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Linux/net/sunrpc/xdr.c

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  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 /**
115  * xdr_terminate_string - '\0'-terminate a string residing in an xdr_buf
116  * @buf: XDR buffer where string resides
117  * @len: length of string, in bytes
118  *
119  */
120 void
121 xdr_terminate_string(struct xdr_buf *buf, const u32 len)
122 {
123         char *kaddr;
124 
125         kaddr = kmap_atomic(buf->pages[0]);
126         kaddr[buf->page_base + len] = '\0';
127         kunmap_atomic(kaddr);
128 }
129 EXPORT_SYMBOL_GPL(xdr_terminate_string);
130 
131 void
132 xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
133                  struct page **pages, unsigned int base, unsigned int len)
134 {
135         struct kvec *head = xdr->head;
136         struct kvec *tail = xdr->tail;
137         char *buf = (char *)head->iov_base;
138         unsigned int buflen = head->iov_len;
139 
140         head->iov_len  = offset;
141 
142         xdr->pages = pages;
143         xdr->page_base = base;
144         xdr->page_len = len;
145 
146         tail->iov_base = buf + offset;
147         tail->iov_len = buflen - offset;
148 
149         xdr->buflen += len;
150 }
151 EXPORT_SYMBOL_GPL(xdr_inline_pages);
152 
153 /*
154  * Helper routines for doing 'memmove' like operations on a struct xdr_buf
155  */
156 
157 /**
158  * _shift_data_right_pages
159  * @pages: vector of pages containing both the source and dest memory area.
160  * @pgto_base: page vector address of destination
161  * @pgfrom_base: page vector address of source
162  * @len: number of bytes to copy
163  *
164  * Note: the addresses pgto_base and pgfrom_base are both calculated in
165  *       the same way:
166  *            if a memory area starts at byte 'base' in page 'pages[i]',
167  *            then its address is given as (i << PAGE_SHIFT) + base
168  * Also note: pgfrom_base must be < pgto_base, but the memory areas
169  *      they point to may overlap.
170  */
171 static void
172 _shift_data_right_pages(struct page **pages, size_t pgto_base,
173                 size_t pgfrom_base, size_t len)
174 {
175         struct page **pgfrom, **pgto;
176         char *vfrom, *vto;
177         size_t copy;
178 
179         BUG_ON(pgto_base <= pgfrom_base);
180 
181         pgto_base += len;
182         pgfrom_base += len;
183 
184         pgto = pages + (pgto_base >> PAGE_SHIFT);
185         pgfrom = pages + (pgfrom_base >> PAGE_SHIFT);
186 
187         pgto_base &= ~PAGE_MASK;
188         pgfrom_base &= ~PAGE_MASK;
189 
190         do {
191                 /* Are any pointers crossing a page boundary? */
192                 if (pgto_base == 0) {
193                         pgto_base = PAGE_SIZE;
194                         pgto--;
195                 }
196                 if (pgfrom_base == 0) {
197                         pgfrom_base = PAGE_SIZE;
198                         pgfrom--;
199                 }
200 
201                 copy = len;
202                 if (copy > pgto_base)
203                         copy = pgto_base;
204                 if (copy > pgfrom_base)
205                         copy = pgfrom_base;
206                 pgto_base -= copy;
207                 pgfrom_base -= copy;
208 
209                 vto = kmap_atomic(*pgto);
210                 if (*pgto != *pgfrom) {
211                         vfrom = kmap_atomic(*pgfrom);
212                         memcpy(vto + pgto_base, vfrom + pgfrom_base, copy);
213                         kunmap_atomic(vfrom);
214                 } else
215                         memmove(vto + pgto_base, vto + pgfrom_base, copy);
216                 flush_dcache_page(*pgto);
217                 kunmap_atomic(vto);
218 
219         } while ((len -= copy) != 0);
220 }
221 
222 /**
223  * _copy_to_pages
224  * @pages: array of pages
225  * @pgbase: page vector address of destination
226  * @p: pointer to source data
227  * @len: length
228  *
229  * Copies data from an arbitrary memory location into an array of pages
230  * The copy is assumed to be non-overlapping.
231  */
232 static void
233 _copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len)
234 {
235         struct page **pgto;
236         char *vto;
237         size_t copy;
238 
239         pgto = pages + (pgbase >> PAGE_SHIFT);
240         pgbase &= ~PAGE_MASK;
241 
242         for (;;) {
243                 copy = PAGE_SIZE - pgbase;
244                 if (copy > len)
245                         copy = len;
246 
247                 vto = kmap_atomic(*pgto);
248                 memcpy(vto + pgbase, p, copy);
249                 kunmap_atomic(vto);
250 
251                 len -= copy;
252                 if (len == 0)
253                         break;
254 
255                 pgbase += copy;
256                 if (pgbase == PAGE_SIZE) {
257                         flush_dcache_page(*pgto);
258                         pgbase = 0;
259                         pgto++;
260                 }
261                 p += copy;
262         }
263         flush_dcache_page(*pgto);
264 }
265 
266 /**
267  * _copy_from_pages
268  * @p: pointer to destination
269  * @pages: array of pages
270  * @pgbase: offset of source data
271  * @len: length
272  *
273  * Copies data into an arbitrary memory location from an array of pages
274  * The copy is assumed to be non-overlapping.
275  */
276 void
277 _copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
278 {
279         struct page **pgfrom;
280         char *vfrom;
281         size_t copy;
282 
283         pgfrom = pages + (pgbase >> PAGE_SHIFT);
284         pgbase &= ~PAGE_MASK;
285 
286         do {
287                 copy = PAGE_SIZE - pgbase;
288                 if (copy > len)
289                         copy = len;
290 
291                 vfrom = kmap_atomic(*pgfrom);
292                 memcpy(p, vfrom + pgbase, copy);
293                 kunmap_atomic(vfrom);
294 
295                 pgbase += copy;
296                 if (pgbase == PAGE_SIZE) {
297                         pgbase = 0;
298                         pgfrom++;
299                 }
300                 p += copy;
301 
302         } while ((len -= copy) != 0);
303 }
304 EXPORT_SYMBOL_GPL(_copy_from_pages);
305 
306 /**
307  * xdr_shrink_bufhead
308  * @buf: xdr_buf
309  * @len: bytes to remove from buf->head[0]
310  *
311  * Shrinks XDR buffer's header kvec buf->head[0] by
312  * 'len' bytes. The extra data is not lost, but is instead
313  * moved into the inlined pages and/or the tail.
