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Date:: Sun Oct 30 17:14:37 2022 UTC
Message:: avoid looping over SHA1Update() in got-fetch-pack; suggested by millert@
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1 /*
2  * Copyright (c) 2019 Ori Bernstein <ori@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/uio.h>
20 #include <sys/time.h>
21 #include <sys/stat.h>
22 
23 #include <stdint.h>
24 #include <errno.h>
25 #include <imsg.h>
26 #include <limits.h>
27 #include <signal.h>
28 #include <stdio.h>
29 #include <stdlib.h>
30 #include <string.h>
31 #include <ctype.h>
32 #include <sha1.h>
33 #include <fcntl.h>
34 #include <unistd.h>
35 #include <zlib.h>
36 #include <err.h>
37 
38 #include "got_error.h"
39 #include "got_object.h"
40 #include "got_path.h"
41 #include "got_version.h"
42 #include "got_fetch.h"
43 #include "got_reference.h"
44 
45 #include "got_lib_sha1.h"
46 #include "got_lib_delta.h"
47 #include "got_lib_object.h"
48 #include "got_lib_object_parse.h"
49 #include "got_lib_privsep.h"
50 #include "got_lib_pack.h"
51 #include "got_lib_pkt.h"
52 #include "got_lib_gitproto.h"
53 #include "got_lib_ratelimit.h"
54 
55 #ifndef MIN
56 #define	MIN(_a,_b) ((_a) < (_b) ? (_a) : (_b))
57 #endif
58 
59 #ifndef nitems
60 #define nitems(_a)	(sizeof((_a)) / sizeof((_a)[0]))
61 #endif
62 
63 struct got_object *indexed;
64 static int chattygot;
65 
66 static const struct got_capability got_capabilities[] = {
67 	{ GOT_CAPA_AGENT, "got/" GOT_VERSION_STR },
68 	{ GOT_CAPA_OFS_DELTA, NULL },
69 	{ GOT_CAPA_SIDE_BAND_64K, NULL },
70 };
71 
72 static void
73 match_remote_ref(struct got_pathlist_head *have_refs,
74     struct got_object_id *my_id, char *refname)
75 {
76 	struct got_pathlist_entry *pe;
77 
78 	/* XXX zero-hash signifies we don't have this ref;
79 	 * we should use a flag instead */
80 	memset(my_id, 0, sizeof(*my_id));
81 
82 	TAILQ_FOREACH(pe, have_refs, entry) {
83 		struct got_object_id *id = pe->data;
84 		if (strcmp(pe->path, refname) == 0) {
85 			memcpy(my_id, id, sizeof(*my_id));
86 			break;
87 		}
88 	}
89 }
90 
91 static int
92 match_branch(const char *branch, const char *wanted_branch)
93 {
94 	if (strncmp(branch, "refs/heads/", 11) != 0)
95 		return 0;
96 
97 	if (strncmp(wanted_branch, "refs/heads/", 11) == 0)
98 		wanted_branch += 11;
99 
100 	return (strcmp(branch + 11, wanted_branch) == 0);
101 }
102 
103 static int
104 match_wanted_ref(const char *refname, const char *wanted_ref)
105 {
106 	if (strncmp(refname, "refs/", 5) != 0)
107 		return 0;
108 	refname += 5;
109 
110 	/*
111 	 * Prevent fetching of references that won't make any
112 	 * sense outside of the remote repository's context.
113 	 */
114 	if (strncmp(refname, "got/", 4) == 0)
115 		return 0;
116 	if (strncmp(refname, "remotes/", 8) == 0)
117 		return 0;
118 
119 	if (strncmp(wanted_ref, "refs/", 5) == 0)
120 		wanted_ref += 5;
121 
122 	/* Allow prefix match. */
123 	if (got_path_is_child(refname, wanted_ref, strlen(wanted_ref)))
124 		return 1;
125 
126 	/* Allow exact match. */
127 	return (strcmp(refname, wanted_ref) == 0);
128 }
129 
130 static const struct got_error *
131 send_fetch_server_progress(struct imsgbuf *ibuf, const char *msg, size_t msglen)
132 {
133 	if (msglen > MAX_IMSGSIZE - IMSG_HEADER_SIZE)
134 		return got_error(GOT_ERR_NO_SPACE);
135 
136 	if (msglen == 0)
137 		return NULL;
138 
139 	if (imsg_compose(ibuf, GOT_IMSG_FETCH_SERVER_PROGRESS, 0, 0, -1,
140 	    msg, msglen) == -1)
141 		return got_error_from_errno(
142 		    "imsg_compose FETCH_SERVER_PROGRESS");
143 
144 	return got_privsep_flush_imsg(ibuf);
145 }
146 
147 static const struct got_error *
148 send_fetch_download_progress(struct imsgbuf *ibuf, off_t bytes,
149     struct got_ratelimit *rl)
150 {
151 	const struct got_error *err;
152 	int elapsed = 0;
153 
154 	if (rl) {
155 		err = got_ratelimit_check(&elapsed, rl);
156 		if (err || !elapsed)
157 			return err;
158 	}
159 
160 	if (imsg_compose(ibuf, GOT_IMSG_FETCH_DOWNLOAD_PROGRESS, 0, 0, -1,
161 	    &bytes, sizeof(bytes)) == -1)
162 		return got_error_from_errno(
163 		    "imsg_compose FETCH_DOWNLOAD_PROGRESS");
164 
165 	return got_privsep_flush_imsg(ibuf);
166 }
167 
168 static const struct got_error *
169 send_fetch_done(struct imsgbuf *ibuf, uint8_t *pack_sha1)
170 {
171 	if (imsg_compose(ibuf, GOT_IMSG_FETCH_DONE, 0, 0, -1,
172 	    pack_sha1, SHA1_DIGEST_LENGTH) == -1)
173 		return got_error_from_errno("imsg_compose FETCH");
174 	return got_privsep_flush_imsg(ibuf);
175 }
176 
177 static const struct got_error *
178 fetch_progress(struct imsgbuf *ibuf, const char *buf, size_t len)
179 {
180 	size_t i;
181 
182 	if (len == 0)
183 		return NULL;
184 
185 	/*
186 	 * Truncate messages which exceed the maximum imsg payload size.
