Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6
[linux-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++ = cpu_to_be32(obj->len);
28         memcpy(p, obj->data, obj->len);
29         return p + XDR_QUADLEN(obj->len);
30 }
31 EXPORT_SYMBOL_GPL(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 = be32_to_cpu(*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_GPL(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_GPL(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++ = cpu_to_be32(nbytes);
87         return xdr_encode_opaque_fixed(p, ptr, nbytes);
88 }
89 EXPORT_SYMBOL_GPL(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_GPL(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 = be32_to_cpu(*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_GPL(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_GPL(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_GPL(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         for (;;) {
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                 len -= copy;
257                 if (len == 0)
258                         break;
259
260                 pgbase += copy;
261                 if (pgbase == PAGE_CACHE_SIZE) {
262                         flush_dcache_page(*pgto);
263                         pgbase = 0;
264                         pgto++;
265                 }
266                 p += copy;
267         }
268         flush_dcache_page(*pgto);
269 }
270
271 /*
272  * _copy_from_pages
273  * @p: pointer to destination
274  * @pages: array of pages
275  * @pgbase: offset of source data
276  * @len: length
277  *
278  * Copies data into an arbitrary memory location from an array of pages
279  * The copy is assumed to be non-overlapping.
280  */
281 static void
282 _copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
283 {
284         struct page **pgfrom;
285         char *vfrom;
286         size_t copy;
287
288         pgfrom = pages + (pgbase >> PAGE_CACHE_SHIFT);
289         pgbase &= ~PAGE_CACHE_MASK;
290
291         do {
292                 copy = PAGE_CACHE_SIZE - pgbase;
293                 if (copy > len)
294                         copy = len;
295
296                 vfrom = kmap_atomic(*pgfrom, KM_USER0);
297                 memcpy(p, vfrom + pgbase, copy);
298                 kunmap_atomic(vfrom, KM_USER0);
299
300                 pgbase += copy;
301                 if (pgbase == PAGE_CACHE_SIZE) {
302                         pgbase = 0;
303                         pgfrom++;
304                 }
305                 p += copy;
306
307         } while ((len -= copy) != 0);
308 }
309
310 /*
311  * xdr_shrink_bufhead
312  * @buf: xdr_buf
313  * @len: bytes to remove from buf->head[0]
314  *
315  * Shrinks XDR buffer's header kvec buf->head[0] by
316  * 'len' bytes. The extra data is not lost, but is instead
317  * moved into the inlined pages and/or the tail.
318  */
319 static void
320 xdr_shrink_bufhead(struct xdr_buf *buf, size_t len)
321 {
322         struct kvec *head, *tail;
323         size_t copy, offs;
324         unsigned int pglen = buf->page_len;
325
326         tail = buf->tail;
327         head = buf->head;
328         BUG_ON (len > head->iov_len);
329
330         /* Shift the tail first */
331         if (tail->iov_len != 0) {
332                 if (tail->iov_len > len) {
333                         copy = tail->iov_len - len;
334                         memmove((char *)tail->iov_base + len,
335                                         tail->iov_base, copy);
336                 }
337                 /* Copy from the inlined pages into the tail */
338                 copy = len;
339                 if (copy > pglen)
340                         copy = pglen;
341                 offs = len - copy;
342                 if (offs >= tail->iov_len)
343                         copy = 0;
344                 else if (copy > tail->iov_len - offs)
345                         copy = tail->iov_len - offs;
346                 if (copy != 0)
347                         _copy_from_pages((char *)tail->iov_base + offs,
348                                         buf->pages,
349                                         buf->page_base + pglen + offs - len,
350                                         copy);
351                 /* Do we also need to copy data from the head into the tail ? */
352                 if (len > pglen) {
353                         offs = copy = len - pglen;
354                         if (copy > tail->iov_len)
355                                 copy = tail->iov_len;
356                         memcpy(tail->iov_base,
357                                         (char *)head->iov_base +
358                                         head->iov_len - offs,
359                                         copy);
360                 }
361         }
362         /* Now handle pages */
363         if (pglen != 0) {
364                 if (pglen > len)
365                         _shift_data_right_pages(buf->pages,
366                                         buf->page_base + len,
367                                         buf->page_base,
368                                         pglen - len);
369                 copy = len;
370                 if (len > pglen)
371                         copy = pglen;
372                 _copy_to_pages(buf->pages, buf->page_base,
373                                 (char *)head->iov_base + head->iov_len - len,
374                                 copy);
375         }
376         head->iov_len -= len;
377         buf->buflen -= len;
378         /* Have we truncated the message? */
379         if (buf->len > buf->buflen)
380                 buf->len = buf->buflen;
381 }
382
383 /*
384  * xdr_shrink_pagelen
385  * @buf: xdr_buf
386  * @len: bytes to remove from buf->pages
387  *
388  * Shrinks XDR buffer's page array buf->pages by
389  * 'len' bytes. The extra data is not lost, but is instead
390  * moved into the tail.
