SELinux: don't BUG if fs reuses a superblock
[sfrench/cifs-2.6.git] / net / sunrpc / xdr.c
1 /*
2  * linux/net/sunrpc/xdr.c
3  *
4  * Generic XDR support.
5  *
6  * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
7  */
8
9 #include <linux/module.h>
10 #include <linux/types.h>
11 #include <linux/string.h>
12 #include <linux/kernel.h>
13 #include <linux/pagemap.h>
14 #include <linux/errno.h>
15 #include <linux/sunrpc/xdr.h>
16 #include <linux/sunrpc/msg_prot.h>
17
18 /*
19  * XDR functions for basic NFS types
20  */
21 __be32 *
22 xdr_encode_netobj(__be32 *p, const struct xdr_netobj *obj)
23 {
24         unsigned int    quadlen = XDR_QUADLEN(obj->len);
25
26         p[quadlen] = 0;         /* zero trailing bytes */
27         *p++ = htonl(obj->len);
28         memcpy(p, obj->data, obj->len);
29         return p + XDR_QUADLEN(obj->len);
30 }
31 EXPORT_SYMBOL(xdr_encode_netobj);
32
33 __be32 *
34 xdr_decode_netobj(__be32 *p, struct xdr_netobj *obj)
35 {
36         unsigned int    len;
37
38         if ((len = ntohl(*p++)) > XDR_MAX_NETOBJ)
39                 return NULL;
40         obj->len  = len;
41         obj->data = (u8 *) p;
42         return p + XDR_QUADLEN(len);
43 }
44 EXPORT_SYMBOL(xdr_decode_netobj);
45
46 /**
47  * xdr_encode_opaque_fixed - Encode fixed length opaque data
48  * @p: pointer to current position in XDR buffer.
49  * @ptr: pointer to data to encode (or NULL)
50  * @nbytes: size of data.
51  *
52  * Copy the array of data of length nbytes at ptr to the XDR buffer
53  * at position p, then align to the next 32-bit boundary by padding
54  * with zero bytes (see RFC1832).
55  * Note: if ptr is NULL, only the padding is performed.
56  *
57  * Returns the updated current XDR buffer position
58  *
59  */
60 __be32 *xdr_encode_opaque_fixed(__be32 *p, const void *ptr, unsigned int nbytes)
61 {
62         if (likely(nbytes != 0)) {
63                 unsigned int quadlen = XDR_QUADLEN(nbytes);
64                 unsigned int padding = (quadlen << 2) - nbytes;
65
66                 if (ptr != NULL)
67                         memcpy(p, ptr, nbytes);
68                 if (padding != 0)
69                         memset((char *)p + nbytes, 0, padding);
70                 p += quadlen;
71         }
72         return p;
73 }
74 EXPORT_SYMBOL(xdr_encode_opaque_fixed);
75
76 /**
77  * xdr_encode_opaque - Encode variable length opaque data
78  * @p: pointer to current position in XDR buffer.
79  * @ptr: pointer to data to encode (or NULL)
80  * @nbytes: size of data.
81  *
82  * Returns the updated current XDR buffer position
83  */
84 __be32 *xdr_encode_opaque(__be32 *p, const void *ptr, unsigned int nbytes)
85 {
86         *p++ = htonl(nbytes);
87         return xdr_encode_opaque_fixed(p, ptr, nbytes);
88 }
89 EXPORT_SYMBOL(xdr_encode_opaque);
90
91 __be32 *
92 xdr_encode_string(__be32 *p, const char *string)
93 {
94         return xdr_encode_array(p, string, strlen(string));
95 }
96 EXPORT_SYMBOL(xdr_encode_string);
97
98 __be32 *
99 xdr_decode_string_inplace(__be32 *p, char **sp,
100                           unsigned int *lenp, unsigned int maxlen)
101 {
102         u32 len;
103
104         len = ntohl(*p++);
105         if (len > maxlen)
106                 return NULL;
107         *lenp = len;
108         *sp = (char *) p;
109         return p + XDR_QUADLEN(len);
110 }
111 EXPORT_SYMBOL(xdr_decode_string_inplace);
112
113 void
114 xdr_encode_pages(struct xdr_buf *xdr, struct page **pages, unsigned int base,
115                  unsigned int len)
116 {
117         struct kvec *tail = xdr->tail;
118         u32 *p;
119
120         xdr->pages = pages;
121         xdr->page_base = base;
122         xdr->page_len = len;
123
124         p = (u32 *)xdr->head[0].iov_base + XDR_QUADLEN(xdr->head[0].iov_len);
125         tail->iov_base = p;
126         tail->iov_len = 0;
127
128         if (len & 3) {
129                 unsigned int pad = 4 - (len & 3);
130
131                 *p = 0;
132                 tail->iov_base = (char *)p + (len & 3);
133                 tail->iov_len  = pad;
134                 len += pad;
135         }
136         xdr->buflen += len;
137         xdr->len += len;
138 }
139 EXPORT_SYMBOL(xdr_encode_pages);
140
141 void
142 xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
143                  struct page **pages, unsigned int base, unsigned int len)
144 {
145         struct kvec *head = xdr->head;
146         struct kvec *tail = xdr->tail;
147         char *buf = (char *)head->iov_base;
148         unsigned int buflen = head->iov_len;
149
150         head->iov_len  = offset;
151
152         xdr->pages = pages;
153         xdr->page_base = base;
154         xdr->page_len = len;
155
156         tail->iov_base = buf + offset;
157         tail->iov_len = buflen - offset;
158
159         xdr->buflen += len;
160 }
161 EXPORT_SYMBOL(xdr_inline_pages);
162
163 /*
164  * Helper routines for doing 'memmove' like operations on a struct xdr_buf
165  *
166  * _shift_data_right_pages
167  * @pages: vector of pages containing both the source and dest memory area.
