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 "got_compat.h"
18 
19 #include <sys/types.h>
20 #include <sys/queue.h>
21 #include <sys/socket.h>
22 #include <sys/stat.h>
23 #include <sys/uio.h>
24 
25 #include <errno.h>
26 #include <event.h>
27 #include <limits.h>
28 #include <signal.h>
29 #include <stdint.h>
30 #include <stdio.h>
31 #include <stdlib.h>
32 #include <string.h>
33 #include <imsg.h>
34 #include <unistd.h>
35 
36 #include "got_compat.h"
37 
38 #include "got_error.h"
39 #include "got_repository.h"
40 #include "got_object.h"
41 #include "got_path.h"
42 #include "got_reference.h"
43 #include "got_opentemp.h"
44 
45 #include "got_lib_hash.h"
46 #include "got_lib_delta.h"
47 #include "got_lib_object.h"
48 #include "got_lib_object_cache.h"
49 #include "got_lib_pack.h"
50 #include "got_lib_repository.h"
51 #include "got_lib_gitproto.h"
52 
53 #include "gotd.h"
54 #include "log.h"
55 #include "session.h"
56 
57 
58 static struct gotd_session {
59 	pid_t pid;
60 	const char *title;
61 	struct got_repository *repo;
62 	int *pack_fds;
63 	int *temp_fds;
64 	struct gotd_imsgev parent_iev;
65 	struct timeval request_timeout;
66 	enum gotd_procid proc_id;
67 } gotd_session;
68 
69 static struct gotd_session_client {
70 	enum gotd_session_state		 state;
71 	int				 is_writing;
72 	struct gotd_client_capability	*capabilities;
73 	size_t				 ncapa_alloc;
74 	size_t				 ncapabilities;
75 	uint32_t			 id;
76 	int				 fd;
77 	int				 delta_cache_fd;
78 	struct gotd_imsgev		 iev;
79 	struct gotd_imsgev		 repo_child_iev;
80 	struct event			 tmo;
81 	uid_t				 euid;
82 	gid_t				 egid;
83 	char				*packfile_path;
84 	char				*packidx_path;
85 	int				 nref_updates;
86 	int				 accept_flush_pkt;
87 	int				 flush_disconnect;
88 } gotd_session_client;
89 
90 void gotd_session_sighdlr(int sig, short event, void *arg);
91 static void gotd_session_shutdown(void);
92 
93 static void
94 disconnect(struct gotd_session_client *client)
95 {
96 	log_debug("uid %d: disconnecting", client->euid);
97 
98 	if (gotd_imsg_compose_event(&gotd_session.parent_iev,
99 	    GOTD_IMSG_DISCONNECT, gotd_session.proc_id, -1, NULL, 0) == -1)
100 		log_warn("imsg compose DISCONNECT");
101 
102 	imsg_clear(&client->repo_child_iev.ibuf);
103 	event_del(&client->repo_child_iev.ev);
104 	evtimer_del(&client->tmo);
105 	close(client->fd);
106 	if (client->delta_cache_fd != -1)
107 		close(client->delta_cache_fd);
108 	if (client->packfile_path) {
109 		if (unlink(client->packfile_path) == -1 && errno != ENOENT)
110 			log_warn("unlink %s: ", client->packfile_path);
111 		free(client->packfile_path);
112 	}
113 	if (client->packidx_path) {
114 		if (unlink(client->packidx_path) == -1 && errno != ENOENT)
115 			log_warn("unlink %s: ", client->packidx_path);
116 		free(client->packidx_path);
117 	}
118 	free(client->capabilities);
119 
120 	gotd_session_shutdown();
121 }
122 
123 static void
124 disconnect_on_error(struct gotd_session_client *client,
125     const struct got_error *err)
126 {
127 	struct imsgbuf ibuf;
128 
129 	if (err->code != GOT_ERR_EOF) {
130 		log_warnx("uid %d: %s", client->euid, err->msg);
131 		imsg_init(&ibuf, client->fd);
132 		gotd_imsg_send_error(&ibuf, 0, gotd_session.proc_id, err);
133 		imsg_clear(&ibuf);
134 	}
135 
136 	disconnect(client);
137 }
138 
139 static void
140 gotd_request_timeout(int fd, short events, void *arg)
141 {
142 	struct gotd_session_client *client = arg;
143 
144 	log_debug("disconnecting uid %d due to timeout", client->euid);
145 	disconnect(client);
146 }
147 
148 void
149 gotd_session_sighdlr(int sig, short event, void *arg)
150 {
151 	/*
152 	 * Normal signal handler rules don't apply because libevent
153 	 * decouples for us.
154 	 */
155 
156 	switch (sig) {
157 	case SIGHUP:
158 		log_info("%s: ignoring SIGHUP", __func__);
159 		break;
160 	case SIGUSR1:
161 		log_info("%s: ignoring SIGUSR1", __func__);
162 		break;
163 	case SIGTERM:
164 	case SIGINT:
165 		gotd_session_shutdown();
166 		/* NOTREACHED */
167 		break;
168 	default:
169 		fatalx("unexpected signal");
170 	}
171 }
172 
173 static const struct got_error *
174 recv_packfile_done(uint32_t *client_id, struct imsg *imsg)
175 {
176 	struct gotd_imsg_packfile_done idone;
177 	size_t datalen;
178 
179 	log_debug("packfile-done received");
180 
181 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
182 	if (datalen != sizeof(idone))
183 		return got_error(GOT_ERR_PRIVSEP_LEN);
184 	memcpy(&idone, imsg->data, sizeof(idone));
185 
186 	*client_id = idone.client_id;
187 	return NULL;
188 }
189 
190 static const struct got_error *
191 recv_packfile_install(uint32_t *client_id, 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 	*client_id = inst.client_id;
204 	return NULL;
205 }
206 
207 static const struct got_error *
208 recv_ref_updates_start(uint32_t *client_id, struct imsg *imsg)
209 {
210 	struct gotd_imsg_ref_updates_start istart;
211 	size_t datalen;
212 
213 	log_debug("ref-updates-start received");
214 
215 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
216 	if (datalen != sizeof(istart))
217 		return got_error(GOT_ERR_PRIVSEP_LEN);
218 	memcpy(&istart, imsg->data, sizeof(istart));
219 
220 	*client_id = istart.client_id;
221 	return NULL;
222 }
223 
224 static const struct got_error *
225 recv_ref_update(uint32_t *client_id, struct imsg *imsg)
226 {
227 	struct gotd_imsg_ref_update iref;
228 	size_t datalen;
229 
230 	log_debug("ref-update received");
231 
232 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
233 	if (datalen < sizeof(iref))
234 		return got_error(GOT_ERR_PRIVSEP_LEN);
235 	memcpy(&iref, imsg->data, sizeof(iref));
236 
237 	*client_id = iref.client_id;
238 	return NULL;
239 }
240 
241 static const struct got_error *
242 send_ref_update_ok(struct gotd_session_client *client,
243     struct gotd_imsg_ref_update *iref, const char *refname)
244 {
245 	struct gotd_imsg_ref_update_ok iok;
246 	struct gotd_imsgev *iev = &client->iev;
247 	struct ibuf *wbuf;
248 	size_t len;
249 
250 	memset(&iok, 0, sizeof(iok));
251 	iok.client_id = client->id;
252 	memcpy(iok.old_id, iref->old_id, SHA1_DIGEST_LENGTH);