187 	 * Server may send up to 64k.
188 	 */
189 	if (len > MAX_IMSGSIZE - IMSG_HEADER_SIZE)
190 		len = MAX_IMSGSIZE - IMSG_HEADER_SIZE;
191 
192 	/* Only allow printable ASCII. */
193 	for (i = 0; i < len; i++) {
194 		if (isprint((unsigned char)buf[i]) ||
195 		    isspace((unsigned char)buf[i]))
196 			continue;
197 		return got_error_msg(GOT_ERR_BAD_PACKET,
198 		    "non-printable progress message received from server");
199 	}
200 
201 	return send_fetch_server_progress(ibuf, buf, len);
202 }
203 
204 static const struct got_error *
205 fetch_error(const char *buf, size_t len)
206 {
207 	static char msg[1024];
208 	size_t i;
209 
210 	for (i = 0; i < len && i < sizeof(msg) - 1; i++) {
211 		if (!isprint(buf[i]))
212 			return got_error_msg(GOT_ERR_BAD_PACKET,
213 			    "non-printable error message received from server");
214 		msg[i] = buf[i];
215 	}
216 	msg[i] = '\0';
217 	return got_error_msg(GOT_ERR_FETCH_FAILED, msg);
218 }
219 
220 static const struct got_error *
221 send_fetch_symrefs(struct imsgbuf *ibuf, struct got_pathlist_head *symrefs)
222 {
223 	struct ibuf *wbuf;
224 	size_t len, nsymrefs = 0;
225 	struct got_pathlist_entry *pe;
226 
227 	len = sizeof(struct got_imsg_fetch_symrefs);
228 	TAILQ_FOREACH(pe, symrefs, entry) {
229 		const char *target = pe->data;
230 		len += sizeof(struct got_imsg_fetch_symref) +
231 		    pe->path_len + strlen(target);
232 		nsymrefs++;
233 	}
234 
235 	if (len >= MAX_IMSGSIZE - IMSG_HEADER_SIZE)
236 		return got_error(GOT_ERR_NO_SPACE);
237 
238 	wbuf = imsg_create(ibuf, GOT_IMSG_FETCH_SYMREFS, 0, 0, len);
239 	if (wbuf == NULL)
240 		return got_error_from_errno("imsg_create FETCH_SYMREFS");
241 
242 	/* Keep in sync with struct got_imsg_fetch_symrefs definition! */
243 	if (imsg_add(wbuf, &nsymrefs, sizeof(nsymrefs)) == -1)
244 		return got_error_from_errno("imsg_add FETCH_SYMREFS");
245 
246 	TAILQ_FOREACH(pe, symrefs, entry) {
247 		const char *name = pe->path;
248 		size_t name_len = pe->path_len;
249 		const char *target = pe->data;
250 		size_t target_len = strlen(target);
251 
252 		/* Keep in sync with struct got_imsg_fetch_symref definition! */
253 		if (imsg_add(wbuf, &name_len, sizeof(name_len)) == -1)
254 			return got_error_from_errno("imsg_add FETCH_SYMREFS");
255 		if (imsg_add(wbuf, &target_len, sizeof(target_len)) == -1)
256 			return got_error_from_errno("imsg_add FETCH_SYMREFS");
257 		if (imsg_add(wbuf, name, name_len) == -1)
258 			return got_error_from_errno("imsg_add FETCH_SYMREFS");
259 		if (imsg_add(wbuf, target, target_len) == -1)
260 			return got_error_from_errno("imsg_add FETCH_SYMREFS");
261 	}
262 
263 	wbuf->fd = -1;
264 	imsg_close(ibuf, wbuf);
265 	return got_privsep_flush_imsg(ibuf);
266 }
267 
268 static const struct got_error *
269 send_fetch_ref(struct imsgbuf *ibuf, struct got_object_id *refid,
270     const char *refname)
271 {
272 	struct ibuf *wbuf;
273 	size_t len, reflen = strlen(refname);
274 
275 	len = sizeof(struct got_imsg_fetch_ref) + reflen;