168  * @pgto_base: page vector address of destination
169  * @pgfrom_base: page vector address of source
170  * @len: number of bytes to copy
171  *
172  * Note: the addresses pgto_base and pgfrom_base are both calculated in
173  *       the same way:
174  *            if a memory area starts at byte 'base' in page 'pages[i]',
175  *            then its address is given as (i << PAGE_CACHE_SHIFT) + base
176  * Also note: pgfrom_base must be < pgto_base, but the memory areas
177  *      they point to may overlap.
178  */
179 static void
180 _shift_data_right_pages(struct page **pages, size_t pgto_base,
181                 size_t pgfrom_base, size_t len)
182 {
183         struct page **pgfrom, **pgto;
184         char *vfrom, *vto;
185         size_t copy;
186
187         BUG_ON(pgto_base <= pgfrom_base);
188
189         pgto_base += len;
190         pgfrom_base += len;
191
192         pgto = pages + (pgto_base >> PAGE_CACHE_SHIFT);
193         pgfrom = pages + (pgfrom_base >> PAGE_CACHE_SHIFT);
194
195         pgto_base &= ~PAGE_CACHE_MASK;
196         pgfrom_base &= ~PAGE_CACHE_MASK;
197
198         do {
199                 /* Are any pointers crossing a page boundary? */
200                 if (pgto_base == 0) {
201                         pgto_base = PAGE_CACHE_SIZE;
202                         pgto--;
203                 }
204                 if (pgfrom_base == 0) {
205                         pgfrom_base = PAGE_CACHE_SIZE;
206                         pgfrom--;
207                 }
208
209                 copy = len;
210                 if (copy > pgto_base)
211                         copy = pgto_base;
212                 if (copy > pgfrom_base)
213                         copy = pgfrom_base;
214                 pgto_base -= copy;
215                 pgfrom_base -= copy;
216
217                 vto = kmap_atomic(*pgto, KM_USER0);
218                 vfrom = kmap_atomic(*pgfrom, KM_USER1);
219                 memmove(vto + pgto_base, vfrom + pgfrom_base, copy);
220                 flush_dcache_page(*pgto);
221                 kunmap_atomic(vfrom, KM_USER1);
222                 kunmap_atomic(vto, KM_USER0);
223
224         } while ((len -= copy) != 0);
225 }
226
227 /*
228  * _copy_to_pages
229  * @pages: array of pages
230  * @pgbase: page vector address of destination
231  * @p: pointer to source data
232  * @len: length
233  *
234  * Copies data from an arbitrary memory location into an array of pages
235  * The copy is assumed to be non-overlapping.
236  */
237 static void
238 _copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len)
239 {
240         struct page **pgto;
241         char *vto;
242         size_t copy;
243
244         pgto = pages + (pgbase >> PAGE_CACHE_SHIFT);
245         pgbase &= ~PAGE_CACHE_MASK;
246
247         do {
248                 copy = PAGE_CACHE_SIZE - pgbase;
249                 if (copy > len)
250                         copy = len;
251
252                 vto = kmap_atomic(*pgto, KM_USER0);
253                 memcpy(vto + pgbase, p, copy);
254                 kunmap_atomic(vto, KM_USER0);
255
256                 pgbase += copy;
257                 if (pgbase == PAGE_CACHE_SIZE) {
258                         flush_dcache_page(*pgto);
259                         pgbase = 0;
260                         pgto++;
261                 }
262                 p += copy;
263
264         } while ((len -= copy) != 0);
265         flush_dcache_page(*pgto);
266 }
267
268 /*
269  * _copy_from_pages
270  * @p: pointer to destination
271  * @pages: array of pages
272  * @pgbase: offset of source data
273  * @len: length
274  *
275  * Copies data into an arbitrary memory location from an array of pages
276  * The copy is assumed to be non-overlapping.