314  */
315 static void
316 xdr_shrink_bufhead(struct xdr_buf *buf, size_t len)
317 {
318         struct kvec *head, *tail;
319         size_t copy, offs;
320         unsigned int pglen = buf->page_len;
321 
322         tail = buf->tail;
323         head = buf->head;
324 
325         WARN_ON_ONCE(len > head->iov_len);
326         if (len > head->iov_len)
327                 len = head->iov_len;
328 
329         /* Shift the tail first */
330         if (tail->iov_len != 0) {
331                 if (tail->iov_len > len) {
332                         copy = tail->iov_len - len;
333                         memmove((char *)tail->iov_base + len,
334                                         tail->iov_base, copy);
335                 }
336                 /* Copy from the inlined pages into the tail */
337                 copy = len;
338                 if (copy > pglen)
339                         copy = pglen;
340                 offs = len - copy;
341                 if (offs >= tail->iov_len)
342                         copy = 0;
343                 else if (copy > tail->iov_len - offs)
344                         copy = tail->iov_len - offs;
345                 if (copy != 0)
346                         _copy_from_pages((char *)tail->iov_base + offs,
347                                         buf->pages,
348                                         buf->page_base + pglen + offs - len,
349                                         copy);
350                 /* Do we also need to copy data from the head into the tail ? */
351                 if (len > pglen) {
352                         offs = copy = len - pglen;
353                         if (copy > tail->iov_len)
354                                 copy = tail->iov_len;
355                         memcpy(tail->iov_base,
356                                         (char *)head->iov_base +
357                                         head->iov_len - offs,
358                                         copy);
359                 }
360         }
361         /* Now handle pages */
362         if (pglen != 0) {
363                 if (pglen > len)
364                         _shift_data_right_pages(buf->pages,
365                                         buf->page_base + len,
366                                         buf->page_base,
367                                         pglen - len);
368                 copy = len;
369                 if (len > pglen)
370                         copy = pglen;
371                 _copy_to_pages(buf->pages, buf->page_base,
372                                 (char *)head->iov_base + head->iov_len - len,
373                                 copy);
374         }
375         head->iov_len -= len;
376         buf->buflen -= len;
377         /* Have we truncated the message? */
378         if (buf->len > buf->buflen)
379                 buf->len = buf->buflen;
380 }
381 
382 /**
383  * xdr_shrink_pagelen
384  * @buf: xdr_buf
385  * @len: bytes to remove from buf->pages
386  *
387  * Shrinks XDR buffer's page array buf->pages by
388  * 'len' bytes. The extra data is not lost, but is instead
389  * moved into the tail.
390  */
391 static void
392 xdr_shrink_pagelen(struct xdr_buf *buf, size_t len)
393 {
394         struct kvec *tail;
395         size_t copy;
396         unsigned int pglen = buf->page_len;
397         unsigned int tailbuf_len;
398 
399         tail = buf->tail;
400         BUG_ON (len > pglen);
401 
402         tailbuf_len = buf->buflen - buf->head->iov_len - buf->page_len;
403 
404         /* Shift the tail first */
405         if (tailbuf_len != 0) {
406                 unsigned int free_space = tailbuf_len - tail->iov_len;
407 
408                 if (len < free_space)
409                         free_space = len;
410                 tail->iov_len += free_space;
411 
412                 copy = len;
413                 if (tail->iov_len > len) {
414                         char *p = (char *)tail->iov_base + len;
415                         memmove(p, tail->iov_base, tail->iov_len - len);
416                 } else
417                         copy = tail->iov_len;
418                 /* Copy from the inlined pages into the tail */
419                 _copy_from_pages((char *)tail->iov_base,
420                                 buf->pages, buf->page_base + pglen - len,
421                                 copy);
422         }
423         buf->page_len -= len;
424         buf->buflen -= len;
425         /* Have we truncated the message? */
426         if (buf->len > buf->buflen)
427                 buf->len = buf->buflen;
428 }
429 
430 void
431 xdr_shift_buf(struct xdr_buf *buf, size_t len)
432 {
433         xdr_shrink_bufhead(buf, len);
434 }
435 EXPORT_SYMBOL_GPL(xdr_shift_buf);
436 
437 /**
438  * xdr_stream_pos - Return the current offset from the start of the xdr_stream
439  * @xdr: pointer to struct xdr_stream
440  */
441 unsigned int xdr_stream_pos(const struct xdr_stream *xdr)
442 {
443         return (unsigned int)(XDR_QUADLEN(xdr->buf->len) - xdr->nwords) << 2;
444 }
445 EXPORT_SYMBOL_GPL(xdr_stream_pos);
446 
447 /**
448  * xdr_init_encode - Initialize a struct xdr_stream for sending data.
449  * @xdr: pointer to xdr_stream struct
450  * @buf: pointer to XDR buffer in which to encode data
451  * @p: current pointer inside XDR buffer
452  *
453  * Note: at the moment the RPC client only passes the length of our
454  *       scratch buffer in the xdr_buf's header kvec. Previously this
455  *       meant we needed to call xdr_adjust_iovec() after encoding the
456  *       data. With the new scheme, the xdr_stream manages the details
457  *       of the buffer length, and takes care of adjusting the kvec
458  *       length for us.
459  */
460 void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
461 {
462         struct kvec *iov = buf->head;
463         int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
464 
465         xdr_set_scratch_buffer(xdr, NULL, 0);
466         BUG_ON(scratch_len < 0);
467         xdr->buf = buf;
468         xdr->iov = iov;
469         xdr->p = (__be32 *)((char *)iov->iov_base + iov->iov_len);
470         xdr->end = (__be32 *)((char *)iov->iov_base + scratch_len);
471         BUG_ON(iov->iov_len > scratch_len);
472 
473         if (p != xdr->p && p != NULL) {
474                 size_t len;
475 
476                 BUG_ON(p < xdr->p || p > xdr->end);
477                 len = (char *)p - (char *)xdr->p;
478                 xdr->p = p;
479                 buf->len += len;
480                 iov->iov_len += len;
481         }
482 }
483 EXPORT_SYMBOL_GPL(xdr_init_encode);
484 
485 /**
486  * xdr_commit_encode - Ensure all data is written to buffer
487  * @xdr: pointer to xdr_stream
488  *
489  * We handle encoding across page boundaries by giving the caller a
490  * temporary location to write to, then later copying the data into
491  * place; xdr_commit_encode does that copying.