276 	if (len >= MAX_IMSGSIZE - IMSG_HEADER_SIZE)
277 		return got_error(GOT_ERR_NO_SPACE);
278 
279 	wbuf = imsg_create(ibuf, GOT_IMSG_FETCH_REF, 0, 0, len);
280 	if (wbuf == NULL)
281 		return got_error_from_errno("imsg_create FETCH_REF");
282 
283 	/* Keep in sync with struct got_imsg_fetch_ref definition! */
284 	if (imsg_add(wbuf, refid->sha1, SHA1_DIGEST_LENGTH) == -1)
285 		return got_error_from_errno("imsg_add FETCH_REF");
286 	if (imsg_add(wbuf, refname, reflen) == -1)
287 		return got_error_from_errno("imsg_add FETCH_REF");
288 
289 	wbuf->fd = -1;
290 	imsg_close(ibuf, wbuf);
291 	return got_privsep_flush_imsg(ibuf);
292 }
293 
294 static const struct got_error *
295 fetch_pack(int fd, int packfd, uint8_t *pack_sha1,
296     struct got_pathlist_head *have_refs, int fetch_all_branches,
297     struct got_pathlist_head *wanted_branches,
298     struct got_pathlist_head *wanted_refs, int list_refs_only,
299     struct imsgbuf *ibuf)
300 {
301 	const struct got_error *err = NULL;
302 	char buf[GOT_PKT_MAX];
303 	char hashstr[SHA1_DIGEST_STRING_LENGTH];
304 	struct got_object_id *have, *want;
305 	int is_firstpkt = 1, nref = 0, refsz = 16;
306 	int i, n, nwant = 0, nhave = 0, acked = 0;
307 	off_t packsz = 0, last_reported_packsz = 0;
308 	char *id_str = NULL, *refname = NULL;
309 	char *server_capabilities = NULL, *my_capabilities = NULL;
310 	const char *default_branch = NULL;
311 	struct got_pathlist_head symrefs;
312 	struct got_pathlist_entry *pe;
313 	int sent_my_capabilites = 0, have_sidebands = 0;
314 	int found_branch = 0;
315 	SHA1_CTX sha1_ctx;
316 	uint8_t sha1_buf[SHA1_DIGEST_LENGTH];
317 	size_t sha1_buf_len = 0;
318 	ssize_t w;
319 	struct got_ratelimit rl;
320 
321 	TAILQ_INIT(&symrefs);
322 	SHA1Init(&sha1_ctx);
323 	got_ratelimit_init(&rl, 0, 500);
324 
325 	have = malloc(refsz * sizeof(have[0]));
326 	if (have == NULL)
327 		return got_error_from_errno("malloc");
328 	want = malloc(refsz * sizeof(want[0]));
329 	if (want == NULL) {
330 		err = got_error_from_errno("malloc");
331 		goto done;
332 	}
333 	while (1) {
334 		err = got_pkt_readpkt(&n, fd, buf, sizeof(buf), chattygot);
335 		if (err)
336 			goto done;
337 		if (n == 0)
338 			break;
339 		if (n >= 4 && strncmp(buf, "ERR ", 4) == 0) {
340 			err = fetch_error(&buf[4], n - 4);
341 			goto done;
342 		}
343 		free(id_str);
344 		free(refname);
345 		err = got_gitproto_parse_refline(&id_str, &refname,
346 		    &server_capabilities, buf, n);
347 		if (err)
348 			goto done;
349 		if (is_firstpkt) {
350 			if (chattygot && server_capabilities[0] != '\0')
351 				fprintf(stderr, "%s: server capabilities: %s\n",
352 				    getprogname(), server_capabilities);
353 			err = got_gitproto_match_capabilities(&my_capabilities,
354 			    &symrefs, server_capabilities,
355 			    got_capabilities, nitems(got_capabilities));
356 			if (err)
357 				goto done;
358 			if (chattygot)
359 				fprintf(stderr, "%s: my capabilities:%s\n",
360 				    getprogname(), my_capabilities != NULL ?