277  */
278 static void
279 _copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
280 {
281         struct page **pgfrom;
282         char *vfrom;
283         size_t copy;
284
285         pgfrom = pages + (pgbase >> PAGE_CACHE_SHIFT);
286         pgbase &= ~PAGE_CACHE_MASK;
287
288         do {
289                 copy = PAGE_CACHE_SIZE - pgbase;
290                 if (copy > len)
291                         copy = len;
292
293                 vfrom = kmap_atomic(*pgfrom, KM_USER0);
294                 memcpy(p, vfrom + pgbase, copy);
295                 kunmap_atomic(vfrom, KM_USER0);
296
297                 pgbase += copy;
298                 if (pgbase == PAGE_CACHE_SIZE) {
299                         pgbase = 0;
300                         pgfrom++;
301                 }
302                 p += copy;
303
304         } while ((len -= copy) != 0);
305 }
306
307 /*
308  * xdr_shrink_bufhead
309  * @buf: xdr_buf
310  * @len: bytes to remove from buf->head[0]
311  *
312  * Shrinks XDR buffer's header kvec buf->head[0] by
313  * 'len' bytes. The extra data is not lost, but is instead
314  * moved into the inlined pages and/or the tail.
315  */
316 static void
317 xdr_shrink_bufhead(struct xdr_buf *buf, size_t len)
318 {
319         struct kvec *head, *tail;
320         size_t copy, offs;
321         unsigned int pglen = buf->page_len;
322
323         tail = buf->tail;
324         head = buf->head;
325         BUG_ON (len > head->iov_len);
326
327         /* Shift the tail first */
328         if (tail->iov_len != 0) {
329                 if (tail->iov_len > len) {
330                         copy = tail->iov_len - len;
331                         memmove((char *)tail->iov_base + len,
332                                         tail->iov_base, copy);
333                 }
334                 /* Copy from the inlined pages into the tail */
335                 copy = len;
336                 if (copy > pglen)
337                         copy = pglen;
338                 offs = len - copy;
339                 if (offs >= tail->iov_len)
340                         copy = 0;
341                 else if (copy > tail->iov_len - offs)
342                         copy = tail->iov_len - offs;
343                 if (copy != 0)
344                         _copy_from_pages((char *)tail->iov_base + offs,
345                                         buf->pages,
346                                         buf->page_base + pglen + offs - len,
347                                         copy);
348                 /* Do we also need to copy data from the head into the tail ? */
349                 if (len > pglen) {
350                         offs = copy = len - pglen;
351                         if (copy > tail->iov_len)
352                                 copy = tail->iov_len;
353                         memcpy(tail->iov_base,
354                                         (char *)head->iov_base +
355                                         head->iov_len - offs,
356                                         copy);
357                 }
358         }
359         /* Now handle pages */
360         if (pglen != 0) {
361                 if (pglen > len)
362                         _shift_data_right_pages(buf->pages,
363                                         buf->page_base + len,
364                                         buf->page_base,
365                                         pglen - len);
366                 copy = len;
367                 if (len > pglen)
368                         copy = pglen;
369                 _copy_to_pages(buf->pages, buf->page_base,
370                                 (char *)head->iov_base + head->iov_len - len,
371                                 copy);
372         }
373         head->iov_len -= len;
374         buf->buflen -= len;
375         /* Have we truncated the message? */
376         if (buf->len > buf->buflen)
377                 buf->len = buf->buflen;
378 }
379
380 /*
381  * xdr_shrink_pagelen
382  * @buf: xdr_buf
383  * @len: bytes to remove from buf->pages
384  *
385  * Shrinks XDR buffer's page array buf->pages by
386  * 'len' bytes. The extra data is not lost, but is instead
387  * moved into the tail.
388  */
389 static void
390 xdr_shrink_pagelen(struct xdr_buf *buf, size_t len)
391 {
392         struct kvec *tail;
393         size_t copy;
394         char *p;
395         unsigned int pglen = buf->page_len;
396
397         tail = buf->tail;
398         BUG_ON (len > pglen);
399
400         /* Shift the tail first */
401         if (tail->iov_len != 0) {
402                 p = (char *)tail->iov_base + len;
403                 if (tail->iov_len > len) {
404                         copy = tail->iov_len - len;
405                         memmove(p, tail->iov_base, copy);
406                 } else
407                         buf->buflen -= len;
408                 /* Copy from the inlined pages into the tail */
409                 copy = len;
410                 if (copy > tail->iov_len)
411                         copy = tail->iov_len;
412                 _copy_from_pages((char *)tail->iov_base,
413                                 buf->pages, buf->page_base + pglen - len,
414                                 copy);
415         }
416         buf->page_len -= len;
417         buf->buflen -= len;
418         /* Have we truncated the message? */
419         if (buf->len > buf->buflen)
420                 buf->len = buf->buflen;
421 }
422
423 void
424 xdr_shift_buf(struct xdr_buf *buf, size_t len)
425 {
426         xdr_shrink_bufhead(buf, len);
427 }
428 EXPORT_SYMBOL(xdr_shift_buf);
429
430 /**
431  * xdr_init_encode - Initialize a struct xdr_stream for sending data.