253 	memcpy(iok.new_id, iref->new_id, SHA1_DIGEST_LENGTH);
254 	iok.name_len = strlen(refname);
255 
256 	len = sizeof(iok) + iok.name_len;
257 	wbuf = imsg_create(&iev->ibuf, GOTD_IMSG_REF_UPDATE_OK,
258 	    gotd_session.proc_id, gotd_session.pid, len);
259 	if (wbuf == NULL)
260 		return got_error_from_errno("imsg_create REF_UPDATE_OK");
261 
262 	if (imsg_add(wbuf, &iok, sizeof(iok)) == -1)
263 		return got_error_from_errno("imsg_add REF_UPDATE_OK");
264 	if (imsg_add(wbuf, refname, iok.name_len) == -1)
265 		return got_error_from_errno("imsg_add REF_UPDATE_OK");
266 
267 	imsg_close(&iev->ibuf, wbuf);
268 	gotd_imsg_event_add(iev);
269 	return NULL;
270 }
271 
272 static void
273 send_refs_updated(struct gotd_session_client *client)
274 {
275 	if (gotd_imsg_compose_event(&client->iev, GOTD_IMSG_REFS_UPDATED,
276 	    gotd_session.proc_id, -1, NULL, 0) == -1)
277 		log_warn("imsg compose REFS_UPDATED");
278 }
279 
280 static const struct got_error *
281 send_ref_update_ng(struct gotd_session_client *client,
282     struct gotd_imsg_ref_update *iref, const char *refname,
283     const char *reason)
284 {
285 	const struct got_error *ng_err;
286 	struct gotd_imsg_ref_update_ng ing;
287 	struct gotd_imsgev *iev = &client->iev;
288 	struct ibuf *wbuf;
289 	size_t len;
290 
291 	memset(&ing, 0, sizeof(ing));
292 	ing.client_id = client->id;
293 	memcpy(ing.old_id, iref->old_id, SHA1_DIGEST_LENGTH);
294 	memcpy(ing.new_id, iref->new_id, SHA1_DIGEST_LENGTH);
295 	ing.name_len = strlen(refname);
296 
297 	ng_err = got_error_fmt(GOT_ERR_REF_BUSY, "%s", reason);
298 	ing.reason_len = strlen(ng_err->msg);
299 
300 	len = sizeof(ing) + ing.name_len + ing.reason_len;
301 	wbuf = imsg_create(&iev->ibuf, GOTD_IMSG_REF_UPDATE_NG,
302 	    gotd_session.proc_id, gotd_session.pid, len);
303 	if (wbuf == NULL)
304 		return got_error_from_errno("imsg_create REF_UPDATE_NG");
305 
306 	if (imsg_add(wbuf, &ing, sizeof(ing)) == -1)
307 		return got_error_from_errno("imsg_add REF_UPDATE_NG");
308 	if (imsg_add(wbuf, refname, ing.name_len) == -1)
309 		return got_error_from_errno("imsg_add REF_UPDATE_NG");
310 	if (imsg_add(wbuf, ng_err->msg, ing.reason_len) == -1)
311 		return got_error_from_errno("imsg_add REF_UPDATE_NG");
312 
313 	imsg_close(&iev->ibuf, wbuf);
314 	gotd_imsg_event_add(iev);
315 	return NULL;
316 }
317 
318 static const struct got_error *
319 install_pack(struct gotd_session_client *client, const char *repo_path,
320     struct imsg *imsg)
321 {
322 	const struct got_error *err = NULL;
323 	struct gotd_imsg_packfile_install inst;
324 	char hex[SHA1_DIGEST_STRING_LENGTH];
325 	size_t datalen;
326 	char *packfile_path = NULL, *packidx_path = NULL;
327 
328 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
329 	if (datalen != sizeof(inst))
330 		return got_error(GOT_ERR_PRIVSEP_LEN);
331 	memcpy(&inst, imsg->data, sizeof(inst));
332 
333 	if (client->packfile_path == NULL)
334 		return got_error_msg(GOT_ERR_BAD_REQUEST,
335 		    "client has no pack file");
336 	if (client->packidx_path == NULL)
337 		return got_error_msg(GOT_ERR_BAD_REQUEST,
338 		    "client has no pack file index");
339 
340 	if (got_sha1_digest_to_str(inst.pack_sha1, hex, sizeof(hex)) == NULL)
341 		return got_error_msg(GOT_ERR_NO_SPACE,
342 		    "could not convert pack file SHA1 to hex");
343 
344 	if (asprintf(&packfile_path, "/%s/%s/pack-%s.pack",
345 	    repo_path, GOT_OBJECTS_PACK_DIR, hex) == -1) {
346 		err = got_error_from_errno("asprintf");
347 		goto done;
348 	}
349 
350 	if (asprintf(&packidx_path, "/%s/%s/pack-%s.idx",
351 	    repo_path, GOT_OBJECTS_PACK_DIR, hex) == -1) {
352 		err = got_error_from_errno("asprintf");
353 		goto done;
354 	}
355 
356 	if (rename(client->packfile_path, packfile_path) == -1) {
357 		err = got_error_from_errno3("rename", client->packfile_path,
358 		    packfile_path);
359 		goto done;
360 	}
361 
362 	free(client->packfile_path);
363 	client->packfile_path = NULL;
364 
365 	if (rename(client->packidx_path, packidx_path) == -1) {
366 		err = got_error_from_errno3("rename", client->packidx_path,
367 		    packidx_path);
368 		goto done;
369 	}
370 
371 	/* Ensure we re-read the pack index list upon next access. */
372 	gotd_session.repo->pack_path_mtime.tv_sec = 0;
373 	gotd_session.repo->pack_path_mtime.tv_nsec = 0;
374 
375 	free(client->packidx_path);
376 	client->packidx_path = NULL;
377 done:
378 	free(packfile_path);
379 	free(packidx_path);
380 	return err;
381 }
382 
383 static const struct got_error *
384 begin_ref_updates(struct gotd_session_client *client, struct imsg *imsg)
385 {
386 	struct gotd_imsg_ref_updates_start istart;
387 	size_t datalen;
388 
389 	if (client->nref_updates != -1)
390 		return got_error(GOT_ERR_PRIVSEP_MSG);
391 
392 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
393 	if (datalen != sizeof(istart))
394 		return got_error(GOT_ERR_PRIVSEP_LEN);
395 	memcpy(&istart, imsg->data, sizeof(istart));
396 
397 	if (istart.nref_updates <= 0)
398 		return got_error(GOT_ERR_PRIVSEP_MSG);
399 
400 	client->nref_updates = istart.nref_updates;
401 	return NULL;
402 }
403 
404 static const struct got_error *
405 update_ref(int *shut, struct gotd_session_client *client,
406     const char *repo_path, struct imsg *imsg)
407 {
408 	const struct got_error *err = NULL;
409 	struct got_repository *repo = gotd_session.repo;
410 	struct got_reference *ref = NULL;
411 	struct gotd_imsg_ref_update iref;
412 	struct got_object_id old_id, new_id;
413 	struct got_object_id *id = NULL;
414 	char *refname = NULL;
415 	size_t datalen;
416 	int locked = 0;
417 	char hex1[SHA1_DIGEST_STRING_LENGTH];
418 	char hex2[SHA1_DIGEST_STRING_LENGTH];
419 
420 	log_debug("update-ref from uid %d", client->euid);
421 
422 	if (client->nref_updates <= 0)
423 		return got_error(GOT_ERR_PRIVSEP_MSG);
424 
425 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
426 	if (datalen < sizeof(iref))
427 		return got_error(GOT_ERR_PRIVSEP_LEN);
428 	memcpy(&iref, imsg->data, sizeof(iref));
429 	if (datalen != sizeof(iref) + iref.name_len)
430 		return got_error(GOT_ERR_PRIVSEP_LEN);
431 	refname = strndup(imsg->data + sizeof(iref), iref.name_len);
