xdr: Add an export for the helper function write_bytes_to_xdr_buf()
[linux-3.10.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/slab.h>
11 #include <linux/types.h>
12 #include <linux/string.h>
13 #include <linux/kernel.h>
14 #include <linux/pagemap.h>
15 #include <linux/errno.h>
16 #include <linux/sunrpc/xdr.h>
17 #include <linux/sunrpc/msg_prot.h>
18
19 /*
20  * XDR functions for basic NFS types
21  */
22 __be32 *
23 xdr_encode_netobj(__be32 *p, const struct xdr_netobj *obj)
24 {
25         unsigned int    quadlen = XDR_QUADLEN(obj->len);
26
27         p[quadlen] = 0;         /* zero trailing bytes */
28         *p++ = cpu_to_be32(obj->len);
29         memcpy(p, obj->data, obj->len);
30         return p + XDR_QUADLEN(obj->len);
31 }
32 EXPORT_SYMBOL_GPL(xdr_encode_netobj);
33
34 __be32 *
35 xdr_decode_netobj(__be32 *p, struct xdr_netobj *obj)
36 {
37         unsigned int    len;
38
39         if ((len = be32_to_cpu(*p++)) > XDR_MAX_NETOBJ)
40                 return NULL;
41         obj->len  = len;
42         obj->data = (u8 *) p;
43         return p + XDR_QUADLEN(len);
44 }
45 EXPORT_SYMBOL_GPL(xdr_decode_netobj);
46
47 /**
48  * xdr_encode_opaque_fixed - Encode fixed length opaque data
49  * @p: pointer to current position in XDR buffer.
50  * @ptr: pointer to data to encode (or NULL)
51  * @nbytes: size of data.
52  *
53  * Copy the array of data of length nbytes at ptr to the XDR buffer
54  * at position p, then align to the next 32-bit boundary by padding
55  * with zero bytes (see RFC1832).
56  * Note: if ptr is NULL, only the padding is performed.
57  *
58  * Returns the updated current XDR buffer position
59  *
60  */
61 __be32 *xdr_encode_opaque_fixed(__be32 *p, const void *ptr, unsigned int nbytes)
62 {
63         if (likely(nbytes != 0)) {
64                 unsigned int quadlen = XDR_QUADLEN(nbytes);
65                 unsigned int padding = (quadlen << 2) - nbytes;
66
67                 if (ptr != NULL)
68                         memcpy(p, ptr, nbytes);
69                 if (padding != 0)
70                         memset((char *)p + nbytes, 0, padding);
71                 p += quadlen;
72         }
73         return p;
74 }
75 EXPORT_SYMBOL_GPL(xdr_encode_opaque_fixed);
76
77 /**
78  * xdr_encode_opaque - Encode variable length opaque data
79  * @p: pointer to current position in XDR buffer.
80  * @ptr: pointer to data to encode (or NULL)
81  * @nbytes: size of data.
82  *
83  * Returns the updated current XDR buffer position
84  */
85 __be32 *xdr_encode_opaque(__be32 *p, const void *ptr, unsigned int nbytes)
86 {
87         *p++ = cpu_to_be32(nbytes);
88         return xdr_encode_opaque_fixed(p, ptr, nbytes);
89 }
90 EXPORT_SYMBOL_GPL(xdr_encode_opaque);
91
92 __be32 *
93 xdr_encode_string(__be32 *p, const char *string)
94 {
95         return xdr_encode_array(p, string, strlen(string));
96 }
97 EXPORT_SYMBOL_GPL(xdr_encode_string);
98
99 __be32 *
100 xdr_decode_string_inplace(__be32 *p, char **sp,
101                           unsigned int *lenp, unsigned int maxlen)
102 {
103         u32 len;
104
105         len = be32_to_cpu(*p++);
106         if (len > maxlen)
107                 return NULL;
108         *lenp = len;
109         *sp = (char *) p;
110         return p + XDR_QUADLEN(len);
111 }
112 EXPORT_SYMBOL_GPL(xdr_decode_string_inplace);
113
114 void
115 xdr_encode_pages(struct xdr_buf *xdr, struct page **pages, unsigned int base,
116                  unsigned int len)
117 {
118         struct kvec *tail = xdr->tail;
119         u32 *p;
120
121         xdr->pages = pages;
122         xdr->page_base = base;
123         xdr->page_len = len;
124
125         p = (u32 *)xdr->head[0].iov_base + XDR_QUADLEN(xdr->head[0].iov_len);
126         tail->iov_base = p;
127         tail->iov_len = 0;
128
129         if (len & 3) {
130                 unsigned int pad = 4 - (len & 3);
131
132                 *p = 0;
133                 tail->iov_base = (char *)p + (len & 3);
134                 tail->iov_len  = pad;
135                 len += pad;
136         }
137         xdr->buflen += len;
138         xdr->len += len;
139 }
140 EXPORT_SYMBOL_GPL(xdr_encode_pages);
141
142 void
143 xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
144                  struct page **pages, unsigned int base, unsigned int len)
145 {
146         struct kvec *head = xdr->head;
147         struct kvec *tail = xdr->tail;
148         char *buf = (char *)head->iov_base;
149         unsigned int buflen = head->iov_len;
150
151         head->iov_len  = offset;
152
153         xdr->pages = pages;
154         xdr->page_base = base;
155         xdr->page_len = len;
156
157         tail->iov_base = buf + offset;
158         tail->iov_len = buflen - offset;
159
160         xdr->buflen += len;
161 }
162 EXPORT_SYMBOL_GPL(xdr_inline_pages);
163
164 /*
165  * Helper routines for doing 'memmove' like operations on a struct xdr_buf
166  *
167  * _shift_data_right_pages
168  * @pages: vector of pages containing both the source and dest memory area.
