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Date:: Wed Mar 18 16:11:32 2020 UTC
Message:: rename imsg FETCH_PROGRESS to FETCH_REF
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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 #include <sys/syslimits.h>
23 
24 #include <stdint.h>
25 #include <errno.h>
26 #include <imsg.h>
27 #include <limits.h>
28 #include <signal.h>
29 #include <stdio.h>
30 #include <stdlib.h>
31 #include <string.h>
32 #include <ctype.h>
33 #include <sha1.h>
34 #include <fcntl.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 
43 #include "got_lib_sha1.h"
44 #include "got_lib_delta.h"
45 #include "got_lib_object.h"
46 #include "got_lib_object_parse.h"
47 #include "got_lib_privsep.h"
48 #include "got_lib_pack.h"
49 
50 #ifndef nitems
51 #define nitems(_a)	(sizeof((_a)) / sizeof((_a)[0]))
52 #endif
53 
54 #define GOT_PKTMAX	65536
55 
56 struct got_object *indexed;
57 static int chattygit;
58 static char *fetchbranch;
59 static struct got_object_id zhash = {.sha1={0}};
60 
61 static const struct got_error *
62 readn(ssize_t *off, int fd, void *buf, size_t n)
63 {
64 	ssize_t r;
65 
66 	*off = 0;
67 	while (*off != n) {
68 		r = read(fd, buf + *off, n - *off);
69 		if (r == -1)
70 			return got_error_from_errno("read");
71 		if (r == 0)
72 			return NULL;
73 		*off += r;
74 	}
75 	return NULL;
76 }
77 
78 static const struct got_error *
79 flushpkt(int fd)
80 {
81 	ssize_t w;
82 
83 	if (chattygit)
84 		fprintf(stderr, "writepkt: 0000\n");
85 
86 	 w = write(fd, "0000", 4);
87 	 if (w == -1)
88 		return got_error_from_errno("write");
89 	if (w != 4)
90 		return got_error(GOT_ERR_IO);
91 	return NULL;
92 }
93 
94 /*
95  * Packet header contains a 4-byte hexstring which specifies the length
96  * of data which follows.
97  */
98 static const struct got_error *
99 read_pkthdr(int *datalen, int fd)
100 {
101 	static const struct got_error *err = NULL;
102 	char lenstr[5];
103 	long len;
104 	char *e;
105 	int n, i;
106 	ssize_t r;
107 
108 	*datalen = 0;
109 
110 	err = readn(&r, fd, lenstr, 4);
111 	if (err)
112 		return err;
113 	if (r == 0) /* implicit "0000" */
114 		return NULL;
115 	if (r != 4)
116 		return got_error_msg(GOT_ERR_BAD_PACKET,
117 		    "wrong packet header length");
118 
119 	lenstr[4] = '\0';
120 	for (i = 0; i < 4; i++) {
121 		if (!isxdigit(lenstr[i]))
122 			return got_error_msg(GOT_ERR_BAD_PACKET,
123 			    "packet length not specified in hex");
124 	}
125 	errno = 0;
126 	len = strtol(lenstr, &e, 16);
127 	if (lenstr[0] == '\0' || *e != '\0')
128 		return got_error(GOT_ERR_BAD_PACKET);
129 	if (errno == ERANGE && (len == LONG_MAX || len == LONG_MIN))
130 		return got_error_msg(GOT_ERR_BAD_PACKET, "bad packet length");
131 	if (len > INT_MAX || len < INT_MIN)
132 		return got_error_msg(GOT_ERR_BAD_PACKET, "bad packet length");
133 	n = len;
134 	if (n == 0)
135 		return NULL;
136 	if (n <= 4)
137 		return got_error_msg(GOT_ERR_BAD_PACKET, "packet too short");
138 	n  -= 4;
139 
140 	*datalen = n;
141 	return NULL;
142 }
143 
144 static const struct got_error *
145 readpkt(int *outlen, int fd, char *buf, int buflen)
146 {
147 	const struct got_error *err = NULL;
148 	int datalen;
149 	ssize_t n;
150 
151 	err = read_pkthdr(&datalen, fd);
152 	if (err)
153 		return err;
154 
155 	if (datalen > buflen)