432 	if (refname == NULL)
433 		return got_error_from_errno("strndup");
434 
435 	log_debug("updating ref %s for uid %d", refname, client->euid);
436 
437 	memcpy(old_id.sha1, iref.old_id, SHA1_DIGEST_LENGTH);
438 	memcpy(new_id.sha1, iref.new_id, SHA1_DIGEST_LENGTH);
439 	err = got_repo_find_object_id(iref.delete_ref ? &old_id : &new_id,
440 	    repo);
441 	if (err)
442 		goto done;
443 
444 	if (iref.ref_is_new) {
445 		err = got_ref_open(&ref, repo, refname, 0);
446 		if (err) {
447 			if (err->code != GOT_ERR_NOT_REF)
448 				goto done;
449 			err = got_ref_alloc(&ref, refname, &new_id);
450 			if (err)
451 				goto done;
452 			err = got_ref_write(ref, repo); /* will lock/unlock */
453 			if (err)
454 				goto done;
455 		} else {
456 			err = got_ref_resolve(&id, repo, ref);
457 			if (err)
458 				goto done;
459 			got_object_id_hex(&new_id, hex1, sizeof(hex1));
460 			got_object_id_hex(id, hex2, sizeof(hex2));
461 			err = got_error_fmt(GOT_ERR_REF_BUSY,
462 			    "Addition %s: %s failed; %s: %s has been "
463 			    "created by someone else while transaction "
464 			    "was in progress",
465 			    got_ref_get_name(ref), hex1,
466 			    got_ref_get_name(ref), hex2);
467 			goto done;
468 		}
469 	} else if (iref.delete_ref) {
470 		err = got_ref_open(&ref, repo, refname, 1 /* lock */);
471 		if (err)
472 			goto done;
473 		locked = 1;
474 
475 		err = got_ref_resolve(&id, repo, ref);
476 		if (err)
477 			goto done;
478 
479 		if (got_object_id_cmp(id, &old_id) != 0) {
480 			got_object_id_hex(&old_id, hex1, sizeof(hex1));
481 			got_object_id_hex(id, hex2, sizeof(hex2));
482 			err = got_error_fmt(GOT_ERR_REF_BUSY,
483 			    "Deletion %s: %s failed; %s: %s has been "
484 			    "created by someone else while transaction "
485 			    "was in progress",
486 			    got_ref_get_name(ref), hex1,
487 			    got_ref_get_name(ref), hex2);
488 			goto done;
489 		}
490 
491 		err = got_ref_delete(ref, repo);
492 		if (err)
493 			goto done;
494 
495 		free(id);
496 		id = NULL;
497 	} else {
498 		err = got_ref_open(&ref, repo, refname, 1 /* lock */);
499 		if (err)
500 			goto done;
501 		locked = 1;
502 
503 		err = got_ref_resolve(&id, repo, ref);
504 		if (err)
505 			goto done;
506 
507 		if (got_object_id_cmp(id, &old_id) != 0) {
508 			got_object_id_hex(&old_id, hex1, sizeof(hex1));
509 			got_object_id_hex(id, hex2, sizeof(hex2));
510 			err = got_error_fmt(GOT_ERR_REF_BUSY,
511 			    "Update %s: %s failed; %s: %s has been "
512 			    "created by someone else while transaction "
513 			    "was in progress",
514 			    got_ref_get_name(ref), hex1,
515 			    got_ref_get_name(ref), hex2);
516 			goto done;
517 		}
518 
519 		if (got_object_id_cmp(&new_id, &old_id) != 0) {
520 			err = got_ref_change_ref(ref, &new_id);
521 			if (err)
522 				goto done;
523 
524 			err = got_ref_write(ref, repo);
525 			if (err)
526 				goto done;
527 		}
528 
529 		free(id);
530 		id = NULL;
531 	}
532 done:
533 	if (err) {
534 		if (err->code == GOT_ERR_LOCKFILE_TIMEOUT) {
535 			err = got_error_fmt(GOT_ERR_LOCKFILE_TIMEOUT,
536 			    "could not acquire exclusive file lock for %s",
537 			    refname);
538 		}
539 		send_ref_update_ng(client, &iref, refname, err->msg);
540 	} else
541 		send_ref_update_ok(client, &iref, refname);
542 
543 	if (client->nref_updates > 0) {
544 		client->nref_updates--;
545 		if (client->nref_updates == 0) {
546 			send_refs_updated(client);
547 			client->flush_disconnect = 1;
548 		}
549 
550 	}
551 	if (locked) {
552 		const struct got_error *unlock_err;
553 		unlock_err = got_ref_unlock(ref);
554 		if (unlock_err && err == NULL)
555 			err = unlock_err;
556 	}
557 	if (ref)
558 		got_ref_close(ref);
559 	free(refname);
560 	free(id);
561 	return err;
562 }
563 
564 static void
565 session_dispatch_repo_child(int fd, short event, void *arg)
566 {
567 	struct gotd_imsgev *iev = arg;
568 	struct imsgbuf *ibuf = &iev->ibuf;
569 	struct gotd_session_client *client = &gotd_session_client;
570 	ssize_t n;
571 	int shut = 0;
572 	struct imsg imsg;
573 
574 	if (event & EV_READ) {
575 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
576 			fatal("imsg_read error");
577 		if (n == 0) {
578 			/* Connection closed. */
579 			shut = 1;
580 			goto done;
581 		}
582 	}
583 
584 	if (event & EV_WRITE) {
585 		n = msgbuf_write(&ibuf->w);
586 		if (n == -1 && errno != EAGAIN)
587 			fatal("msgbuf_write");
588 		if (n == 0) {
589 			/* Connection closed. */
590 			shut = 1;
591 			goto done;
592 		}
593 	}
594 
595 	for (;;) {
596 		const struct got_error *err = NULL;
597 		uint32_t client_id = 0;
598 		int do_disconnect = 0;
599 		int do_ref_updates = 0, do_ref_update = 0;
600 		int do_packfile_install = 0;
601 
602 		if ((n = imsg_get(ibuf, &imsg)) == -1)
603 			fatal("%s: imsg_get error", __func__);
604 		if (n == 0)	/* No more messages. */
605 			break;
606 
607 		switch (imsg.hdr.type) {
608 		case GOTD_IMSG_ERROR:
609 			do_disconnect = 1;
610 			err = gotd_imsg_recv_error(&client_id, &imsg);
611 			break;
612 		case GOTD_IMSG_PACKFILE_DONE:
613 			do_disconnect = 1;
614 			err = recv_packfile_done(&client_id, &imsg);
615 			break;
616 		case GOTD_IMSG_PACKFILE_INSTALL:
617 			err = recv_packfile_install(&client_id, &imsg);
618 			if (err == NULL)
619 				do_packfile_install = 1;
620 			break;
621 		case GOTD_IMSG_REF_UPDATES_START:
622 			err = recv_ref_updates_start(&client_id, &imsg);
623 			if (err == NULL)
624 				do_ref_updates = 1;
625 			break;
626 		case GOTD_IMSG_REF_UPDATE:
627 			err = recv_ref_update(&client_id, &imsg);
628 			if (err == NULL)
629 				do_ref_update = 1;
630 			break;
631 		default:
632 			log_debug("unexpected imsg %d", imsg.hdr.type);
633 			break;
634 		}
635 
636 		if (do_disconnect) {
637 			if (err)
638 				disconnect_on_error(client, err);
639 			else
640 				disconnect(client);
641 		} else {
642 			if (do_packfile_install)
643 				err = install_pack(client,
644 				    gotd_session.repo->path, &imsg);
645 			else if (do_ref_updates)
646 				err = begin_ref_updates(client, &imsg);
647 			else if (do_ref_update)
648 				err = update_ref(&shut, client,
649 				    gotd_session.repo->path, &imsg);