492  *
493  * Normally the caller doesn't need to call this directly, as the
494  * following xdr_reserve_space will do it.  But an explicit call may be
495  * required at the end of encoding, or any other time when the xdr_buf
496  * data might be read.
497  */
498 void xdr_commit_encode(struct xdr_stream *xdr)
499 {
500         int shift = xdr->scratch.iov_len;
501         void *page;
502 
503         if (shift == 0)
504                 return;
505         page = page_address(*xdr->page_ptr);
506         memcpy(xdr->scratch.iov_base, page, shift);
507         memmove(page, page + shift, (void *)xdr->p - page);
508         xdr->scratch.iov_len = 0;
509 }
510 EXPORT_SYMBOL_GPL(xdr_commit_encode);
511 
512 static __be32 *xdr_get_next_encode_buffer(struct xdr_stream *xdr,
513                 size_t nbytes)
514 {
515         static __be32 *p;
516         int space_left;
517         int frag1bytes, frag2bytes;
518 
519         if (nbytes > PAGE_SIZE)
520                 return NULL; /* Bigger buffers require special handling */
521         if (xdr->buf->len + nbytes > xdr->buf->buflen)
522                 return NULL; /* Sorry, we're totally out of space */
523         frag1bytes = (xdr->end - xdr->p) << 2;
524         frag2bytes = nbytes - frag1bytes;
525         if (xdr->iov)
526                 xdr->iov->iov_len += frag1bytes;
527         else
528                 xdr->buf->page_len += frag1bytes;
529         xdr->page_ptr++;
530         xdr->iov = NULL;
531         /*
532          * If the last encode didn't end exactly on a page boundary, the
533          * next one will straddle boundaries.  Encode into the next
534          * page, then copy it back later in xdr_commit_encode.  We use
535          * the "scratch" iov to track any temporarily unused fragment of
536          * space at the end of the previous buffer:
537          */
538         xdr->scratch.iov_base = xdr->p;
539         xdr->scratch.iov_len = frag1bytes;
540         p = page_address(*xdr->page_ptr);
541         /*
542          * Note this is where the next encode will start after we've
543          * shifted this one back:
544          */
545         xdr->p = (void *)p + frag2bytes;
546         space_left = xdr->buf->buflen - xdr->buf->len;
547         xdr->end = (void *)p + min_t(int, space_left, PAGE_SIZE);
548         xdr->buf->page_len += frag2bytes;
549         xdr->buf->len += nbytes;
550         return p;
551 }
552 
553 /**
554  * xdr_reserve_space - Reserve buffer space for sending
555  * @xdr: pointer to xdr_stream
556  * @nbytes: number of bytes to reserve
557  *
558  * Checks that we have enough buffer space to encode 'nbytes' more
559  * bytes of data. If so, update the total xdr_buf length, and
560  * adjust the length of the current kvec.
561  */
562 __be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
563 {
564         __be32 *p = xdr->p;
565         __be32 *q;
566 
567         xdr_commit_encode(xdr);
568         /* align nbytes on the next 32-bit boundary */
569         nbytes += 3;
570         nbytes &= ~3;
571         q = p + (nbytes >> 2);
572         if (unlikely(q > xdr->end || q < p))
573                 return xdr_get_next_encode_buffer(xdr, nbytes);
574         xdr->p = q;
575         if (xdr->iov)
576                 xdr->iov->iov_len += nbytes;
577         else
578                 xdr->buf->page_len += nbytes;
579         xdr->buf->len += nbytes;
580         return p;
581 }
582 EXPORT_SYMBOL_GPL(xdr_reserve_space);
583 
584 /**
585  * xdr_truncate_encode - truncate an encode buffer
586  * @xdr: pointer to xdr_stream
587  * @len: new length of buffer
588  *
589  * Truncates the xdr stream, so that xdr->buf->len == len,
590  * and xdr->p points at offset len from the start of the buffer, and
591  * head, tail, and page lengths are adjusted to correspond.
592  *
593  * If this means moving xdr->p to a different buffer, we assume that
594  * that the end pointer should be set to the end of the current page,
595  * except in the case of the head buffer when we assume the head
596  * buffer's current length represents the end of the available buffer.
597  *
598  * This is *not* safe to use on a buffer that already has inlined page
599  * cache pages (as in a zero-copy server read reply), except for the
600  * simple case of truncating from one position in the tail to another.
601  *
602  */
603 void xdr_truncate_encode(struct xdr_stream *xdr, size_t len)
604 {
605         struct xdr_buf *buf = xdr->buf;
606         struct kvec *head = buf->head;
607         struct kvec *tail = buf->tail;
608         int fraglen;
609         int new;
610 
611         if (len > buf->len) {
612                 WARN_ON_ONCE(1);
613                 return;
614         }
615         xdr_commit_encode(xdr);
616 
617         fraglen = min_t(int, buf->len - len, tail->iov_len);
618         tail->iov_len -= fraglen;
619         buf->len -= fraglen;
620         if (tail->iov_len) {
621                 xdr->p = tail->iov_base + tail->iov_len;
622                 WARN_ON_ONCE(!xdr->end);
623                 WARN_ON_ONCE(!xdr->iov);
624                 return;
625         }
626         WARN_ON_ONCE(fraglen);
627         fraglen = min_t(int, buf->len - len, buf->page_len);
628         buf->page_len -= fraglen;
629         buf->len -= fraglen;
630 
631         new = buf->page_base + buf->page_len;
632 
633         xdr->page_ptr = buf->pages + (new >> PAGE_SHIFT);
634 
635         if (buf->page_len) {
636                 xdr->p = page_address(*xdr->page_ptr);
637                 xdr->end = (void *)xdr->p + PAGE_SIZE;
638                 xdr->p = (void *)xdr->p + (new % PAGE_SIZE);
639                 WARN_ON_ONCE(xdr->iov);
640                 return;
641         }
642         if (fraglen) {
643                 xdr->end = head->iov_base + head->iov_len;
644                 xdr->page_ptr--;
645         }
646         /* (otherwise assume xdr->end is already set) */
647         head->iov_len = len;
648         buf->len = len;
649         xdr->p = head->iov_base + head->iov_len;
650         xdr->iov = buf->head;
651 }
652 EXPORT_SYMBOL(xdr_truncate_encode);
653 
654 /**
655  * xdr_restrict_buflen - decrease available buffer space
656  * @xdr: pointer to xdr_stream
657  * @newbuflen: new maximum number of bytes available
658  *
659  * Adjust our idea of how much space is available in the buffer.
