rpcgss: krb5: clean up some goto's, etc.
[linux-2.6] / net / sunrpc / xdr.c
1 /*
2  * linux/net/sunrpc/xdr.c
3  *
4  * Generic XDR support.
5  *
6  * Copyright (C) 1995, 1996 Olaf Kirch <okir@monad.swb.de>
7  */
8
9 #include <linux/module.h>
10 #include <linux/types.h>
11 #include <linux/string.h>
12 #include <linux/kernel.h>
13 #include <linux/pagemap.h>
14 #include <linux/errno.h>
15 #include <linux/sunrpc/xdr.h>
16 #include <linux/sunrpc/msg_prot.h>
17
18 /*
19  * XDR functions for basic NFS types
20  */
21 __be32 *
22 xdr_encode_netobj(__be32 *p, const struct xdr_netobj *obj)
23 {
24         unsigned int    quadlen = XDR_QUADLEN(obj->len);
25
26         p[quadlen] = 0;         /* zero trailing bytes */
27         *p++ = htonl(obj->len);
28         memcpy(p, obj->data, obj->len);
29         return p + XDR_QUADLEN(obj->len);
30 }
31
32 __be32 *
33 xdr_decode_netobj(__be32 *p, struct xdr_netobj *obj)
34 {
35         unsigned int    len;
36
37         if ((len = ntohl(*p++)) > XDR_MAX_NETOBJ)
38                 return NULL;
39         obj->len  = len;
40         obj->data = (u8 *) p;
41         return p + XDR_QUADLEN(len);
42 }
43
44 /**
45  * xdr_encode_opaque_fixed - Encode fixed length opaque data
46  * @p: pointer to current position in XDR buffer.
47  * @ptr: pointer to data to encode (or NULL)
48  * @nbytes: size of data.
49  *
50  * Copy the array of data of length nbytes at ptr to the XDR buffer
51  * at position p, then align to the next 32-bit boundary by padding
52  * with zero bytes (see RFC1832).
53  * Note: if ptr is NULL, only the padding is performed.
54  *
55  * Returns the updated current XDR buffer position
56  *
57  */
58 __be32 *xdr_encode_opaque_fixed(__be32 *p, const void *ptr, unsigned int nbytes)
59 {
60         if (likely(nbytes != 0)) {
61                 unsigned int quadlen = XDR_QUADLEN(nbytes);
62                 unsigned int padding = (quadlen << 2) - nbytes;
63
64                 if (ptr != NULL)
65                         memcpy(p, ptr, nbytes);
66                 if (padding != 0)
67                         memset((char *)p + nbytes, 0, padding);
68                 p += quadlen;
69         }
70         return p;
71 }
72 EXPORT_SYMBOL(xdr_encode_opaque_fixed);
73
74 /**
75  * xdr_encode_opaque - Encode variable length opaque data
76  * @p: pointer to current position in XDR buffer.
77  * @ptr: pointer to data to encode (or NULL)
78  * @nbytes: size of data.