650 			if (err)
651 				log_warnx("uid %d: %s", client->euid, err->msg);
652 		}
653 		imsg_free(&imsg);
654 	}
655 done:
656 	if (!shut) {
657 		gotd_imsg_event_add(iev);
658 	} else {
659 		/* This pipe is dead. Remove its event handler */
660 		event_del(&iev->ev);
661 		event_loopexit(NULL);
662 	}
663 }
664 
665 static const struct got_error *
666 recv_capabilities(struct gotd_session_client *client, struct imsg *imsg)
667 {
668 	struct gotd_imsg_capabilities icapas;
669 	size_t datalen;
670 
671 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
672 	if (datalen != sizeof(icapas))
673 		return got_error(GOT_ERR_PRIVSEP_LEN);
674 	memcpy(&icapas, imsg->data, sizeof(icapas));
675 
676 	client->ncapa_alloc = icapas.ncapabilities;
677 	client->capabilities = calloc(client->ncapa_alloc,
678 	    sizeof(*client->capabilities));
679 	if (client->capabilities == NULL) {
680 		client->ncapa_alloc = 0;
681 		return got_error_from_errno("calloc");
682 	}
683 
684 	log_debug("expecting %zu capabilities from uid %d",
685 	    client->ncapa_alloc, client->euid);
686 	return NULL;
687 }
688 
689 static const struct got_error *
690 recv_capability(struct gotd_session_client *client, struct imsg *imsg)
691 {
692 	struct gotd_imsg_capability icapa;
693 	struct gotd_client_capability *capa;
694 	size_t datalen;
695 	char *key, *value = NULL;
696 
697 	if (client->capabilities == NULL ||
698 	    client->ncapabilities >= client->ncapa_alloc) {
699 		return got_error_msg(GOT_ERR_BAD_REQUEST,
700 		    "unexpected capability received");
701 	}
702 
703 	memset(&icapa, 0, sizeof(icapa));
704 
705 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
706 	if (datalen < sizeof(icapa))
707 		return got_error(GOT_ERR_PRIVSEP_LEN);
708 	memcpy(&icapa, imsg->data, sizeof(icapa));
709 
710 	if (datalen != sizeof(icapa) + icapa.key_len + icapa.value_len)
711 		return got_error(GOT_ERR_PRIVSEP_LEN);
712 
713 	key = strndup(imsg->data + sizeof(icapa), icapa.key_len);
714 	if (key == NULL)
715 		return got_error_from_errno("strndup");
716 	if (icapa.value_len > 0) {
717 		value = strndup(imsg->data + sizeof(icapa) + icapa.key_len,
718 		    icapa.value_len);
719 		if (value == NULL) {
720 			free(key);
721 			return got_error_from_errno("strndup");
722 		}
723 	}
724 
725 	capa = &client->capabilities[client->ncapabilities++];
726 	capa->key = key;
727 	capa->value = value;
728 
729 	if (value)
730 		log_debug("uid %d: capability %s=%s", client->euid, key, value);
731 	else
732 		log_debug("uid %d: capability %s", client->euid, key);
733 
734 	return NULL;
735 }
736 
737 static const struct got_error *
738 ensure_client_is_reading(struct gotd_session_client *client)
739 {
740 	if (client->is_writing) {
741 		return got_error_fmt(GOT_ERR_BAD_PACKET,
742 		    "uid %d made a read-request but is not reading from "
743 		    "a repository", client->euid);
744 	}
745 
746 	return NULL;
747 }
748 
749 static const struct got_error *
750 ensure_client_is_writing(struct gotd_session_client *client)
751 {
752 	if (!client->is_writing) {
753 		return got_error_fmt(GOT_ERR_BAD_PACKET,
754 		    "uid %d made a write-request but is not writing to "
755 		    "a repository", client->euid);
756 	}
757 
758 	return NULL;
759 }
760 
761 static const struct got_error *
762 forward_want(struct gotd_session_client *client, struct imsg *imsg)
763 {
764 	struct gotd_imsg_want ireq;
765 	struct gotd_imsg_want iwant;
766 	size_t datalen;
767 
768 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
769 	if (datalen != sizeof(ireq))
770 		return got_error(GOT_ERR_PRIVSEP_LEN);
771 
772 	memcpy(&ireq, imsg->data, datalen);
773 
774 	memset(&iwant, 0, sizeof(iwant));
775 	memcpy(iwant.object_id, ireq.object_id, SHA1_DIGEST_LENGTH);
776 	iwant.client_id = client->id;
777 
778 	if (gotd_imsg_compose_event(&client->repo_child_iev, GOTD_IMSG_WANT,
779 	    gotd_session.proc_id, -1, &iwant, sizeof(iwant)) == -1)
780 		return got_error_from_errno("imsg compose WANT");
781 
782 	return NULL;
783 }
784 
785 static const struct got_error *
786 forward_ref_update(struct gotd_session_client *client, struct imsg *imsg)
787 {
788 	const struct got_error *err = NULL;
789 	struct gotd_imsg_ref_update ireq;
790 	struct gotd_imsg_ref_update *iref = NULL;
791 	size_t datalen;
792 
793 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
794 	if (datalen < sizeof(ireq))
795 		return got_error(GOT_ERR_PRIVSEP_LEN);
796 	memcpy(&ireq, imsg->data, sizeof(ireq));
797 	if (datalen != sizeof(ireq) + ireq.name_len)
798 		return got_error(GOT_ERR_PRIVSEP_LEN);
799 
800 	iref = malloc(datalen);
801 	if (iref == NULL)
802 		return got_error_from_errno("malloc");
803 	memcpy(iref, imsg->data, datalen);
804 
805 	iref->client_id = client->id;
806 	if (gotd_imsg_compose_event(&client->repo_child_iev,
807 	    GOTD_IMSG_REF_UPDATE, gotd_session.proc_id, -1,
808 	    iref, datalen) == -1)
809 		err = got_error_from_errno("imsg compose REF_UPDATE");
810 	free(iref);
811 	return err;
812 }
813 
814 static const struct got_error *
815 forward_have(struct gotd_session_client *client, struct imsg *imsg)
816 {
817 	struct gotd_imsg_have ireq;
818 	struct gotd_imsg_have ihave;
819 	size_t datalen;
820 
821 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
822 	if (datalen != sizeof(ireq))
823 		return got_error(GOT_ERR_PRIVSEP_LEN);
824 
825 	memcpy(&ireq, imsg->data, datalen);
826 
827 	memset(&ihave, 0, sizeof(ihave));
828 	memcpy(ihave.object_id, ireq.object_id, SHA1_DIGEST_LENGTH);
829 	ihave.client_id = client->id;
830 
831 	if (gotd_imsg_compose_event(&client->repo_child_iev, GOTD_IMSG_HAVE,
832 	    gotd_session.proc_id, -1, &ihave, sizeof(ihave)) == -1)
833 		return got_error_from_errno("imsg compose HAVE");
834 
835 	return NULL;
836 }
837 
838 static int
839 client_has_capability(struct gotd_session_client *client, const char *capastr)
840 {
841 	struct gotd_client_capability *capa;
842 	size_t i;
843 
844 	if (client->ncapabilities == 0)
845 		return 0;
846 
847 	for (i = 0; i < client->ncapabilities; i++) {
848 		capa = &client->capabilities[i];
849 		if (strcmp(capa->key, capastr) == 0)