391  */
392 static void
393 xdr_shrink_pagelen(struct xdr_buf *buf, size_t len)
394 {
395         struct kvec *tail;
396         size_t copy;
397         char *p;
398         unsigned int pglen = buf->page_len;
399
400         tail = buf->tail;
401         BUG_ON (len > pglen);
402
403         /* Shift the tail first */
404         if (tail->iov_len != 0) {
405                 p = (char *)tail->iov_base + len;
406                 if (tail->iov_len > len) {
407                         copy = tail->iov_len - len;
408                         memmove(p, tail->iov_base, copy);
409                 } else
410                         buf->buflen -= len;
411                 /* Copy from the inlined pages into the tail */
412                 copy = len;
413                 if (copy > tail->iov_len)
414                         copy = tail->iov_len;
415                 _copy_from_pages((char *)tail->iov_base,
416                                 buf->pages, buf->page_base + pglen - len,
417                                 copy);
418         }
419         buf->page_len -= len;
420         buf->buflen -= len;
421         /* Have we truncated the message? */
422         if (buf->len > buf->buflen)
423                 buf->len = buf->buflen;
424 }
425
426 void
427 xdr_shift_buf(struct xdr_buf *buf, size_t len)
428 {
429         xdr_shrink_bufhead(buf, len);
430 }
431 EXPORT_SYMBOL_GPL(xdr_shift_buf);
432
433 /**
434  * xdr_init_encode - Initialize a struct xdr_stream for sending data.
435  * @xdr: pointer to xdr_stream struct
436  * @buf: pointer to XDR buffer in which to encode data
437  * @p: current pointer inside XDR buffer
438  *
439  * Note: at the moment the RPC client only passes the length of our
440  *       scratch buffer in the xdr_buf's header kvec. Previously this
441  *       meant we needed to call xdr_adjust_iovec() after encoding the
442  *       data. With the new scheme, the xdr_stream manages the details
443  *       of the buffer length, and takes care of adjusting the kvec
444  *       length for us.
445  */
446 void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
447 {
448         struct kvec *iov = buf->head;
449         int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
450
451         BUG_ON(scratch_len < 0);
452         xdr->buf = buf;
453         xdr->iov = iov;
454         xdr->p = (__be32 *)((char *)iov->iov_base + iov->iov_len);
455         xdr->end = (__be32 *)((char *)iov->iov_base + scratch_len);
456         BUG_ON(iov->iov_len > scratch_len);
457
458         if (p != xdr->p && p != NULL) {
459                 size_t len;
460
461                 BUG_ON(p < xdr->p || p > xdr->end);
462                 len = (char *)p - (char *)xdr->p;
463                 xdr->p = p;
464                 buf->len += len;
465                 iov->iov_len += len;
466         }
467 }
468 EXPORT_SYMBOL_GPL(xdr_init_encode);
469
470 /**
471  * xdr_reserve_space - Reserve buffer space for sending
472  * @xdr: pointer to xdr_stream
473  * @nbytes: number of bytes to reserve
474  *
475  * Checks that we have enough buffer space to encode 'nbytes' more
476  * bytes of data. If so, update the total xdr_buf length, and
477  * adjust the length of the current kvec.