79  *
80  * Returns the updated current XDR buffer position
81  */
82 __be32 *xdr_encode_opaque(__be32 *p, const void *ptr, unsigned int nbytes)
83 {
84         *p++ = htonl(nbytes);
85         return xdr_encode_opaque_fixed(p, ptr, nbytes);
86 }
87 EXPORT_SYMBOL(xdr_encode_opaque);
88
89 __be32 *
90 xdr_encode_string(__be32 *p, const char *string)
91 {
92         return xdr_encode_array(p, string, strlen(string));
93 }
94
95 __be32 *
96 xdr_decode_string_inplace(__be32 *p, char **sp, int *lenp, int maxlen)
97 {
98         unsigned int    len;
99
100         if ((len = ntohl(*p++)) > maxlen)
101                 return NULL;
102         *lenp = len;
103         *sp = (char *) p;
104         return p + XDR_QUADLEN(len);
105 }
106
107 void
108 xdr_encode_pages(struct xdr_buf *xdr, struct page **pages, unsigned int base,
109                  unsigned int len)
110 {
111         struct kvec *tail = xdr->tail;
112         u32 *p;
113
114         xdr->pages = pages;
115         xdr->page_base = base;
116         xdr->page_len = len;
117
118         p = (u32 *)xdr->head[0].iov_base + XDR_QUADLEN(xdr->head[0].iov_len);
119         tail->iov_base = p;
120         tail->iov_len = 0;
121
122         if (len & 3) {
123                 unsigned int pad = 4 - (len & 3);
124
125                 *p = 0;
126                 tail->iov_base = (char *)p + (len & 3);
127                 tail->iov_len  = pad;
128                 len += pad;
129         }
130         xdr->buflen += len;
131         xdr->len += len;
132 }
133
134 void
135 xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
136                  struct page **pages, unsigned int base, unsigned int len)
137 {
138         struct kvec *head = xdr->head;
139         struct kvec *tail = xdr->tail;
140         char *buf = (char *)head->iov_base;
141         unsigned int buflen = head->iov_len;
142
143         head->iov_len  = offset;
144
145         xdr->pages = pages;
146         xdr->page_base = base;
147         xdr->page_len = len;
148
149         tail->iov_base = buf + offset;
150         tail->iov_len = buflen - offset;
151
152         xdr->buflen += len;
153 }
154
155
156 /*
157  * Helper routines for doing 'memmove' like operations on a struct xdr_buf
158  *
159  * _shift_data_right_pages
160  * @pages: vector of pages containing both the source and dest memory area.
161  * @pgto_base: page vector address of destination
162  * @pgfrom_base: page vector address of source
163  * @len: number of bytes to copy
164  *
165  * Note: the addresses pgto_base and pgfrom_base are both calculated in
166  *       the same way:
167  *            if a memory area starts at byte 'base' in page 'pages[i]',
168  *            then its address is given as (i << PAGE_CACHE_SHIFT) + base
169  * Also note: pgfrom_base must be < pgto_base, but the memory areas
170  *      they point to may overlap.
171  */
172 static void
173 _shift_data_right_pages(struct page **pages, size_t pgto_base,
174                 size_t pgfrom_base, size_t len)
175 {
176         struct page **pgfrom, **pgto;
177         char *vfrom, *vto;
178         size_t copy;
179
180         BUG_ON(pgto_base <= pgfrom_base);
181
182         pgto_base += len;
183         pgfrom_base += len;
184
185         pgto = pages + (pgto_base >> PAGE_CACHE_SHIFT);
186         pgfrom = pages + (pgfrom_base >> PAGE_CACHE_SHIFT);
187
188         pgto_base &= ~PAGE_CACHE_MASK;
189         pgfrom_base &= ~PAGE_CACHE_MASK;
190
191         do {
192                 /* Are any pointers crossing a page boundary? */
193                 if (pgto_base == 0) {
194                         pgto_base = PAGE_CACHE_SIZE;
195                         pgto--;
196                 }
197                 if (pgfrom_base == 0) {
198                         pgfrom_base = PAGE_CACHE_SIZE;
199                         pgfrom--;
200                 }
201
202                 copy = len;
203                 if (copy > pgto_base)
204                         copy = pgto_base;
205                 if (copy > pgfrom_base)
206                         copy = pgfrom_base;
207                 pgto_base -= copy;
208                 pgfrom_base -= copy;
209
210                 vto = kmap_atomic(*pgto, KM_USER0);
211                 vfrom = kmap_atomic(*pgfrom, KM_USER1);
212                 memmove(vto + pgto_base, vfrom + pgfrom_base, copy);
213                 flush_dcache_page(*pgto);
214                 kunmap_atomic(vfrom, KM_USER1);
215                 kunmap_atomic(vto, KM_USER0);
216
217         } while ((len -= copy) != 0);
218 }
219
220 /*
221  * _copy_to_pages
222  * @pages: array of pages
223  * @pgbase: page vector address of destination
224  * @p: pointer to source data
225  * @len: length
226  *
227  * Copies data from an arbitrary memory location into an array of pages
228  * The copy is assumed to be non-overlapping.