660  * If we've already used too much space in the buffer, returns -1.
661  * If the available space is already smaller than newbuflen, returns 0
662  * and does nothing.  Otherwise, adjusts xdr->buf->buflen to newbuflen
663  * and ensures xdr->end is set at most offset newbuflen from the start
664  * of the buffer.
665  */
666 int xdr_restrict_buflen(struct xdr_stream *xdr, int newbuflen)
667 {
668         struct xdr_buf *buf = xdr->buf;
669         int left_in_this_buf = (void *)xdr->end - (void *)xdr->p;
670         int end_offset = buf->len + left_in_this_buf;
671 
672         if (newbuflen < 0 || newbuflen < buf->len)
673                 return -1;
674         if (newbuflen > buf->buflen)
675                 return 0;
676         if (newbuflen < end_offset)
677                 xdr->end = (void *)xdr->end + newbuflen - end_offset;
678         buf->buflen = newbuflen;
679         return 0;
680 }
681 EXPORT_SYMBOL(xdr_restrict_buflen);
682 
683 /**
684  * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
685  * @xdr: pointer to xdr_stream
686  * @pages: list of pages
687  * @base: offset of first byte
688  * @len: length of data in bytes
689  *
690  */
691 void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
692                  unsigned int len)
693 {
694         struct xdr_buf *buf = xdr->buf;
695         struct kvec *iov = buf->tail;
696         buf->pages = pages;
697         buf->page_base = base;
698         buf->page_len = len;
699 
700         iov->iov_base = (char *)xdr->p;
701         iov->iov_len  = 0;
702         xdr->iov = iov;
703 
704         if (len & 3) {
705                 unsigned int pad = 4 - (len & 3);
706 
707                 BUG_ON(xdr->p >= xdr->end);
708                 iov->iov_base = (char *)xdr->p + (len & 3);
709                 iov->iov_len  += pad;
710                 len += pad;
711                 *xdr->p++ = 0;
712         }
713         buf->buflen += len;
714         buf->len += len;
715 }
716 EXPORT_SYMBOL_GPL(xdr_write_pages);
717 
718 static void xdr_set_iov(struct xdr_stream *xdr, struct kvec *iov,
719                 unsigned int len)
720 {
721         if (len > iov->iov_len)
722                 len = iov->iov_len;
723         xdr->p = (__be32*)iov->iov_base;
724         xdr->end = (__be32*)(iov->iov_base + len);
725         xdr->iov = iov;
726         xdr->page_ptr = NULL;
727 }
728 
729 static int xdr_set_page_base(struct xdr_stream *xdr,
730                 unsigned int base, unsigned int len)
731 {
732         unsigned int pgnr;
733         unsigned int maxlen;
734         unsigned int pgoff;
735         unsigned int pgend;
736         void *kaddr;
737 
738         maxlen = xdr->buf->page_len;
739         if (base >= maxlen)
740                 return -EINVAL;
741         maxlen -= base;
742         if (len > maxlen)
743                 len = maxlen;
744 
745         base += xdr->buf->page_base;
746 
747         pgnr = base >> PAGE_SHIFT;
748         xdr->page_ptr = &xdr->buf->pages[pgnr];
749         kaddr = page_address(*xdr->page_ptr);
750 
751         pgoff = base & ~PAGE_MASK;
752         xdr->p = (__be32*)(kaddr + pgoff);
753 
754         pgend = pgoff + len;
755         if (pgend > PAGE_SIZE)
756                 pgend = PAGE_SIZE;
757         xdr->end = (__be32*)(kaddr + pgend);
758         xdr->iov = NULL;
759         return 0;
760 }
761 
762 static void xdr_set_next_page(struct xdr_stream *xdr)
763 {
764         unsigned int newbase;
765 
766         newbase = (1 + xdr->page_ptr - xdr->buf->pages) << PAGE_SHIFT;
767         newbase -= xdr->buf->page_base;
768 
769         if (xdr_set_page_base(xdr, newbase, PAGE_SIZE) < 0)
770                 xdr_set_iov(xdr, xdr->buf->tail, xdr->buf->len);
771 }
772 
773 static bool xdr_set_next_buffer(struct xdr_stream *xdr)
774 {
775         if (xdr->page_ptr != NULL)
776                 xdr_set_next_page(xdr);
777         else if (xdr->iov == xdr->buf->head) {
778                 if (xdr_set_page_base(xdr, 0, PAGE_SIZE) < 0)
779                         xdr_set_iov(xdr, xdr->buf->tail, xdr->buf->len);
780         }
781         return xdr->p != xdr->end;
782 }
783 
784 /**
785  * xdr_init_decode - Initialize an xdr_stream for decoding data.
786  * @xdr: pointer to xdr_stream struct
787  * @buf: pointer to XDR buffer from which to decode data
788  * @p: current pointer inside XDR buffer
789  */
790 void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
791 {
792         xdr->buf = buf;
793         xdr->scratch.iov_base = NULL;
794         xdr->scratch.iov_len = 0;
795         xdr->nwords = XDR_QUADLEN(buf->len);
796         if (buf->head[0].iov_len != 0)
797                 xdr_set_iov(xdr, buf->head, buf->len);
798         else if (buf->page_len != 0)
799                 xdr_set_page_base(xdr, 0, buf->len);
800         else
801                 xdr_set_iov(xdr, buf->head, buf->len);
802         if (p != NULL && p > xdr->p && xdr->end >= p) {
803                 xdr->nwords -= p - xdr->p;
804                 xdr->p = p;
805         }
806 }
807 EXPORT_SYMBOL_GPL(xdr_init_decode);
808 
809 /**
810  * xdr_init_decode - Initialize an xdr_stream for decoding data.