361 				    my_capabilities : "");
362 			err = send_fetch_symrefs(ibuf, &symrefs);
363 			if (err)
364 				goto done;
365 			is_firstpkt = 0;
366 			if (!fetch_all_branches) {
367 				TAILQ_FOREACH(pe, &symrefs, entry) {
368 					const char *name = pe->path;
369 					const char *symref_target = pe->data;
370 					if (strcmp(name, GOT_REF_HEAD) != 0)
371 						continue;
372 					default_branch = symref_target;
373 					break;
374 				}
375 			}
376 			continue;
377 		}
378 		if (strstr(refname, "^{}")) {
379 			if (chattygot) {
380 				fprintf(stderr, "%s: ignoring %s\n",
381 				    getprogname(), refname);
382 			}
383 			continue;
384 		}
385 
386 		if (strncmp(refname, "refs/heads/", 11) == 0) {
387 			if (fetch_all_branches || list_refs_only) {
388 				found_branch = 1;
389 			} else if (!TAILQ_EMPTY(wanted_branches)) {
390 				TAILQ_FOREACH(pe, wanted_branches, entry) {
391 					if (match_branch(refname, pe->path))
392 						break;
393 				}
394 				if (pe == NULL) {
395 					if (chattygot) {
396 						fprintf(stderr,
397 						    "%s: ignoring %s\n",
398 						    getprogname(), refname);
399 					}
400 					continue;
401 				}
402 				found_branch = 1;
403 			} else if (default_branch != NULL) {
404 				if (!match_branch(refname, default_branch)) {
405 					if (chattygot) {
406 						fprintf(stderr,
407 						    "%s: ignoring %s\n",
408 						    getprogname(), refname);
409 					}
410 					continue;
411 				}
412 				found_branch = 1;
413 			}
414 		} else if (strncmp(refname, "refs/tags/", 10) != 0) {
415 			if (!TAILQ_EMPTY(wanted_refs)) {
416 				TAILQ_FOREACH(pe, wanted_refs, entry) {
417 					if (match_wanted_ref(refname, pe->path))
418 						break;
419 				}
420 				if (pe == NULL) {
421 					if (chattygot) {
422 						fprintf(stderr,
423 						    "%s: ignoring %s\n",
424 						    getprogname(), refname);
425 					}
426 					continue;
427 				}
428 				found_branch = 1;
429 			} else if (!list_refs_only) {
430 				if (chattygot) {
431 					fprintf(stderr, "%s: ignoring %s\n",
432 					    getprogname(), refname);
433 				}
434 				continue;
435 			}
436 		}
437 
438 		if (refsz == nref + 1) {
439 			refsz *= 2;
440 			have = reallocarray(have, refsz, sizeof(have[0]));
441 			if (have == NULL) {
442 				err = got_error_from_errno("reallocarray");
443 				goto done;
444 			}
445 			want = reallocarray(want, refsz, sizeof(want[0]));
446 			if (want == NULL) {
447 				err = got_error_from_errno("reallocarray");
448 				goto done;
449 			}
450 		}
451 		if (!got_parse_sha1_digest(want[nref].sha1, id_str)) {
452 			err = got_error(GOT_ERR_BAD_OBJ_ID_STR);
453 			goto done;
454 		}
455 		match_remote_ref(have_refs, &have[nref], refname);
456 		err = send_fetch_ref(ibuf, &want[nref], refname);
457 		if (err)
458 			goto done;
459 
460 		if (chattygot)
461 			fprintf(stderr, "%s: %s will be fetched\n",
462 			    getprogname(), refname);
463 		if (chattygot > 1) {
464 			char *theirs, *mine;
465 			err = got_object_id_str(&theirs, &want[nref]);
466 			if (err)
467 				goto done;
468 			err = got_object_id_str(&mine, &have[nref]);
469 			if (err) {
470 				free(theirs);
471 				goto done;
472 			}
473 			fprintf(stderr, "%s: remote: %s\n%s: local:  %s\n",
474 			    getprogname(), theirs, getprogname(), mine);
475 			free(theirs);
476 			free(mine);
477 		}
478 		nref++;
479 	}
480 
481 	if (list_refs_only)
482 		goto done;
483 
484 	/* Abort if we haven't found any branch to fetch. */
485 	if (!found_branch) {
486 		err = got_error(GOT_ERR_FETCH_NO_BRANCH);
487 		goto done;
488 	}
489 
490 	for (i = 0; i < nref; i++) {
491 		if (got_object_id_cmp(&have[i], &want[i]) == 0)
492 			continue;
493 		got_sha1_digest_to_str(want[i].sha1, hashstr, sizeof(hashstr));
494 		n = snprintf(buf, sizeof(buf), "want %s%s\n", hashstr,
495 		    sent_my_capabilites || my_capabilities == NULL ?