169  * @pgto_base: page vector address of destination
170  * @pgfrom_base: page vector address of source
171  * @len: number of bytes to copy
172  *
173  * Note: the addresses pgto_base and pgfrom_base are both calculated in
174  *       the same way:
175  *            if a memory area starts at byte 'base' in page 'pages[i]',
176  *            then its address is given as (i << PAGE_CACHE_SHIFT) + base
177  * Also note: pgfrom_base must be < pgto_base, but the memory areas
178  *      they point to may overlap.
179  */
180 static void
181 _shift_data_right_pages(struct page **pages, size_t pgto_base,
182                 size_t pgfrom_base, size_t len)
183 {
184         struct page **pgfrom, **pgto;
185         char *vfrom, *vto;
186         size_t copy;
187
188         BUG_ON(pgto_base <= pgfrom_base);
189
190         pgto_base += len;
191         pgfrom_base += len;
192
193         pgto = pages + (pgto_base >> PAGE_CACHE_SHIFT);
194         pgfrom = pages + (pgfrom_base >> PAGE_CACHE_SHIFT);
195
196         pgto_base &= ~PAGE_CACHE_MASK;
197         pgfrom_base &= ~PAGE_CACHE_MASK;
198
199         do {
200                 /* Are any pointers crossing a page boundary? */
201                 if (pgto_base == 0) {
202                         pgto_base = PAGE_CACHE_SIZE;
203                         pgto--;
204                 }
205                 if (pgfrom_base == 0) {
206                         pgfrom_base = PAGE_CACHE_SIZE;
207                         pgfrom--;
208                 }
209
210                 copy = len;
211                 if (copy > pgto_base)
212                         copy = pgto_base;
213                 if (copy > pgfrom_base)
214                         copy = pgfrom_base;
215                 pgto_base -= copy;
216                 pgfrom_base -= copy;
217
218                 vto = kmap_atomic(*pgto, KM_USER0);
219                 vfrom = kmap_atomic(*pgfrom, KM_USER1);
220                 memmove(vto + pgto_base, vfrom + pgfrom_base, copy);
221                 flush_dcache_page(*pgto);
222                 kunmap_atomic(vfrom, KM_USER1);
223                 kunmap_atomic(vto, KM_USER0);
224
225         } while ((len -= copy) != 0);
226 }
227
228 /*
229  * _copy_to_pages
230  * @pages: array of pages
231  * @pgbase: page vector address of destination
232  * @p: pointer to source data
233  * @len: length
234  *
235  * Copies data from an arbitrary memory location into an array of pages
236  * The copy is assumed to be non-overlapping.
237  */
238 static void
239 _copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len)
240 {
241         struct page **pgto;
242         char *vto;
243         size_t copy;
244
245         pgto = pages + (pgbase >> PAGE_CACHE_SHIFT);
246         pgbase &= ~PAGE_CACHE_MASK;
247
248         for (;;) {
249                 copy = PAGE_CACHE_SIZE - pgbase;
250                 if (copy > len)
251                         copy = len;
252
253                 vto = kmap_atomic(*pgto, KM_USER0);
254                 memcpy(vto + pgbase, p, copy);
255                 kunmap_atomic(vto, KM_USER0);
256
257                 len -= copy;
258                 if (len == 0)
259                         break;
260
261                 pgbase += copy;
262                 if (pgbase == PAGE_CACHE_SIZE) {
263                         flush_dcache_page(*pgto);
264                         pgbase = 0;
265                         pgto++;
266                 }
267                 p += copy;
268         }
269         flush_dcache_page(*pgto);
270 }
271
272 /*
273  * _copy_from_pages
274  * @p: pointer to destination
275  * @pages: array of pages
276  * @pgbase: offset of source data
277  * @len: length
278  *
279  * Copies data into an arbitrary memory location from an array of pages
280  * The copy is assumed to be non-overlapping.