156 		return got_error(GOT_ERR_NO_SPACE);
157 
158 	err = readn(&n, fd, buf, datalen);
159 	if (err)
160 		return err;
161 	if (n != datalen)
162 		return got_error_msg(GOT_ERR_BAD_PACKET, "short packet");
163 
164 	*outlen = n;
165 	return NULL;
166 }
167 
168 static const struct got_error *
169 writepkt(int fd, char *buf, int nbuf)
170 {
171 	char len[5];
172 	int i;
173 	ssize_t w;
174 
175 	if (snprintf(len, sizeof(len), "%04x", nbuf + 4) >= sizeof(len))
176 		return got_error(GOT_ERR_NO_SPACE);
177 	w = write(fd, len, 4);
178 	if (w == -1)
179 		return got_error_from_errno("write");
180 	if (w != 4)
181 		return got_error(GOT_ERR_IO);
182 	w = write(fd, buf, nbuf);
183 	if (w == -1)
184 		return got_error_from_errno("write");
185 	if (w != nbuf)
186 		return got_error(GOT_ERR_IO);
187 	if (chattygit) {
188 		fprintf(stderr, "writepkt: %s:\t", len);
189 		fwrite(buf, 1, nbuf, stderr);
190 		for (i = 0; i < nbuf; i++) {
191 			if (isprint(buf[i]))
192 				fputc(buf[i], stderr);
193 		}
194 		fputc('\n', stderr);
195 	}
196 	return NULL;
197 }
198 
199 static const struct got_error *
200 match_remote_ref(struct got_pathlist_head *have_refs, struct got_object_id *id,
201     char *refname, char *id_str)
202 {
203 	struct got_pathlist_entry *pe;
204 
205 	memset(id, 0, sizeof(*id));
206 
207 	TAILQ_FOREACH(pe, have_refs, entry) {
208 		if (strcmp(pe->path, refname) == 0) {
209 			if (!got_parse_sha1_digest(id->sha1, id_str))
210 				return got_error(GOT_ERR_BAD_OBJ_ID_STR);
211 			break;
212 		}
213 	}
214 	return NULL;
215 }
216 
217 static const struct got_error *
218 check_pack_hash(int fd, size_t sz, uint8_t *hcomp)
219 {
220 	const struct got_error *err = NULL;
221 	SHA1_CTX ctx;
222 	uint8_t hexpect[SHA1_DIGEST_LENGTH];
223 	uint8_t buf[32 * 1024];
224 	ssize_t n, r, nr;
225 
226 	if (sz < sizeof(struct got_packfile_hdr) + SHA1_DIGEST_LENGTH)
227 		return got_error(GOT_ERR_BAD_PACKFILE);
228 
229 	n = 0;
230 	SHA1Init(&ctx);
231 	while (n < sz - 20) {
232 		nr = sizeof(buf);
233 		if (sz - n - 20 < sizeof(buf))
234 			nr = sz - n - 20;
235 		err = readn(&r, fd, buf, nr);
236 		if (err)
237 			return err;
238 		if (r != nr)
239 			return got_error(GOT_ERR_BAD_PACKFILE);
240 		SHA1Update(&ctx, buf, nr);
241 		n += r;
242 	}
243 	SHA1Final(hcomp, &ctx);
244 
245 	err = readn(&r, fd, hexpect, sizeof(hexpect));
246 	if (err)
247 		return err;
248 	if (r != sizeof(hexpect))
249 		return got_error(GOT_ERR_BAD_PACKFILE);
250 	if (memcmp(hcomp, hexpect, SHA1_DIGEST_LENGTH) != 0)
251 		return got_error(GOT_ERR_BAD_PACKFILE);
252 	return NULL;
253 }
254 
255 static int
256 match_branch(char *br, char *pat)
257 {
258 	char name[128];
259 
260 	if (strstr(pat, "refs/heads") == pat) {
261 		if (snprintf(name, sizeof(name), "%s", pat) >= sizeof(name))
262 			return -1;
263 	} else if (strstr(pat, "heads")) {
264 		if (snprintf(name, sizeof(name), "refs/%s", pat)
265 		    >= sizeof(name))
266 			return -1;
267 	} else {
268 		if (snprintf(name, sizeof(name), "refs/heads/%s", pat)
269 		    >= sizeof(name))
270 			return -1;
271 	}
272 	return strcmp(br, name) == 0;
273 }
274 
275 static const struct got_error *
276 tokenize_refline(char **tokens, char *line, int len, int maxtokens)
277 {
278 	const struct got_error *err = NULL;
279 	char *p;
280 	size_t i, n = 0;
281 
282 	for (i = 0; i < maxtokens; i++)