496 		    "" : my_capabilities);
497 		if (n < 0 || (size_t)n >= sizeof(buf)) {
498 			err = got_error(GOT_ERR_NO_SPACE);
499 			goto done;
500 		}
501 		err = got_pkt_writepkt(fd, buf, n, chattygot);
502 		if (err)
503 			goto done;
504 		sent_my_capabilites = 1;
505 		nwant++;
506 	}
507 	err = got_pkt_flushpkt(fd, chattygot);
508 	if (err)
509 		goto done;
510 
511 	if (nwant == 0)
512 		goto done;
513 
514 	TAILQ_FOREACH(pe, have_refs, entry) {
515 		struct got_object_id *id = pe->data;
516 		got_sha1_digest_to_str(id->sha1, hashstr, sizeof(hashstr));
517 		n = snprintf(buf, sizeof(buf), "have %s\n", hashstr);
518 		if (n < 0 || (size_t)n >= sizeof(buf)) {
519 			err = got_error(GOT_ERR_NO_SPACE);
520 			goto done;
521 		}
522 		err = got_pkt_writepkt(fd, buf, n, chattygot);
523 		if (err)
524 			goto done;
525 		nhave++;
526 	}
527 
528 	while (nhave > 0 && !acked) {
529 		struct got_object_id common_id;
530 
531 		/* The server should ACK the object IDs we need. */
532 		err = got_pkt_readpkt(&n, fd, buf, sizeof(buf), chattygot);
533 		if (err)
534 			goto done;
535 		if (n >= 4 && strncmp(buf, "ERR ", 4) == 0) {
536 			err = fetch_error(&buf[4], n - 4);
537 			goto done;
538 		}
539 		if (n >= 4 && strncmp(buf, "NAK\n", 4) == 0) {
540 			/* Server has not located our objects yet. */
541 			continue;
542 		}
543 		if (n < 4 + SHA1_DIGEST_STRING_LENGTH ||
544 		    strncmp(buf, "ACK ", 4) != 0) {
545 			err = got_error_msg(GOT_ERR_BAD_PACKET,
546 			    "unexpected message from server");
547 			goto done;
548 		}
549 		if (!got_parse_sha1_digest(common_id.sha1, buf + 4)) {
550 			err = got_error_msg(GOT_ERR_BAD_PACKET,
551 			    "bad object ID in ACK packet from server");
552 			goto done;
553 		}
554 		acked++;
555 	}
556 
557 	n = strlcpy(buf, "done\n", sizeof(buf));
558 	err = got_pkt_writepkt(fd, buf, n, chattygot);
559 	if (err)
560 		goto done;
561 
562 	if (nhave == 0) {
563 		err = got_pkt_readpkt(&n, fd, buf, sizeof(buf), chattygot);
564 		if (err)
565 			goto done;
566 		if (n != 4 || strncmp(buf, "NAK\n", n) != 0) {
567 			err = got_error_msg(GOT_ERR_BAD_PACKET,
568 			    "unexpected message from server");
569 			goto done;
570 		}
571 	}
572 
573 	if (chattygot)
574 		fprintf(stderr, "%s: fetching...\n", getprogname());
575 
576 	if (my_capabilities != NULL &&
577 	    strstr(my_capabilities, GOT_CAPA_SIDE_BAND_64K) != NULL)
578 		have_sidebands = 1;
579 
580 	while (1) {
581 		ssize_t r = 0;
582 		int datalen = -1;
583 
584 		if (have_sidebands) {
585 			err = got_pkt_readhdr(&datalen, fd, chattygot);
586 			if (err)
587 				goto done;
588 			if (datalen <= 0)
589 				break;
590 
591 			/* Read sideband channel ID (one byte). */
592 			r = read(fd, buf, 1);
593 			if (r == -1) {
594 				err = got_error_from_errno("read");
595 				goto done;
596 			}
597 			if (r != 1) {
598 				err = got_error_msg(GOT_ERR_BAD_PACKET,
599 				    "short packet");
600 				goto done;
601 			}
602 			if (datalen > sizeof(buf) - 5) {
603 				err = got_error_msg(GOT_ERR_BAD_PACKET,
604 				    "bad packet length");
605 				goto done;
606 			}
607 			datalen--; /* sideband ID has been read */
608 			if (buf[0] == GOT_SIDEBAND_PACKFILE_DATA) {
609 				/* Read packfile data. */
610 				err = got_pkt_readn(&r, fd, buf, datalen);
611 				if (err)
612 					goto done;
613 				if (r != datalen) {
614 					err = got_error_msg(GOT_ERR_BAD_PACKET,
615 					    "packet too short");
616 					goto done;
617 				}
618 			} else if (buf[0] == GOT_SIDEBAND_PROGRESS_INFO) {
619 				err = got_pkt_readn(&r, fd, buf, datalen);
620 				if (err)
621 					goto done;
622 				if (r != datalen) {
623 					err = got_error_msg(GOT_ERR_BAD_PACKET,
624 					    "packet too short");
625 					goto done;
626 				}
627 				err = fetch_progress(ibuf, buf, r);
628 				if (err)
629 					goto done;
630 				continue;
631 			} else if (buf[0] == GOT_SIDEBAND_ERROR_INFO) {
632 				err = got_pkt_readn(&r, fd, buf, datalen);
633 				if (err)
634 					goto done;
635 				if (r != datalen) {
636 					err = got_error_msg(GOT_ERR_BAD_PACKET,
637 					    "packet too short");
638 					goto done;
639 				}
640 				err = fetch_error(buf, r);
641 				goto done;
642 			} else if (buf[0] == 'A') {
643 				err = got_pkt_readn(&r, fd, buf, datalen);
644 				if (err)
645 					goto done;
646 				if (r != datalen) {
647 					err = got_error_msg(GOT_ERR_BAD_PACKET,
648 					    "packet too short");
649 					goto done;
650 				}
651 				/*
652 				 * Git server responds with ACK after 'done'
653 				 * even though multi_ack is disabled?!?