281  */
282 static void
283 _copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
284 {
285         struct page **pgfrom;
286         char *vfrom;
287         size_t copy;
288
289         pgfrom = pages + (pgbase >> PAGE_CACHE_SHIFT);
290         pgbase &= ~PAGE_CACHE_MASK;
291
292         do {
293                 copy = PAGE_CACHE_SIZE - pgbase;
294                 if (copy > len)
295                         copy = len;
296
297                 vfrom = kmap_atomic(*pgfrom, KM_USER0);
298                 memcpy(p, vfrom + pgbase, copy);
299                 kunmap_atomic(vfrom, KM_USER0);
300
301                 pgbase += copy;
302                 if (pgbase == PAGE_CACHE_SIZE) {
303                         pgbase = 0;
304                         pgfrom++;
305                 }
306                 p += copy;
307
308         } while ((len -= copy) != 0);
309 }
310
311 /*
312  * xdr_shrink_bufhead
313  * @buf: xdr_buf
314  * @len: bytes to remove from buf->head[0]
315  *
316  * Shrinks XDR buffer's header kvec buf->head[0] by
317  * 'len' bytes. The extra data is not lost, but is instead
318  * moved into the inlined pages and/or the tail.
319  */
320 static void
321 xdr_shrink_bufhead(struct xdr_buf *buf, size_t len)
322 {
323         struct kvec *head, *tail;
324         size_t copy, offs;
325         unsigned int pglen = buf->page_len;
326
327         tail = buf->tail;
328         head = buf->head;
329         BUG_ON (len > head->iov_len);
330
331         /* Shift the tail first */
332         if (tail->iov_len != 0) {
333                 if (tail->iov_len > len) {
334                         copy = tail->iov_len - len;
335                         memmove((char *)tail->iov_base + len,
336                                         tail->iov_base, copy);
337                 }
338                 /* Copy from the inlined pages into the tail */
339                 copy = len;
340                 if (copy > pglen)
341                         copy = pglen;
342                 offs = len - copy;
343                 if (offs >= tail->iov_len)
344                         copy = 0;
345                 else if (copy > tail->iov_len - offs)
346                         copy = tail->iov_len - offs;
347                 if (copy != 0)
348                         _copy_from_pages((char *)tail->iov_base + offs,
349                                         buf->pages,
350                                         buf->page_base + pglen + offs - len,
351                                         copy);
352                 /* Do we also need to copy data from the head into the tail ? */
353                 if (len > pglen) {
354                         offs = copy = len - pglen;
355                         if (copy > tail->iov_len)
356                                 copy = tail->iov_len;
357                         memcpy(tail->iov_base,
358                                         (char *)head->iov_base +
359                                         head->iov_len - offs,
360                                         copy);
361                 }
362         }
363         /* Now handle pages */
364         if (pglen != 0) {
365                 if (pglen > len)
366                         _shift_data_right_pages(buf->pages,
367                                         buf->page_base + len,
368                                         buf->page_base,
369                                         pglen - len);
370                 copy = len;
371                 if (len > pglen)
372                         copy = pglen;
373                 _copy_to_pages(buf->pages, buf->page_base,
374                                 (char *)head->iov_base + head->iov_len - len,
375                                 copy);
376         }
377         head->iov_len -= len;
378         buf->buflen -= len;
379         /* Have we truncated the message? */
380         if (buf->len > buf->buflen)
381                 buf->len = buf->buflen;
382 }
383
384 /*
385  * xdr_shrink_pagelen
386  * @buf: xdr_buf
387  * @len: bytes to remove from buf->pages
388  *
389  * Shrinks XDR buffer's page array buf->pages by
390  * 'len' bytes. The extra data is not lost, but is instead
391  * moved into the tail.
392  */
393 static void
394 xdr_shrink_pagelen(struct xdr_buf *buf, size_t len)
395 {
396         struct kvec *tail;
397         size_t copy;
398         char *p;
399         unsigned int pglen = buf->page_len;
400
401         tail = buf->tail;
402         BUG_ON (len > pglen);
403
404         /* Shift the tail first */
405         if (tail->iov_len != 0) {
406                 p = (char *)tail->iov_base + len;
407                 if (tail->iov_len > len) {
408                         copy = tail->iov_len - len;
409                         memmove(p, tail->iov_base, copy);
410                 } else
411                         buf->buflen -= len;
412                 /* Copy from the inlined pages into the tail */
413                 copy = len;
414                 if (copy > tail->iov_len)
415                         copy = tail->iov_len;
416                 _copy_from_pages((char *)tail->iov_base,
417                                 buf->pages, buf->page_base + pglen - len,
418                                 copy);
419         }
420         buf->page_len -= len;
421         buf->buflen -= len;
422         /* Have we truncated the message? */
423         if (buf->len > buf->buflen)
424                 buf->len = buf->buflen;
425 }
426
427 void
428 xdr_shift_buf(struct xdr_buf *buf, size_t len)
429 {
430         xdr_shrink_bufhead(buf, len);
431 }
432 EXPORT_SYMBOL_GPL(xdr_shift_buf);
433
434 /**
435  * xdr_init_encode - Initialize a struct xdr_stream for sending data.
