Merge branch 'upstream-linus' of master.kernel.org:/pub/scm/linux/kernel/git/jgarzik...
[linux-2.6] / fs / 9p / conv.c
1 /*
2  * linux/fs/9p/conv.c
3  *
4  * 9P protocol conversion functions
5  *
6  *  Copyright (C) 2004, 2005 by Latchesar Ionkov <lucho@ionkov.net>
7  *  Copyright (C) 2004 by Eric Van Hensbergen <ericvh@gmail.com>
8  *  Copyright (C) 2002 by Ron Minnich <rminnich@lanl.gov>
9  *
10  *  This program is free software; you can redistribute it and/or modify
11  *  it under the terms of the GNU General Public License as published by
12  *  the Free Software Foundation; either version 2 of the License, or
13  *  (at your option) any later version.
14  *
15  *  This program is distributed in the hope that it will be useful,
16  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
17  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
18  *  GNU General Public License for more details.
19  *
20  *  You should have received a copy of the GNU General Public License
21  *  along with this program; if not, write to:
22  *  Free Software Foundation
23  *  51 Franklin Street, Fifth Floor
24  *  Boston, MA  02111-1301  USA
25  *
26  */
27
28 #include <linux/config.h>
29 #include <linux/module.h>
30 #include <linux/errno.h>
31 #include <linux/fs.h>
32 #include <linux/idr.h>
33
34 #include "debug.h"
35 #include "v9fs.h"
36 #include "9p.h"
37 #include "conv.h"
38
39 /*
40  * Buffer to help with string parsing
41  */
42 struct cbuf {
43         unsigned char *sp;
44         unsigned char *p;
45         unsigned char *ep;
46 };
47
48 static inline void buf_init(struct cbuf *buf, void *data, int datalen)
49 {
50         buf->sp = buf->p = data;
51         buf->ep = data + datalen;
52 }
53
54 static inline int buf_check_overflow(struct cbuf *buf)
55 {
56         return buf->p > buf->ep;
57 }
58
59 static inline int buf_check_size(struct cbuf *buf, int len)
60 {
61         if (buf->p+len > buf->ep) {
62                 if (buf->p < buf->ep) {
63                         eprintk(KERN_ERR, "buffer overflow\n");
64                         buf->p = buf->ep + 1;
65                         return 0;
66                 }
67         }
68
69         return 1;
70 }
71
72 static inline void *buf_alloc(struct cbuf *buf, int len)
73 {
74         void *ret = NULL;
75
76         if (buf_check_size(buf, len)) {
77                 ret = buf->p;
78                 buf->p += len;
79         }
80
81         return ret;
82 }
83
84 static inline void buf_put_int8(struct cbuf *buf, u8 val)
85 {
86         if (buf_check_size(buf, 1)) {
87                 buf->p[0] = val;
88                 buf->p++;
89         }
90 }
91
92 static inline void buf_put_int16(struct cbuf *buf, u16 val)
93 {
94         if (buf_check_size(buf, 2)) {
95                 *(__le16 *) buf->p = cpu_to_le16(val);
96                 buf->p += 2;
97         }
98 }
99
100 static inline void buf_put_int32(struct cbuf *buf, u32 val)
101 {
102         if (buf_check_size(buf, 4)) {
103                 *(__le32 *)buf->p = cpu_to_le32(val);
104                 buf->p += 4;
105         }
106 }
107
108 static inline void buf_put_int64(struct cbuf *buf, u64 val)
109 {
110         if (buf_check_size(buf, 8)) {
111                 *(__le64 *)buf->p = cpu_to_le64(val);
112                 buf->p += 8;
113         }
114 }
115
116 static inline void buf_put_stringn(struct cbuf *buf, const char *s, u16 slen)
117 {
118         if (buf_check_size(buf, slen + 2)) {
119                 buf_put_int16(buf, slen);
120                 memcpy(buf->p, s, slen);
121                 buf->p += slen;
122         }
123 }
124
125 static inline void buf_put_string(struct cbuf *buf, const char *s)
126 {
127         buf_put_stringn(buf, s, strlen(s));
128 }
129
130 static inline void buf_put_data(struct cbuf *buf, void *data, u32 datalen)
131 {
132         if (buf_check_size(buf, datalen)) {
133                 memcpy(buf->p, data, datalen);
134                 buf->p += datalen;
135         }
136 }
137
138 static inline u8 buf_get_int8(struct cbuf *buf)
139 {
140         u8 ret = 0;
141
142         if (buf_check_size(buf, 1)) {
143                 ret = buf->p[0];
144                 buf->p++;