283 		tokens[i] = NULL;
284 
285 	for (i = 0; n < len && i < maxtokens; i++) {
286 		while (isspace(*line)) {
287 			line++;
288 			n++;
289 		}
290 		p = line;
291 		while (*line != '\0' &&
292 		    (!isspace(*line) || i == maxtokens - 1)) {
293 			line++;
294 			n++;
295 		}
296 		tokens[i] = strndup(p, line - p);
297 		if (tokens[i] == NULL) {
298 			err = got_error_from_errno("strndup");
299 			goto done;
300 		}
301 		/* Skip \0 field-delimiter at end of token. */
302 		while (line[0] == '\0' && n < len) {
303 			line++;
304 			n++;
305 		}
306 	}
307 	if (i <= 2)
308 		err = got_error(GOT_ERR_NOT_REF);
309 done:
310 	if (err) {
311 		int j;
312 		for (j = 0; j < i; j++)
313 			free(tokens[j]);
314 			tokens[j] = NULL;
315 	}
316 	return err;
317 }
318 
319 static const struct got_error *
320 parse_refline(char **id_str, char **refname, char **server_capabilities,
321     char *line, int len)
322 {
323 	const struct got_error *err = NULL;
324 	char *tokens[3];
325 
326 	err = tokenize_refline(tokens, line, len, nitems(tokens));
327 	if (err)
328 		return err;
329 
330 	if (tokens[0])
331 		*id_str = tokens[0];
332 	if (tokens[1])
333 		*refname = tokens[1];
334 	if (tokens[2])
335 		*server_capabilities = tokens[2];
336 	
337 	return NULL;
338 }
339 
340 #define GOT_CAPA_AGENT			"agent"
341 #define GOT_CAPA_OFS_DELTA		"ofs-delta"
342 #define GOT_CAPA_SIDE_BAND_64K		"side-band-64k"
343 
344 #define GOT_SIDEBAND_PACKFILE_DATA	1
345 #define GOT_SIDEBAND_PROGRESS_INFO	2
346 #define GOT_SIDEBAND_ERROR_INFO		3
347 
348 
349 struct got_capability {
350 	const char *key;
351 	const char *value;
352 };
353 static const struct got_capability got_capabilities[] = {
354 	{ GOT_CAPA_AGENT, "got/" GOT_VERSION_STR },
355 	{ GOT_CAPA_OFS_DELTA, NULL },
356 	{ GOT_CAPA_SIDE_BAND_64K, NULL },
357 };
358 
359 static const struct got_error *
360 match_capability(char **my_capabilities, const char *capa,
361     const struct got_capability *mycapa)
362 {
363 	char *equalsign;
364 	char *s;
365 
366 	equalsign = strchr(capa, '=');
367 	if (equalsign) {
368 		if (strncmp(capa, mycapa->key, equalsign - capa) != 0)
369 			return NULL;
370 	} else {
371 		if (strcmp(capa, mycapa->key) != 0)
372 			return NULL;
373 	}
374 
375 	if (asprintf(&s, "%s%s%s%s%s",
376 	    *my_capabilities != NULL ? *my_capabilities : "",
377 	    *my_capabilities != NULL ? " " : "",
378 	    mycapa->key,
379 	    mycapa->value != NULL ? "=" : "",
380 	    mycapa->value != NULL? mycapa->value : "") == -1)
381 		return got_error_from_errno("asprintf");
382 
383 	free(*my_capabilities);
384 	*my_capabilities = s;
385 	return NULL;
386 }
387 
388 static const struct got_error *
389 add_symref(struct got_pathlist_head *symrefs, char *capa)
390 {
391 	const struct got_error *err = NULL;
392 	char *colon, *name = NULL, *target = NULL;
393 
394 	/* Need at least "A:B" */
395 	if (strlen(capa) < 3)
396 		return NULL;
397 
398 	colon = strchr(capa, ':');
399 	if (colon == NULL)
400 		return NULL;
401 
402 	*colon = '\0';
403 	name = strdup(capa);
404 	if (name == NULL)
405 		return got_error_from_errno("strdup");
406 
407 	target = strdup(colon + 1);
408 	if (target == NULL) {
409 		err = got_error_from_errno("strdup");
410 		goto done;
411 	}
412 
413 	/* We can't validate the ref itself here. The main process will. */
