summaryrefslogtreecommitdiffstats
path: root/fs/nfs.c
blob: 797e3bd47130095333a826ab8f84c2930cf0d2b9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
/*
 * nfs.c - barebox NFS driver
 *
 * Copyright (c) 2012 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
 * Copyright (c) Masami Komiya <mkomiya@sonare.it> 2004
 *
 * Based on U-Boot NFS code which is based on NetBSD code
 *
 * See file CREDITS for list of people who contributed to this
 * project.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <common.h>
#include <net.h>
#include <driver.h>
#include <fs.h>
#include <errno.h>
#include <libgen.h>
#include <fcntl.h>
#include <fs.h>
#include <init.h>
#include <linux/stat.h>
#include <linux/err.h>
#include <kfifo.h>
#include <sizes.h>

#define SUNRPC_PORT     111

#define PROG_PORTMAP    100000
#define PROG_NFS        100003
#define PROG_MOUNT      100005

#define MSG_CALL        0
#define MSG_REPLY       1

#define PORTMAP_GETPORT 3

#define MOUNT_ADDENTRY	1
#define MOUNT_UMOUNT	3

#define NFS_GETATTR     1
#define NFS_LOOKUP      4
#define NFS_READLINK    5
#define NFS_READ        6
#define NFS_READDIR	16

#define NFS_FHSIZE      32

enum nfs_stat {
	NFS_OK		= 0,
	NFSERR_PERM	= 1,
	NFSERR_NOENT	= 2,
	NFSERR_IO	= 5,
	NFSERR_NXIO	= 6,
	NFSERR_ACCES	= 13,
	NFSERR_EXIST	= 17,
	NFSERR_NODEV	= 19,
	NFSERR_NOTDIR	= 20,
	NFSERR_ISDIR	= 21,
	NFSERR_FBIG	= 27,
	NFSERR_NOSPC	= 28,
	NFSERR_ROFS	= 30,
	NFSERR_NAMETOOLONG=63,
	NFSERR_NOTEMPTY	= 66,
	NFSERR_DQUOT	= 69,
	NFSERR_STALE	= 70,
	NFSERR_WFLUSH	= 99,
};

static void *nfs_packet;
static int nfs_len;

struct rpc_call {
	uint32_t id;
	uint32_t type;
	uint32_t rpcvers;
	uint32_t prog;
	uint32_t vers;
	uint32_t proc;
	uint32_t data[0];
};

struct rpc_reply {
	uint32_t id;
	uint32_t type;
	uint32_t rstatus;
	uint32_t verifier;
	uint32_t v2;
	uint32_t astatus;
	uint32_t data[0];
};

#define NFS_TIMEOUT	(2 * SECOND)
#define NFS_MAX_RESEND	5

struct nfs_priv {
	struct net_connection *con;
	IPaddr_t server;
	char *path;
	int mount_port;
	int nfs_port;
	unsigned long rpc_id;
	char rootfh[NFS_FHSIZE];
};

struct file_priv {
	struct kfifo *fifo;
	void *buf;
	char filefh[NFS_FHSIZE];
	struct nfs_priv *npriv;
};

static uint64_t nfs_timer_start;

static int	nfs_state;
#define STATE_DONE			1
#define STATE_START			2

enum ftype {
	NFNON = 0,
	NFREG = 1,
	NFDIR = 2,
	NFBLK = 3,
	NFCHR = 4,
	NFLNK = 5
};

struct fattr {
	uint32_t type;
	uint32_t mode;
	uint32_t nlink;
	uint32_t uid;
	uint32_t gid;
	uint32_t size;
	uint32_t blocksize;
	uint32_t rdev;
	uint32_t blocks;
};

struct readdirargs {
	char filefh[NFS_FHSIZE];
	uint32_t cookie;
	uint32_t count;
};

struct xdr_stream {
	__be32 *p;
	void *buf;
	__be32 *end;
};