432  * @xdr: pointer to xdr_stream struct
433  * @buf: pointer to XDR buffer in which to encode data
434  * @p: current pointer inside XDR buffer
435  *
436  * Note: at the moment the RPC client only passes the length of our
437  *       scratch buffer in the xdr_buf's header kvec. Previously this
438  *       meant we needed to call xdr_adjust_iovec() after encoding the
439  *       data. With the new scheme, the xdr_stream manages the details
440  *       of the buffer length, and takes care of adjusting the kvec
441  *       length for us.
442  */
443 void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
444 {
445         struct kvec *iov = buf->head;
446         int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
447
448         BUG_ON(scratch_len < 0);
449         xdr->buf = buf;
450         xdr->iov = iov;
451         xdr->p = (__be32 *)((char *)iov->iov_base + iov->iov_len);
452         xdr->end = (__be32 *)((char *)iov->iov_base + scratch_len);
453         BUG_ON(iov->iov_len > scratch_len);
454
455         if (p != xdr->p && p != NULL) {
456                 size_t len;
457
458                 BUG_ON(p < xdr->p || p > xdr->end);
459                 len = (char *)p - (char *)xdr->p;
460                 xdr->p = p;
461                 buf->len += len;
462                 iov->iov_len += len;
463         }
464 }
465 EXPORT_SYMBOL(xdr_init_encode);
466
467 /**
468  * xdr_reserve_space - Reserve buffer space for sending
469  * @xdr: pointer to xdr_stream
470  * @nbytes: number of bytes to reserve
471  *
472  * Checks that we have enough buffer space to encode 'nbytes' more
473  * bytes of data. If so, update the total xdr_buf length, and
474  * adjust the length of the current kvec.
475  */
476 __be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
477 {
478         __be32 *p = xdr->p;
479         __be32 *q;
480
481         /* align nbytes on the next 32-bit boundary */
482         nbytes += 3;
483         nbytes &= ~3;
484         q = p + (nbytes >> 2);
485         if (unlikely(q > xdr->end || q < p))
486                 return NULL;
487         xdr->p = q;
488         xdr->iov->iov_len += nbytes;
489         xdr->buf->len += nbytes;
490         return p;
491 }
492 EXPORT_SYMBOL(xdr_reserve_space);
493
494 /**
495  * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
496  * @xdr: pointer to xdr_stream
497  * @pages: list of pages
498  * @base: offset of first byte
499  * @len: length of data in bytes
500  *
501  */
502 void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
503                  unsigned int len)
504 {
505         struct xdr_buf *buf = xdr->buf;
506         struct kvec *iov = buf->tail;
507         buf->pages = pages;
508         buf->page_base = base;
509         buf->page_len = len;
510
511         iov->iov_base = (char *)xdr->p;
512         iov->iov_len  = 0;
513         xdr->iov = iov;
514
515         if (len & 3) {
516                 unsigned int pad = 4 - (len & 3);
517
518                 BUG_ON(xdr->p >= xdr->end);
519                 iov->iov_base = (char *)xdr->p + (len & 3);
520                 iov->iov_len  += pad;
521                 len += pad;
522                 *xdr->p++ = 0;
523         }
524         buf->buflen += len;
525         buf->len += len;
526 }
527 EXPORT_SYMBOL(xdr_write_pages);
528
529 /**
530  * xdr_init_decode - Initialize an xdr_stream for decoding data.
531  * @xdr: pointer to xdr_stream struct
532  * @buf: pointer to XDR buffer from which to decode data
533  * @p: current pointer inside XDR buffer
534  */
535 void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
536 {
537         struct kvec *iov = buf->head;
538         unsigned int len = iov->iov_len;
539
540         if (len > buf->len)
541                 len = buf->len;
542         xdr->buf = buf;
543         xdr->iov = iov;
544         xdr->p = p;
545         xdr->end = (__be32 *)((char *)iov->iov_base + len);
546 }
547 EXPORT_SYMBOL(xdr_init_decode);
548
549 /**
550  * xdr_inline_decode - Retrieve non-page XDR data to decode
551  * @xdr: pointer to xdr_stream struct
552  * @nbytes: number of bytes of data to decode
553  *
554  * Check if the input buffer is long enough to enable us to decode
555  * 'nbytes' more bytes of data starting at the current position.