850 			return 1;
851 	}
852 
853 	return 0;
854 }
855 
856 static const struct got_error *
857 recv_packfile(struct gotd_session_client *client)
858 {
859 	const struct got_error *err = NULL;
860 	struct gotd_imsg_recv_packfile ipack;
861 	struct gotd_imsg_packfile_pipe ipipe;
862 	struct gotd_imsg_packidx_file ifile;
863 	char *basepath = NULL, *pack_path = NULL, *idx_path = NULL;
864 	int packfd = -1, idxfd = -1;
865 	int pipe[2] = { -1, -1 };
866 
867 	if (client->packfile_path) {
868 		return got_error_fmt(GOT_ERR_PRIVSEP_MSG,
869 		    "uid %d already has a pack file", client->euid);
870 	}
871 
872 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pipe) == -1)
873 		return got_error_from_errno("socketpair");
874 
875 	memset(&ipipe, 0, sizeof(ipipe));
876 	ipipe.client_id = client->id;
877 
878 	/* Send pack pipe end 0 to repo child process. */
879 	if (gotd_imsg_compose_event(&client->repo_child_iev,
880 	    GOTD_IMSG_PACKFILE_PIPE, gotd_session.proc_id, pipe[0],
881 	        &ipipe, sizeof(ipipe)) == -1) {
882 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
883 		pipe[0] = -1;
884 		goto done;
885 	}
886 	pipe[0] = -1;
887 
888 	/* Send pack pipe end 1 to gotsh(1) (expects just an fd, no data). */
889 	if (gotd_imsg_compose_event(&client->iev,
890 	    GOTD_IMSG_PACKFILE_PIPE, gotd_session.proc_id, pipe[1],
891 	    NULL, 0) == -1)
892 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
893 	pipe[1] = -1;
894 
895 	if (asprintf(&basepath, "%s/%s/receiving-from-uid-%d.pack",
896 	    got_repo_get_path(gotd_session.repo), GOT_OBJECTS_PACK_DIR,
897 	    client->euid) == -1) {
898 		err = got_error_from_errno("asprintf");
899 		goto done;
900 	}
901 
902 	err = got_opentemp_named_fd(&pack_path, &packfd, basepath, "");
903 	if (err)
904 		goto done;
905 	if (fchmod(packfd, GOT_DEFAULT_PACK_MODE) == -1) {
906 		err = got_error_from_errno2("fchmod", pack_path);
907 		goto done;
908 	}
909 
910 	free(basepath);
911 	if (asprintf(&basepath, "%s/%s/receiving-from-uid-%d.idx",
912 	    got_repo_get_path(gotd_session.repo), GOT_OBJECTS_PACK_DIR,
913 	    client->euid) == -1) {
914 		err = got_error_from_errno("asprintf");
915 		basepath = NULL;
916 		goto done;
917 	}
918 	err = got_opentemp_named_fd(&idx_path, &idxfd, basepath, "");
919 	if (err)
920 		goto done;
921 	if (fchmod(idxfd, GOT_DEFAULT_PACK_MODE) == -1) {
922 		err = got_error_from_errno2("fchmod", idx_path);
923 		goto done;
924 	}
925 
926 	memset(&ifile, 0, sizeof(ifile));
927 	ifile.client_id = client->id;
928 	if (gotd_imsg_compose_event(&client->repo_child_iev,
929 	    GOTD_IMSG_PACKIDX_FILE, gotd_session.proc_id,
930 	    idxfd, &ifile, sizeof(ifile)) == -1) {
931 		err = got_error_from_errno("imsg compose PACKIDX_FILE");
932 		idxfd = -1;
933 		goto done;
934 	}
935 	idxfd = -1;
936 
937 	memset(&ipack, 0, sizeof(ipack));
938 	ipack.client_id = client->id;
939 	if (client_has_capability(client, GOT_CAPA_REPORT_STATUS))
940 		ipack.report_status = 1;
941 
942 	if (gotd_imsg_compose_event(&client->repo_child_iev,
943 	    GOTD_IMSG_RECV_PACKFILE, gotd_session.proc_id, packfd,
944 	    &ipack, sizeof(ipack)) == -1) {
945 		err = got_error_from_errno("imsg compose RECV_PACKFILE");
946 		packfd = -1;
947 		goto done;
948 	}
949 	packfd = -1;
950 
951 done:
952 	free(basepath);
953 	if (pipe[0] != -1 && close(pipe[0]) == -1 && err == NULL)
954 		err = got_error_from_errno("close");
955 	if (pipe[1] != -1 && close(pipe[1]) == -1 && err == NULL)
956 		err = got_error_from_errno("close");
957 	if (packfd != -1 && close(packfd) == -1 && err == NULL)
958 		err = got_error_from_errno("close");
959 	if (idxfd != -1 && close(idxfd) == -1 && err == NULL)
960 		err = got_error_from_errno("close");
961 	if (err) {
962 		free(pack_path);
963 		free(idx_path);
964 	} else {
965 		client->packfile_path = pack_path;
966 		client->packidx_path = idx_path;
967 	}
968 	return err;
969 }
970 
971 static const struct got_error *
972 send_packfile(struct gotd_session_client *client)
973 {
974 	const struct got_error *err = NULL;
975 	struct gotd_imsg_send_packfile ipack;
976 	struct gotd_imsg_packfile_pipe ipipe;
977 	int pipe[2];
978 
979 	if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, pipe) == -1)
980 		return got_error_from_errno("socketpair");
981 
982 	memset(&ipack, 0, sizeof(ipack));
983 	memset(&ipipe, 0, sizeof(ipipe));
984 
985 	ipack.client_id = client->id;
986 	if (client_has_capability(client, GOT_CAPA_SIDE_BAND_64K))
987 		ipack.report_progress = 1;
988 
989 	client->delta_cache_fd = got_opentempfd();
990 	if (client->delta_cache_fd == -1)
991 		return got_error_from_errno("got_opentempfd");
992 
993 	if (gotd_imsg_compose_event(&client->repo_child_iev,
994 	    GOTD_IMSG_SEND_PACKFILE, PROC_GOTD, client->delta_cache_fd,
995 	    &ipack, sizeof(ipack)) == -1) {
996 		err = got_error_from_errno("imsg compose SEND_PACKFILE");
997 		close(pipe[0]);
998 		close(pipe[1]);
999 		return err;
1000 	}
1001 
1002 	ipipe.client_id = client->id;
1003 
1004 	/* Send pack pipe end 0 to repo child process. */
1005 	if (gotd_imsg_compose_event(&client->repo_child_iev,
1006 	    GOTD_IMSG_PACKFILE_PIPE, PROC_GOTD,
1007 	    pipe[0], &ipipe, sizeof(ipipe)) == -1) {
1008 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
1009 		close(pipe[1]);
1010 		return err;
1011 	}
1012 
1013 	/* Send pack pipe end 1 to gotsh(1) (expects just an fd, no data). */
1014 	if (gotd_imsg_compose_event(&client->iev,
1015 	    GOTD_IMSG_PACKFILE_PIPE, PROC_GOTD, pipe[1], NULL, 0) == -1)
1016 		err = got_error_from_errno("imsg compose PACKFILE_PIPE");
1017 
1018 	return err;
1019 }
1020 
1021 static void
1022 session_dispatch_client(int fd, short events, void *arg)
1023 {
1024 	struct gotd_imsgev *iev = arg;
1025 	struct imsgbuf *ibuf = &iev->ibuf;
1026 	struct gotd_session_client *client = &gotd_session_client;
1027 	const struct got_error *err = NULL;
1028 	struct imsg imsg;
1029 	ssize_t n;
1030 
1031 	if (events & EV_WRITE) {
1032 		while (ibuf->w.queued) {
1033 			n = msgbuf_write(&ibuf->w);
1034 			if (n == -1 && errno == EPIPE) {
1035 				/*
1036 				 * The client has closed its socket.