#define xdr_zero 0
#define XDR_QUADLEN(l)		(((l) + 3) >> 2)

static void xdr_init(struct xdr_stream *stream, void *buf, int len)
{
	stream->p = stream->buf = buf;
	stream->end = stream->buf + len;
}

static __be32 *__xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
{
	__be32 *p = xdr->p;
	__be32 *q = p + XDR_QUADLEN(nbytes);

        if (q > xdr->end || q < p)
		return NULL;
	xdr->p = q;
	return p;
}

static __be32 *xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
{
	__be32 *p;

	if (nbytes == 0)
		return xdr->p;
	if (xdr->p == xdr->end)
		return NULL;
	p = __xdr_inline_decode(xdr, nbytes);

	return p;
}

static int decode_filename(struct xdr_stream *xdr,
		char *name, u32 *length)
{
	__be32 *p;
	u32 count;

	p = xdr_inline_decode(xdr, 4);
	if (!p)
		goto out_overflow;
	count = be32_to_cpup(p);
	if (count > 255)
		goto out_nametoolong;
	p = xdr_inline_decode(xdr, count);
	if (!p)
		goto out_overflow;
	memcpy(name, p, count);
	name[count] = 0;
	*length = count;
	return 0;
out_nametoolong:
	printk("NFS: returned filename too long: %u\n", count);
	return -ENAMETOOLONG;
out_overflow:
	printf("%s overflow\n",__func__);
	return -EIO;
}

/*
 * rpc_add_credentials - Add RPC authentication/verifier entries
 */
static uint32_t *rpc_add_credentials(uint32_t *p)
{
	int hl;
	int hostnamelen = 0;

	/*
	 * Here's the executive summary on authentication requirements of the
	 * various NFS server implementations:	Linux accepts both AUTH_NONE
	 * and AUTH_UNIX authentication (also accepts an empty hostname field
	 * in the AUTH_UNIX scheme).  *BSD refuses AUTH_NONE, but accepts
	 * AUTH_UNIX (also accepts an empty hostname field in the AUTH_UNIX
	 * scheme).  To be safe, use AUTH_UNIX and pass the hostname if we have
	 * it (if the BOOTP/DHCP reply didn't give one, just use an empty
	 * hostname).
	 */

	hl = (hostnamelen + 3) & ~3;

	/* Provide an AUTH_UNIX credential.  */
	*p++ = htonl(1);		/* AUTH_UNIX */
	*p++ = htonl(hl + 20);		/* auth length */
	*p++ = htonl(0);		/* stamp */
	*p++ = htonl(hostnamelen);	/* hostname string */

	if (hostnamelen & 3)
		*(p + hostnamelen / 4) = 0; /* add zero padding */

	/* memcpy(p, hostname, hostnamelen); */ /* empty hostname */

	p += hl / 4;
	*p++ = 0;			/* uid */
	*p++ = 0;			/* gid */
	*p++ = 0;			/* auxiliary gid list */

	/* Provide an AUTH_NONE verifier.  */
	*p++ = 0;			/* AUTH_NONE */
	*p++ = 0;			/* auth length */

	return p;
}

static int rpc_check_reply(unsigned char *pkt, int rpc_prog, unsigned long rpc_id, int *nfserr)
{
	uint32_t *data;
	struct rpc_reply rpc;

	*nfserr = 0;

	if (!pkt)
		return -EAGAIN;

	memcpy(&rpc, pkt, sizeof(rpc));

	if (ntohl(rpc.id) != rpc_id)
		return -EINVAL;

	if (rpc.rstatus  ||
	    rpc.verifier ||
	    rpc.astatus ) {
		return -EINVAL;
	}

	if (rpc_prog == PROG_PORTMAP)
		return 0;

	data = (uint32_t *)(pkt + sizeof(struct rpc_reply));
	*nfserr = ntohl(net_read_uint32(data));
	*nfserr = -*nfserr;

	debug("%s: state: %d, err %d\n", __func__, nfs_state, *nfserr);