229  */
230 static void
231 _copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len)
232 {
233         struct page **pgto;
234         char *vto;
235         size_t copy;
236
237         pgto = pages + (pgbase >> PAGE_CACHE_SHIFT);
238         pgbase &= ~PAGE_CACHE_MASK;
239
240         do {
241                 copy = PAGE_CACHE_SIZE - pgbase;
242                 if (copy > len)
243                         copy = len;
244
245                 vto = kmap_atomic(*pgto, KM_USER0);
246                 memcpy(vto + pgbase, p, copy);
247                 kunmap_atomic(vto, KM_USER0);
248
249                 pgbase += copy;
250                 if (pgbase == PAGE_CACHE_SIZE) {
251                         flush_dcache_page(*pgto);
252                         pgbase = 0;
253                         pgto++;
254                 }
255                 p += copy;
256
257         } while ((len -= copy) != 0);
258         flush_dcache_page(*pgto);
259 }
260
261 /*
262  * _copy_from_pages
263  * @p: pointer to destination
264  * @pages: array of pages
265  * @pgbase: offset of source data
266  * @len: length
267  *
268  * Copies data into an arbitrary memory location from an array of pages
269  * The copy is assumed to be non-overlapping.
270  */
271 static void
272 _copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
273 {
274         struct page **pgfrom;
275         char *vfrom;
276         size_t copy;
277
278         pgfrom = pages + (pgbase >> PAGE_CACHE_SHIFT);
279         pgbase &= ~PAGE_CACHE_MASK;
280
281         do {
282                 copy = PAGE_CACHE_SIZE - pgbase;
283                 if (copy > len)
284                         copy = len;
285
286                 vfrom = kmap_atomic(*pgfrom, KM_USER0);
287                 memcpy(p, vfrom + pgbase, copy);
288                 kunmap_atomic(vfrom, KM_USER0);
289
290                 pgbase += copy;
291                 if (pgbase == PAGE_CACHE_SIZE) {
292                         pgbase = 0;
293                         pgfrom++;
294                 }
295                 p += copy;
296
297         } while ((len -= copy) != 0);
298 }
299
300 /*
301  * xdr_shrink_bufhead
302  * @buf: xdr_buf
303  * @len: bytes to remove from buf->head[0]
304  *
305  * Shrinks XDR buffer's header kvec buf->head[0] by 
306  * 'len' bytes. The extra data is not lost, but is instead
307  * moved into the inlined pages and/or the tail.
308  */
309 static void
310 xdr_shrink_bufhead(struct xdr_buf *buf, size_t len)
311 {
312         struct kvec *head, *tail;
313         size_t copy, offs;
314         unsigned int pglen = buf->page_len;
315
316         tail = buf->tail;
317         head = buf->head;
318         BUG_ON (len > head->iov_len);
319
320         /* Shift the tail first */
321         if (tail->iov_len != 0) {
322                 if (tail->iov_len > len) {
323                         copy = tail->iov_len - len;
324                         memmove((char *)tail->iov_base + len,
325                                         tail->iov_base, copy);
326                 }
327                 /* Copy from the inlined pages into the tail */
328                 copy = len;
329                 if (copy > pglen)
330                         copy = pglen;
331                 offs = len - copy;
332                 if (offs >= tail->iov_len)
333                         copy = 0;
334                 else if (copy > tail->iov_len - offs)
335                         copy = tail->iov_len - offs;
336                 if (copy != 0)
337                         _copy_from_pages((char *)tail->iov_base + offs,
338                                         buf->pages,
339                                         buf->page_base + pglen + offs - len,
340                                         copy);
341                 /* Do we also need to copy data from the head into the tail ? */
342                 if (len > pglen) {
343                         offs = copy = len - pglen;
344                         if (copy > tail->iov_len)
345                                 copy = tail->iov_len;
346                         memcpy(tail->iov_base,
347                                         (char *)head->iov_base +
348                                         head->iov_len - offs,
349                                         copy);
350                 }
351         }
352         /* Now handle pages */
353         if (pglen != 0) {
354                 if (pglen > len)
355                         _shift_data_right_pages(buf->pages,
356                                         buf->page_base + len,
357                                         buf->page_base,
358                                         pglen - len);
359                 copy = len;
360                 if (len > pglen)
361                         copy = pglen;
362                 _copy_to_pages(buf->pages, buf->page_base,
363                                 (char *)head->iov_base + head->iov_len - len,
364                                 copy);
365         }
366         head->iov_len -= len;
367         buf->buflen -= len;
368         /* Have we truncated the message? */
369         if (buf->len > buf->buflen)
370                 buf->len = buf->buflen;
371 }
372
373 /*
374  * xdr_shrink_pagelen
375  * @buf: xdr_buf
376  * @len: bytes to remove from buf->pages
377  *
378  * Shrinks XDR buffer's page array buf->pages by 
379  * 'len' bytes. The extra data is not lost, but is instead
380  * moved into the tail.