654 				 */
655 				buf[r] = '\0';
656 				if (strncmp(buf, "CK ", 3) == 0)
657 					continue; /* ignore */
658 				err = got_error_msg(GOT_ERR_BAD_PACKET,
659 				    "unexpected message from server");
660 				goto done;
661 			} else {
662 				err = got_error_msg(GOT_ERR_BAD_PACKET,
663 				    "unknown side-band received from server");
664 				goto done;
665 			}
666 		} else {
667 			/* No sideband channel. Every byte is packfile data. */
668 			err = got_pkt_readn(&r, fd, buf, sizeof buf);
669 			if (err)
670 				goto done;
671 			if (r <= 0)
672 				break;
673 		}
674 
675 		/*
676 		 * An expected SHA1 checksum sits at the end of the pack file.
677 		 * Since we don't know the file size ahead of time we have to
678 		 * keep SHA1_DIGEST_LENGTH bytes buffered and avoid mixing
679 		 * those bytes into our SHA1 checksum computation until we
680 		 * know for sure that additional pack file data bytes follow.
681 		 *
682 		 * We can assume r > 0 since otherwise the loop would exit.
683 		 */
684 		if (r < SHA1_DIGEST_LENGTH) {
685 			if (sha1_buf_len < SHA1_DIGEST_LENGTH) {
686 				/*
687 				 * If there's enough buffered + read data to
688 				 * fill up the buffer then shift a sufficient
689 				 * amount of bytes out at the front to make
690 				 * room, mixing those bytes into the checksum.
691 				 */
692 				if (sha1_buf_len > 0 &&
693 				    sha1_buf_len + r > SHA1_DIGEST_LENGTH) {
694 					size_t nshift = MIN(sha1_buf_len + r -
695 					    SHA1_DIGEST_LENGTH, sha1_buf_len);
696 					SHA1Update(&sha1_ctx, sha1_buf, nshift);
697 					memmove(sha1_buf, sha1_buf + nshift,
698 					    sha1_buf_len - nshift);
699 					sha1_buf_len -= nshift;
700 				}
701 
702 				/* Buffer potential checksum bytes. */
703 				memcpy(sha1_buf + sha1_buf_len, buf, r);
704 				sha1_buf_len += r;
705 			} else {
706 				/*
707 				 * Mix in previously buffered bytes which
708 				 * are not part of the checksum after all.
709 				 */
710 				SHA1Update(&sha1_ctx, sha1_buf, r);
711 
712 				/* Update potential checksum buffer. */
713 				memmove(sha1_buf, sha1_buf + r,
714 				    sha1_buf_len - r);
715 				memcpy(sha1_buf + sha1_buf_len - r, buf, r);
716 			}
717 		} else {
718 			/* Mix in any previously buffered bytes. */
719 			SHA1Update(&sha1_ctx, sha1_buf, sha1_buf_len);
720 
721 			/* Mix in bytes read minus potential checksum bytes. */
722 			SHA1Update(&sha1_ctx, buf, r - SHA1_DIGEST_LENGTH);
723 
724 			/* Buffer potential checksum bytes. */
725 			memcpy(sha1_buf, buf + r - SHA1_DIGEST_LENGTH,
726 			    SHA1_DIGEST_LENGTH);
727 			sha1_buf_len = SHA1_DIGEST_LENGTH;
728 		}
729 
730 		/* Write packfile data to temporary pack file. */
731 		w = write(packfd, buf, r);
732 		if (w == -1) {
733 			err = got_error_from_errno("write");
734 			goto done;
735 		}
736 		if (w != r) {
737 			err = got_error(GOT_ERR_IO);
738 			goto done;
739 		}
740 		packsz += w;
741 
742 		/* Don't send too many progress privsep messages. */
743 		if (packsz > last_reported_packsz + 1024) {
744 			err = send_fetch_download_progress(ibuf, packsz, &rl);
745 			if (err)
746 				goto done;
747 			last_reported_packsz = packsz;
748 		}
749 	}
750 	err = send_fetch_download_progress(ibuf, packsz, NULL);
751 	if (err)
752 		goto done;
753 
754 	SHA1Final(pack_sha1, &sha1_ctx);
755 	if (sha1_buf_len != SHA1_DIGEST_LENGTH ||
756 	    memcmp(pack_sha1, sha1_buf, sha1_buf_len) != 0) {
757 		err = got_error_msg(GOT_ERR_BAD_PACKFILE,
758 		    "pack file checksum mismatch");
759 	}
760 done:
761 	TAILQ_FOREACH(pe, &symrefs, entry) {
762 		free((void *)pe->path);
763 		free(pe->data);
