATE_EXPECT_WANT;
1108 				client->accept_flush_pkt = 1;
1109 				log_debug("uid %d: expecting want-lines",
1110 				    client->euid);
1111 			} else if (client->is_writing) {
1112 				client->state = GOTD_STATE_EXPECT_REF_UPDATE;
1113 				client->accept_flush_pkt = 1;
1114 				log_debug("uid %d: expecting ref-update-lines",
1115 				    client->euid);
1116 			} else
1117 				fatalx("client %d is both reading and writing",
1118 				    client->euid);
1119 			break;
1120 		case GOTD_IMSG_WANT:
1121 			if (client->state != GOTD_STATE_EXPECT_WANT) {
1122 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1123 				    "unexpected want-line received");
1124 				break;
1125 			}
1126 			log_debug("received want-line from uid %d",
1127 			    client->euid);
1128 			err = ensure_client_is_reading(client);
1129 			if (err)
1130 				break;
1131 			client->accept_flush_pkt = 1;
1132 			err = forward_want(client, &imsg);
1133 			break;
1134 		case GOTD_IMSG_REF_UPDATE:
1135 			if (client->state != GOTD_STATE_EXPECT_REF_UPDATE &&
1136 			    client->state !=
1137 			    GOTD_STATE_EXPECT_MORE_REF_UPDATES) {
1138 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1139 				    "unexpected ref-update-line received");
1140 				break;
1141 			}
1142 			log_debug("received ref-update-line from uid %d",
1143 			    client->euid);
1144 			err = ensure_client_is_writing(client);
1145 			if (err)
1146 				break;
1147 			err = forward_ref_update(client, &imsg);
1148 			if (err)
1149 				break;
1150 			client->state = GOTD_STATE_EXPECT_MORE_REF_UPDATES;
1151 			client->accept_flush_pkt = 1;
1152 			break;
1153 		case GOTD_IMSG_HAVE:
1154 			if (client->state != GOTD_STATE_EXPECT_HAVE) {
1155 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1156 				    "unexpected have-line received");
1157 				break;
1158 			}
1159 			log_debug("received have-line from uid %d",
1160 			    client->euid);
1161 			err = ensure_client_is_reading(client);
1162 			if (err)
1163 				break;
1164 			err = forward_have(client, &imsg);
1165 			if (err)
1166 				break;
1167 			client->accept_flush_pkt = 1;
1168 			break;
1169 		case GOTD_IMSG_FLUSH:
1170 			if (client->state == GOTD_STATE_EXPECT_WANT ||
1171 			    client->state == GOTD_STATE_EXPECT_HAVE) {
1172 				err = ensure_client_is_reading(client);
1173 				if (err)
1174 					break;
1175 			} else if (client->state ==
1176 			    GOTD_STATE_EXPECT_MORE_REF_UPDATES) {
1177 				err = ensure_client_is_writing(client);
1178 				if (err)
1179 					break;
1180 			} else if (client->state != GOTD_STATE_EXPECT_DONE) {
1181 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1182 				    "unexpected flush-pkt received");
1183 				break;
1184 			}
1185 			if (!client->accept_flush_pkt) {
1186 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1187 				    "unexpected flush-pkt received");
1188 				break;
1189 			}
1190 
1191 			/*
1192 			 * Accept just one flush packet at a time.
1193 			 * Future client state transitions will set this flag
1194 			 * again if another flush packet is expected.