556  * If so return the current pointer, then update the current
557  * pointer position.
558  */
559 __be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
560 {
561         __be32 *p = xdr->p;
562         __be32 *q = p + XDR_QUADLEN(nbytes);
563
564         if (unlikely(q > xdr->end || q < p))
565                 return NULL;
566         xdr->p = q;
567         return p;
568 }
569 EXPORT_SYMBOL(xdr_inline_decode);
570
571 /**
572  * xdr_read_pages - Ensure page-based XDR data to decode is aligned at current pointer position
573  * @xdr: pointer to xdr_stream struct
574  * @len: number of bytes of page data
575  *
576  * Moves data beyond the current pointer position from the XDR head[] buffer
577  * into the page list. Any data that lies beyond current position + "len"
578  * bytes is moved into the XDR tail[].
579  */
580 void xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
581 {
582         struct xdr_buf *buf = xdr->buf;
583         struct kvec *iov;
584         ssize_t shift;
585         unsigned int end;
586         int padding;
587
588         /* Realign pages to current pointer position */
589         iov  = buf->head;
590         shift = iov->iov_len + (char *)iov->iov_base - (char *)xdr->p;
591         if (shift > 0)
592                 xdr_shrink_bufhead(buf, shift);
593
594         /* Truncate page data and move it into the tail */
595         if (buf->page_len > len)
596                 xdr_shrink_pagelen(buf, buf->page_len - len);
597         padding = (XDR_QUADLEN(len) << 2) - len;
598         xdr->iov = iov = buf->tail;
599         /* Compute remaining message length.  */
600         end = iov->iov_len;
601         shift = buf->buflen - buf->len;
602         if (shift < end)
603                 end -= shift;
604         else if (shift > 0)
605                 end = 0;
606         /*
607          * Position current pointer at beginning of tail, and
608          * set remaining message length.
609          */
610         xdr->p = (__be32 *)((char *)iov->iov_base + padding);
611         xdr->end = (__be32 *)((char *)iov->iov_base + end);
612 }
613 EXPORT_SYMBOL(xdr_read_pages);
614
615 /**
616  * xdr_enter_page - decode data from the XDR page
617  * @xdr: pointer to xdr_stream struct
618  * @len: number of bytes of page data
619  *
620  * Moves data beyond the current pointer position from the XDR head[] buffer
621  * into the page list. Any data that lies beyond current position + "len"
622  * bytes is moved into the XDR tail[]. The current pointer is then
623  * repositioned at the beginning of the first XDR page.
624  */
625 void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
626 {
627         char * kaddr = page_address(xdr->buf->pages[0]);
628         xdr_read_pages(xdr, len);
629         /*
630          * Position current pointer at beginning of tail, and
631          * set remaining message length.
632          */
633         if (len > PAGE_CACHE_SIZE - xdr->buf->page_base)
634                 len = PAGE_CACHE_SIZE - xdr->buf->page_base;
635         xdr->p = (__be32 *)(kaddr + xdr->buf->page_base);
636         xdr->end = (__be32 *)((char *)xdr->p + len);
637 }
638 EXPORT_SYMBOL(xdr_enter_page);
639
640 static struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
641
642 void
643 xdr_buf_from_iov(struct kvec *iov, struct xdr_buf *buf)
644 {
645         buf->head[0] = *iov;
646         buf->tail[0] = empty_iov;
647         buf->page_len = 0;
648         buf->buflen = buf->len = iov->iov_len;
649 }
650 EXPORT_SYMBOL(xdr_buf_from_iov);
651
652 /* Sets subbuf to the portion of buf of length len beginning base bytes
653  * from the start of buf. Returns -1 if base of length are out of bounds. */
654 int
655 xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
656                         unsigned int base, unsigned int len)
657 {
658         subbuf->buflen = subbuf->len = len;
659         if (base < buf->head[0].iov_len) {
660                 subbuf->head[0].iov_base = buf->head[0].iov_base + base;
661                 subbuf->head[0].iov_len = min_t(unsigned int, len,
662                                                 buf->head[0].iov_len - base);
663                 len -= subbuf->head[0].iov_len;
664                 base = 0;
665         } else {
666                 subbuf->head[0].iov_base = NULL;
667                 subbuf->head[0].iov_len = 0;
668                 base -= buf->head[0].iov_len;
669         }
670
671         if (base < buf->page_len) {
672                 subbuf->page_len = min(buf->page_len - base, len);
673                 base += buf->page_base;
674                 subbuf->page_base = base & ~PAGE_CACHE_MASK;
675                 subbuf->pages = &buf->pages[base >> PAGE_CACHE_SHIFT];
676                 len -= subbuf->page_len;
677                 base = 0;
678         } else {
679                 base -= buf->page_len;