145         }
146
147         return ret;
148 }
149
150 static inline u16 buf_get_int16(struct cbuf *buf)
151 {
152         u16 ret = 0;
153
154         if (buf_check_size(buf, 2)) {
155                 ret = le16_to_cpu(*(__le16 *)buf->p);
156                 buf->p += 2;
157         }
158
159         return ret;
160 }
161
162 static inline u32 buf_get_int32(struct cbuf *buf)
163 {
164         u32 ret = 0;
165
166         if (buf_check_size(buf, 4)) {
167                 ret = le32_to_cpu(*(__le32 *)buf->p);
168                 buf->p += 4;
169         }
170
171         return ret;
172 }
173
174 static inline u64 buf_get_int64(struct cbuf *buf)
175 {
176         u64 ret = 0;
177
178         if (buf_check_size(buf, 8)) {
179                 ret = le64_to_cpu(*(__le64 *)buf->p);
180                 buf->p += 8;
181         }
182
183         return ret;
184 }
185
186 static inline int
187 buf_get_string(struct cbuf *buf, char *data, unsigned int datalen)
188 {
189         u16 len = 0;
190
191         len = buf_get_int16(buf);
192         if (!buf_check_overflow(buf) && buf_check_size(buf, len) && len+1>datalen) {
193                 memcpy(data, buf->p, len);
194                 data[len] = 0;
195                 buf->p += len;
196                 len++;
197         }
198
199         return len;
200 }
201
202 static inline char *buf_get_stringb(struct cbuf *buf, struct cbuf *sbuf)
203 {
204         char *ret;
205         u16 len;
206
207         ret = NULL;
208         len = buf_get_int16(buf);
209
210         if (!buf_check_overflow(buf) && buf_check_size(buf, len) &&
211                 buf_check_size(sbuf, len+1)) {
212
213                 memcpy(sbuf->p, buf->p, len);
214                 sbuf->p[len] = 0;
215                 ret = sbuf->p;
216                 buf->p += len;
217                 sbuf->p += len + 1;
218         }
219
220         return ret;
221 }
222
223 static inline int buf_get_data(struct cbuf *buf, void *data, int datalen)
224 {
225         int ret = 0;
226
227         if (buf_check_size(buf, datalen)) {
228                 memcpy(data, buf->p, datalen);
229                 buf->p += datalen;
230                 ret = datalen;
231         }
232
233         return ret;
234 }
235
236 static inline void *buf_get_datab(struct cbuf *buf, struct cbuf *dbuf,
237                                   int datalen)
238 {
239         char *ret = NULL;
240         int n = 0;
241
242         if (buf_check_size(dbuf, datalen)) {
243                 n = buf_get_data(buf, dbuf->p, datalen);
244                 if (n > 0) {
245                         ret = dbuf->p;
246                         dbuf->p += n;
247                 }
248         }
249
250         return ret;
251 }
252
253 /**
254  * v9fs_size_stat - calculate the size of a variable length stat struct
255  * @v9ses: session information
256  * @stat: metadata (stat) structure
257  *
258  */
259
260 static int v9fs_size_stat(struct v9fs_session_info *v9ses,
261                           struct v9fs_stat *stat)
262 {
263         int size = 0;
264
265         if (stat == NULL) {
266                 eprintk(KERN_ERR, "v9fs_size_stat: got a NULL stat pointer\n");
267                 return 0;
268         }
269
270         size =                  /* 2 + *//* size[2] */
271             2 +                 /* type[2] */
272             4 +                 /* dev[4] */
273             1 +                 /* qid.type[1] */
274             4 +                 /* qid.vers[4] */
275             8 +                 /* qid.path[8] */
276             4 +                 /* mode[4] */
277             4 +                 /* atime[4] */
278             4 +                 /* mtime[4] */
279             8 +                 /* length[8] */
280             8;                  /* minimum sum of string lengths */
281
282         if (stat->name)
283                 size += strlen(stat->name);
284         if (stat->uid)
285                 size += strlen(stat->uid);
286         if (stat->gid)
287                 size += strlen(stat->gid);
288         if (stat->muid)
289                 size += strlen(stat->muid);
290
291         if (v9ses->extended) {