	return 0;
}

/*
 * rpc_req - synchronous RPC request
 */
static int rpc_req(struct nfs_priv *npriv, int rpc_prog, int rpc_proc,
		uint32_t *data, int datalen)
{
	struct rpc_call pkt;
	unsigned long id;
	int dport;
	int ret;
	unsigned char *payload = net_udp_get_payload(npriv->con);
	int nfserr;
	int tries = 0;

	npriv->rpc_id++;
	id = npriv->rpc_id;

	pkt.id = htonl(id);
	pkt.type = htonl(MSG_CALL);
	pkt.rpcvers = htonl(2);	/* use RPC version 2 */
	pkt.prog = htonl(rpc_prog);
	pkt.vers = htonl(2);	/* portmapper is version 2 */
	pkt.proc = htonl(rpc_proc);

	memcpy(payload, &pkt, sizeof(pkt));
	memcpy(payload + sizeof(pkt), data, datalen * sizeof(uint32_t));

	if (rpc_prog == PROG_PORTMAP)
		dport = SUNRPC_PORT;
	else if (rpc_prog == PROG_MOUNT)
		dport = npriv->mount_port;
	else
		dport = npriv->nfs_port;

	npriv->con->udp->uh_dport = htons(dport);

again:
	ret = net_udp_send(npriv->con, sizeof(pkt) + datalen * sizeof(uint32_t));

	nfs_timer_start = get_time_ns();

	nfs_state = STATE_START;
	nfs_packet = NULL;

	while (nfs_state != STATE_DONE) {
		if (ctrlc()) {
			ret = -EINTR;
			break;
		}
		net_poll();

		if (is_timeout(nfs_timer_start, NFS_TIMEOUT)) {
			tries++;
			if (tries == NFS_MAX_RESEND)
				return -ETIMEDOUT;
			goto again;
		}

		ret = rpc_check_reply(nfs_packet, rpc_prog,
				npriv->rpc_id, &nfserr);
		if (!ret) {
			ret = nfserr;
			break;
		}
	}

	return ret;
}

/*
 * rpc_lookup_req - Lookup RPC Port numbers
 */
static int rpc_lookup_req(struct nfs_priv *npriv, int prog, int ver)
{
	uint32_t data[16];
	int ret;
	uint32_t port;

	data[0] = 0; data[1] = 0;	/* auth credential */
	data[2] = 0; data[3] = 0;	/* auth verifier */
	data[4] = htonl(prog);
	data[5] = htonl(ver);
	data[6] = htonl(17);	/* IP_UDP */
	data[7] = 0;

	ret = rpc_req(npriv, PROG_PORTMAP, PORTMAP_GETPORT, data, 8);
	if (ret)
		return ret;

	port = net_read_uint32((uint32_t *)(nfs_packet + sizeof(struct rpc_reply)));

	switch (prog) {
	case PROG_MOUNT:
		npriv->mount_port = ntohl(port);
		debug("mount port: %d\n", npriv->mount_port);
		break;
	case PROG_NFS:
		npriv->nfs_port = ntohl(port);
		debug("nfs port: %d\n", npriv->nfs_port);
		break;
	default:
		return -EINVAL;
	}

	return 0;
}

/*
 * nfs_mount_req - Mount an NFS Filesystem
 */
static int nfs_mount_req(struct nfs_priv *npriv)
{
	uint32_t data[1024];
	uint32_t *p;
	int len;
	int pathlen;
	int ret;

	pathlen = strlen(npriv->path);

	debug("%s: %s\n", __func__, npriv->path);

	p = &(data[0]);
	p = rpc_add_credentials(p);