1037 				 * This can happen when Git clients are
1038 				 * done sending pack file data.
1039 				 */
1040 				msgbuf_clear(&ibuf->w);
1041 				continue;
1042 			} else if (n == -1 && errno != EAGAIN) {
1043 				err = got_error_from_errno("imsg_flush");
1044 				disconnect_on_error(client, err);
1045 				return;
1046 			}
1047 			if (n == 0) {
1048 				/* Connection closed. */
1049 				err = got_error(GOT_ERR_EOF);
1050 				disconnect_on_error(client, err);
1051 				return;
1052 			}
1053 		}
1054 
1055 		if (client->flush_disconnect) {
1056 			disconnect(client);
1057 			return;
1058 		}
1059 	}
1060 
1061 	if ((events & EV_READ) == 0)
1062 		return;
1063 
1064 	memset(&imsg, 0, sizeof(imsg));
1065 
1066 	while (err == NULL) {
1067 		err = gotd_imsg_recv(&imsg, ibuf, 0);
1068 		if (err) {
1069 			if (err->code == GOT_ERR_PRIVSEP_READ)
1070 				err = NULL;
1071 			else if (err->code == GOT_ERR_EOF &&
1072 			    client->state == GOTD_STATE_EXPECT_CAPABILITIES) {
1073 				/*
1074 				 * The client has closed its socket before
1075 				 * sending its capability announcement.
1076 				 * This can happen when Git clients have
1077 				 * no ref-updates to send.
1078 				 */
1079 				disconnect_on_error(client, err);
1080 				return;
1081 			}
1082 			break;
1083 		}
1084 
1085 		evtimer_del(&client->tmo);
1086 
1087 		switch (imsg.hdr.type) {
1088 		case GOTD_IMSG_CAPABILITIES:
1089 			if (client->state != GOTD_STATE_EXPECT_CAPABILITIES) {
1090 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1091 				    "unexpected capabilities received");
1092 				break;
1093 			}
1094 			log_debug("receiving capabilities from uid %d",
1095 			    client->euid);
1096 			err = recv_capabilities(client, &imsg);
1097 			break;
1098 		case GOTD_IMSG_CAPABILITY:
1099 			if (client->state != GOTD_STATE_EXPECT_CAPABILITIES) {
1100 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1101 				    "unexpected capability received");
1102 				break;
1103 			}
1104 			err = recv_capability(client, &imsg);
1105 			if (err || client->ncapabilities < client->ncapa_alloc)
1106 				break;
1107 			if (!client->is_writing) {
1108 				client->state = GOTD_STATE_EXPECT_WANT;
1109 				client->accept_flush_pkt = 1;
1110 				log_debug("uid %d: expecting want-lines",
1111 				    client->euid);
1112 			} else if (client->is_writing) {
1113 				client->state = GOTD_STATE_EXPECT_REF_UPDATE;
1114 				client->accept_flush_pkt = 1;
1115 				log_debug("uid %d: expecting ref-update-lines",
1116 				    client->euid);
1117 			} else
1118 				fatalx("client %d is both reading and writing",
1119 				    client->euid);
1120 			break;
1121 		case GOTD_IMSG_WANT:
1122 			if (client->state != GOTD_STATE_EXPECT_WANT) {
1123 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1124 				    "unexpected want-line received");
1125 				break;
1126 			}
1127 			log_debug("received want-line from uid %d",
1128 			    client->euid);
1129 			err = ensure_client_is_reading(client);
1130 			if (err)
1131 				break;
1132 			client->accept_flush_pkt = 1;
1133 			err = forward_want(client, &imsg);
1134 			break;
1135 		case GOTD_IMSG_REF_UPDATE:
1136 			if (client->state != GOTD_STATE_EXPECT_REF_UPDATE &&
1137 			    client->state !=
1138 			    GOTD_STATE_EXPECT_MORE_REF_UPDATES) {
1139 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1140 				    "unexpected ref-update-line received");
1141 				break;
1142 			}
1143 			log_debug("received ref-update-line from uid %d",
1144 			    client->euid);
1145 			err = ensure_client_is_writing(client);
1146 			if (err)
1147 				break;
1148 			err = forward_ref_update(client, &imsg);
1149 			if (err)
1150 				break;
1151 			client->state = GOTD_STATE_EXPECT_MORE_REF_UPDATES;
1152 			client->accept_flush_pkt = 1;
1153 			break;
1154 		case GOTD_IMSG_HAVE:
1155 			if (client->state != GOTD_STATE_EXPECT_HAVE) {
1156 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1157 				    "unexpected have-line received");
1158 				break;
1159 			}
1160 			log_debug("received have-line from uid %d",
1161 			    client->euid);
1162 			err = ensure_client_is_reading(client);
1163 			if (err)
1164 				break;
1165 			err = forward_have(client, &imsg);
1166 			if (err)
1167 				break;
1168 			client->accept_flush_pkt = 1;
1169 			break;
1170 		case GOTD_IMSG_FLUSH:
1171 			if (client->state == GOTD_STATE_EXPECT_WANT ||
1172 			    client->state == GOTD_STATE_EXPECT_HAVE) {
1173 				err = ensure_client_is_reading(client);
1174 				if (err)
1175 					break;
1176 			} else if (client->state ==
1177 			    GOTD_STATE_EXPECT_MORE_REF_UPDATES) {
1178 				err = ensure_client_is_writing(client);
1179 				if (err)
1180 					break;
1181 			} else if (client->state != GOTD_STATE_EXPECT_DONE) {
1182 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1183 				    "unexpected flush-pkt received");
1184 				break;
1185 			}
1186 			if (!client->accept_flush_pkt) {
1187 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1188 				    "unexpected flush-pkt received");
1189 				break;
1190 			}
1191 
1192 			/*
1193 			 * Accept just one flush packet at a time.