436  * @xdr: pointer to xdr_stream struct
437  * @buf: pointer to XDR buffer in which to encode data
438  * @p: current pointer inside XDR buffer
439  *
440  * Note: at the moment the RPC client only passes the length of our
441  *       scratch buffer in the xdr_buf's header kvec. Previously this
442  *       meant we needed to call xdr_adjust_iovec() after encoding the
443  *       data. With the new scheme, the xdr_stream manages the details
444  *       of the buffer length, and takes care of adjusting the kvec
445  *       length for us.
446  */
447 void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
448 {
449         struct kvec *iov = buf->head;
450         int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
451
452         BUG_ON(scratch_len < 0);
453         xdr->buf = buf;
454         xdr->iov = iov;
455         xdr->p = (__be32 *)((char *)iov->iov_base + iov->iov_len);
456         xdr->end = (__be32 *)((char *)iov->iov_base + scratch_len);
457         BUG_ON(iov->iov_len > scratch_len);
458
459         if (p != xdr->p && p != NULL) {
460                 size_t len;
461
462                 BUG_ON(p < xdr->p || p > xdr->end);
463                 len = (char *)p - (char *)xdr->p;
464                 xdr->p = p;
465                 buf->len += len;
466                 iov->iov_len += len;
467         }
468 }
469 EXPORT_SYMBOL_GPL(xdr_init_encode);
470
471 /**
472  * xdr_reserve_space - Reserve buffer space for sending
473  * @xdr: pointer to xdr_stream
474  * @nbytes: number of bytes to reserve
475  *
476  * Checks that we have enough buffer space to encode 'nbytes' more
477  * bytes of data. If so, update the total xdr_buf length, and
478  * adjust the length of the current kvec.
479  */
480 __be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
481 {
482         __be32 *p = xdr->p;
483         __be32 *q;
484
485         /* align nbytes on the next 32-bit boundary */
486         nbytes += 3;
487         nbytes &= ~3;
488         q = p + (nbytes >> 2);
489         if (unlikely(q > xdr->end || q < p))
490                 return NULL;
491         xdr->p = q;
492         xdr->iov->iov_len += nbytes;
493         xdr->buf->len += nbytes;
494         return p;
495 }
496 EXPORT_SYMBOL_GPL(xdr_reserve_space);
497
498 /**
499  * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
500  * @xdr: pointer to xdr_stream
501  * @pages: list of pages
502  * @base: offset of first byte
503  * @len: length of data in bytes
504  *
505  */
506 void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
507                  unsigned int len)
508 {
509         struct xdr_buf *buf = xdr->buf;
510         struct kvec *iov = buf->tail;
511         buf->pages = pages;
512         buf->page_base = base;
513         buf->page_len = len;
514
515         iov->iov_base = (char *)xdr->p;
516         iov->iov_len  = 0;
517         xdr->iov = iov;
518
519         if (len & 3) {
520                 unsigned int pad = 4 - (len & 3);
521
522                 BUG_ON(xdr->p >= xdr->end);
523                 iov->iov_base = (char *)xdr->p + (len & 3);
524                 iov->iov_len  += pad;
525                 len += pad;
526                 *xdr->p++ = 0;
527         }
528         buf->buflen += len;
529         buf->len += len;
530 }
531 EXPORT_SYMBOL_GPL(xdr_write_pages);
532
533 /**
534  * xdr_init_decode - Initialize an xdr_stream for decoding data.
535  * @xdr: pointer to xdr_stream struct
536  * @buf: pointer to XDR buffer from which to decode data
537  * @p: current pointer inside XDR buffer
538  */
539 void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
540 {
541         struct kvec *iov = buf->head;
542         unsigned int len = iov->iov_len;
543
544         if (len > buf->len)
545                 len = buf->len;
546         xdr->buf = buf;
547         xdr->iov = iov;
548         xdr->p = p;
549         xdr->end = (__be32 *)((char *)iov->iov_base + len);
550 }
551 EXPORT_SYMBOL_GPL(xdr_init_decode);
552
553 /**
554  * xdr_inline_decode - Retrieve non-page XDR data to decode
555  * @xdr: pointer to xdr_stream struct
556  * @nbytes: number of bytes of data to decode
557  *
558  * Check if the input buffer is long enough to enable us to decode
559  * 'nbytes' more bytes of data starting at the current position.