811  * @xdr: pointer to xdr_stream struct
812  * @buf: pointer to XDR buffer from which to decode data
813  * @pages: list of pages to decode into
814  * @len: length in bytes of buffer in pages
815  */
816 void xdr_init_decode_pages(struct xdr_stream *xdr, struct xdr_buf *buf,
817                            struct page **pages, unsigned int len)
818 {
819         memset(buf, 0, sizeof(*buf));
820         buf->pages =  pages;
821         buf->page_len =  len;
822         buf->buflen =  len;
823         buf->len = len;
824         xdr_init_decode(xdr, buf, NULL);
825 }
826 EXPORT_SYMBOL_GPL(xdr_init_decode_pages);
827 
828 static __be32 * __xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
829 {
830         unsigned int nwords = XDR_QUADLEN(nbytes);
831         __be32 *p = xdr->p;
832         __be32 *q = p + nwords;
833 
834         if (unlikely(nwords > xdr->nwords || q > xdr->end || q < p))
835                 return NULL;
836         xdr->p = q;
837         xdr->nwords -= nwords;
838         return p;
839 }
840 
841 /**
842  * xdr_set_scratch_buffer - Attach a scratch buffer for decoding data.
843  * @xdr: pointer to xdr_stream struct
844  * @buf: pointer to an empty buffer
845  * @buflen: size of 'buf'
846  *
847  * The scratch buffer is used when decoding from an array of pages.
848  * If an xdr_inline_decode() call spans across page boundaries, then
849  * we copy the data into the scratch buffer in order to allow linear
850  * access.
851  */
852 void xdr_set_scratch_buffer(struct xdr_stream *xdr, void *buf, size_t buflen)
853 {
854         xdr->scratch.iov_base = buf;
855         xdr->scratch.iov_len = buflen;
856 }
857 EXPORT_SYMBOL_GPL(xdr_set_scratch_buffer);
858 
859 static __be32 *xdr_copy_to_scratch(struct xdr_stream *xdr, size_t nbytes)
860 {
861         __be32 *p;
862         void *cpdest = xdr->scratch.iov_base;
863         size_t cplen = (char *)xdr->end - (char *)xdr->p;
864 
865         if (nbytes > xdr->scratch.iov_len)
866                 return NULL;
867         memcpy(cpdest, xdr->p, cplen);
868         cpdest += cplen;
869         nbytes -= cplen;
870         if (!xdr_set_next_buffer(xdr))
871                 return NULL;
872         p = __xdr_inline_decode(xdr, nbytes);
873         if (p == NULL)
874                 return NULL;
875         memcpy(cpdest, p, nbytes);
876         return xdr->scratch.iov_base;
877 }
878 
879 /**
880  * xdr_inline_decode - Retrieve XDR data to decode
881  * @xdr: pointer to xdr_stream struct
882  * @nbytes: number of bytes of data to decode
883  *
884  * Check if the input buffer is long enough to enable us to decode
885  * 'nbytes' more bytes of data starting at the current position.
886  * If so return the current pointer, then update the current
887  * pointer position.
888  */
889 __be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
890 {
891         __be32 *p;
892 
893         if (nbytes == 0)
894                 return xdr->p;
895         if (xdr->p == xdr->end && !xdr_set_next_buffer(xdr))
896                 return NULL;
897         p = __xdr_inline_decode(xdr, nbytes);
898         if (p != NULL)
899                 return p;
900         return xdr_copy_to_scratch(xdr, nbytes);
901 }
902 EXPORT_SYMBOL_GPL(xdr_inline_decode);
903 
904 static unsigned int xdr_align_pages(struct xdr_stream *xdr, unsigned int len)
905 {
906         struct xdr_buf *buf = xdr->buf;
907         struct kvec *iov;
908         unsigned int nwords = XDR_QUADLEN(len);
909         unsigned int cur = xdr_stream_pos(xdr);
910 
911         if (xdr->nwords == 0)
912                 return 0;
913         /* Realign pages to current pointer position */
914         iov  = buf->head;
915         if (iov->iov_len > cur) {
916                 xdr_shrink_bufhead(buf, iov->iov_len - cur);
917                 xdr->nwords = XDR_QUADLEN(buf->len - cur);
918         }
919 
920         if (nwords > xdr->nwords) {
921                 nwords = xdr->nwords;
922                 len = nwords << 2;
923         }
924         if (buf->page_len <= len)
925                 len = buf->page_len;
926         else if (nwords < xdr->nwords) {
927                 /* Truncate page data and move it into the tail */
928                 xdr_shrink_pagelen(buf, buf->page_len - len);
929                 xdr->nwords = XDR_QUADLEN(buf->len - cur);
930         }
931         return len;
932 }
933 
934 /**
935  * xdr_read_pages - Ensure page-based XDR data to decode is aligned at current pointer position
936  * @xdr: pointer to xdr_stream struct
937  * @len: number of bytes of page data
938  *
939  * Moves data beyond the current pointer position from the XDR head[] buffer
940  * into the page list. Any data that lies beyond current position + "len"
941  * bytes is moved into the XDR tail[].
942  *
943  * Returns the number of XDR encoded bytes now contained in the pages
944  */
945 unsigned int xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
946 {
947         struct xdr_buf *buf = xdr->buf;
948         struct kvec *iov;
949         unsigned int nwords;
950         unsigned int end;
951         unsigned int padding;
952 
953         len = xdr_align_pages(xdr, len);
954         if (len == 0)
955                 return 0;
956         nwords = XDR_QUADLEN(len);
957         padding = (nwords << 2) - len;
958         xdr->iov = iov = buf->tail;
959         /* Compute remaining message length.  */
960         end = ((xdr->nwords - nwords) << 2) + padding;
961         if (end > iov->iov_len)
962                 end = iov->iov_len;
963 
964         /*
965          * Position current pointer at beginning of tail, and
966          * set remaining message length.
967          */
968         xdr->p = (__be32 *)((char *)iov->iov_base + padding);
969         xdr->end = (__be32 *)((char *)iov->iov_base + end);
970         xdr->page_ptr = NULL;
971         xdr->nwords = XDR_QUADLEN(end - padding);
972         return len;
973 }
974 EXPORT_SYMBOL_GPL(xdr_read_pages);
975 
976 /**
977  * xdr_enter_page - decode data from the XDR page
978  * @xdr: pointer to xdr_stream struct
979  * @len: number of bytes of page data
980  *
981  * Moves data beyond the current pointer position from the XDR head[] buffer
982  * into the page list. Any data that lies beyond current position + "len"
983  * bytes is moved into the XDR tail[]. The current pointer is then
984  * repositioned at the beginning of the first XDR page.