1194 			 * Future client state transitions will set this flag
1195 			 * again if another flush packet is expected.
1196 			 */
1197 			client->accept_flush_pkt = 0;
1198 
1199 			log_debug("received flush-pkt from uid %d",
1200 			    client->euid);
1201 			if (client->state == GOTD_STATE_EXPECT_WANT) {
1202 				client->state = GOTD_STATE_EXPECT_HAVE;
1203 				log_debug("uid %d: expecting have-lines",
1204 				    client->euid);
1205 			} else if (client->state == GOTD_STATE_EXPECT_HAVE) {
1206 				client->state = GOTD_STATE_EXPECT_DONE;
1207 				client->accept_flush_pkt = 1;
1208 				log_debug("uid %d: expecting 'done'",
1209 				    client->euid);
1210 			} else if (client->state ==
1211 			    GOTD_STATE_EXPECT_MORE_REF_UPDATES) {
1212 				client->state = GOTD_STATE_EXPECT_PACKFILE;
1213 				log_debug("uid %d: expecting packfile",
1214 				    client->euid);
1215 				err = recv_packfile(client);
1216 			} else if (client->state != GOTD_STATE_EXPECT_DONE) {
1217 				/* should not happen, see above */
1218 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1219 				    "unexpected client state");
1220 				break;
1221 			}
1222 			break;
1223 		case GOTD_IMSG_DONE:
1224 			if (client->state != GOTD_STATE_EXPECT_HAVE &&
1225 			    client->state != GOTD_STATE_EXPECT_DONE) {
1226 				err = got_error_msg(GOT_ERR_BAD_REQUEST,
1227 				    "unexpected flush-pkt received");
1228 				break;
1229 			}
1230 			log_debug("received 'done' from uid %d", client->euid);
1231 			err = ensure_client_is_reading(client);
1232 			if (err)
1233 				break;
1234 			client->state = GOTD_STATE_DONE;
1235 			client->accept_flush_pkt = 1;
1236 			err = send_packfile(client);
1237 			break;
1238 		default:
1239 			log_debug("unexpected imsg %d", imsg.hdr.type);
1240 			err = got_error(GOT_ERR_PRIVSEP_MSG);
1241 			break;
1242 		}
1243 
1244 		imsg_free(&imsg);
1245 	}
1246 
1247 	if (err) {
1248 		if (err->code != GOT_ERR_EOF ||
1249 		    client->state != GOTD_STATE_EXPECT_PACKFILE)
1250 			disconnect_on_error(client, err);
1251 	} else {
1252 		gotd_imsg_event_add(iev);
1253 		evtimer_add(&client->tmo, &gotd_session.request_timeout);
1254 	}
1255 }
1256 
1257 static const struct got_error *
1258 list_refs_request(void)
1259 {
1260 	static const struct got_error *err;
1261 	struct gotd_session_client *client = &gotd_session_client;
1262 	struct gotd_imsgev *iev = &client->repo_child_iev;
1263 	struct gotd_imsg_list_refs_internal ilref;
1264 	int fd;
1265 
1266 	if (client->state != GOTD_STATE_EXPECT_LIST_REFS)
1267 		return got_error(GOT_ERR_PRIVSEP_MSG);
1268 
1269 	memset(&ilref, 0, sizeof(ilref));
1270 	ilref.client_id = client->id;
1271 
1272 	fd = dup(client->fd);
1273 	if (fd == -1)
1274 		return got_error_from_errno("dup");
1275 
1276 	if (gotd_imsg_compose_event(iev, GOTD_IMSG_LIST_REFS_INTERNAL,
1277 	    gotd_session.proc_id, fd, &ilref, sizeof(ilref)) == -1) {
1278 		err = got_error_from_errno("imsg compose LIST_REFS_INTERNAL");
1279 		close(fd);
1280 		return err;
1281 	}
1282 
1283 	client->state = GOTD_STATE_EXPECT_CAPABILITIES;
1284 	log_debug("uid %d: expecting capabilities", client->euid);
1285 	return NULL;
1286 }
1287 
1288 static const struct got_error *
1289 recv_connect(struct imsg *imsg)
1290 {
1291 	struct gotd_session_client *client = &gotd_session_client;
1292 	struct gotd_imsg_connect iconnect;
1293 	size_t datalen;
1294 
1295 	if (client->state != GOTD_STATE_EXPECT_LIST_REFS)
1296 		return got_error(GOT_ERR_PRIVSEP_MSG);
1297 
1298 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1299 	if (datalen != sizeof(iconnect))
1300 		return got_error(GOT_ERR_PRIVSEP_LEN);
1301 	memcpy(&iconnect, imsg->data, sizeof(iconnect));
1302 
1303 	client->euid = iconnect.euid;
1304 	client->egid = iconnect.egid;
1305 	client->fd = imsg_get_fd(imsg);
1306 	if (client->fd == -1)
1307 		return got_error(GOT_ERR_PRIVSEP_NO_FD);
1308 
1309 	imsg_init(&client->iev.ibuf, client->fd);
1310 	client->iev.handler = session_dispatch_client;
1311 	client->iev.events = EV_READ;
1312 	client->iev.handler_arg = NULL;
1313 	event_set(&client->iev.ev, client->iev.ibuf.fd, EV_READ,
1314 	    session_dispatch_client, &client->iev);
1315 	gotd_imsg_event_add(&client->iev);
1316 	evtimer_set(&client->tmo, gotd_request_timeout, client);
1317 
1318 	return NULL;
1319 }
1320 
1321 static const struct got_error *
1322 recv_repo_child(struct imsg *imsg)
1323 {
1324 	struct gotd_imsg_connect_repo_child ichild;
1325 	struct gotd_session_client *client = &gotd_session_client;
1326 	size_t datalen;
1327 	int fd;
1328 
1329 	if (client->state != GOTD_STATE_EXPECT_LIST_REFS)
1330 		return got_error(GOT_ERR_PRIVSEP_MSG);
1331 
1332 	/* We should already have received a pipe to the listener. */
1333 	if (client->fd == -1)
1334 		return got_error(GOT_ERR_PRIVSEP_MSG);
1335 
1336 	datalen = imsg->hdr.len - IMSG_HEADER_SIZE;
1337 	if (datalen != sizeof(ichild))
1338 		return got_error(GOT_ERR_PRIVSEP_LEN);
1339 
1340 	memcpy(&ichild, imsg->data, sizeof(ichild));
1341 
1342 	client->id = ichild.client_id;
1343 	if (ichild.proc_id == PROC_REPO_WRITE)
1344 		client->is_writing = 1;
1345 	else if (ichild.proc_id == PROC_REPO_READ)
1346 		client->is_writing = 0;
1347 	else
1348 		return got_error_msg(GOT_ERR_PRIVSEP_MSG,
1349 		    "bad child process type");
1350 
1351 	fd = imsg_get_fd(imsg);
1352 	if (fd == -1)
1353 		return got_error(GOT_ERR_PRIVSEP_NO_FD);
1354 
1355 	imsg_init(&client->repo_child_iev.ibuf, fd);