478  */
479 __be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
480 {
481         __be32 *p = xdr->p;
482         __be32 *q;
483
484         /* align nbytes on the next 32-bit boundary */
485         nbytes += 3;
486         nbytes &= ~3;
487         q = p + (nbytes >> 2);
488         if (unlikely(q > xdr->end || q < p))
489                 return NULL;
490         xdr->p = q;
491         xdr->iov->iov_len += nbytes;
492         xdr->buf->len += nbytes;
493         return p;
494 }
495 EXPORT_SYMBOL_GPL(xdr_reserve_space);
496
497 /**
498  * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
499  * @xdr: pointer to xdr_stream
500  * @pages: list of pages
501  * @base: offset of first byte
502  * @len: length of data in bytes
503  *
504  */
505 void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
506                  unsigned int len)
507 {
508         struct xdr_buf *buf = xdr->buf;
509         struct kvec *iov = buf->tail;
510         buf->pages = pages;
511         buf->page_base = base;
512         buf->page_len = len;
513
514         iov->iov_base = (char *)xdr->p;
515         iov->iov_len  = 0;
516         xdr->iov = iov;
517
518         if (len & 3) {
519                 unsigned int pad = 4 - (len & 3);
520
521                 BUG_ON(xdr->p >= xdr->end);
522                 iov->iov_base = (char *)xdr->p + (len & 3);
523                 iov->iov_len  += pad;
524                 len += pad;
525                 *xdr->p++ = 0;
526         }
527         buf->buflen += len;
528         buf->len += len;
529 }
530 EXPORT_SYMBOL_GPL(xdr_write_pages);
531
532 /**
533  * xdr_init_decode - Initialize an xdr_stream for decoding data.
534  * @xdr: pointer to xdr_stream struct
535  * @buf: pointer to XDR buffer from which to decode data
536  * @p: current pointer inside XDR buffer
537  */
538 void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
539 {
540         struct kvec *iov = buf->head;
541         unsigned int len = iov->iov_len;
542
543         if (len > buf->len)
544                 len = buf->len;
545         xdr->buf = buf;
546         xdr->iov = iov;
547         xdr->p = p;
548         xdr->end = (__be32 *)((char *)iov->iov_base + len);
549 }
550 EXPORT_SYMBOL_GPL(xdr_init_decode);
551
552 /**
553  * xdr_inline_decode - Retrieve non-page XDR data to decode
554  * @xdr: pointer to xdr_stream struct
555  * @nbytes: number of bytes of data to decode
556  *
557  * Check if the input buffer is long enough to enable us to decode
558  * 'nbytes' more bytes of data starting at the current position.
559  * If so return the current pointer, then update the current
560  * pointer position.
561  */
562 __be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
563 {
564         __be32 *p = xdr->p;
565         __be32 *q = p + XDR_QUADLEN(nbytes);
566
567         if (unlikely(q > xdr->end || q < p))
568                 return NULL;
569         xdr->p = q;
570         return p;
571 }
572 EXPORT_SYMBOL_GPL(xdr_inline_decode);
573
574 /**
575  * xdr_read_pages - Ensure page-based XDR data to decode is aligned at current pointer position
576  * @xdr: pointer to xdr_stream struct
577  * @len: number of bytes of page data
578  *
579  * Moves data beyond the current pointer position from the XDR head[] buffer
580  * into the page list. Any data that lies beyond current position + "len"
581  * bytes is moved into the XDR tail[].
582  */
583 void xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
584 {
585         struct xdr_buf *buf = xdr->buf;
586         struct kvec *iov;
587         ssize_t shift;
588         unsigned int end;
589         int padding;
590
591         /* Realign pages to current pointer position */
592         iov  = buf->head;
593         shift = iov->iov_len + (char *)iov->iov_base - (char *)xdr->p;
594         if (shift > 0)
595                 xdr_shrink_bufhead(buf, shift);
596
597         /* Truncate page data and move it into the tail */
598         if (buf->page_len > len)
599                 xdr_shrink_pagelen(buf, buf->page_len - len);
600         padding = (XDR_QUADLEN(len) << 2) - len;
601         xdr->iov = iov = buf->tail;
602         /* Compute remaining message length.  */
603         end = iov->iov_len;
604         shift = buf->buflen - buf->len;
605         if (shift < end)
606                 end -= shift;
607         else if (shift > 0)
608                 end = 0;
609         /*
610          * Position current pointer at beginning of tail, and
611          * set remaining message length.