1195 			 */
1196 			client->accept_flush_pkt = 0;
1197 
1198 			log_debug("received flush-pkt from uid %d",
1199 			    client->euid);
1200 			if (client->state == GOTD_STATE_EXPECT_WANT) {
1201 				client->state = GOTD_STATE_EXPECT_HAVE;
1202 				log_debug("uid %d: expecting have-lines",
1203 				    client->euid);
1204 			} else if (client->state == GOTD_STATE_EXPECT_HAVE) {
1205 				client->state = GOTD_STATE_EXPECT_DONE;
1206 				client->accept_flush_pkt = 1;
1207 				log_debug("uid %d: expecting 'done'",
1208 				    client->euid);
1209 			} else if (client->state ==
1210 			    GOTD_STATE_EXPECT_MORE_REF_UPDATES) {
1211 				client->state = GOTD_STATE_EXPECT_PACKFILE;
1212 				log_debug("uid %d: expecting packfile",
1213 				    client->euid);
1214 				err = recv_packfile(client);
1215 			} else if (client->state != GOTD_STATE_EXPECT_DONE) {
1216 				/* should not happen, see above */
1217 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1218 				    "unexpected client state");
1219 				break;
1220 			}
1221 			break;
1222 		case GOTD_IMSG_DONE:
1223 			if (client->state != GOTD_STATE_EXPECT_HAVE &&
1224 			    client->state != GOTD_STATE_EXPECT_DONE) {
1225 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1226 				    "unexpected flush-pkt received");
1227 				break;
1228 			}
1229 			log_debug("received 'done' from uid %d", client->euid);
1230 			err = ensure_client_is_reading(client);
1231 			if (err)
1232 				break;
1233 			client->state = GOTD_STATE_DONE;
1234 			client->accept_flush_pkt = 1;
1235 			err = send_packfile(client);
1236 			break;
1237 		default:
1238 			log_debug("unexpected imsg %d", imsg.hdr.type);
1239 			err = got_error(GOT_ERR_PRIVSEP_MSG);
1240 			break;
1241 		}
1242 
1243 		imsg_free(&imsg);
1244 	}
1245 
1246 	if (err) {
1247 		if (err->code != GOT_ERR_EOF ||
1248 		    client->state != GOTD_STATE_EXPECT_PACKFILE)
1249 			disconnect_on_error(client, err);
1250 	} else {
1251 		gotd_imsg_event_add(iev);
1252 		evtimer_add(&client->tmo, &gotd_session.request_timeout);
1253 	}
1254 }
1255 
1256 static const struct got_error *
1257 list_refs_request(void)
1258 {
1259 	static const struct got_error *err;
1260 	struct gotd_session_client *client = &gotd_session_client;
1261 	struct gotd_imsgev *iev = &client->repo_child_iev;
1262 	struct gotd_imsg_list_refs_internal ilref;
1263 	int fd;
1264 
1265 	if (client->state != GOTD_STATE_EXPECT_LIST_REFS)
1266 		return got_error(GOT_ERR_PRIVSEP_MSG);
1267 
1268 	memset(&ilref, 0, sizeof(ilref));
1269 	ilref.client_id = client->id;
1270 
1271 	fd = dup(client->fd);
1272 	if (fd == -1)
1273 		return got_error_from_errno("dup");
1274 
1275 	if (gotd_imsg_compose_event(iev, GOTD_IMSG_LIST_REFS_INTERNAL,
1276 	    gotd_session.proc_id, fd, &ilref, sizeof(ilref)) == -1) {
1277 		err = got_error_from_errno("imsg compose LIST_REFS_INTERNAL");
1278 		close(fd);
1279 		return err;
1280 	}
1281 
1282 	client->state = GOTD_STATE_EXPECT_CAPABILITIES;
1283 	log_debug("uid %d: expecting capabilities", client->euid);
1284 	return NULL;
1285 }
1286 
1287 static const struct got_error *
1288 recv_connect(struct imsg *imsg)
1289 {
1290 	struct gotd_session_client *client = &gotd_session_client;
1291 	struct gotd_imsg_connect iconnect;
1292 	size_t datalen;
1293 
1294 	if (client->state != GOTD_STATE_EXPECT_LIST_REFS)
1295 		return got_error(GOT_ERR_PRIVSEP_MSG);
1296 
1297 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1298 	if (datalen != sizeof(iconnect))
1299 		return got_error(GOT_ERR_PRIVSEP_LEN);
1300 	memcpy(&iconnect, imsg->data, sizeof(iconnect));
1301 