680                 subbuf->page_len = 0;
681         }
682
683         if (base < buf->tail[0].iov_len) {
684                 subbuf->tail[0].iov_base = buf->tail[0].iov_base + base;
685                 subbuf->tail[0].iov_len = min_t(unsigned int, len,
686                                                 buf->tail[0].iov_len - base);
687                 len -= subbuf->tail[0].iov_len;
688                 base = 0;
689         } else {
690                 subbuf->tail[0].iov_base = NULL;
691                 subbuf->tail[0].iov_len = 0;
692                 base -= buf->tail[0].iov_len;
693         }
694
695         if (base || len)
696                 return -1;
697         return 0;
698 }
699 EXPORT_SYMBOL(xdr_buf_subsegment);
700
701 static void __read_bytes_from_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
702 {
703         unsigned int this_len;
704
705         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
706         memcpy(obj, subbuf->head[0].iov_base, this_len);
707         len -= this_len;
708         obj += this_len;
709         this_len = min_t(unsigned int, len, subbuf->page_len);
710         if (this_len)
711                 _copy_from_pages(obj, subbuf->pages, subbuf->page_base, this_len);
712         len -= this_len;
713         obj += this_len;
714         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
715         memcpy(obj, subbuf->tail[0].iov_base, this_len);
716 }
717
718 /* obj is assumed to point to allocated memory of size at least len: */
719 int read_bytes_from_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
720 {
721         struct xdr_buf subbuf;
722         int status;
723
724         status = xdr_buf_subsegment(buf, &subbuf, base, len);
725         if (status != 0)
726                 return status;
727         __read_bytes_from_xdr_buf(&subbuf, obj, len);
728         return 0;
729 }
730 EXPORT_SYMBOL(read_bytes_from_xdr_buf);
731
732 static void __write_bytes_to_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
733 {
734         unsigned int this_len;
735
736         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
737         memcpy(subbuf->head[0].iov_base, obj, this_len);
738         len -= this_len;
739         obj += this_len;
740         this_len = min_t(unsigned int, len, subbuf->page_len);
741         if (this_len)
742                 _copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
743         len -= this_len;
744         obj += this_len;
745         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
746         memcpy(subbuf->tail[0].iov_base, obj, this_len);
747 }
748
749 /* obj is assumed to point to allocated memory of size at least len: */
750 int write_bytes_to_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
751 {
752         struct xdr_buf subbuf;
753         int status;
754
755         status = xdr_buf_subsegment(buf, &subbuf, base, len);
756         if (status != 0)
757                 return status;
758         __write_bytes_to_xdr_buf(&subbuf, obj, len);
759         return 0;
760 }
761
762 int
763 xdr_decode_word(struct xdr_buf *buf, unsigned int base, u32 *obj)
764 {
765         __be32  raw;
766         int     status;
767
768         status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
769         if (status)
770                 return status;
771         *obj = ntohl(raw);
772         return 0;
773 }
774 EXPORT_SYMBOL(xdr_decode_word);
775
776 int
777 xdr_encode_word(struct xdr_buf *buf, unsigned int base, u32 obj)
778 {
779         __be32  raw = htonl(obj);
780
781         return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
782 }
783 EXPORT_SYMBOL(xdr_encode_word);
784
785 /* If the netobj starting offset bytes from the start of xdr_buf is contained
786  * entirely in the head or the tail, set object to point to it; otherwise
787  * try to find space for it at the end of the tail, copy it there, and
788  * set obj to point to it. */
789 int xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, unsigned int offset)
790 {
791         struct xdr_buf subbuf;
792
793         if (xdr_decode_word(buf, offset, &obj->len))
794                 return -EFAULT;
795         if (xdr_buf_subsegment(buf, &subbuf, offset + 4, obj->len))
796                 return -EFAULT;
797
798         /* Is the obj contained entirely in the head? */
799         obj->data = subbuf.head[0].iov_base;
800         if (subbuf.head[0].iov_len == obj->len)
801                 return 0;
802         /* ..or is the obj contained entirely in the tail? */
803         obj->data = subbuf.tail[0].iov_base;
804         if (subbuf.tail[0].iov_len == obj->len)
805                 return 0;
806
807         /* use end of tail as storage for obj:
808          * (We don't copy to the beginning because then we'd have
809          * to worry about doing a potentially overlapping copy.