	*p++ = htonl(pathlen);
	if (pathlen & 3)
		*(p + pathlen / 4) = 0;

	memcpy (p, npriv->path, pathlen);
	p += (pathlen + 3) / 4;

	len = p - &(data[0]);

	ret = rpc_req(npriv, PROG_MOUNT, MOUNT_ADDENTRY, data, len);
	if (ret)
		return ret;

	memcpy(npriv->rootfh, nfs_packet + sizeof(struct rpc_reply) + 4, NFS_FHSIZE);

	return 0;
}

/*
 * nfs_umountall_req - Unmount all our NFS Filesystems on the Server
 */
static void nfs_umount_req(struct nfs_priv *npriv)
{
	uint32_t data[1024];
	uint32_t *p;
	int len;
	int pathlen;

	pathlen = strlen(npriv->path);

	p = &(data[0]);
	p = rpc_add_credentials(p);

	*p++ = htonl(pathlen);
	if (pathlen & 3)
		*(p + pathlen / 4) = 0;

	memcpy (p, npriv->path, pathlen);
	p += (pathlen + 3) / 4;

	len = p - &(data[0]);

	rpc_req(npriv, PROG_MOUNT, MOUNT_UMOUNT, data, len);
}

/*
 * nfs_lookup_req - Lookup Pathname
 */
static int nfs_lookup_req(struct file_priv *priv, const char *filename,
		int fnamelen)
{
	uint32_t data[1024];
	uint32_t *p;
	int len;
	int ret;

	p = &(data[0]);
	p = rpc_add_credentials(p);

	memcpy(p, priv->filefh, NFS_FHSIZE);

	p += (NFS_FHSIZE / 4);
	*p++ = htonl(fnamelen);

	if (fnamelen & 3)
		*(p + fnamelen / 4) = 0;

	memcpy(p, filename, fnamelen);
	p += (fnamelen + 3) / 4;

	len = p - &(data[0]);

	ret = rpc_req(priv->npriv, PROG_NFS, NFS_LOOKUP, data, len);
	if (ret)
		return ret;

	memcpy(priv->filefh, nfs_packet + sizeof(struct rpc_reply) + 4, NFS_FHSIZE);

	return 0;
}

static int nfs_attr_req(struct file_priv *priv, struct stat *s)
{
	uint32_t data[1024];
	uint32_t *p;
	int len;
	int ret;
	struct fattr *fattr;
	uint32_t type;

	p = &(data[0]);
	p = rpc_add_credentials(p);

	memcpy(p, priv->filefh, NFS_FHSIZE);
	p += (NFS_FHSIZE / 4);
	*p++ = 0;

	len = p - &(data[0]);

	ret = rpc_req(priv->npriv, PROG_NFS, NFS_GETATTR, data, len);
	if (ret)
		return ret;

	fattr = nfs_packet + sizeof(struct rpc_reply) + 4;

	type = ntohl(net_read_uint32(&fattr->type));

	s->st_size = ntohl(net_read_uint32(&fattr->size));
	s->st_mode = ntohl(net_read_uint32(&fattr->mode));

	return 0;
}

static void *nfs_readdirattr_req(struct file_priv *priv, int *plen, uint32_t cookie)
{
	uint32_t data[1024];
	uint32_t *p;
	int len;
	int ret;
	void *buf;

	p = &(data[0]);
	p = rpc_add_credentials(p);

	memcpy(p, priv->filefh, NFS_FHSIZE);
	p += (NFS_FHSIZE / 4);
	*p++ = htonl(cookie); /* cookie */
	*p++ = htonl(1024); /* count */
	*p++ = 0;

	len = p - &(data[0]);

	ret = rpc_req(priv->npriv, PROG_NFS, NFS_READDIR, data, len);
	if (ret)
		return NULL;