414 	err = got_pathlist_append(symrefs, name, target);
415 done:
416 	if (err) {
417 		free(name);
418 		free(target);
419 	}
420 	return err;
421 }
422 
423 static const struct got_error *
424 match_capabilities(char **my_capabilities, struct got_pathlist_head *symrefs,
425     char *server_capabilities)
426 {
427 	const struct got_error *err = NULL;
428 	char *capa, *equalsign;
429 	int i;
430 
431 	*my_capabilities = NULL;
432 	do {
433 		capa = strsep(&server_capabilities, " ");
434 		if (capa == NULL)
435 			return NULL;
436 
437 		equalsign = strchr(capa, '=');
438 		if (equalsign != NULL &&
439 		    strncmp(capa, "symref", equalsign - capa) == 0) {
440 			err = add_symref(symrefs, equalsign + 1);
441 			if (err)
442 				break;
443 			continue;
444 		}
445 
446 		for (i = 0; i < nitems(got_capabilities); i++) {
447 			err = match_capability(my_capabilities,
448 			    capa, &got_capabilities[i]);
449 			if (err)
450 				break;
451 		}
452 	} while (capa);
453 
454 	return err;
455 }
456 
457 static const struct got_error *
458 fetch_progress(struct imsgbuf *ibuf, const char *buf, size_t len)
459 {
460 	int i;
461 
462 
463 	if (len == 0)
464 		return NULL;
465 
466 	/*
467 	 * Truncate messages which exceed the maximum imsg payload size.
468 	 * Server may send up to 64k.
469 	 */
470 	if (len > MAX_IMSGSIZE - IMSG_HEADER_SIZE)
471 		len = MAX_IMSGSIZE - IMSG_HEADER_SIZE;
472 
473 	/* Only allow printable ASCII. */
474 	for (i = 0; i < len; i++) {
475 		if (isprint((unsigned char)buf[i]) ||
476 		    isspace((unsigned char)buf[i]))
477 			continue;
478 		return got_error_msg(GOT_ERR_BAD_PACKET,
479 		    "non-printable progress message received from server");
480 	}
481 
482 	return got_privsep_send_fetch_server_progress(ibuf, buf, len);
483 }
484 
485 static const struct got_error *
486 fetch_error(const char *buf, size_t len)
487 {
488 	static char msg[1024];
489 	int i;
490 
491 	for (i = 0; i < len && i < sizeof(msg) - 1; i++) {
492 		if (!isprint(buf[i]))
493 			return got_error_msg(GOT_ERR_BAD_PACKET,
494 			    "non-printable error message received from server");
495 		msg[i] = buf[i];
496 	}
497 	msg[i] = '\0';
498 	return got_error_msg(GOT_ERR_FETCH_FAILED, msg);
499 }
500 
501 static const struct got_error *
502 fetch_pack(int fd, int packfd, struct got_object_id *packid,
503     struct got_pathlist_head *have_refs, struct imsgbuf *ibuf)
504 {
505 	const struct got_error *err = NULL;
506 	char buf[GOT_PKTMAX];
507 	char hashstr[SHA1_DIGEST_STRING_LENGTH];
508 	struct got_object_id *have, *want;
509 	int is_firstpkt = 1, nref = 0, refsz = 16;
510 	int i, n, req;
511 	off_t packsz;
512 	char *id_str = NULL, *refname = NULL;
513 	char *server_capabilities = NULL, *my_capabilities = NULL;
514 	struct got_pathlist_head symrefs;
515 	struct got_pathlist_entry *pe;
516 	int have_sidebands = 0;
517 	uint32_t nobjects = 0;
518 
519 	TAILQ_INIT(&symrefs);
520 
521 	have = malloc(refsz * sizeof(have[0]));
522 	if (have == NULL)
523 		return got_error_from_errno("malloc");
524 	want = malloc(refsz * sizeof(want[0]));
525 	if (want == NULL) {
526 		err = got_error_from_errno("malloc");
527 		goto done;
528 	}
529 	if (chattygit)
530 		fprintf(stderr, "starting fetch\n");
531 	while (1) {
532 		err = readpkt(&n, fd, buf, sizeof(buf));
533 		if (err)