612          */
613         xdr->p = (__be32 *)((char *)iov->iov_base + padding);
614         xdr->end = (__be32 *)((char *)iov->iov_base + end);
615 }
616 EXPORT_SYMBOL_GPL(xdr_read_pages);
617
618 /**
619  * xdr_enter_page - decode data from the XDR page
620  * @xdr: pointer to xdr_stream struct
621  * @len: number of bytes of page data
622  *
623  * Moves data beyond the current pointer position from the XDR head[] buffer
624  * into the page list. Any data that lies beyond current position + "len"
625  * bytes is moved into the XDR tail[]. The current pointer is then
626  * repositioned at the beginning of the first XDR page.
627  */
628 void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
629 {
630         char * kaddr = page_address(xdr->buf->pages[0]);
631         xdr_read_pages(xdr, len);
632         /*
633          * Position current pointer at beginning of tail, and
634          * set remaining message length.
635          */
636         if (len > PAGE_CACHE_SIZE - xdr->buf->page_base)
637                 len = PAGE_CACHE_SIZE - xdr->buf->page_base;
638         xdr->p = (__be32 *)(kaddr + xdr->buf->page_base);
639         xdr->end = (__be32 *)((char *)xdr->p + len);
640 }
641 EXPORT_SYMBOL_GPL(xdr_enter_page);
642
643 static struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
644
645 void
646 xdr_buf_from_iov(struct kvec *iov, struct xdr_buf *buf)
647 {
648         buf->head[0] = *iov;
649         buf->tail[0] = empty_iov;
650         buf->page_len = 0;
651         buf->buflen = buf->len = iov->iov_len;
652 }
653 EXPORT_SYMBOL_GPL(xdr_buf_from_iov);
654
655 /* Sets subbuf to the portion of buf of length len beginning base bytes
656  * from the start of buf. Returns -1 if base of length are out of bounds. */
657 int
658 xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
659                         unsigned int base, unsigned int len)
660 {
661         subbuf->buflen = subbuf->len = len;
662         if (base < buf->head[0].iov_len) {
663                 subbuf->head[0].iov_base = buf->head[0].iov_base + base;
664                 subbuf->head[0].iov_len = min_t(unsigned int, len,
665                                                 buf->head[0].iov_len - base);
666                 len -= subbuf->head[0].iov_len;
667                 base = 0;
668         } else {
669                 subbuf->head[0].iov_base = NULL;
670                 subbuf->head[0].iov_len = 0;
671                 base -= buf->head[0].iov_len;
672         }
673
674         if (base < buf->page_len) {
675                 subbuf->page_len = min(buf->page_len - base, len);
676                 base += buf->page_base;
677                 subbuf->page_base = base & ~PAGE_CACHE_MASK;
678                 subbuf->pages = &buf->pages[base >> PAGE_CACHE_SHIFT];
679                 len -= subbuf->page_len;
680                 base = 0;
681         } else {
682                 base -= buf->page_len;
683                 subbuf->page_len = 0;
684         }
685
686         if (base < buf->tail[0].iov_len) {
687                 subbuf->tail[0].iov_base = buf->tail[0].iov_base + base;
688                 subbuf->tail[0].iov_len = min_t(unsigned int, len,
689                                                 buf->tail[0].iov_len - base);
690                 len -= subbuf->tail[0].iov_len;
691                 base = 0;
692         } else {
693                 subbuf->tail[0].iov_base = NULL;
694                 subbuf->tail[0].iov_len = 0;
695                 base -= buf->tail[0].iov_len;
696         }
697
698         if (base || len)
699                 return -1;
700         return 0;
701 }
702 EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
703
704 static void __read_bytes_from_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
705 {
706         unsigned int this_len;
707
708         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
709         memcpy(obj, subbuf->head[0].iov_base, this_len);
710         len -= this_len;
711         obj += this_len;
712         this_len = min_t(unsigned int, len, subbuf->page_len);
713         if (this_len)
714                 _copy_from_pages(obj, subbuf->pages, subbuf->page_base, this_len);
715         len -= this_len;
716         obj += this_len;
717         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
718         memcpy(obj, subbuf->tail[0].iov_base, this_len);
719 }
720
721 /* obj is assumed to point to allocated memory of size at least len: */
722 int read_bytes_from_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
723 {
724         struct xdr_buf subbuf;
725         int status;
726
727         status = xdr_buf_subsegment(buf, &subbuf, base, len);
728         if (status != 0)
729                 return status;
730         __read_bytes_from_xdr_buf(&subbuf, obj, len);
731         return 0;
732 }
733 EXPORT_SYMBOL_GPL(read_bytes_from_xdr_buf);
734
735 static void __write_bytes_to_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
736 {
737         unsigned int this_len;
738
739         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
740         memcpy(subbuf->head[0].iov_base, obj, this_len);
741         len -= this_len;
742         obj += this_len;
743         this_len = min_t(unsigned int, len, subbuf->page_len);