764 	}
765 	got_pathlist_free(&symrefs);
766 	free(have);
767 	free(want);
768 	free(id_str);
769 	free(refname);
770 	free(server_capabilities);
771 	return err;
772 }
773 
774 
775 int
776 main(int argc, char **argv)
777 {
778 	const struct got_error *err = NULL;
779 	int fetchfd, packfd = -1;
780 	uint8_t pack_sha1[SHA1_DIGEST_LENGTH];
781 	struct imsgbuf ibuf;
782 	struct imsg imsg;
783 	struct got_pathlist_head have_refs;
784 	struct got_pathlist_head wanted_branches;
785 	struct got_pathlist_head wanted_refs;
786 	struct got_pathlist_entry *pe;
787 	struct got_imsg_fetch_request fetch_req;
788 	struct got_imsg_fetch_have_ref href;
789 	struct got_imsg_fetch_wanted_branch wbranch;
790 	struct got_imsg_fetch_wanted_ref wref;
791 	size_t datalen, i;
792 #if 0
793 	static int attached;
794 	while (!attached)
795 		sleep (1);
796 #endif
797 
798 	TAILQ_INIT(&have_refs);
799 	TAILQ_INIT(&wanted_branches);
800 	TAILQ_INIT(&wanted_refs);
801 
802 	imsg_init(&ibuf, GOT_IMSG_FD_CHILD);
803 #ifndef PROFILE
804 	/* revoke access to most system calls */
805 	if (pledge("stdio recvfd", NULL) == -1) {
806 		err = got_error_from_errno("pledge");
807 		got_privsep_send_error(&ibuf, err);
808 		return 1;
809 	}
810 #endif
811 	err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
812 	if (err) {
813 		if (err->code == GOT_ERR_PRIVSEP_PIPE)
814 			err = NULL;
815 		goto done;
816 	}
817 	if (imsg.hdr.type == GOT_IMSG_STOP)
818 		goto done;
819 	if (imsg.hdr.type != GOT_IMSG_FETCH_REQUEST) {
820 		err = got_error(GOT_ERR_PRIVSEP_MSG);
821 		goto done;
822 	}
823 	datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
824 	if (datalen < sizeof(fetch_req)) {
825 		err = got_error(GOT_ERR_PRIVSEP_LEN);
826 		goto done;
827 	}
828 	memcpy(&fetch_req, imsg.data, sizeof(fetch_req));
829 	fetchfd = imsg.fd;
830 	imsg_free(&imsg);
831 
832 	if (fetch_req.verbosity > 0)
833 		chattygot += fetch_req.verbosity;
834 
835 	for (i = 0; i < fetch_req.n_have_refs; i++) {
836 		struct got_object_id *id;
837 		char *refname;
838 
839 		err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
840 		if (err) {
841 			if (err->code == GOT_ERR_PRIVSEP_PIPE)
842 				err = NULL;
843 			goto done;
844 		}
845 		if (imsg.hdr.type == GOT_IMSG_STOP)
846 			goto done;
847 		if (imsg.hdr.type != GOT_IMSG_FETCH_HAVE_REF) {
848 			err = got_error(GOT_ERR_PRIVSEP_MSG);
849 			goto done;
850 		}
851 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
852 		if (datalen < sizeof(href)) {
853 			err = got_error(GOT_ERR_PRIVSEP_LEN);
854 			goto done;
855 		}
856 		memcpy(&href, imsg.data, sizeof(href));
857 		if (datalen - sizeof(href) < href.name_len) {
858 			err = got_error(GOT_ERR_PRIVSEP_LEN);
859 			goto done;
860 		}
861 		refname = malloc(href.name_len + 1);
862 		if (refname == NULL) {
863 			err = got_error_from_errno("malloc");
864 			goto done;
865 		}
866 		memcpy(refname, imsg.data + sizeof(href), href.name_len);
867 		refname[href.name_len] = '\0';
868 
869 		id = malloc(sizeof(*id));
870 		if (id == NULL) {
871 			free(refname);
872 			err = got_error_from_errno("malloc");
873 			goto done;
874 		}
875 		memcpy(id->sha1, href.id, SHA1_DIGEST_LENGTH);
876 		err = got_pathlist_append(&have_refs, refname, id);
877 		if (err) {
878 			free(refname);
879 			free(id);
880 			goto done;
881 		}
882 
883 		imsg_free(&imsg);
884 	}
885 
886 	for (i = 0; i < fetch_req.n_wanted_branches; i++) {
887 		char *refname;
888 
889 		err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
890 		if (err) {
891 			if (err->code == GOT_ERR_PRIVSEP_PIPE)
892 				err = NULL;