985  */
986 void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
987 {
988         len = xdr_align_pages(xdr, len);
989         /*
990          * Position current pointer at beginning of tail, and
991          * set remaining message length.
992          */
993         if (len != 0)
994                 xdr_set_page_base(xdr, 0, len);
995 }
996 EXPORT_SYMBOL_GPL(xdr_enter_page);
997 
998 static struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
999 
1000 void
1001 xdr_buf_from_iov(struct kvec *iov, struct xdr_buf *buf)
1002 {
1003         buf->head[0] = *iov;
1004         buf->tail[0] = empty_iov;
1005         buf->page_len = 0;
1006         buf->buflen = buf->len = iov->iov_len;
1007 }
1008 EXPORT_SYMBOL_GPL(xdr_buf_from_iov);
1009 
1010 /**
1011  * xdr_buf_subsegment - set subbuf to a portion of buf
1012  * @buf: an xdr buffer
1013  * @subbuf: the result buffer
1014  * @base: beginning of range in bytes
1015  * @len: length of range in bytes
1016  *
1017  * sets @subbuf to an xdr buffer representing the portion of @buf of
1018  * length @len starting at offset @base.
1019  *
1020  * @buf and @subbuf may be pointers to the same struct xdr_buf.
1021  *
1022  * Returns -1 if base of length are out of bounds.
1023  */
1024 int
1025 xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
1026                         unsigned int base, unsigned int len)
1027 {
1028         subbuf->buflen = subbuf->len = len;
1029         if (base < buf->head[0].iov_len) {
1030                 subbuf->head[0].iov_base = buf->head[0].iov_base + base;
1031                 subbuf->head[0].iov_len = min_t(unsigned int, len,
1032                                                 buf->head[0].iov_len - base);
1033                 len -= subbuf->head[0].iov_len;
1034                 base = 0;
1035         } else {
1036                 base -= buf->head[0].iov_len;
1037                 subbuf->head[0].iov_len = 0;
1038         }
1039 
1040         if (base < buf->page_len) {
1041                 subbuf->page_len = min(buf->page_len - base, len);
1042                 base += buf->page_base;
1043                 subbuf->page_base = base & ~PAGE_MASK;
1044                 subbuf->pages = &buf->pages[base >> PAGE_SHIFT];
1045                 len -= subbuf->page_len;
1046                 base = 0;
1047         } else {
1048                 base -= buf->page_len;
1049                 subbuf->page_len = 0;
1050         }
1051 
1052         if (base < buf->tail[0].iov_len) {
1053                 subbuf->tail[0].iov_base = buf->tail[0].iov_base + base;
1054                 subbuf->tail[0].iov_len = min_t(unsigned int, len,
1055                                                 buf->tail[0].iov_len - base);
1056                 len -= subbuf->tail[0].iov_len;
1057                 base = 0;
1058         } else {
1059                 base -= buf->tail[0].iov_len;
1060                 subbuf->tail[0].iov_len = 0;
1061         }
1062 
1063         if (base || len)
1064                 return -1;
1065         return 0;
1066 }
1067 EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
1068 
1069 /**
1070  * xdr_buf_trim - lop at most "len" bytes off the end of "buf"
1071  * @buf: buf to be trimmed
1072  * @len: number of bytes to reduce "buf" by
1073  *
1074  * Trim an xdr_buf by the given number of bytes by fixing up the lengths. Note
1075  * that it's possible that we'll trim less than that amount if the xdr_buf is
1076  * too small, or if (for instance) it's all in the head and the parser has
1077  * already read too far into it.
1078  */
1079 void xdr_buf_trim(struct xdr_buf *buf, unsigned int len)
1080 {
1081         size_t cur;
1082         unsigned int trim = len;
1083 
1084         if (buf->tail[0].iov_len) {
1085                 cur = min_t(size_t, buf->tail[0].iov_len, trim);
1086                 buf->tail[0].iov_len -= cur;
1087                 trim -= cur;
1088                 if (!trim)
1089                         goto fix_len;
1090         }
1091 
1092         if (buf->page_len) {
1093                 cur = min_t(unsigned int, buf->page_len, trim);
1094                 buf->page_len -= cur;
1095                 trim -= cur;
1096                 if (!trim)
1097                         goto fix_len;
1098         }
1099 
1100         if (buf->head[0].iov_len) {
1101                 cur = min_t(size_t, buf->head[0].iov_len, trim);
1102                 buf->head[0].iov_len -= cur;
1103                 trim -= cur;
1104         }
1105 fix_len:
1106         buf->len -= (len - trim);
1107 }
1108 EXPORT_SYMBOL_GPL(xdr_buf_trim);
1109 
1110 static void __read_bytes_from_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
1111 {
1112         unsigned int this_len;
1113 
1114         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1115         memcpy(obj, subbuf->head[0].iov_base, this_len);
1116         len -= this_len;
1117         obj += this_len;
1118         this_len = min_t(unsigned int, len, subbuf->page_len);
1119         if (this_len)
1120                 _copy_from_pages(obj, subbuf->pages, subbuf->page_base, this_len);
1121         len -= this_len;
1122         obj += this_len;
1123         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1124         memcpy(obj, subbuf->tail[0].iov_base, this_len);
1125 }
1126 
1127 /* obj is assumed to point to allocated memory of size at least len: */
1128 int read_bytes_from_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
1129 {
1130         struct xdr_buf subbuf;
1131         int status;
1132 
1133         status = xdr_buf_subsegment(buf, &subbuf, base, len);
1134         if (status != 0)
1135                 return status;
1136         __read_bytes_from_xdr_buf(&subbuf, obj, len);
1137         return 0;
1138 }
1139 EXPORT_SYMBOL_GPL(read_bytes_from_xdr_buf);
1140 
1141 static void __write_bytes_to_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
1142 {
1143         unsigned int this_len;
1144 
1145         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
1146         memcpy(subbuf->head[0].iov_base, obj, this_len);
1147         len -= this_len;
1148         obj += this_len;
1149         this_len = min_t(unsigned int, len, subbuf->page_len);
1150         if (this_len)
1151                 _copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
1152         len -= this_len;
1153         obj += this_len;
1154         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
1155         memcpy(subbuf->tail[0].iov_base, obj, this_len);
1156 }
1157 
1158 /* obj is assumed to point to allocated memory of size at least len: */
1159 int write_bytes_to_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
1160 {
1161         struct xdr_buf subbuf;
1162         int status;
1163 
1164         status = xdr_buf_subsegment(buf, &subbuf, base, len);
1165         if (status != 0)
1166                 return status;
1167         __write_bytes_to_xdr_buf(&subbuf, obj, len);
1168         return 0;
1169 }
1170 EXPORT_SYMBOL_GPL(write_bytes_to_xdr_buf);
1171 
1172 int
1173 xdr_decode_word(struct xdr_buf *buf, unsigned int base, u32 *obj)
1174 {
1175         __be32  raw;
1176         int     status;
1177 
1178         status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
1179         if (status)
1180                 return status;
1181         *obj = be32_to_cpu(raw);
1182         return 0;
1183 }
1184 EXPORT_SYMBOL_GPL(xdr_decode_word);
1185 
1186 int