560  * If so return the current pointer, then update the current
561  * pointer position.
562  */
563 __be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
564 {
565         __be32 *p = xdr->p;
566         __be32 *q = p + XDR_QUADLEN(nbytes);
567
568         if (unlikely(q > xdr->end || q < p))
569                 return NULL;
570         xdr->p = q;
571         return p;
572 }
573 EXPORT_SYMBOL_GPL(xdr_inline_decode);
574
575 /**
576  * xdr_read_pages - Ensure page-based XDR data to decode is aligned at current pointer position
577  * @xdr: pointer to xdr_stream struct
578  * @len: number of bytes of page data
579  *
580  * Moves data beyond the current pointer position from the XDR head[] buffer
581  * into the page list. Any data that lies beyond current position + "len"
582  * bytes is moved into the XDR tail[].
583  */
584 void xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
585 {
586         struct xdr_buf *buf = xdr->buf;
587         struct kvec *iov;
588         ssize_t shift;
589         unsigned int end;
590         int padding;
591
592         /* Realign pages to current pointer position */
593         iov  = buf->head;
594         shift = iov->iov_len + (char *)iov->iov_base - (char *)xdr->p;
595         if (shift > 0)
596                 xdr_shrink_bufhead(buf, shift);
597
598         /* Truncate page data and move it into the tail */
599         if (buf->page_len > len)
600                 xdr_shrink_pagelen(buf, buf->page_len - len);
601         padding = (XDR_QUADLEN(len) << 2) - len;
602         xdr->iov = iov = buf->tail;
603         /* Compute remaining message length.  */
604         end = iov->iov_len;
605         shift = buf->buflen - buf->len;
606         if (shift < end)
607                 end -= shift;
608         else if (shift > 0)
609                 end = 0;
610         /*
611          * Position current pointer at beginning of tail, and
612          * set remaining message length.
613          */
614         xdr->p = (__be32 *)((char *)iov->iov_base + padding);
615         xdr->end = (__be32 *)((char *)iov->iov_base + end);
616 }
617 EXPORT_SYMBOL_GPL(xdr_read_pages);
618
619 /**
620  * xdr_enter_page - decode data from the XDR page
621  * @xdr: pointer to xdr_stream struct
622  * @len: number of bytes of page data
623  *
624  * Moves data beyond the current pointer position from the XDR head[] buffer
625  * into the page list. Any data that lies beyond current position + "len"
626  * bytes is moved into the XDR tail[]. The current pointer is then
627  * repositioned at the beginning of the first XDR page.
628  */
629 void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
630 {
631         char * kaddr = page_address(xdr->buf->pages[0]);
632         xdr_read_pages(xdr, len);
633         /*
634          * Position current pointer at beginning of tail, and
635          * set remaining message length.
636          */
637         if (len > PAGE_CACHE_SIZE - xdr->buf->page_base)
638                 len = PAGE_CACHE_SIZE - xdr->buf->page_base;
639         xdr->p = (__be32 *)(kaddr + xdr->buf->page_base);
640         xdr->end = (__be32 *)((char *)xdr->p + len);
641 }
642 EXPORT_SYMBOL_GPL(xdr_enter_page);
643
644 static struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
645
646 void
647 xdr_buf_from_iov(struct kvec *iov, struct xdr_buf *buf)
648 {
649         buf->head[0] = *iov;
650         buf->tail[0] = empty_iov;
651         buf->page_len = 0;
652         buf->buflen = buf->len = iov->iov_len;
653 }
654 EXPORT_SYMBOL_GPL(xdr_buf_from_iov);
655
656 /* Sets subbuf to the portion of buf of length len beginning base bytes
657  * from the start of buf. Returns -1 if base of length are out of bounds. */
658 int
659 xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
660                         unsigned int base, unsigned int len)
661 {
662         subbuf->buflen = subbuf->len = len;
663         if (base < buf->head[0].iov_len) {
664                 subbuf->head[0].iov_base = buf->head[0].iov_base + base;
665                 subbuf->head[0].iov_len = min_t(unsigned int, len,
666                                                 buf->head[0].iov_len - base);
667                 len -= subbuf->head[0].iov_len;
668                 base = 0;
669         } else {
670                 subbuf->head[0].iov_base = NULL;
671                 subbuf->head[0].iov_len = 0;
672                 base -= buf->head[0].iov_len;
673         }
674
675         if (base < buf->page_len) {
676                 subbuf->page_len = min(buf->page_len - base, len);
677                 base += buf->page_base;
678                 subbuf->page_base = base & ~PAGE_CACHE_MASK;
679                 subbuf->pages = &buf->pages[base >> PAGE_CACHE_SHIFT];
680                 len -= subbuf->page_len;
681                 base = 0;
682         } else {
683                 base -= buf->page_len;
684                 subbuf->page_len = 0;