381  */
382 static void
383 xdr_shrink_pagelen(struct xdr_buf *buf, size_t len)
384 {
385         struct kvec *tail;
386         size_t copy;
387         char *p;
388         unsigned int pglen = buf->page_len;
389
390         tail = buf->tail;
391         BUG_ON (len > pglen);
392
393         /* Shift the tail first */
394         if (tail->iov_len != 0) {
395                 p = (char *)tail->iov_base + len;
396                 if (tail->iov_len > len) {
397                         copy = tail->iov_len - len;
398                         memmove(p, tail->iov_base, copy);
399                 } else
400                         buf->buflen -= len;
401                 /* Copy from the inlined pages into the tail */
402                 copy = len;
403                 if (copy > tail->iov_len)
404                         copy = tail->iov_len;
405                 _copy_from_pages((char *)tail->iov_base,
406                                 buf->pages, buf->page_base + pglen - len,
407                                 copy);
408         }
409         buf->page_len -= len;
410         buf->buflen -= len;
411         /* Have we truncated the message? */
412         if (buf->len > buf->buflen)
413                 buf->len = buf->buflen;
414 }
415
416 void
417 xdr_shift_buf(struct xdr_buf *buf, size_t len)
418 {
419         xdr_shrink_bufhead(buf, len);
420 }
421
422 /**
423  * xdr_init_encode - Initialize a struct xdr_stream for sending data.
424  * @xdr: pointer to xdr_stream struct
425  * @buf: pointer to XDR buffer in which to encode data
426  * @p: current pointer inside XDR buffer
427  *
428  * Note: at the moment the RPC client only passes the length of our
429  *       scratch buffer in the xdr_buf's header kvec. Previously this
430  *       meant we needed to call xdr_adjust_iovec() after encoding the
431  *       data. With the new scheme, the xdr_stream manages the details
432  *       of the buffer length, and takes care of adjusting the kvec
433  *       length for us.
434  */
435 void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
436 {
437         struct kvec *iov = buf->head;
438         int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
439
440         BUG_ON(scratch_len < 0);
441         xdr->buf = buf;
442         xdr->iov = iov;
443         xdr->p = (__be32 *)((char *)iov->iov_base + iov->iov_len);
444         xdr->end = (__be32 *)((char *)iov->iov_base + scratch_len);
445         BUG_ON(iov->iov_len > scratch_len);
446
447         if (p != xdr->p && p != NULL) {
448                 size_t len;
449
450                 BUG_ON(p < xdr->p || p > xdr->end);
451                 len = (char *)p - (char *)xdr->p;
452                 xdr->p = p;
453                 buf->len += len;
454                 iov->iov_len += len;
455         }
456 }
457 EXPORT_SYMBOL(xdr_init_encode);
458
459 /**
460  * xdr_reserve_space - Reserve buffer space for sending
461  * @xdr: pointer to xdr_stream
462  * @nbytes: number of bytes to reserve
463  *
464  * Checks that we have enough buffer space to encode 'nbytes' more
465  * bytes of data. If so, update the total xdr_buf length, and
466  * adjust the length of the current kvec.