	*plen = nfs_len - sizeof(struct rpc_reply) + 4;

	buf = xzalloc(*plen);

	memcpy(buf, nfs_packet + sizeof(struct rpc_reply) + 4, *plen);

	return buf;
}

/*
 * nfs_read_req - Read File on NFS Server
 */
static int nfs_read_req(struct file_priv *priv, int offset, int readlen)
{
	uint32_t data[1024];
	uint32_t *p;
	uint32_t *filedata;
	int len;
	int ret;
	int rlen;

	p = &(data[0]);
	p = rpc_add_credentials(p);

	memcpy (p, priv->filefh, NFS_FHSIZE);
	p += (NFS_FHSIZE / 4);
	*p++ = htonl(offset);
	*p++ = htonl(readlen);
	*p++ = 0;

	len = p - &(data[0]);

	ret = rpc_req(priv->npriv, PROG_NFS, NFS_READ, data, len);
	if (ret)
		return ret;

	filedata = (uint32_t *)(nfs_packet + sizeof(struct rpc_reply));

	rlen = ntohl(net_read_uint32(filedata + 18));

	kfifo_put(priv->fifo, (char *)(filedata + 19), rlen);

	return 0;
}

static void nfs_handler(void *ctx, char *packet, unsigned len)
{
	char *pkt = net_eth_to_udp_payload(packet);

	nfs_state = STATE_DONE;
	nfs_packet = pkt;
	nfs_len = len;
}

static int nfs_create(struct device_d *dev, const char *pathname, mode_t mode)
{
	return -ENOSYS;
}

static int nfs_unlink(struct device_d *dev, const char *pathname)
{
	return -ENOSYS;
}

static int nfs_mkdir(struct device_d *dev, const char *pathname)
{
	return -ENOSYS;
}

static int nfs_rmdir(struct device_d *dev, const char *pathname)
{
	return -ENOSYS;
}

static int nfs_truncate(struct device_d *dev, FILE *f, ulong size)
{
	return -ENOSYS;
}

static struct file_priv *nfs_do_open(struct device_d *dev, const char *filename)
{
	struct file_priv *priv;
	struct nfs_priv *npriv = dev->priv;
	int ret;
	const char *fname, *tok;

	priv = xzalloc(sizeof(*priv));

	priv->npriv = npriv;

	if (!*filename) {
		memcpy(priv->filefh, npriv->rootfh, NFS_FHSIZE);
		return priv;
	}

	filename++;

	fname = filename;

	memcpy(priv->filefh, npriv->rootfh, NFS_FHSIZE);

	while (*fname) {
		int flen;

		tok = strchr(fname, '/');
		if (tok)
			flen = tok - fname;
		else
			flen = strlen(fname);

		ret = nfs_lookup_req(priv, fname, flen);
		if (ret)
			goto out;

		if (tok)
			fname += flen + 1;
		else
			break;
	}

	return priv;

out:
	free(priv);

	return ERR_PTR(ret);
}

static void nfs_do_close(struct file_priv *priv)
{
	if (priv->fifo)
		kfifo_free(priv->fifo);

	free(priv);
}

static struct file_priv *nfs_do_stat(struct device_d *dev, const char *filename, struct stat *s)
{
	struct file_priv *priv;
	int ret;

	priv = nfs_do_open(dev, filename);
	if (IS_ERR(priv))
		return priv;

	ret = nfs_attr_req(priv, s);
	if (ret) {
		nfs_do_close(priv);
		return ERR_PTR(ret);
	}

	return priv;
}

static int nfs_readlink_req(struct file_priv *priv, char* buf, size_t size)
{
	uint32_t data[1024];
	uint32_t *p;
	int len;
	int ret;
	char *path;
	uint32_t *filedata;

	p = &(data[0]);
	p = rpc_add_credentials(p);

	memcpy(p, priv->filefh, NFS_FHSIZE);
	p += (NFS_FHSIZE / 4);

	len = p - &(data[0]);

	ret = rpc_req(priv->npriv, PROG_NFS, NFS_READLINK, data, len);
	if (ret)
		return ret;

	filedata = nfs_packet + sizeof(struct rpc_reply);
	filedata++;

	len = ntohl(net_read_uint32(filedata)); /* new path length */
	filedata++;

	path = (char *)filedata;

	if (len > size)
		len = size;

	memcpy(buf, path, len);