1356 	client->repo_child_iev.handler = session_dispatch_repo_child;
1357 	client->repo_child_iev.events = EV_READ;
1358 	client->repo_child_iev.handler_arg = NULL;
1359 	event_set(&client->repo_child_iev.ev, client->repo_child_iev.ibuf.fd,
1360 	    EV_READ, session_dispatch_repo_child, &client->repo_child_iev);
1361 	gotd_imsg_event_add(&client->repo_child_iev);
1362 
1363 	/* The "recvfd" pledge promise is no longer needed. */
1364 	if (pledge("stdio rpath wpath cpath sendfd fattr flock", NULL) == -1)
1365 		fatal("pledge");
1366 
1367 	return NULL;
1368 }
1369 
1370 static void
1371 session_dispatch(int fd, short event, void *arg)
1372 {
1373 	struct gotd_imsgev *iev = arg;
1374 	struct imsgbuf *ibuf = &iev->ibuf;
1375 	struct gotd_session_client *client = &gotd_session_client;
1376 	ssize_t n;
1377 	int shut = 0;
1378 	struct imsg imsg;
1379 
1380 	if (event & EV_READ) {
1381 		if ((n = imsg_read(ibuf)) == -1 && errno != EAGAIN)
1382 			fatal("imsg_read error");
1383 		if (n == 0) {
1384 			/* Connection closed. */
1385 			shut = 1;
1386 			goto done;
1387 		}
1388 	}
1389 
1390 	if (event & EV_WRITE) {
1391 		n = msgbuf_write(&ibuf->w);
1392 		if (n == -1 && errno != EAGAIN)
1393 			fatal("msgbuf_write");
1394 		if (n == 0) {
1395 			/* Connection closed. */
1396 			shut = 1;
1397 			goto done;
1398 		}
1399 	}
1400 
1401 	for (;;) {
1402 		const struct got_error *err = NULL;
1403 		uint32_t client_id = 0;
1404 		int do_disconnect = 0, do_list_refs = 0;
1405 
1406 		if ((n = imsg_get(ibuf, &imsg)) == -1)
1407 			fatal("%s: imsg_get error", __func__);
1408 		if (n == 0)	/* No more messages. */
1409 			break;
1410 
1411 		switch (imsg.hdr.type) {
1412 		case GOTD_IMSG_ERROR:
1413 			do_disconnect = 1;
1414 			err = gotd_imsg_recv_error(&client_id, &imsg);
1415 			break;
1416 		case GOTD_IMSG_CONNECT:
1417 			err = recv_connect(&imsg);
1418 			break;
1419 		case GOTD_IMSG_DISCONNECT:
1420 			do_disconnect = 1;
1421 			break;
1422 		case GOTD_IMSG_CONNECT_REPO_CHILD:
1423 			err = recv_repo_child(&imsg);
1424 			if (err)
1425 				break;
1426 			do_list_refs = 1;
1427 			break;
1428 		default:
1429 			log_debug("unexpected imsg %d", imsg.hdr.type);
1430 			break;
1431 		}
1432 		imsg_free(&imsg);
1433 
1434 		if (do_disconnect) {
1435 			if (err)
1436 				disconnect_on_error(client, err);
1437 			else
1438 				disconnect(client);
1439 		} else if (do_list_refs)
1440 			err = list_refs_request();
1441 
1442 		if (err)
1443 			log_warnx("uid %d: %s", client->euid, err->msg);
1444 	}
1445 done:
1446 	if (!shut) {
1447 		gotd_imsg_event_add(iev);
1448 	} else {
1449 		/* This pipe is dead. Remove its event handler */
1450 		event_del(&iev->ev);
1451 		event_loopexit(NULL);
1452 	}
1453 }
1454 
1455 void
1456 session_main(const char *title, const char *repo_path,
1457     int *pack_fds, int *temp_fds, struct timeval *request_timeout,
1458     enum gotd_procid proc_id)
1459 {
1460 	const struct got_error *err = NULL;
1461 	struct event evsigint, evsigterm, evsighup, evsigusr1;
1462 
1463 	gotd_session.title = title;
1464 	gotd_session.pid = getpid();
1465 	gotd_session.pack_fds = pack_fds;
1466 	gotd_session.temp_fds = temp_fds;
1467 	memcpy(&gotd_session.request_timeout, request_timeout,
1468 	    sizeof(gotd_session.request_timeout));
1469 	gotd_session.proc_id = proc_id;
1470 
1471 	err = got_repo_open(&gotd_session.repo, repo_path, NULL, pack_fds);
1472 	if (err)
1473 		goto done;
1474 	if (!got_repo_is_bare(gotd_session.repo)) {
1475 		err = got_error_msg(GOT_ERR_NOT_GIT_REPO,
1476 		    "bare git repository required");
1477 		goto done;
1478 	}
1479 
1480 	got_repo_temp_fds_set(gotd_session.repo, temp_fds);
1481 
1482 	signal_set(&evsigint, SIGINT, gotd_session_sighdlr, NULL);
1483 	signal_set(&evsigterm, SIGTERM, gotd_session_sighdlr, NULL);
1484 	signal_set(&evsighup, SIGHUP, gotd_session_sighdlr, NULL);
1485 	signal_set(&evsigusr1, SIGUSR1, gotd_session_sighdlr, NULL);
1486 	signal(SIGPIPE, SIG_IGN);
1487 
1488 	signal_add(&evsigint, NULL);
1489 	signal_add(&evsigterm, NULL);
1490 	signal_add(&evsighup, NULL);
1491 	signal_add(&evsigusr1, NULL);
1492 
1493 	gotd_session_client.state = GOTD_STATE_EXPECT_LIST_REFS;
1494 	gotd_session_client.fd = -1;
1495 	gotd_session_client.nref_updates = -1;
1496 	gotd_session_client.delta_cache_fd = -1;
1497 	gotd_session_client.accept_flush_pkt = 1;
1498 
1499 	imsg_init(&gotd_session.parent_iev.ibuf, GOTD_FILENO_MSG_PIPE);
1500 	gotd_session.parent_iev.handler = session_dispatch;
1501 	gotd_session.parent_iev.events = EV_READ;
1502 	gotd_session.parent_iev.handler_arg = NULL;
1503 	event_set(&gotd_session.parent_iev.ev, gotd_session.parent_iev.ibuf.fd,
1504 	    EV_READ, session_dispatch, &gotd_session.parent_iev);
1505 	if (gotd_imsg_compose_event(&gotd_session.parent_iev,
1506 	    GOTD_IMSG_CLIENT_SESSION_READY, gotd_session.proc_id,
1507 	    -1, NULL, 0) == -1) {
1508 		err = got_error_from_errno("imsg compose CLIENT_SESSION_READY");
1509 		goto done;
1510 	}
1511 
1512 	event_dispatch();
1513 done:
1514 	if (err)
1515 		log_warnx("%s: %s", title, err->msg);
1516 	gotd_session_shutdown();
1517 }
1518 
1519 void
1520 gotd_session_shutdown(void)
1521 {
1522 	log_debug("shutting down");
1523 	if (gotd_session.repo)
1524 		got_repo_close(gotd_session.repo);
1525 	got_repo_pack_fds_close(gotd_session.pack_fds);
1526 	got_repo_temp_fds_close(gotd_session.temp_fds);
1527 	exit(0);
1528 }