1187 xdr_encode_word(struct xdr_buf *buf, unsigned int base, u32 obj)
1188 {
1189         __be32  raw = cpu_to_be32(obj);
1190 
1191         return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
1192 }
1193 EXPORT_SYMBOL_GPL(xdr_encode_word);
1194 
1195 /* If the netobj starting offset bytes from the start of xdr_buf is contained
1196  * entirely in the head or the tail, set object to point to it; otherwise
1197  * try to find space for it at the end of the tail, copy it there, and
1198  * set obj to point to it. */
1199 int xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, unsigned int offset)
1200 {
1201         struct xdr_buf subbuf;
1202 
1203         if (xdr_decode_word(buf, offset, &obj->len))
1204                 return -EFAULT;
1205         if (xdr_buf_subsegment(buf, &subbuf, offset + 4, obj->len))
1206                 return -EFAULT;
1207 
1208         /* Is the obj contained entirely in the head? */
1209         obj->data = subbuf.head[0].iov_base;
1210         if (subbuf.head[0].iov_len == obj->len)
1211                 return 0;
1212         /* ..or is the obj contained entirely in the tail? */
1213         obj->data = subbuf.tail[0].iov_base;
1214         if (subbuf.tail[0].iov_len == obj->len)
1215                 return 0;
1216 
1217         /* use end of tail as storage for obj:
1218          * (We don't copy to the beginning because then we'd have
1219          * to worry about doing a potentially overlapping copy.
1220          * This assumes the object is at most half the length of the
1221          * tail.) */
1222         if (obj->len > buf->buflen - buf->len)
1223                 return -ENOMEM;
1224         if (buf->tail[0].iov_len != 0)
1225                 obj->data = buf->tail[0].iov_base + buf->tail[0].iov_len;
1226         else
1227                 obj->data = buf->head[0].iov_base + buf->head[0].iov_len;
1228         __read_bytes_from_xdr_buf(&subbuf, obj->data, obj->len);
1229         return 0;
1230 }
1231 EXPORT_SYMBOL_GPL(xdr_buf_read_netobj);
1232 
1233 /* Returns 0 on success, or else a negative error code. */
1234 static int
1235 xdr_xcode_array2(struct xdr_buf *buf, unsigned int base,
1236                  struct xdr_array2_desc *desc, int encode)
1237 {
1238         char *elem = NULL, *c;
1239         unsigned int copied = 0, todo, avail_here;
1240         struct page **ppages = NULL;
1241         int err;
1242 
1243         if (encode) {
1244                 if (xdr_encode_word(buf, base, desc->array_len) != 0)
1245                         return -EINVAL;
1246         } else {
1247                 if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
1248                     desc->array_len > desc->array_maxlen ||
1249                     (unsigned long) base + 4 + desc->array_len *
1250                                     desc->elem_size > buf->len)
1251                         return -EINVAL;
1252         }
1253         base += 4;
1254 
1255         if (!desc->xcode)
1256                 return 0;
1257 
1258         todo = desc->array_len * desc->elem_size;
1259 
1260         /* process head */
1261         if (todo && base < buf->head->iov_len) {
1262                 c = buf->head->iov_base + base;
1263                 avail_here = min_t(unsigned int, todo,
1264                                    buf->head->iov_len - base);
1265                 todo -= avail_here;
1266 
1267                 while (avail_here >= desc->elem_size) {
1268                         err = desc->xcode(desc, c);
1269                         if (err)
1270                                 goto out;
1271                         c += desc->elem_size;
1272                         avail_here -= desc->elem_size;
1273                 }
1274                 if (avail_here) {
1275                         if (!elem) {
1276                                 elem = kmalloc(desc->elem_size, GFP_KERNEL);
1277                                 err = -ENOMEM;
1278                                 if (!elem)
1279                                         goto out;
1280                         }
1281                         if (encode) {
1282                                 err = desc->xcode(desc, elem);
1283                                 if (err)
1284                                         goto out;
1285                                 memcpy(c, elem, avail_here);
1286                         } else
1287                                 memcpy(elem, c, avail_here);
1288                         copied = avail_here;
1289                 }
1290                 base = buf->head->iov_len;  /* align to start of pages */
1291         }
1292 
1293         /* process pages array */
1294         base -= buf->head->iov_len;
1295         if (todo && base < buf->page_len) {
1296                 unsigned int avail_page;
1297 
1298                 avail_here = min(todo, buf->page_len - base);
1299                 todo -= avail_here;
1300 
1301                 base += buf->page_base;
1302                 ppages = buf->pages + (base >> PAGE_SHIFT);
1303                 base &= ~PAGE_MASK;
1304                 avail_page = min_t(unsigned int, PAGE_SIZE - base,
1305                                         avail_here);
1306                 c = kmap(*ppages) + base;
1307 
1308                 while (avail_here) {
1309                         avail_here -= avail_page;
1310                         if (copied || avail_page < desc->elem_size) {
1311                                 unsigned int l = min(avail_page,
1312                                         desc->elem_size - copied);
1313                                 if (!elem) {
1314                                         elem = kmalloc(desc->elem_size,
1315                                                        GFP_KERNEL);
1316                                         err = -ENOMEM;
1317                                         if (!elem)
1318                                                 goto out;
1319                                 }
1320                                 if (encode) {
1321                                         if (!copied) {
1322                                                 err = desc->xcode(desc, elem);
1323                                                 if (err)
1324                                                         goto out;
1325                                         }
1326                                         memcpy(c, elem + copied, l);
1327                                         copied += l;
1328                                         if (copied == desc->elem_size)
1329                                                 copied = 0;
1330                                 } else {
1331                                         memcpy(elem + copied, c, l);
1332                                         copied += l;
1333                                         if (copied == desc->elem_size) {
1334                                                 err = desc->xcode(desc, elem);
1335                                                 if (err)
1336                                                         goto out;
1337                                                 copied = 0;
1338                                         }
1339                                 }
1340                                 avail_page -= l;
1341                                 c += l;
1342                         }
1343                         while (avail_page >= desc->elem_size) {