744         if (this_len)
745                 _copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
746         len -= this_len;
747         obj += this_len;
748         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
749         memcpy(subbuf->tail[0].iov_base, obj, this_len);
750 }
751
752 /* obj is assumed to point to allocated memory of size at least len: */
753 int write_bytes_to_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
754 {
755         struct xdr_buf subbuf;
756         int status;
757
758         status = xdr_buf_subsegment(buf, &subbuf, base, len);
759         if (status != 0)
760                 return status;
761         __write_bytes_to_xdr_buf(&subbuf, obj, len);
762         return 0;
763 }
764
765 int
766 xdr_decode_word(struct xdr_buf *buf, unsigned int base, u32 *obj)
767 {
768         __be32  raw;
769         int     status;
770
771         status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
772         if (status)
773                 return status;
774         *obj = be32_to_cpu(raw);
775         return 0;
776 }
777 EXPORT_SYMBOL_GPL(xdr_decode_word);
778
779 int
780 xdr_encode_word(struct xdr_buf *buf, unsigned int base, u32 obj)
781 {
782         __be32  raw = cpu_to_be32(obj);
783
784         return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
785 }
786 EXPORT_SYMBOL_GPL(xdr_encode_word);
787
788 /* If the netobj starting offset bytes from the start of xdr_buf is contained
789  * entirely in the head or the tail, set object to point to it; otherwise
790  * try to find space for it at the end of the tail, copy it there, and
791  * set obj to point to it. */
792 int xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, unsigned int offset)
793 {
794         struct xdr_buf subbuf;
795
796         if (xdr_decode_word(buf, offset, &obj->len))
797                 return -EFAULT;
798         if (xdr_buf_subsegment(buf, &subbuf, offset + 4, obj->len))
799                 return -EFAULT;
800
801         /* Is the obj contained entirely in the head? */
802         obj->data = subbuf.head[0].iov_base;
803         if (subbuf.head[0].iov_len == obj->len)
804                 return 0;
805         /* ..or is the obj contained entirely in the tail? */
806         obj->data = subbuf.tail[0].iov_base;
807         if (subbuf.tail[0].iov_len == obj->len)
808                 return 0;
809
810         /* use end of tail as storage for obj:
811          * (We don't copy to the beginning because then we'd have
812          * to worry about doing a potentially overlapping copy.
813          * This assumes the object is at most half the length of the
814          * tail.) */
815         if (obj->len > buf->buflen - buf->len)
816                 return -ENOMEM;
817         if (buf->tail[0].iov_len != 0)
818                 obj->data = buf->tail[0].iov_base + buf->tail[0].iov_len;
819         else
820                 obj->data = buf->head[0].iov_base + buf->head[0].iov_len;
821         __read_bytes_from_xdr_buf(&subbuf, obj->data, obj->len);
822         return 0;
823 }
824 EXPORT_SYMBOL_GPL(xdr_buf_read_netobj);
825
826 /* Returns 0 on success, or else a negative error code. */
827 static int
828 xdr_xcode_array2(struct xdr_buf *buf, unsigned int base,
829                  struct xdr_array2_desc *desc, int encode)
830 {
831         char *elem = NULL, *c;
832         unsigned int copied = 0, todo, avail_here;
833         struct page **ppages = NULL;
834         int err;
835
836         if (encode) {
837                 if (xdr_encode_word(buf, base, desc->array_len) != 0)
838                         return -EINVAL;
839         } else {
840                 if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
841                     desc->array_len > desc->array_maxlen ||
842                     (unsigned long) base + 4 + desc->array_len *
843                                     desc->elem_size > buf->len)
844                         return -EINVAL;
845         }
846         base += 4;
847
848         if (!desc->xcode)
849                 return 0;
850
851         todo = desc->array_len * desc->elem_size;
852
853         /* process head */
854         if (todo && base < buf->head->iov_len) {
855                 c = buf->head->iov_base + base;
856                 avail_here = min_t(unsigned int, todo,
857                                    buf->head->iov_len - base);
858                 todo -= avail_here;
859
860                 while (avail_here >= desc->elem_size) {
861                         err = desc->xcode(desc, c);
862                         if (err)
863                                 goto out;
864                         c += desc->elem_size;
865                         avail_here -= desc->elem_size;
866                 }
867                 if (avail_here) {
868                         if (!elem) {
869                                 elem = kmalloc(desc->elem_size, GFP_KERNEL);
870                                 err = -ENOMEM;
871                                 if (!elem)
872                                         goto out;
873                         }
874                         if (encode) {
875                                 err = desc->xcode(desc, elem);
876                                 if (err)