810          * This assumes the object is at most half the length of the
811          * tail.) */
812         if (obj->len > buf->buflen - buf->len)
813                 return -ENOMEM;
814         if (buf->tail[0].iov_len != 0)
815                 obj->data = buf->tail[0].iov_base + buf->tail[0].iov_len;
816         else
817                 obj->data = buf->head[0].iov_base + buf->head[0].iov_len;
818         __read_bytes_from_xdr_buf(&subbuf, obj->data, obj->len);
819         return 0;
820 }
821 EXPORT_SYMBOL(xdr_buf_read_netobj);
822
823 /* Returns 0 on success, or else a negative error code. */
824 static int
825 xdr_xcode_array2(struct xdr_buf *buf, unsigned int base,
826                  struct xdr_array2_desc *desc, int encode)
827 {
828         char *elem = NULL, *c;
829         unsigned int copied = 0, todo, avail_here;
830         struct page **ppages = NULL;
831         int err;
832
833         if (encode) {
834                 if (xdr_encode_word(buf, base, desc->array_len) != 0)
835                         return -EINVAL;
836         } else {
837                 if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
838                     desc->array_len > desc->array_maxlen ||
839                     (unsigned long) base + 4 + desc->array_len *
840                                     desc->elem_size > buf->len)
841                         return -EINVAL;
842         }
843         base += 4;
844
845         if (!desc->xcode)
846                 return 0;
847
848         todo = desc->array_len * desc->elem_size;
849
850         /* process head */
851         if (todo && base < buf->head->iov_len) {
852                 c = buf->head->iov_base + base;
853                 avail_here = min_t(unsigned int, todo,
854                                    buf->head->iov_len - base);
855                 todo -= avail_here;
856
857                 while (avail_here >= desc->elem_size) {
858                         err = desc->xcode(desc, c);
859                         if (err)
860                                 goto out;
861                         c += desc->elem_size;
862                         avail_here -= desc->elem_size;
863                 }
864                 if (avail_here) {
865                         if (!elem) {
866                                 elem = kmalloc(desc->elem_size, GFP_KERNEL);
867                                 err = -ENOMEM;
868                                 if (!elem)
869                                         goto out;
870                         }
871                         if (encode) {
872                                 err = desc->xcode(desc, elem);
873                                 if (err)
874                                         goto out;
875                                 memcpy(c, elem, avail_here);
876                         } else
877                                 memcpy(elem, c, avail_here);
878                         copied = avail_here;
879                 }
880                 base = buf->head->iov_len;  /* align to start of pages */
881         }
882
883         /* process pages array */
884         base -= buf->head->iov_len;
885         if (todo && base < buf->page_len) {
886                 unsigned int avail_page;
887
888                 avail_here = min(todo, buf->page_len - base);
889                 todo -= avail_here;
890
891                 base += buf->page_base;
892                 ppages = buf->pages + (base >> PAGE_CACHE_SHIFT);
893                 base &= ~PAGE_CACHE_MASK;
894                 avail_page = min_t(unsigned int, PAGE_CACHE_SIZE - base,
895                                         avail_here);
896                 c = kmap(*ppages) + base;
897
898                 while (avail_here) {
899                         avail_here -= avail_page;
900                         if (copied || avail_page < desc->elem_size) {
901                                 unsigned int l = min(avail_page,
902                                         desc->elem_size - copied);
903                                 if (!elem) {
904                                         elem = kmalloc(desc->elem_size,
905                                                        GFP_KERNEL);
906                                         err = -ENOMEM;
907                                         if (!elem)
908                                                 goto out;
909                                 }
910                                 if (encode) {
911                                         if (!copied) {
912                                                 err = desc->xcode(desc, elem);
913                                                 if (err)
914                                                         goto out;
915                                         }
916                                         memcpy(c, elem + copied, l);
917                                         copied += l;
918                                         if (copied == desc->elem_size)
919                                                 copied = 0;
920                                 } else {
921                                         memcpy(elem + copied, c, l);
922                                         copied += l;
923                                         if (copied == desc->elem_size) {
924                                                 err = desc->xcode(desc, elem);
925                                                 if (err)
926                                                         goto out;
927                                                 copied = 0;
928                                         }
929                                 }
930                                 avail_page -= l;
931                                 c += l;
932                         }
933                         while (avail_page >= desc->elem_size) {
934                                 err = desc->xcode(desc, c);
935                                 if (err)
936                                         goto out;
937                                 c += desc->elem_size;
938                                 avail_page -= desc->elem_size;
939                         }
940                         if (avail_page) {
941                                 unsigned int l = min(avail_page,
942                                             desc->elem_size - copied);
943                                 if (!elem) {
944                                         elem = kmalloc(desc->elem_size,
945                                                        GFP_KERNEL);