534 			goto done;
535 		if (n == 0)
536 			break;
537 		if (n >= 4 && strncmp(buf, "ERR ", 4) == 0) {
538 			err = fetch_error(&buf[4], n - 4);
539 			goto done;
540 		}
541 		err = parse_refline(&id_str, &refname, &server_capabilities,
542 		    buf, n);
543 		if (err)
544 			goto done;
545 		if (chattygit && server_capabilities[0] != '\0')
546 			fprintf(stderr, "server capabilities: %s\n",
547 			    server_capabilities);
548 		if (is_firstpkt) {
549 			err = match_capabilities(&my_capabilities, &symrefs,
550 			    server_capabilities);
551 			if (err)
552 				goto done;
553 			if (chattygit && my_capabilities)
554 				fprintf(stderr, "my matched capabilities: %s\n",
555 				    my_capabilities);
556 			err = got_privsep_send_fetch_symrefs(ibuf, &symrefs);
557 			if (err)
558 				goto done;
559 		}
560 		is_firstpkt = 0;
561 		if (strstr(refname, "^{}"))
562 			continue;
563 		if (fetchbranch && !match_branch(refname, fetchbranch))
564 			continue;
565 		if (refsz == nref + 1) {
566 			refsz *= 2;
567 			have = reallocarray(have, refsz, sizeof(have[0]));
568 			if (have == NULL) {
569 				err = got_error_from_errno("reallocarray");
570 				goto done;
571 			}
572 			want = reallocarray(want, refsz, sizeof(want[0]));
573 			if (want == NULL) {
574 				err = got_error_from_errno("reallocarray");
575 				goto done;
576 			}
577 		}
578 		if (!got_parse_sha1_digest(want[nref].sha1, id_str)) {
579 			err = got_error(GOT_ERR_BAD_OBJ_ID_STR);
580 			goto done;
581 		}
582 
583 		err = match_remote_ref(have_refs, &have[nref], id_str, refname);
584 		if (err)
585 			goto done;
586 
587 		err = got_privsep_send_fetch_ref(ibuf, &want[nref],
588 		    refname);
589 		if (err)
590 			goto done;
591 		if (chattygit)
592 			fprintf(stderr, "remote %s\n", refname);
593 		nref++;
594 	}
595 
596 	req = 0;
597 	for (i = 0; i < nref; i++) {
598 		if (got_object_id_cmp(&have[i], &want[i]) == 0)
599 			continue;
600 		got_sha1_digest_to_str(want[i].sha1, hashstr, sizeof(hashstr));
601 		n = snprintf(buf, sizeof(buf), "want %s%s%s\n", hashstr,
602 		   i == 0 && my_capabilities ? " " : "",
603 		   i == 0 && my_capabilities ? my_capabilities : "");
604 		if (n >= sizeof(buf)) {
605 			err = got_error(GOT_ERR_NO_SPACE);
606 			goto done;
607 		}
608 		err = writepkt(fd, buf, n);
609 		if (err)
610 			goto done;
611 		req = 1;
612 	}
613 	err = flushpkt(fd);
614 	if (err)
615 		goto done;
616 	for (i = 0; i < nref; i++) {
617 		if (got_object_id_cmp(&have[i], &zhash) == 0)
618 			continue;
619 		got_sha1_digest_to_str(want[i].sha1, hashstr, sizeof(hashstr));
620 		n = snprintf(buf, sizeof(buf), "have %s\n", hashstr);
621 		if (n >= sizeof(buf)) {
622 			err = got_error(GOT_ERR_NO_SPACE);
623 			goto done;
624 		}
625 		err = writepkt(fd, buf, n + 1);
626 		if (err)
627 			goto done;
628 	}
629 	if (!req) {
630 		if (chattygit)
631 			fprintf(stderr, "up to date\n");
632 		err = flushpkt(fd);
633 		if (err)
634 			goto done;
635 	}
636 	n = snprintf(buf, sizeof(buf), "done\n");
637 	err = writepkt(fd, buf, n);
638 	if (err)
639 		goto done;
640 	if (!req)
641 		return 0;
642 
643 	err = readpkt(&n, fd, buf, sizeof(buf));
644 	if (err)
645 		goto done;
646 	/*
647 	 * For now, we only support a full clone, in which case the server
648 	 * will now send a "NAK" (meaning no common objects were found).