1302 	client->euid = iconnect.euid;
1303 	client->egid = iconnect.egid;
1304 	client->fd = imsg_get_fd(imsg);
1305 	if (client->fd == -1)
1306 		return got_error(GOT_ERR_PRIVSEP_NO_FD);
1307 
1308 	imsg_init(&client->iev.ibuf, client->fd);
1309 	client->iev.handler = session_dispatch_client;
1310 	client->iev.events = EV_READ;
1311 	client->iev.handler_arg = NULL;
1312 	event_set(&client->iev.ev, client->iev.ibuf.fd, EV_READ,
1313 	    session_dispatch_client, &client->iev);
1314 	gotd_imsg_event_add(&client->iev);
1315 	evtimer_set(&client->tmo, gotd_request_timeout, client);
1316 
1317 	return NULL;
1318 }
1319 
1320 static const struct got_error *
1321 recv_repo_child(struct imsg *imsg)
1322 {
1323 	struct gotd_imsg_connect_repo_child ichild;
1324 	struct gotd_session_client *client = &gotd_session_client;
1325 	size_t datalen;
1326 	int fd;
1327 
1328 	if (client->state != GOTD_STATE_EXPECT_LIST_REFS)
1329 		return got_error(GOT_ERR_PRIVSEP_MSG);
1330 
1331 	/* We should already have received a pipe to the listener. */
1332 	if (client->fd == -1)
1333 		return got_error(GOT_ERR_PRIVSEP_MSG);
1334 
1335 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1336 	if (datalen != sizeof(ichild))
1337 		return got_error(GOT_ERR_PRIVSEP_LEN);
1338 
1339 	memcpy(&ichild, imsg->data, sizeof(ichild));
1340 
1341 	client->id = ichild.client_id;
1342 	if (ichild.proc_id == PROC_REPO_WRITE)
1343 		client->is_writing = 1;
1344 	else if (ichild.proc_id == PROC_REPO_READ)
1345 		client->is_writing = 0;
1346 	else
1347 		return got_error_msg(GOT_ERR_PRIVSEP_MSG,
1348 		    "bad child process type");
1349 
1350 	fd = imsg_get_fd(imsg);
1351 	if (fd == -1)
1352 		return got_error(GOT_ERR_PRIVSEP_NO_FD);
1353 
1354 	imsg_init(&client->repo_child_iev.ibuf, fd);
1355 	client->repo_child_iev.handler = session_dispatch_repo_child;
1356 	client->repo_child_iev.events = EV_READ;
1357 	client->repo_child_iev.handler_arg = NULL;
1358 	event_set(&client->repo_child_iev.ev, client->repo_child_iev.ibuf.fd,
1359 	    EV_READ, session_dispatch_repo_child, &client->repo_child_iev);
1360 	gotd_imsg_event_add(&client->repo_child_iev);
1361 
1362 	/* The "recvfd" pledge promise is no longer needed. */
1363 	if (pledge("stdio rpath wpath cpath sendfd fattr flock", NULL) == -1)
1364 		fatal("pledge");
1365 
1366 	return NULL;
1367 }
1368 
1369 static void
1370 session_dispatch(int fd, short event, void *arg)
1371 {
1372 	struct gotd_imsgev *iev = arg;
1373 	struct imsgbuf *ibuf = &iev->ibuf;
1374 	struct gotd_session_client *client = &gotd_session_client;
1375 	ssize_t n;
1376 	int shut = 0;
1377 	struct imsg imsg;
1378 
1379 	if (event & EV_READ) {
1380 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1381 			fatal("imsg_read error");
1382 		if (n == 0) {
1383 			/* Connection closed. */
1384 			shut = 1;
1385 			goto done;
1386 		}
1387 	}
1388 
1389 	if (event & EV_WRITE) {
1390 		n = msgbuf_write(&ibuf->w);
1391 		if (n == -1 && errno != EAGAIN)
1392 			fatal("msgbuf_write");
1393 		if (n == 0) {
1394 			/* Connection closed. */
1395 			shut = 1;
1396 			goto done;
1397 		}
1398 	}
1399 
1400 	for (;;) {
1401 		const struct got_error *err = NULL;
1402 		uint32_t client_id = 0;
1403 		int do_disconnect = 0, do_list_refs = 0;
1404 
1405 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1406 			fatal("%s: imsg_get error", __func__);
1407 		if (n == 0)	/* No more messages. */
1408 			break;
1409 
1410 		switch (imsg.hdr.type) {
1411 		case GOTD_IMSG_ERROR:
1412 			do_disconnect = 1;
1413 			err = gotd_imsg_recv_error(&client_id, &imsg);
1414 			break;
1415 		case GOTD_IMSG_CONNECT:
1416 			err = recv_connect(&imsg);
1417 			break;
1418 		case GOTD_IMSG_DISCONNECT:
1419 			do_disconnect = 1;
1420 			break;
1421 		case GOTD_IMSG_CONNECT_REPO_CHILD:
1422 			err = recv_repo_child(&imsg);
1423 			if (err)
1424 				break;
1425 			do_list_refs = 1;
1426 			break;
1427 		default:
1428 			log_debug("unexpected imsg %d", imsg.hdr.type);
1429 			break;
1430 		}
1431 		imsg_free(&imsg);
1432 
1433 		if (do_disconnect) {
1434 			if (err)
1435 				disconnect_on_error(client, err);
1436 			else
1437 				disconnect(client);
1438 		} else if (do_list_refs)
1439 			err = list_refs_request();
1440 
1441 		if (err)
1442 			log_warnx("uid %d: %s", client->euid, err->msg);
1443 	}
1444 done:
1445 	if (!shut) {
1446 		gotd_imsg_event_add(iev);
1447 	} else {
1448 		/* This pipe is dead. Remove its event handler */
1449 		event_del(&iev->ev);
1450 		event_loopexit(NULL);
1451 	}
1452 }
1453 
1454 void
1455 session_main(const char *title, const char *repo_path,
1456     int *pack_fds, int *temp_fds, struct timeval *request_timeout,
1457     enum gotd_procid proc_id)
1458 {
1459 	const struct got_error *err = NULL;
1460 	struct event evsigint, evsigterm, evsighup, evsigusr1;
1461 
1462 	gotd_session.title = title;
1463 	gotd_session.pid = getpid();
1464 	gotd_session.pack_fds = pack_fds;
1465 	gotd_session.temp_fds = temp_fds;
1466 	memcpy(&gotd_session.request_timeout, request_timeout,
1467 	    sizeof(gotd_session.request_timeout));
1468 	gotd_session.proc_id = proc_id;
1469 
1470 	err = got_repo_open(&gotd_session.repo, repo_path, NULL, pack_fds);
1471 	if (err)
1472 		goto done;
1473 	if (!got_repo_is_bare(gotd_session.repo)) {
1474 		err = got_error_msg(GOT_ERR_NOT_GIT_REPO,
1475 		    "bare git repository required");
1476 		goto done;
1477 	}
1478 
1479 	got_repo_temp_fds_set(gotd_session.repo, temp_fds);
1480 
1481 	signal_set(&evsigint, SIGINT, gotd_session_sighdlr, NULL);
1482 	signal_set(&evsigterm, SIGTERM, gotd_session_sighdlr, NULL);
1483 	signal_set(&evsighup, SIGHUP, gotd_session_sighdlr, NULL);
1484 	signal_set(&evsigusr1, SIGUSR1, gotd_session_sighdlr, NULL);
1485 	signal(SIGPIPE, SIG_IGN);
1486 
1487 	signal_add(&evsigint, NULL);
1488 	signal_add(&evsigterm, NULL);
1489 	signal_add(&evsighup, NULL);
1490 	signal_add(&evsigusr1, NULL);
1491 
1492 	gotd_session_client.state = GOTD_STATE_EXPECT_LIST_REFS;
1493 	gotd_session_client.fd = -1;
1494 	gotd_session_client.nref_updates = -1;
1495 	gotd_session_client.delta_cache_fd = -1;
1496 	gotd_session_client.accept_flush_pkt = 1;
1497 
1498 	imsg_init(&gotd_session.parent_iev.ibuf, GOTD_FILENO_MSG_PIPE);
1499 	gotd_session.parent_iev.handler = session_dispatch;
1500 	gotd_session.parent_iev.events = EV_READ;
1501 	gotd_session.parent_iev.handler_arg = NULL;
1502 	event_set(&gotd_session.parent_iev.ev, gotd_session.parent_iev.ibuf.fd,
1503 	    EV_READ, session_dispatch, &gotd_session.parent_iev);
1504 	if (gotd_imsg_compose_event(&gotd_session.parent_iev,
1505 	    GOTD_IMSG_CLIENT_SESSION_READY, gotd_session.proc_id,
1506 	    -1, NULL, 0) == -1) {
1507 		err = got_error_from_errno("imsg compose CLIENT_SESSION_READY");
1508 		goto done;
1509 	}
1510 
1511 	event_dispatch();
1512 done:
1513 	if (err)
1514 		log_warnx("%s: %s", title, err->msg);
1515 	gotd_session_shutdown();
1516 }
1517 
1518 void
1519 gotd_session_shutdown(void)
1520 {
1521 	log_debug("shutting down");
1522 	if (gotd_session.repo)
1523 		got_repo_close(gotd_session.repo);
1524 	got_repo_pack_fds_close(gotd_session.pack_fds);
1525 	got_repo_temp_fds_close(gotd_session.temp_fds);
1526 	exit(0);
1527 }