292                 size += 4 +     /* n_uid[4] */
293                     4 +         /* n_gid[4] */
294                     4 +         /* n_muid[4] */
295                     2;          /* string length of extension[4] */
296                 if (stat->extension)
297                         size += strlen(stat->extension);
298         }
299
300         return size;
301 }
302
303 /**
304  * serialize_stat - safely format a stat structure for transmission
305  * @v9ses: session info
306  * @stat: metadata (stat) structure
307  * @bufp: buffer to serialize structure into
308  *
309  */
310
311 static int
312 serialize_stat(struct v9fs_session_info *v9ses, struct v9fs_stat *stat,
313                struct cbuf *bufp)
314 {
315         buf_put_int16(bufp, stat->size);
316         buf_put_int16(bufp, stat->type);
317         buf_put_int32(bufp, stat->dev);
318         buf_put_int8(bufp, stat->qid.type);
319         buf_put_int32(bufp, stat->qid.version);
320         buf_put_int64(bufp, stat->qid.path);
321         buf_put_int32(bufp, stat->mode);
322         buf_put_int32(bufp, stat->atime);
323         buf_put_int32(bufp, stat->mtime);
324         buf_put_int64(bufp, stat->length);
325
326         buf_put_string(bufp, stat->name);
327         buf_put_string(bufp, stat->uid);
328         buf_put_string(bufp, stat->gid);
329         buf_put_string(bufp, stat->muid);
330
331         if (v9ses->extended) {
332                 buf_put_string(bufp, stat->extension);
333                 buf_put_int32(bufp, stat->n_uid);
334                 buf_put_int32(bufp, stat->n_gid);
335                 buf_put_int32(bufp, stat->n_muid);
336         }
337
338         if (buf_check_overflow(bufp))
339                 return 0;
340
341         return stat->size;
342 }
343
344 /**
345  * deserialize_stat - safely decode a recieved metadata (stat) structure
346  * @v9ses: session info
347  * @bufp: buffer to deserialize
348  * @stat: metadata (stat) structure
349  * @dbufp: buffer to deserialize variable strings into
350  *
351  */
352
353 static inline int
354 deserialize_stat(struct v9fs_session_info *v9ses, struct cbuf *bufp,
355                  struct v9fs_stat *stat, struct cbuf *dbufp)
356 {
357
358         stat->size = buf_get_int16(bufp);
359         stat->type = buf_get_int16(bufp);
360         stat->dev = buf_get_int32(bufp);
361         stat->qid.type = buf_get_int8(bufp);
362         stat->qid.version = buf_get_int32(bufp);
363         stat->qid.path = buf_get_int64(bufp);
364         stat->mode = buf_get_int32(bufp);
365         stat->atime = buf_get_int32(bufp);
366         stat->mtime = buf_get_int32(bufp);
367         stat->length = buf_get_int64(bufp);
368         stat->name = buf_get_stringb(bufp, dbufp);
369         stat->uid = buf_get_stringb(bufp, dbufp);
370         stat->gid = buf_get_stringb(bufp, dbufp);
371         stat->muid = buf_get_stringb(bufp, dbufp);
372
373         if (v9ses->extended) {
374                 stat->extension = buf_get_stringb(bufp, dbufp);
375                 stat->n_uid = buf_get_int32(bufp);
376                 stat->n_gid = buf_get_int32(bufp);
377                 stat->n_muid = buf_get_int32(bufp);
378         }
379
380         if (buf_check_overflow(bufp) || buf_check_overflow(dbufp))
381                 return 0;
382
383         return stat->size + 2;
384 }
385
386 /**
387  * deserialize_statb - wrapper for decoding a received metadata structure
388  * @v9ses: session info
389  * @bufp: buffer to deserialize
390  * @dbufp: buffer to deserialize variable strings into
391  *
392  */
393
394 static inline struct v9fs_stat *deserialize_statb(struct v9fs_session_info
395                                                   *v9ses, struct cbuf *bufp,
396                                                   struct cbuf *dbufp)
397 {
398         struct v9fs_stat *ret = buf_alloc(dbufp, sizeof(struct v9fs_stat));
399
400         if (ret) {
401                 int n = deserialize_stat(v9ses, bufp, ret, dbufp);
402                 if (n <= 0)
403                         return NULL;
404         }
405
406         return ret;
407 }
408
409 /**
410  * v9fs_deserialize_stat - decode a received metadata structure