685         }
686
687         if (base < buf->tail[0].iov_len) {
688                 subbuf->tail[0].iov_base = buf->tail[0].iov_base + base;
689                 subbuf->tail[0].iov_len = min_t(unsigned int, len,
690                                                 buf->tail[0].iov_len - base);
691                 len -= subbuf->tail[0].iov_len;
692                 base = 0;
693         } else {
694                 subbuf->tail[0].iov_base = NULL;
695                 subbuf->tail[0].iov_len = 0;
696                 base -= buf->tail[0].iov_len;
697         }
698
699         if (base || len)
700                 return -1;
701         return 0;
702 }
703 EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
704
705 static void __read_bytes_from_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
706 {
707         unsigned int this_len;
708
709         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
710         memcpy(obj, subbuf->head[0].iov_base, this_len);
711         len -= this_len;
712         obj += this_len;
713         this_len = min_t(unsigned int, len, subbuf->page_len);
714         if (this_len)
715                 _copy_from_pages(obj, subbuf->pages, subbuf->page_base, this_len);
716         len -= this_len;
717         obj += this_len;
718         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
719         memcpy(obj, subbuf->tail[0].iov_base, this_len);
720 }
721
722 /* obj is assumed to point to allocated memory of size at least len: */
723 int read_bytes_from_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
724 {
725         struct xdr_buf subbuf;
726         int status;
727
728         status = xdr_buf_subsegment(buf, &subbuf, base, len);
729         if (status != 0)
730                 return status;
731         __read_bytes_from_xdr_buf(&subbuf, obj, len);
732         return 0;
733 }
734 EXPORT_SYMBOL_GPL(read_bytes_from_xdr_buf);
735
736 static void __write_bytes_to_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
737 {
738         unsigned int this_len;
739
740         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
741         memcpy(subbuf->head[0].iov_base, obj, this_len);
742         len -= this_len;
743         obj += this_len;
744         this_len = min_t(unsigned int, len, subbuf->page_len);
745         if (this_len)
746                 _copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
747         len -= this_len;
748         obj += this_len;
749         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
750         memcpy(subbuf->tail[0].iov_base, obj, this_len);
751 }
752
753 /* obj is assumed to point to allocated memory of size at least len: */
754 int write_bytes_to_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
755 {
756         struct xdr_buf subbuf;
757         int status;
758
759         status = xdr_buf_subsegment(buf, &subbuf, base, len);
760         if (status != 0)
761                 return status;
762         __write_bytes_to_xdr_buf(&subbuf, obj, len);
763         return 0;
764 }
765 EXPORT_SYMBOL_GPL(write_bytes_to_xdr_buf);
766
767 int
768 xdr_decode_word(struct xdr_buf *buf, unsigned int base, u32 *obj)
769 {
770         __be32  raw;
771         int     status;
772
773         status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
774         if (status)
775                 return status;
776         *obj = be32_to_cpu(raw);
777         return 0;
778 }
779 EXPORT_SYMBOL_GPL(xdr_decode_word);
780
781 int
782 xdr_encode_word(struct xdr_buf *buf, unsigned int base, u32 obj)
783 {
784         __be32  raw = cpu_to_be32(obj);
785
786         return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
787 }
788 EXPORT_SYMBOL_GPL(xdr_encode_word);
789
790 /* If the netobj starting offset bytes from the start of xdr_buf is contained
791  * entirely in the head or the tail, set object to point to it; otherwise
792  * try to find space for it at the end of the tail, copy it there, and
793  * set obj to point to it. */
794 int xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, unsigned int offset)
795 {
796         struct xdr_buf subbuf;
797
798         if (xdr_decode_word(buf, offset, &obj->len))
799                 return -EFAULT;
800         if (xdr_buf_subsegment(buf, &subbuf, offset + 4, obj->len))
801                 return -EFAULT;
802
803         /* Is the obj contained entirely in the head? */
804         obj->data = subbuf.head[0].iov_base;
805         if (subbuf.head[0].iov_len == obj->len)
806                 return 0;
807         /* ..or is the obj contained entirely in the tail? */
808         obj->data = subbuf.tail[0].iov_base;
809         if (subbuf.tail[0].iov_len == obj->len)
810                 return 0;
811
812         /* use end of tail as storage for obj:
813          * (We don't copy to the beginning because then we'd have
814          * to worry about doing a potentially overlapping copy.