649 	 */
650 	if (n != 4 || strncmp(buf, "NAK\n", n) != 0) {
651 		err = got_error_msg(GOT_ERR_BAD_PACKET,
652 		    "unexpected message from server");
653 		goto done;
654 	}
655 
656 	if (chattygit)
657 		fprintf(stderr, "fetching...\n");
658 
659 	if (my_capabilities != NULL &&
660 	    strstr(my_capabilities, GOT_CAPA_SIDE_BAND_64K) != NULL)
661 		have_sidebands = 1;
662 
663 	packsz = 0;
664 	while (1) {
665 		ssize_t r = 0, w;
666 		int datalen = -1;
667 
668 		if (have_sidebands) {
669 			err = read_pkthdr(&datalen, fd);
670 			if (err)
671 				goto done;
672 			if (datalen <= 0)
673 				break;
674 
675 			/* Read sideband channel ID (one byte). */
676 			r = read(fd, buf, 1);
677 			if (r == -1) {
678 				err = got_error_from_errno("read");
679 				goto done;
680 			}
681 			if (r != 1) {
682 				err = got_error_msg(GOT_ERR_BAD_PACKET,
683 				    "short packet");
684 				goto done;
685 			}
686 			if (datalen > sizeof(buf) - 5) {
687 				err = got_error_msg(GOT_ERR_BAD_PACKET,
688 				    "bad packet length");
689 				goto done;
690 			}
691 			datalen--; /* sideband ID has been read */
692 			if (buf[0] == GOT_SIDEBAND_PACKFILE_DATA) {
693 				/* Read packfile data. */
694 				err = readn(&r, fd, buf, datalen);
695 				if (err)
696 					goto done;
697 				if (r != datalen) {
698 					err = got_error_msg(GOT_ERR_BAD_PACKET,
699 					    "packet too short");
700 					goto done;
701 				}
702 			} else if (buf[0] == GOT_SIDEBAND_PROGRESS_INFO) {
703 				err = readn(&r, fd, buf, datalen);
704 				if (err)
705 					goto done;
706 				if (r != datalen) {
707 					err = got_error_msg(GOT_ERR_BAD_PACKET,
708 					    "packet too short");
709 					goto done;
710 				}
711 				err = fetch_progress(ibuf, buf, r);
712 				if (err)
713 					goto done;
714 				continue;
715 			} else if (buf[0] == GOT_SIDEBAND_ERROR_INFO) {
716 				err = readn(&r, fd, buf, datalen);
717 				if (err)
718 					goto done;
719 				if (r != datalen) {
720 					err = got_error_msg(GOT_ERR_BAD_PACKET,
721 					    "packet too short");
722 					goto done;
723 				}
724 				err = fetch_error(buf, r);
725 				goto done;
726 			} else {
727 				err = got_error_msg(GOT_ERR_BAD_PACKET,
728 				    "unknown side-band received from server");
729 				goto done;
730 			}
731 		} else {
732 			/* No sideband channel. Every byte is packfile data. */
733 			err = readn(&r, fd, buf, sizeof buf);
734 			if (err)
735 				goto done;
736 			if (r <= 0)
737 				break;
738 		}
739 
740 		/* Check pack file header. */
741 		if (nobjects == 0) {
742 			struct got_packfile_hdr *hdr = (void *)buf;
743 			if (r < sizeof(*hdr)) {
744 				err = got_error_msg(GOT_ERR_BAD_PACKFILE,
745 				    "short packfile header");
746 				goto done;
747 			}
748 			if (hdr->signature != htobe32(GOT_PACKFILE_SIGNATURE)) {
749 				err = got_error_msg(GOT_ERR_BAD_PACKFILE,
750 				    "bad packfile signature");
751 				goto done;
752 			}
753 			if (hdr->version != htobe32(GOT_PACKFILE_VERSION)) {
754 				err = got_error_msg(GOT_ERR_BAD_PACKFILE,
755 				    "bad packfile version");
756 				goto done;
757 			}
758 			nobjects = betoh32(hdr->nobjects);
759 			if (nobjects == 0) {
760 				err = got_error_msg(GOT_ERR_BAD_PACKFILE,
761 				    "bad packfile with zero objects");
762 				goto done;
763 			}
764 		}
765 
766 		/* Write packfile data to temporary pack file. */