877                                         goto out;
878                                 memcpy(c, elem, avail_here);
879                         } else
880                                 memcpy(elem, c, avail_here);
881                         copied = avail_here;
882                 }
883                 base = buf->head->iov_len;  /* align to start of pages */
884         }
885
886         /* process pages array */
887         base -= buf->head->iov_len;
888         if (todo && base < buf->page_len) {
889                 unsigned int avail_page;
890
891                 avail_here = min(todo, buf->page_len - base);
892                 todo -= avail_here;
893
894                 base += buf->page_base;
895                 ppages = buf->pages + (base >> PAGE_CACHE_SHIFT);
896                 base &= ~PAGE_CACHE_MASK;
897                 avail_page = min_t(unsigned int, PAGE_CACHE_SIZE - base,
898                                         avail_here);
899                 c = kmap(*ppages) + base;
900
901                 while (avail_here) {
902                         avail_here -= avail_page;
903                         if (copied || avail_page < desc->elem_size) {
904                                 unsigned int l = min(avail_page,
905                                         desc->elem_size - copied);
906                                 if (!elem) {
907                                         elem = kmalloc(desc->elem_size,
908                                                        GFP_KERNEL);
909                                         err = -ENOMEM;
910                                         if (!elem)
911                                                 goto out;
912                                 }
913                                 if (encode) {
914                                         if (!copied) {
915                                                 err = desc->xcode(desc, elem);
916                                                 if (err)
917                                                         goto out;
918                                         }
919                                         memcpy(c, elem + copied, l);
920                                         copied += l;
921                                         if (copied == desc->elem_size)
922                                                 copied = 0;
923                                 } else {
924                                         memcpy(elem + copied, c, l);
925                                         copied += l;
926                                         if (copied == desc->elem_size) {
927                                                 err = desc->xcode(desc, elem);
928                                                 if (err)
929                                                         goto out;
930                                                 copied = 0;
931                                         }
932                                 }
933                                 avail_page -= l;
934                                 c += l;
935                         }
936                         while (avail_page >= desc->elem_size) {
937                                 err = desc->xcode(desc, c);
938                                 if (err)
939                                         goto out;
940                                 c += desc->elem_size;
941                                 avail_page -= desc->elem_size;
942                         }
943                         if (avail_page) {
944                                 unsigned int l = min(avail_page,
945                                             desc->elem_size - copied);
946                                 if (!elem) {
947                                         elem = kmalloc(desc->elem_size,
948                                                        GFP_KERNEL);
949                                         err = -ENOMEM;
950                                         if (!elem)
951                                                 goto out;
952                                 }
953                                 if (encode) {
954                                         if (!copied) {
955                                                 err = desc->xcode(desc, elem);
956                                                 if (err)
957                                                         goto out;
958                                         }
959                                         memcpy(c, elem + copied, l);
960                                         copied += l;
961                                         if (copied == desc->elem_size)
962                                                 copied = 0;
963                                 } else {
964                                         memcpy(elem + copied, c, l);
965                                         copied += l;
966                                         if (copied == desc->elem_size) {
967                                                 err = desc->xcode(desc, elem);
968                                                 if (err)
969                                                         goto out;
970                                                 copied = 0;