815          * This assumes the object is at most half the length of the
816          * tail.) */
817         if (obj->len > buf->buflen - buf->len)
818                 return -ENOMEM;
819         if (buf->tail[0].iov_len != 0)
820                 obj->data = buf->tail[0].iov_base + buf->tail[0].iov_len;
821         else
822                 obj->data = buf->head[0].iov_base + buf->head[0].iov_len;
823         __read_bytes_from_xdr_buf(&subbuf, obj->data, obj->len);
824         return 0;
825 }
826 EXPORT_SYMBOL_GPL(xdr_buf_read_netobj);
827
828 /* Returns 0 on success, or else a negative error code. */
829 static int
830 xdr_xcode_array2(struct xdr_buf *buf, unsigned int base,
831                  struct xdr_array2_desc *desc, int encode)
832 {
833         char *elem = NULL, *c;
834         unsigned int copied = 0, todo, avail_here;
835         struct page **ppages = NULL;
836         int err;
837
838         if (encode) {
839                 if (xdr_encode_word(buf, base, desc->array_len) != 0)
840                         return -EINVAL;
841         } else {
842                 if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
843                     desc->array_len > desc->array_maxlen ||
844                     (unsigned long) base + 4 + desc->array_len *
845                                     desc->elem_size > buf->len)
846                         return -EINVAL;
847         }
848         base += 4;
849
850         if (!desc->xcode)
851                 return 0;
852
853         todo = desc->array_len * desc->elem_size;
854
855         /* process head */
856         if (todo && base < buf->head->iov_len) {
857                 c = buf->head->iov_base + base;
858                 avail_here = min_t(unsigned int, todo,
859                                    buf->head->iov_len - base);
860                 todo -= avail_here;
861
862                 while (avail_here >= desc->elem_size) {
863                         err = desc->xcode(desc, c);
864                         if (err)
865                                 goto out;
866                         c += desc->elem_size;
867                         avail_here -= desc->elem_size;
868                 }
869                 if (avail_here) {
870                         if (!elem) {
871                                 elem = kmalloc(desc->elem_size, GFP_KERNEL);
872                                 err = -ENOMEM;
873                                 if (!elem)
874                                         goto out;
875                         }
876                         if (encode) {
877                                 err = desc->xcode(desc, elem);
878                                 if (err)
879                                         goto out;
880                                 memcpy(c, elem, avail_here);
881                         } else
882                                 memcpy(elem, c, avail_here);
883                         copied = avail_here;
884                 }
885                 base = buf->head->iov_len;  /* align to start of pages */
886         }
887
888         /* process pages array */
889         base -= buf->head->iov_len;
890         if (todo && base < buf->page_len) {
891                 unsigned int avail_page;
892
893                 avail_here = min(todo, buf->page_len - base);
894                 todo -= avail_here;
895
896                 base += buf->page_base;
897                 ppages = buf->pages + (base >> PAGE_CACHE_SHIFT);
898                 base &= ~PAGE_CACHE_MASK;
899                 avail_page = min_t(unsigned int, PAGE_CACHE_SIZE - base,
900                                         avail_here);
901                 c = kmap(*ppages) + base;
902
903                 while (avail_here) {
904                         avail_here -= avail_page;
905                         if (copied || avail_page < desc->elem_size) {
906                                 unsigned int l = min(avail_page,
907                                         desc->elem_size - copied);
908                                 if (!elem) {
909                                         elem = kmalloc(desc->elem_size,
910                                                        GFP_KERNEL);
911                                         err = -ENOMEM;
912                                         if (!elem)
913                                                 goto out;
914                                 }
915                                 if (encode) {
916                                         if (!copied) {
917                                                 err = desc->xcode(desc, elem);
918                                                 if (err)
919                                                         goto out;
920                                         }
921                                         memcpy(c, elem + copied, l);
922                                         copied += l;
923                                         if (copied == desc->elem_size)
924                                                 copied = 0;
925                                 } else {
926                                         memcpy(elem + copied, c, l);
927                                         copied += l;
928                                         if (copied == desc->elem_size) {
929                                                 err = desc->xcode(desc, elem);
930                                                 if (err)
931                                                         goto out;
932                                                 copied = 0;
933                                         }
934                                 }
935                                 avail_page -= l;
936                                 c += l;
937                         }
938                         while (avail_page >= desc->elem_size) {
939                                 err = desc->xcode(desc, c);
940                                 if (err)
941                                         goto out;
942                                 c += desc->elem_size;
943                                 avail_page -= desc->elem_size;
944                         }
945                         if (avail_page) {
946                                 unsigned int l = min(avail_page,
947                                             desc->elem_size - copied);
948                                 if (!elem) {
949                                         elem = kmalloc(desc->elem_size,
950                                                        GFP_KERNEL);