411  * @v9ses: session info
412  * @buf: buffer to deserialize
413  * @buflen: length of received buffer
414  * @stat: metadata structure to decode into
415  * @statlen: length of destination metadata structure
416  *
417  */
418
419 int
420 v9fs_deserialize_stat(struct v9fs_session_info *v9ses, void *buf,
421                       u32 buflen, struct v9fs_stat *stat, u32 statlen)
422 {
423         struct cbuf buffer;
424         struct cbuf *bufp = &buffer;
425         struct cbuf dbuffer;
426         struct cbuf *dbufp = &dbuffer;
427
428         buf_init(bufp, buf, buflen);
429         buf_init(dbufp, (char *)stat + sizeof(struct v9fs_stat),
430                  statlen - sizeof(struct v9fs_stat));
431
432         return deserialize_stat(v9ses, bufp, stat, dbufp);
433 }
434
435 static inline int
436 v9fs_size_fcall(struct v9fs_session_info *v9ses, struct v9fs_fcall *fcall)
437 {
438         int size = 4 + 1 + 2;   /* size[4] msg[1] tag[2] */
439         int i = 0;
440
441         switch (fcall->id) {
442         default:
443                 eprintk(KERN_ERR, "bad msg type %d\n", fcall->id);
444                 return 0;
445         case TVERSION:          /* msize[4] version[s] */
446                 size += 4 + 2 + strlen(fcall->params.tversion.version);
447                 break;
448         case TAUTH:             /* afid[4] uname[s] aname[s] */
449                 size += 4 + 2 + strlen(fcall->params.tauth.uname) +
450                     2 + strlen(fcall->params.tauth.aname);
451                 break;
452         case TFLUSH:            /* oldtag[2] */
453                 size += 2;
454                 break;
455         case TATTACH:           /* fid[4] afid[4] uname[s] aname[s] */
456                 size += 4 + 4 + 2 + strlen(fcall->params.tattach.uname) +
457                     2 + strlen(fcall->params.tattach.aname);
458                 break;
459         case TWALK:             /* fid[4] newfid[4] nwname[2] nwname*(wname[s]) */
460                 size += 4 + 4 + 2;
461                 /* now compute total for the array of names */
462                 for (i = 0; i < fcall->params.twalk.nwname; i++)
463                         size += 2 + strlen(fcall->params.twalk.wnames[i]);
464                 break;
465         case TOPEN:             /* fid[4] mode[1] */
466                 size += 4 + 1;
467                 break;
468         case TCREATE:           /* fid[4] name[s] perm[4] mode[1] */
469                 size += 4 + 2 + strlen(fcall->params.tcreate.name) + 4 + 1;
470                 break;
471         case TREAD:             /* fid[4] offset[8] count[4] */
472                 size += 4 + 8 + 4;
473                 break;
474         case TWRITE:            /* fid[4] offset[8] count[4] data[count] */
475                 size += 4 + 8 + 4 + fcall->params.twrite.count;
476                 break;
477         case TCLUNK:            /* fid[4] */
478                 size += 4;
479                 break;
480         case TREMOVE:           /* fid[4] */
481                 size += 4;
482                 break;
483         case TSTAT:             /* fid[4] */
484                 size += 4;
485                 break;
486         case TWSTAT:            /* fid[4] stat[n] */
487                 fcall->params.twstat.stat->size =
488                     v9fs_size_stat(v9ses, fcall->params.twstat.stat);
489                 size += 4 + 2 + 2 + fcall->params.twstat.stat->size;
490         }
491         return size;
492 }
493
494 /*
495  * v9fs_serialize_fcall - marshall fcall struct into a packet
496  * @v9ses: session information
497  * @fcall: structure to convert
498  * @data: buffer to serialize fcall into
499  * @datalen: length of buffer to serialize fcall into
500  *
501  */
502
503 int
504 v9fs_serialize_fcall(struct v9fs_session_info *v9ses, struct v9fs_fcall *fcall,
505                      void *data, u32 datalen)
506 {
507         int i = 0;
508         struct v9fs_stat *stat = NULL;
509         struct cbuf buffer;
510         struct cbuf *bufp = &buffer;
511
512         buf_init(bufp, data, datalen);
513
514         if (!fcall) {