971                                         }
972                                 }
973                         }
974                         if (avail_here) {
975                                 kunmap(*ppages);
976                                 ppages++;
977                                 c = kmap(*ppages);
978                         }
979
980                         avail_page = min(avail_here,
981                                  (unsigned int) PAGE_CACHE_SIZE);
982                 }
983                 base = buf->page_len;  /* align to start of tail */
984         }
985
986         /* process tail */
987         base -= buf->page_len;
988         if (todo) {
989                 c = buf->tail->iov_base + base;
990                 if (copied) {
991                         unsigned int l = desc->elem_size - copied;
992
993                         if (encode)
994                                 memcpy(c, elem + copied, l);
995                         else {
996                                 memcpy(elem + copied, c, l);
997                                 err = desc->xcode(desc, elem);
998                                 if (err)
999                                         goto out;
1000                         }
1001                         todo -= l;
1002                         c += l;
1003                 }
1004                 while (todo) {
1005                         err = desc->xcode(desc, c);
1006                         if (err)
1007                                 goto out;
1008                         c += desc->elem_size;
1009                         todo -= desc->elem_size;
1010                 }
1011         }
1012         err = 0;
1013
1014 out:
1015         kfree(elem);
1016         if (ppages)
1017                 kunmap(*ppages);
1018         return err;
1019 }
1020
1021 int
1022 xdr_decode_array2(struct xdr_buf *buf, unsigned int base,
1023                   struct xdr_array2_desc *desc)
1024 {
1025         if (base >= buf->len)
1026                 return -EINVAL;
1027
1028         return xdr_xcode_array2(buf, base, desc, 0);
1029 }
1030 EXPORT_SYMBOL_GPL(xdr_decode_array2);
1031
1032 int
1033 xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
1034                   struct xdr_array2_desc *desc)
1035 {
1036         if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
1037             buf->head->iov_len + buf->page_len + buf->tail->iov_len)
1038                 return -EINVAL;
1039
1040         return xdr_xcode_array2(buf, base, desc, 1);
1041 }
1042 EXPORT_SYMBOL_GPL(xdr_encode_array2);
1043
1044 int
1045 xdr_process_buf(struct xdr_buf *buf, unsigned int offset, unsigned int len,
1046                 int (*actor)(struct scatterlist *, void *), void *data)
1047 {
1048         int i, ret = 0;
1049         unsigned page_len, thislen, page_offset;
1050         struct scatterlist      sg[1];
1051
1052         sg_init_table(sg, 1);
1053
1054         if (offset >= buf->head[0].iov_len) {
1055                 offset -= buf->head[0].iov_len;
1056         } else {
1057                 thislen = buf->head[0].iov_len - offset;
1058                 if (thislen > len)
1059                         thislen = len;
1060                 sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
1061                 ret = actor(sg, data);
1062                 if (ret)
1063                         goto out;
1064                 offset = 0;
1065                 len -= thislen;
1066         }
1067         if (len == 0)
1068                 goto out;
1069
1070         if (offset >= buf->page_len) {
1071                 offset -= buf->page_len;
1072         } else {
1073                 page_len = buf->page_len - offset;
1074                 if (page_len > len)
1075                         page_len = len;
1076                 len -= page_len;
1077                 page_offset = (offset + buf->page_base) & (PAGE_CACHE_SIZE - 1);
1078                 i = (offset + buf->page_base) >> PAGE_CACHE_SHIFT;
1079                 thislen = PAGE_CACHE_SIZE - page_offset;
1080                 do {
1081                         if (thislen > page_len)
1082                                 thislen = page_len;
1083                         sg_set_page(sg, buf->pages[i], thislen, page_offset);
1084                         ret = actor(sg, data);
1085                         if (ret)
1086                                 goto out;
1087                         page_len -= thislen;
1088                         i++;
1089                         page_offset = 0;
1090                         thislen = PAGE_CACHE_SIZE;
1091                 } while (page_len != 0);
1092                 offset = 0;
1093         }
1094         if (len == 0)
1095                 goto out;
1096         if (offset < buf->tail[0].iov_len) {
1097                 thislen = buf->tail[0].iov_len - offset;
1098                 if (thislen > len)
1099                         thislen = len;
1100                 sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
1101                 ret = actor(sg, data);
1102                 len -= thislen;
1103         }
1104         if (len != 0)
1105                 ret = -EINVAL;
1106 out:
1107         return ret;
1108 }
1109 EXPORT_SYMBOL_GPL(xdr_process_buf);
1110