	return 0;
}

static int nfs_readlink(struct device_d *dev, const char *filename,
			char *realname, size_t size)
{
	struct file_priv *priv;
	int ret;
	struct stat s;

	priv = nfs_do_stat(dev, filename, &s);
	if (IS_ERR(priv))
		return PTR_ERR(priv);

	ret = nfs_readlink_req(priv, realname, size);
	if (ret) {
		nfs_do_close(priv);
		return ret;
	}

	return 0;
}

static int nfs_open(struct device_d *dev, FILE *file, const char *filename)
{
	struct file_priv *priv;
	struct stat s;

	priv = nfs_do_stat(dev, filename, &s);
	if (IS_ERR(priv))
		return PTR_ERR(priv);

	file->inode = priv;
	file->size = s.st_size;

	priv->fifo = kfifo_alloc(1024);
	if (!priv->fifo) {
		free(priv);
		return -ENOMEM;
	}

	return 0;
}

static int nfs_close(struct device_d *dev, FILE *file)
{
	struct file_priv *priv = file->inode;

	nfs_do_close(priv);

	return 0;
}

static int nfs_write(struct device_d *_dev, FILE *file, const void *inbuf,
		size_t insize)
{
	return -ENOSYS;
}

static int nfs_read(struct device_d *dev, FILE *file, void *buf, size_t insize)
{
	struct file_priv *priv = file->inode;
	int now, outsize = 0, ret, pos = file->pos;

	while (insize) {
		now = kfifo_get(priv->fifo, buf, insize);
		outsize += now;
		buf += now;
		insize -= now;

		if (insize) {
			/* do not use min as insize is a size_t */
			if (insize < 1024)
				now = insize;
			else
				now = 1024;

			if (pos + now > file->size)
				now = file->size - pos;

			ret = nfs_read_req(priv, pos, now);
			if (ret)
				return ret;
			pos += now;
		}
	}

	return outsize;
}

static loff_t nfs_lseek(struct device_d *dev, FILE *file, loff_t pos)
{
	struct file_priv *priv = file->inode;

	file->pos = pos;
	kfifo_reset(priv->fifo);

	return file->pos;
}

struct nfs_dir {
	DIR dir;
	struct xdr_stream stream;
	struct dirent ent;
	struct file_priv *priv;
	uint32_t cookie;
};

static DIR *nfs_opendir(struct device_d *dev, const char *pathname)
{
	struct file_priv *priv;
	struct stat s;
	int ret;
	void *buf;
	struct nfs_dir *dir;
	int len;

	priv = nfs_do_open(dev, pathname);
	if (IS_ERR(priv))
		return NULL;

	ret = nfs_attr_req(priv, &s);
	if (ret)
		return NULL;

	if (!S_ISDIR(s.st_mode))
		return NULL;

	dir = xzalloc(sizeof(*dir));
	dir->priv = priv;

	buf = nfs_readdirattr_req(priv, &len, 0);
	if (!buf)
		return NULL;

	xdr_init(&dir->stream, buf, len);

	return &dir->dir;
}

static struct dirent *nfs_readdir(struct device_d *dev, DIR *dir)
{
	struct nfs_dir *ndir = (void *)dir;
	__be32 *p;
	int ret;
	int len;
	struct xdr_stream *xdr = &ndir->stream;

again:
	p = xdr_inline_decode(xdr, 4);
	if (!p)
		goto out_overflow;

	if (*p++ == xdr_zero) {
		p = xdr_inline_decode(xdr, 4);
		if (!p)
			goto out_overflow;
		if (*p++ == xdr_zero) {
			void *buf;
			int len;

			/*
			 * End of current entries, read next chunk.
			 */

			free(ndir->stream.buf);

			buf = nfs_readdirattr_req(ndir->priv, &len, ndir->cookie);
			if (!buf)
				return NULL;

			xdr_init(&ndir->stream, buf, len);

			goto again;
		}
		return NULL; /* -EINVAL */
	}

	p = xdr_inline_decode(xdr, 4);
	if (!p)
		goto out_overflow;

	ret = decode_filename(xdr, ndir->ent.d_name, &len);
	if (ret)
		return NULL;