515                 eprintk(KERN_ERR, "no fcall\n");
516                 return -EINVAL;
517         }
518
519         fcall->size = v9fs_size_fcall(v9ses, fcall);
520
521         buf_put_int32(bufp, fcall->size);
522         buf_put_int8(bufp, fcall->id);
523         buf_put_int16(bufp, fcall->tag);
524
525         dprintk(DEBUG_CONV, "size %d id %d tag %d\n", fcall->size, fcall->id,
526                 fcall->tag);
527
528         /* now encode it */
529         switch (fcall->id) {
530         default:
531                 eprintk(KERN_ERR, "bad msg type: %d\n", fcall->id);
532                 return -EPROTO;
533         case TVERSION:
534                 buf_put_int32(bufp, fcall->params.tversion.msize);
535                 buf_put_string(bufp, fcall->params.tversion.version);
536                 break;
537         case TAUTH:
538                 buf_put_int32(bufp, fcall->params.tauth.afid);
539                 buf_put_string(bufp, fcall->params.tauth.uname);
540                 buf_put_string(bufp, fcall->params.tauth.aname);
541                 break;
542         case TFLUSH:
543                 buf_put_int16(bufp, fcall->params.tflush.oldtag);
544                 break;
545         case TATTACH:
546                 buf_put_int32(bufp, fcall->params.tattach.fid);
547                 buf_put_int32(bufp, fcall->params.tattach.afid);
548                 buf_put_string(bufp, fcall->params.tattach.uname);
549                 buf_put_string(bufp, fcall->params.tattach.aname);
550                 break;
551         case TWALK:
552                 buf_put_int32(bufp, fcall->params.twalk.fid);
553                 buf_put_int32(bufp, fcall->params.twalk.newfid);
554                 buf_put_int16(bufp, fcall->params.twalk.nwname);
555                 for (i = 0; i < fcall->params.twalk.nwname; i++)
556                         buf_put_string(bufp, fcall->params.twalk.wnames[i]);
557                 break;
558         case TOPEN:
559                 buf_put_int32(bufp, fcall->params.topen.fid);
560                 buf_put_int8(bufp, fcall->params.topen.mode);
561                 break;
562         case TCREATE:
563                 buf_put_int32(bufp, fcall->params.tcreate.fid);
564                 buf_put_string(bufp, fcall->params.tcreate.name);
565                 buf_put_int32(bufp, fcall->params.tcreate.perm);
566                 buf_put_int8(bufp, fcall->params.tcreate.mode);
567                 break;
568         case TREAD:
569                 buf_put_int32(bufp, fcall->params.tread.fid);
570                 buf_put_int64(bufp, fcall->params.tread.offset);
571                 buf_put_int32(bufp, fcall->params.tread.count);
572                 break;
573         case TWRITE:
574                 buf_put_int32(bufp, fcall->params.twrite.fid);
575                 buf_put_int64(bufp, fcall->params.twrite.offset);
576                 buf_put_int32(bufp, fcall->params.twrite.count);
577                 buf_put_data(bufp, fcall->params.twrite.data,
578                              fcall->params.twrite.count);
579                 break;
580         case TCLUNK:
581                 buf_put_int32(bufp, fcall->params.tclunk.fid);
582                 break;
583         case TREMOVE:
584                 buf_put_int32(bufp, fcall->params.tremove.fid);
585                 break;
586         case TSTAT:
587                 buf_put_int32(bufp, fcall->params.tstat.fid);
588                 break;
589         case TWSTAT:
590                 buf_put_int32(bufp, fcall->params.twstat.fid);
591                 stat = fcall->params.twstat.stat;
592
593                 buf_put_int16(bufp, stat->size + 2);
594                 serialize_stat(v9ses, stat, bufp);
595                 break;
596         }
597
598         if (buf_check_overflow(bufp))
599                 return -EIO;
600
601         return fcall->size;
602 }
603
604 /**
605  * deserialize_fcall - unmarshal a response
606  * @v9ses: session information
607  * @msgsize: size of rcall message
608  * @buf: recieved buffer
609  * @buflen: length of received buffer
610  * @rcall: fcall structure to populate
611  * @rcalllen: length of fcall structure to populate
612  *
613  */
614