951                                         err = -ENOMEM;
952                                         if (!elem)
953                                                 goto out;
954                                 }
955                                 if (encode) {
956                                         if (!copied) {
957                                                 err = desc->xcode(desc, elem);
958                                                 if (err)
959                                                         goto out;
960                                         }
961                                         memcpy(c, elem + copied, l);
962                                         copied += l;
963                                         if (copied == desc->elem_size)
964                                                 copied = 0;
965                                 } else {
966                                         memcpy(elem + copied, c, l);
967                                         copied += l;
968                                         if (copied == desc->elem_size) {
969                                                 err = desc->xcode(desc, elem);
970                                                 if (err)
971                                                         goto out;
972                                                 copied = 0;
973                                         }
974                                 }
975                         }
976                         if (avail_here) {
977                                 kunmap(*ppages);
978                                 ppages++;
979                                 c = kmap(*ppages);
980                         }
981
982                         avail_page = min(avail_here,
983                                  (unsigned int) PAGE_CACHE_SIZE);
984                 }
985                 base = buf->page_len;  /* align to start of tail */
986         }
987
988         /* process tail */
989         base -= buf->page_len;
990         if (todo) {
991                 c = buf->tail->iov_base + base;
992                 if (copied) {
993                         unsigned int l = desc->elem_size - copied;
994
995                         if (encode)
996                                 memcpy(c, elem + copied, l);
997                         else {
998                                 memcpy(elem + copied, c, l);
999                                 err = desc->xcode(desc, elem);
1000                                 if (err)
1001                                         goto out;
1002                         }
1003                         todo -= l;
1004                         c += l;
1005                 }
1006                 while (todo) {
1007                         err = desc->xcode(desc, c);
1008                         if (err)
1009                                 goto out;
1010                         c += desc->elem_size;
1011                         todo -= desc->elem_size;
1012                 }
1013         }
1014         err = 0;
1015
1016 out:
1017         kfree(elem);
1018         if (ppages)
1019                 kunmap(*ppages);
1020         return err;
1021 }
1022
1023 int
1024 xdr_decode_array2(struct xdr_buf *buf, unsigned int base,
1025                   struct xdr_array2_desc *desc)
1026 {
1027         if (base >= buf->len)
1028                 return -EINVAL;
1029
1030         return xdr_xcode_array2(buf, base, desc, 0);
1031 }
1032 EXPORT_SYMBOL_GPL(xdr_decode_array2);
1033
1034 int
1035 xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
1036                   struct xdr_array2_desc *desc)
1037 {
1038         if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
1039             buf->head->iov_len + buf->page_len + buf->tail->iov_len)
1040                 return -EINVAL;
1041
1042         return xdr_xcode_array2(buf, base, desc, 1);
1043 }
1044 EXPORT_SYMBOL_GPL(xdr_encode_array2);
1045
1046 int
1047 xdr_process_buf(struct xdr_buf *buf, unsigned int offset, unsigned int len,
1048                 int (*actor)(struct scatterlist *, void *), void *data)
1049 {
1050         int i, ret = 0;
1051         unsigned page_len, thislen, page_offset;
1052         struct scatterlist      sg[1];
1053
1054         sg_init_table(sg, 1);
1055
1056         if (offset >= buf->head[0].iov_len) {
1057                 offset -= buf->head[0].iov_len;
1058         } else {
1059                 thislen = buf->head[0].iov_len - offset;
1060                 if (thislen > len)
1061                         thislen = len;
1062                 sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
1063                 ret = actor(sg, data);
1064                 if (ret)
1065                         goto out;
1066                 offset = 0;
1067                 len -= thislen;
1068         }
1069         if (len == 0)
1070                 goto out;
1071
1072         if (offset >= buf->page_len) {
1073                 offset -= buf->page_len;
1074         } else {
1075                 page_len = buf->page_len - offset;
1076                 if (page_len > len)
1077                         page_len = len;
1078                 len -= page_len;
1079                 page_offset = (offset + buf->page_base) & (PAGE_CACHE_SIZE - 1);
1080                 i = (offset + buf->page_base) >> PAGE_CACHE_SHIFT;
1081                 thislen = PAGE_CACHE_SIZE - page_offset;
1082                 do {
1083                         if (thislen > page_len)
1084                                 thislen = page_len;
1085                         sg_set_page(sg, buf->pages[i], thislen, page_offset);
1086                         ret = actor(sg, data);
1087                         if (ret)
1088                                 goto out;
1089                         page_len -= thislen;
1090                         i++;
1091                         page_offset = 0;
1092                         thislen = PAGE_CACHE_SIZE;
1093                 } while (page_len != 0);
1094                 offset = 0;
1095         }
1096         if (len == 0)
1097                 goto out;
1098         if (offset < buf->tail[0].iov_len) {
1099                 thislen = buf->tail[0].iov_len - offset;
1100                 if (thislen > len)
1101                         thislen = len;
1102                 sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
1103                 ret = actor(sg, data);
1104                 len -= thislen;
1105         }
1106         if (len != 0)
1107                 ret = -EINVAL;
1108 out:
1109         return ret;
1110 }
1111 EXPORT_SYMBOL_GPL(xdr_process_buf);
1112