767 		w = write(packfd, buf, r);
768 		if (w == -1) {
769 			err = got_error_from_errno("write");
770 			goto done;
771 		}
772 		if (w != r) {
773 			err = got_error(GOT_ERR_IO);
774 			goto done;
775 		}
776 		packsz += w;
777 	}
778 	if (lseek(packfd, 0, SEEK_SET) == -1) {
779 		err = got_error_from_errno("lseek");
780 		goto done;
781 	}
782 	err = check_pack_hash(packfd, packsz, packid->sha1);
783 done:
784 	TAILQ_FOREACH(pe, &symrefs, entry) {
785 		free((void *)pe->path);
786 		free(pe->data);
787 	}
788 	got_pathlist_free(&symrefs);
789 	free(have);
790 	free(want);
791 	free(id_str);
792 	free(refname);
793 	free(server_capabilities);
794 	return err;
795 }
796 
797 
798 int
799 main(int argc, char **argv)
800 {
801 	const struct got_error *err = NULL;
802 	int fetchfd, packfd = -1;
803 	struct got_object_id packid;
804 	struct imsgbuf ibuf;
805 	struct imsg imsg;
806 	struct got_pathlist_head have_refs;
807 	struct got_imsg_fetch_have_refs *fetch_have_refs = NULL;
808 	size_t datalen;
809 
810 	TAILQ_INIT(&have_refs);
811 
812 	if (getenv("GOT_DEBUG") != NULL) {
813 		fprintf(stderr, "fetch-pack being chatty!\n");
814 		chattygit = 1;
815 	}
816 
817 	imsg_init(&ibuf, GOT_IMSG_FD_CHILD);
818 #ifndef PROFILE
819 	/* revoke access to most system calls */
820 	if (pledge("stdio recvfd", NULL) == -1) {
821 		err = got_error_from_errno("pledge");
822 		got_privsep_send_error(&ibuf, err);
823 		return 1;
824 	}
825 #endif
826 	if ((err = got_privsep_recv_imsg(&imsg, &ibuf, 0)) != 0) {
827 		if (err->code == GOT_ERR_PRIVSEP_PIPE)
828 			err = NULL;
829 		goto done;
830 	}
831 	if (imsg.hdr.type == GOT_IMSG_STOP)
832 		goto done;
833 	if (imsg.hdr.type != GOT_IMSG_FETCH_REQUEST) {
834 		err = got_error(GOT_ERR_PRIVSEP_MSG);
835 		goto done;
836 	}
837 	datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
838 	if (datalen < sizeof(struct got_imsg_fetch_have_refs)) {
839 		err = got_error(GOT_ERR_PRIVSEP_LEN);
840 		goto done;
841 	}
842 	fetch_have_refs = (struct got_imsg_fetch_have_refs *)imsg.data;
843 	if (datalen != sizeof(struct got_imsg_fetch_have_refs) +
844 	    sizeof(struct got_imsg_fetch_have_ref) *
845 	    fetch_have_refs->n_have_refs) {
846 		err = got_error(GOT_ERR_PRIVSEP_LEN);
847 		goto done;
848 	}
849 	if (fetch_have_refs->n_have_refs != 0) {
850 		/* TODO: Incremental fetch support */
851 		err = got_error(GOT_ERR_NOT_IMPL);
852 		goto done;
853 	}
854 	fetchfd = imsg.fd;
855 
856 	if ((err = got_privsep_recv_imsg(&imsg, &ibuf, 0)) != 0) {
857 		if (err->code == GOT_ERR_PRIVSEP_PIPE)
858 			err = NULL;
859 		goto done;
860 	}
861 	if (imsg.hdr.type == GOT_IMSG_STOP)
862 		goto done;
863 	if (imsg.hdr.type != GOT_IMSG_TMPFD) {
864 		err = got_error(GOT_ERR_PRIVSEP_MSG);
865 		goto done;
866 	}
867 	if (imsg.hdr.len - IMSG_HEADER_SIZE != 0) {
868 		err = got_error(GOT_ERR_PRIVSEP_LEN);
869 		goto done;
870 	}
871 	packfd = imsg.fd;
872 
873 	err = fetch_pack(fetchfd, packfd, &packid, &have_refs, &ibuf);
874 done:
875 	if (packfd != -1 && close(packfd) == -1 && err == NULL)
876 		err = got_error_from_errno("close");
877 	if (err != NULL)
878 		got_privsep_send_error(&ibuf, err);
879 	else
880 		err = got_privsep_send_fetch_done(&ibuf, packid);
881 	if (err != NULL) {
882 		fprintf(stderr, "%s: %s\n", getprogname(), err->msg);
883 		got_privsep_send_error(&ibuf, err);
884 	}
885 
886 	exit(0);
887 }