946                                         err = -ENOMEM;
947                                         if (!elem)
948                                                 goto out;
949                                 }
950                                 if (encode) {
951                                         if (!copied) {
952                                                 err = desc->xcode(desc, elem);
953                                                 if (err)
954                                                         goto out;
955                                         }
956                                         memcpy(c, elem + copied, l);
957                                         copied += l;
958                                         if (copied == desc->elem_size)
959                                                 copied = 0;
960                                 } else {
961                                         memcpy(elem + copied, c, l);
962                                         copied += l;
963                                         if (copied == desc->elem_size) {
964                                                 err = desc->xcode(desc, elem);
965                                                 if (err)
966                                                         goto out;
967                                                 copied = 0;
968                                         }
969                                 }
970                         }
971                         if (avail_here) {
972                                 kunmap(*ppages);
973                                 ppages++;
974                                 c = kmap(*ppages);
975                         }
976
977                         avail_page = min(avail_here,
978                                  (unsigned int) PAGE_CACHE_SIZE);
979                 }
980                 base = buf->page_len;  /* align to start of tail */
981         }
982
983         /* process tail */
984         base -= buf->page_len;
985         if (todo) {
986                 c = buf->tail->iov_base + base;
987                 if (copied) {
988                         unsigned int l = desc->elem_size - copied;
989
990                         if (encode)
991                                 memcpy(c, elem + copied, l);
992                         else {
993                                 memcpy(elem + copied, c, l);
994                                 err = desc->xcode(desc, elem);
995                                 if (err)
996                                         goto out;
997                         }
998                         todo -= l;
999                         c += l;
1000                 }
1001                 while (todo) {
1002                         err = desc->xcode(desc, c);
1003                         if (err)
1004                                 goto out;
1005                         c += desc->elem_size;
1006                         todo -= desc->elem_size;
1007                 }
1008         }
1009         err = 0;
1010
1011 out:
1012         kfree(elem);
1013         if (ppages)
1014                 kunmap(*ppages);
1015         return err;
1016 }
1017
1018 int
1019 xdr_decode_array2(struct xdr_buf *buf, unsigned int base,
1020                   struct xdr_array2_desc *desc)
1021 {
1022         if (base >= buf->len)
1023                 return -EINVAL;
1024
1025         return xdr_xcode_array2(buf, base, desc, 0);
1026 }
1027 EXPORT_SYMBOL(xdr_decode_array2);
1028
1029 int
1030 xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
1031                   struct xdr_array2_desc *desc)
1032 {
1033         if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
1034             buf->head->iov_len + buf->page_len + buf->tail->iov_len)
1035                 return -EINVAL;
1036
1037         return xdr_xcode_array2(buf, base, desc, 1);
1038 }
1039 EXPORT_SYMBOL(xdr_encode_array2);
1040
1041 int
1042 xdr_process_buf(struct xdr_buf *buf, unsigned int offset, unsigned int len,
1043                 int (*actor)(struct scatterlist *, void *), void *data)
1044 {
1045         int i, ret = 0;
1046         unsigned page_len, thislen, page_offset;
1047         struct scatterlist      sg[1];
1048
1049         sg_init_table(sg, 1);
1050
1051         if (offset >= buf->head[0].iov_len) {
1052                 offset -= buf->head[0].iov_len;
1053         } else {
1054                 thislen = buf->head[0].iov_len - offset;
1055                 if (thislen > len)
1056                         thislen = len;
1057                 sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
1058                 ret = actor(sg, data);
1059                 if (ret)
1060                         goto out;
1061                 offset = 0;
1062                 len -= thislen;
1063         }
1064         if (len == 0)
1065                 goto out;
1066
1067         if (offset >= buf->page_len) {
1068                 offset -= buf->page_len;
1069         } else {
1070                 page_len = buf->page_len - offset;
1071                 if (page_len > len)
1072                         page_len = len;
1073                 len -= page_len;
1074                 page_offset = (offset + buf->page_base) & (PAGE_CACHE_SIZE - 1);
1075                 i = (offset + buf->page_base) >> PAGE_CACHE_SHIFT;
1076                 thislen = PAGE_CACHE_SIZE - page_offset;
1077                 do {
1078                         if (thislen > page_len)
1079                                 thislen = page_len;
1080                         sg_set_page(sg, buf->pages[i], thislen, page_offset);
1081                         ret = actor(sg, data);
1082                         if (ret)
1083                                 goto out;
1084                         page_len -= thislen;
1085                         i++;
1086                         page_offset = 0;
1087                         thislen = PAGE_CACHE_SIZE;
1088                 } while (page_len != 0);
1089                 offset = 0;
1090         }
1091         if (len == 0)
1092                 goto out;
1093         if (offset < buf->tail[0].iov_len) {
1094                 thislen = buf->tail[0].iov_len - offset;
1095                 if (thislen > len)
1096                         thislen = len;
1097                 sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
1098                 ret = actor(sg, data);
1099                 len -= thislen;
1100         }
1101         if (len != 0)
1102                 ret = -EINVAL;
1103 out:
1104         return ret;
1105 }
1106 EXPORT_SYMBOL(xdr_process_buf);
1107