893 			goto done;
894 		}
895 		if (imsg.hdr.type == GOT_IMSG_STOP)
896 			goto done;
897 		if (imsg.hdr.type != GOT_IMSG_FETCH_WANTED_BRANCH) {
898 			err = got_error(GOT_ERR_PRIVSEP_MSG);
899 			goto done;
900 		}
901 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
902 		if (datalen < sizeof(wbranch)) {
903 			err = got_error(GOT_ERR_PRIVSEP_LEN);
904 			goto done;
905 		}
906 		memcpy(&wbranch, imsg.data, sizeof(wbranch));
907 		if (datalen - sizeof(wbranch) < wbranch.name_len) {
908 			err = got_error(GOT_ERR_PRIVSEP_LEN);
909 			goto done;
910 		}
911 		refname = malloc(wbranch.name_len + 1);
912 		if (refname == NULL) {
913 			err = got_error_from_errno("malloc");
914 			goto done;
915 		}
916 		memcpy(refname, imsg.data + sizeof(wbranch), wbranch.name_len);
917 		refname[wbranch.name_len] = '\0';
918 
919 		err = got_pathlist_append(&wanted_branches, refname, NULL);
920 		if (err) {
921 			free(refname);
922 			goto done;
923 		}
924 
925 		imsg_free(&imsg);
926 	}
927 
928 	for (i = 0; i < fetch_req.n_wanted_refs; i++) {
929 		char *refname;
930 
931 		err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
932 		if (err) {
933 			if (err->code == GOT_ERR_PRIVSEP_PIPE)
934 				err = NULL;
935 			goto done;
936 		}
937 		if (imsg.hdr.type == GOT_IMSG_STOP)
938 			goto done;
939 		if (imsg.hdr.type != GOT_IMSG_FETCH_WANTED_REF) {
940 			err = got_error(GOT_ERR_PRIVSEP_MSG);
941 			goto done;
942 		}
943 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
944 		if (datalen < sizeof(wref)) {
945 			err = got_error(GOT_ERR_PRIVSEP_LEN);
946 			goto done;
947 		}
948 		memcpy(&wref, imsg.data, sizeof(wref));
949 		if (datalen - sizeof(wref) < wref.name_len) {
950 			err = got_error(GOT_ERR_PRIVSEP_LEN);
951 			goto done;
952 		}
953 		refname = malloc(wref.name_len + 1);
954 		if (refname == NULL) {
955 			err = got_error_from_errno("malloc");
956 			goto done;
957 		}
958 		memcpy(refname, imsg.data + sizeof(wref), wref.name_len);
959 		refname[wref.name_len] = '\0';
960 
961 		err = got_pathlist_append(&wanted_refs, refname, NULL);
962 		if (err) {
963 			free(refname);
964 			goto done;
965 		}
966 
967 		imsg_free(&imsg);
968 	}
969 
970 	err = got_privsep_recv_imsg(&imsg, &ibuf, 0);
971 	if (err) {
972 		if (err->code == GOT_ERR_PRIVSEP_PIPE)
973 			err = NULL;
974 		goto done;
975 	}
976 	if (imsg.hdr.type == GOT_IMSG_STOP)
977 		goto done;
978 	if (imsg.hdr.type != GOT_IMSG_FETCH_OUTFD) {
979 		err = got_error(GOT_ERR_PRIVSEP_MSG);
980 		goto done;
981 	}
982 	if (imsg.hdr.len - IMSG_HEADER_SIZE != 0) {
983 		err = got_error(GOT_ERR_PRIVSEP_LEN);
984 		goto done;
985 	}
986 	packfd = imsg.fd;
987 
988 	err = fetch_pack(fetchfd, packfd, pack_sha1, &have_refs,
989 	    fetch_req.fetch_all_branches, &wanted_branches,
990 	    &wanted_refs, fetch_req.list_refs_only, &ibuf);
991 done:
992 	TAILQ_FOREACH(pe, &have_refs, entry) {
993 		free((char *)pe->path);
994 		free(pe->data);
995 	}
996 	got_pathlist_free(&have_refs);
997 	TAILQ_FOREACH(pe, &wanted_branches, entry)
998 		free((char *)pe->path);
999 	got_pathlist_free(&wanted_branches);
1000 	if (fetchfd != -1 && close(fetchfd) == -1 && err == NULL)
1001 		err = got_error_from_errno("close");
1002 	if (packfd != -1 && close(packfd) == -1 && err == NULL)
1003 		err = got_error_from_errno("close");
1004 	if (err != NULL)
1005 		got_privsep_send_error(&ibuf, err);
1006 	else
1007 		err = send_fetch_done(&ibuf, pack_sha1);
1008 	if (err != NULL) {
1009 		fprintf(stderr, "%s: %s\n", getprogname(), err->msg);
1010 		got_privsep_send_error(&ibuf, err);
1011 	}
1012 
1013 	exit(0);
1014 }