467  */
468 __be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
469 {
470         __be32 *p = xdr->p;
471         __be32 *q;
472
473         /* align nbytes on the next 32-bit boundary */
474         nbytes += 3;
475         nbytes &= ~3;
476         q = p + (nbytes >> 2);
477         if (unlikely(q > xdr->end || q < p))
478                 return NULL;
479         xdr->p = q;
480         xdr->iov->iov_len += nbytes;
481         xdr->buf->len += nbytes;
482         return p;
483 }
484 EXPORT_SYMBOL(xdr_reserve_space);
485
486 /**
487  * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
488  * @xdr: pointer to xdr_stream
489  * @pages: list of pages
490  * @base: offset of first byte
491  * @len: length of data in bytes
492  *
493  */
494 void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
495                  unsigned int len)
496 {
497         struct xdr_buf *buf = xdr->buf;
498         struct kvec *iov = buf->tail;
499         buf->pages = pages;
500         buf->page_base = base;
501         buf->page_len = len;
502
503         iov->iov_base = (char *)xdr->p;
504         iov->iov_len  = 0;
505         xdr->iov = iov;
506
507         if (len & 3) {
508                 unsigned int pad = 4 - (len & 3);
509
510                 BUG_ON(xdr->p >= xdr->end);
511                 iov->iov_base = (char *)xdr->p + (len & 3);
512                 iov->iov_len  += pad;
513                 len += pad;
514                 *xdr->p++ = 0;
515         }
516         buf->buflen += len;
517         buf->len += len;
518 }
519 EXPORT_SYMBOL(xdr_write_pages);
520
521 /**
522  * xdr_init_decode - Initialize an xdr_stream for decoding data.
523  * @xdr: pointer to xdr_stream struct
524  * @buf: pointer to XDR buffer from which to decode data
525  * @p: current pointer inside XDR buffer
526  */
527 void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
528 {
529         struct kvec *iov = buf->head;
530         unsigned int len = iov->iov_len;
531
532         if (len > buf->len)
533                 len = buf->len;
534         xdr->buf = buf;
535         xdr->iov = iov;
536         xdr->p = p;
537         xdr->end = (__be32 *)((char *)iov->iov_base + len);
538 }
539 EXPORT_SYMBOL(xdr_init_decode);
540
541 /**
542  * xdr_inline_decode - Retrieve non-page XDR data to decode
543  * @xdr: pointer to xdr_stream struct
544  * @nbytes: number of bytes of data to decode
545  *
546  * Check if the input buffer is long enough to enable us to decode
547  * 'nbytes' more bytes of data starting at the current position.
548  * If so return the current pointer, then update the current
549  * pointer position.
550  */
551 __be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
552 {
553         __be32 *p = xdr->p;
554         __be32 *q = p + XDR_QUADLEN(nbytes);
555
556         if (unlikely(q > xdr->end || q < p))
557                 return NULL;
558         xdr->p = q;
559         return p;
560 }
561 EXPORT_SYMBOL(xdr_inline_decode);
562
563 /**
564  * xdr_read_pages - Ensure page-based XDR data to decode is aligned at current pointer position
565  * @xdr: pointer to xdr_stream struct
566  * @len: number of bytes of page data
567  *
568  * Moves data beyond the current pointer position from the XDR head[] buffer
569  * into the page list. Any data that lies beyond current position + "len"
570  * bytes is moved into the XDR tail[].
571  */
572 void xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
573 {
574         struct xdr_buf *buf = xdr->buf;
575         struct kvec *iov;
576         ssize_t shift;
577         unsigned int end;
578         int padding;
579
580         /* Realign pages to current pointer position */
581         iov  = buf->head;
582         shift = iov->iov_len + (char *)iov->iov_base - (char *)xdr->p;
583         if (shift > 0)
584                 xdr_shrink_bufhead(buf, shift);
585
586         /* Truncate page data and move it into the tail */
587         if (buf->page_len > len)
588                 xdr_shrink_pagelen(buf, buf->page_len - len);
589         padding = (XDR_QUADLEN(len) << 2) - len;
590         xdr->iov = iov = buf->tail;
591         /* Compute remaining message length.  */
592         end = iov->iov_len;
593         shift = buf->buflen - buf->len;
594         if (shift < end)
595                 end -= shift;
596         else if (shift > 0)
597                 end = 0;
598         /*
599          * Position current pointer at beginning of tail, and
600          * set remaining message length.