1344                                 err = desc->xcode(desc, c);
1345                                 if (err)
1346                                         goto out;
1347                                 c += desc->elem_size;
1348                                 avail_page -= desc->elem_size;
1349                         }
1350                         if (avail_page) {
1351                                 unsigned int l = min(avail_page,
1352                                             desc->elem_size - copied);
1353                                 if (!elem) {
1354                                         elem = kmalloc(desc->elem_size,
1355                                                        GFP_KERNEL);
1356                                         err = -ENOMEM;
1357                                         if (!elem)
1358                                                 goto out;
1359                                 }
1360                                 if (encode) {
1361                                         if (!copied) {
1362                                                 err = desc->xcode(desc, elem);
1363                                                 if (err)
1364                                                         goto out;
1365                                         }
1366                                         memcpy(c, elem + copied, l);
1367                                         copied += l;
1368                                         if (copied == desc->elem_size)
1369                                                 copied = 0;
1370                                 } else {
1371                                         memcpy(elem + copied, c, l);
1372                                         copied += l;
1373                                         if (copied == desc->elem_size) {
1374                                                 err = desc->xcode(desc, elem);
1375                                                 if (err)
1376                                                         goto out;
1377                                                 copied = 0;
1378                                         }
1379                                 }
1380                         }
1381                         if (avail_here) {
1382                                 kunmap(*ppages);
1383                                 ppages++;
1384                                 c = kmap(*ppages);
1385                         }
1386 
1387                         avail_page = min(avail_here,
1388                                  (unsigned int) PAGE_SIZE);
1389                 }
1390                 base = buf->page_len;  /* align to start of tail */
1391         }
1392 
1393         /* process tail */
1394         base -= buf->page_len;
1395         if (todo) {
1396                 c = buf->tail->iov_base + base;
1397                 if (copied) {
1398                         unsigned int l = desc->elem_size - copied;
1399 
1400                         if (encode)
1401                                 memcpy(c, elem + copied, l);
1402                         else {
1403                                 memcpy(elem + copied, c, l);
1404                                 err = desc->xcode(desc, elem);
1405                                 if (err)
1406                                         goto out;
1407                         }
1408                         todo -= l;
1409                         c += l;
1410                 }
1411                 while (todo) {
1412                         err = desc->xcode(desc, c);
1413                         if (err)
1414                                 goto out;
1415                         c += desc->elem_size;
1416                         todo -= desc->elem_size;
1417                 }
1418         }
1419         err = 0;
1420 
1421 out:
1422         kfree(elem);
1423         if (ppages)
1424                 kunmap(*ppages);
1425         return err;
1426 }
1427 
1428 int
1429 xdr_decode_array2(struct xdr_buf *buf, unsigned int base,
1430                   struct xdr_array2_desc *desc)
1431 {
1432         if (base >= buf->len)
1433                 return -EINVAL;
1434 
1435         return xdr_xcode_array2(buf, base, desc, 0);
1436 }
1437 EXPORT_SYMBOL_GPL(xdr_decode_array2);
1438 
1439 int
1440 xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
1441                   struct xdr_array2_desc *desc)
1442 {
1443         if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
1444             buf->head->iov_len + buf->page_len + buf->tail->iov_len)
1445                 return -EINVAL;
1446 
1447         return xdr_xcode_array2(buf, base, desc, 1);
1448 }
1449 EXPORT_SYMBOL_GPL(xdr_encode_array2);
1450 
1451 int
1452 xdr_process_buf(struct xdr_buf *buf, unsigned int offset, unsigned int len,
1453                 int (*actor)(struct scatterlist *, void *), void *data)
1454 {
1455         int i, ret = 0;
1456         unsigned int page_len, thislen, page_offset;
1457         struct scatterlist      sg[1];
1458 
1459         sg_init_table(sg, 1);
1460 
1461         if (offset >= buf->head[0].iov_len) {
1462                 offset -= buf->head[0].iov_len;
1463         } else {
1464                 thislen = buf->head[0].iov_len - offset;
1465                 if (thislen > len)
1466                         thislen = len;
1467                 sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
1468                 ret = actor(sg, data);
1469                 if (ret)
1470                         goto out;
1471                 offset = 0;
1472                 len -= thislen;
1473         }
1474         if (len == 0)
1475                 goto out;
1476 
1477         if (offset >= buf->page_len) {
1478                 offset -= buf->page_len;
1479         } else {
1480                 page_len = buf->page_len - offset;
1481                 if (page_len > len)
1482                         page_len = len;
1483                 len -= page_len;
1484                 page_offset = (offset + buf->page_base) & (PAGE_SIZE - 1);
1485                 i = (offset + buf->page_base) >> PAGE_SHIFT;
1486                 thislen = PAGE_SIZE - page_offset;
1487                 do {
1488                         if (thislen > page_len)
1489                                 thislen = page_len;
1490                         sg_set_page(sg, buf->pages[i], thislen, page_offset);
1491                         ret = actor(sg, data);
1492                         if (ret)
1493                                 goto out;
1494                         page_len -= thislen;
1495                         i++;
1496                         page_offset = 0;
1497                         thislen = PAGE_SIZE;
1498                 } while (page_len != 0);
1499                 offset = 0;
1500         }
1501         if (len == 0)
1502                 goto out;
1503         if (offset < buf->tail[0].iov_len) {
1504                 thislen = buf->tail[0].iov_len - offset;
1505                 if (thislen > len)
1506                         thislen = len;
1507                 sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
1508                 ret = actor(sg, data);
1509                 len -= thislen;
1510         }
1511         if (len != 0)
1512                 ret = -EINVAL;
1513 out:
1514         return ret;
1515 }
1516 EXPORT_SYMBOL_GPL(xdr_process_buf);
1517 
1518 

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