	/*
	 * The type (size and byte order) of nfscookie isn't defined in
	 * RFC 1094.  This implementation assumes that it's an XDR uint32.
	 */
	p = xdr_inline_decode(xdr, 4);
	if (!p)
		goto out_overflow;

	ndir->cookie = be32_to_cpup(p);

	return &ndir->ent;

out_overflow:

	printf("nfs: overflow error\n");

	return NULL;

}

static int nfs_closedir(struct device_d *dev, DIR *dir)
{
	struct nfs_dir *ndir = (void *)dir;

	nfs_do_close(ndir->priv);
	free(ndir->stream.buf);
	free(ndir);

	return 0;
}

static int nfs_stat(struct device_d *dev, const char *filename, struct stat *s)
{
	struct file_priv *priv;

	priv = nfs_do_stat(dev, filename, s);
	if (IS_ERR(priv)) {
		return PTR_ERR(priv);
	} else {
		nfs_do_close(priv);
		return 0;
	}
}

static int nfs_probe(struct device_d *dev)
{
	struct fs_device_d *fsdev = dev_to_fs_device(dev);
	struct nfs_priv *npriv = xzalloc(sizeof(struct nfs_priv));
	char *tmp = xstrdup(fsdev->backingstore);
	char *path;
	int ret;

	dev->priv = npriv;

	debug("nfs: mount: %s\n", fsdev->backingstore);

	path = strchr(tmp, ':');
	if (!path) {
		ret = -EINVAL;
		goto err;
	}

	*path = 0;

	npriv->path = xstrdup(path + 1);

	npriv->server = resolv(tmp);

	debug("nfs: server: %s path: %s\n", tmp, npriv->path);

	npriv->con = net_udp_new(npriv->server, 0, nfs_handler, npriv);
	if (IS_ERR(npriv->con)) {
		ret = PTR_ERR(npriv->con);
		goto err1;
	}

	/* Need a priviliged source port */
	net_udp_bind(npriv->con, 1000);

	ret = rpc_lookup_req(npriv, PROG_MOUNT, 1);
	if (ret) {
		printf("lookup mount port failed with %d\n", ret);
		goto err2;
	}

	ret = rpc_lookup_req(npriv, PROG_NFS, 2);
	if (ret) {
		printf("lookup nfs port failed with %d\n", ret);
		goto err2;
	}

	ret = nfs_mount_req(npriv);
	if (ret) {
		printf("mounting failed with %d\n", ret);
		goto err2;
	}

	free(tmp);

	return 0;

err2:
	net_unregister(npriv->con);
err1:
	free(npriv->path);
err:
	free(tmp);
	free(npriv);

	return ret;
}

static void nfs_remove(struct device_d *dev)
{
	struct nfs_priv *npriv = dev->priv;

	nfs_umount_req(npriv);

	net_unregister(npriv->con);
	free(npriv->path);
	free(npriv);
}

static struct fs_driver_d nfs_driver = {
	.open      = nfs_open,
	.close     = nfs_close,
	.read      = nfs_read,
	.lseek     = nfs_lseek,
	.opendir   = nfs_opendir,
	.readdir   = nfs_readdir,
	.closedir  = nfs_closedir,
	.stat      = nfs_stat,
	.create    = nfs_create,
	.unlink    = nfs_unlink,
	.mkdir     = nfs_mkdir,
	.rmdir     = nfs_rmdir,
	.write     = nfs_write,
	.truncate  = nfs_truncate,
	.readlink  = nfs_readlink,
	.flags     = 0,
	.drv = {
		.probe  = nfs_probe,
		.remove = nfs_remove,
		.name = "nfs",
	}
};

static int nfs_init(void)
{
	return register_fs_driver(&nfs_driver);
}
coredevice_initcall(nfs_init);