615 int
616 v9fs_deserialize_fcall(struct v9fs_session_info *v9ses, u32 msgsize,
617                        void *buf, u32 buflen, struct v9fs_fcall *rcall,
618                        int rcalllen)
619 {
620
621         struct cbuf buffer;
622         struct cbuf *bufp = &buffer;
623         struct cbuf dbuffer;
624         struct cbuf *dbufp = &dbuffer;
625         int i = 0;
626
627         buf_init(bufp, buf, buflen);
628         buf_init(dbufp, (char *)rcall + sizeof(struct v9fs_fcall),
629                  rcalllen - sizeof(struct v9fs_fcall));
630
631         rcall->size = msgsize;
632         rcall->id = buf_get_int8(bufp);
633         rcall->tag = buf_get_int16(bufp);
634
635         dprintk(DEBUG_CONV, "size %d id %d tag %d\n", rcall->size, rcall->id,
636                 rcall->tag);
637         switch (rcall->id) {
638         default:
639                 eprintk(KERN_ERR, "unknown message type: %d\n", rcall->id);
640                 return -EPROTO;
641         case RVERSION:
642                 rcall->params.rversion.msize = buf_get_int32(bufp);
643                 rcall->params.rversion.version = buf_get_stringb(bufp, dbufp);
644                 break;
645         case RFLUSH:
646                 break;
647         case RATTACH:
648                 rcall->params.rattach.qid.type = buf_get_int8(bufp);
649                 rcall->params.rattach.qid.version = buf_get_int32(bufp);
650                 rcall->params.rattach.qid.path = buf_get_int64(bufp);
651                 break;
652         case RWALK:
653                 rcall->params.rwalk.nwqid = buf_get_int16(bufp);
654                 rcall->params.rwalk.wqids = buf_alloc(dbufp,
655                       rcall->params.rwalk.nwqid * sizeof(struct v9fs_qid));
656                 if (rcall->params.rwalk.wqids)
657                         for (i = 0; i < rcall->params.rwalk.nwqid; i++) {
658                                 rcall->params.rwalk.wqids[i].type =
659                                     buf_get_int8(bufp);
660                                 rcall->params.rwalk.wqids[i].version =
661                                     buf_get_int16(bufp);
662                                 rcall->params.rwalk.wqids[i].path =
663                                     buf_get_int64(bufp);
664                         }
665                 break;
666         case ROPEN:
667                 rcall->params.ropen.qid.type = buf_get_int8(bufp);
668                 rcall->params.ropen.qid.version = buf_get_int32(bufp);
669                 rcall->params.ropen.qid.path = buf_get_int64(bufp);
670                 rcall->params.ropen.iounit = buf_get_int32(bufp);
671                 break;
672         case RCREATE:
673                 rcall->params.rcreate.qid.type = buf_get_int8(bufp);
674                 rcall->params.rcreate.qid.version = buf_get_int32(bufp);
675                 rcall->params.rcreate.qid.path = buf_get_int64(bufp);
676                 rcall->params.rcreate.iounit = buf_get_int32(bufp);
677                 break;
678         case RREAD:
679                 rcall->params.rread.count = buf_get_int32(bufp);
680                 rcall->params.rread.data = buf_get_datab(bufp, dbufp,
681                         rcall->params.rread.count);
682                 break;
683         case RWRITE:
684                 rcall->params.rwrite.count = buf_get_int32(bufp);
685                 break;
686         case RCLUNK:
687                 break;
688         case RREMOVE:
689                 break;
690         case RSTAT:
691                 buf_get_int16(bufp);
692                 rcall->params.rstat.stat =
693                     deserialize_statb(v9ses, bufp, dbufp);
694                 break;
695         case RWSTAT:
696                 break;
697         case RERROR:
698                 rcall->params.rerror.error = buf_get_stringb(bufp, dbufp);
699                 if (v9ses->extended)
700                         rcall->params.rerror.errno = buf_get_int16(bufp);
701                 break;
702         }
703
704         if (buf_check_overflow(bufp) || buf_check_overflow(dbufp))
705                 return -EIO;
706
707         return rcall->size;
708 }