601          */
602         xdr->p = (__be32 *)((char *)iov->iov_base + padding);
603         xdr->end = (__be32 *)((char *)iov->iov_base + end);
604 }
605 EXPORT_SYMBOL(xdr_read_pages);
606
607 /**
608  * xdr_enter_page - decode data from the XDR page
609  * @xdr: pointer to xdr_stream struct
610  * @len: number of bytes of page data
611  *
612  * Moves data beyond the current pointer position from the XDR head[] buffer
613  * into the page list. Any data that lies beyond current position + "len"
614  * bytes is moved into the XDR tail[]. The current pointer is then
615  * repositioned at the beginning of the first XDR page.
616  */
617 void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
618 {
619         char * kaddr = page_address(xdr->buf->pages[0]);
620         xdr_read_pages(xdr, len);
621         /*
622          * Position current pointer at beginning of tail, and
623          * set remaining message length.
624          */
625         if (len > PAGE_CACHE_SIZE - xdr->buf->page_base)
626                 len = PAGE_CACHE_SIZE - xdr->buf->page_base;
627         xdr->p = (__be32 *)(kaddr + xdr->buf->page_base);
628         xdr->end = (__be32 *)((char *)xdr->p + len);
629 }
630 EXPORT_SYMBOL(xdr_enter_page);
631
632 static struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
633
634 void
635 xdr_buf_from_iov(struct kvec *iov, struct xdr_buf *buf)
636 {
637         buf->head[0] = *iov;
638         buf->tail[0] = empty_iov;
639         buf->page_len = 0;
640         buf->buflen = buf->len = iov->iov_len;
641 }
642
643 /* Sets subbuf to the portion of buf of length len beginning base bytes
644  * from the start of buf. Returns -1 if base of length are out of bounds. */
645 int
646 xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
647                         unsigned int base, unsigned int len)
648 {
649         subbuf->buflen = subbuf->len = len;
650         if (base < buf->head[0].iov_len) {
651                 subbuf->head[0].iov_base = buf->head[0].iov_base + base;
652                 subbuf->head[0].iov_len = min_t(unsigned int, len,
653                                                 buf->head[0].iov_len - base);
654                 len -= subbuf->head[0].iov_len;
655                 base = 0;
656         } else {
657                 subbuf->head[0].iov_base = NULL;
658                 subbuf->head[0].iov_len = 0;
659                 base -= buf->head[0].iov_len;
660         }
661
662         if (base < buf->page_len) {
663                 subbuf->page_len = min(buf->page_len - base, len);
664                 base += buf->page_base;
665                 subbuf->page_base = base & ~PAGE_CACHE_MASK;
666                 subbuf->pages = &buf->pages[base >> PAGE_CACHE_SHIFT];
667                 len -= subbuf->page_len;
668                 base = 0;
669         } else {
670                 base -= buf->page_len;
671                 subbuf->page_len = 0;
672         }
673
674         if (base < buf->tail[0].iov_len) {
675                 subbuf->tail[0].iov_base = buf->tail[0].iov_base + base;
676                 subbuf->tail[0].iov_len = min_t(unsigned int, len,
677                                                 buf->tail[0].iov_len - base);
678                 len -= subbuf->tail[0].iov_len;
679                 base = 0;
680         } else {
681                 subbuf->tail[0].iov_base = NULL;
682                 subbuf->tail[0].iov_len = 0;
683                 base -= buf->tail[0].iov_len;
684         }
685
686         if (base || len)
687                 return -1;
688         return 0;
689 }
690
691 static void __read_bytes_from_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
692 {
693         unsigned int this_len;
694
695         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
696         memcpy(obj, subbuf->head[0].iov_base, this_len);
697         len -= this_len;
698         obj += this_len;
699         this_len = min_t(unsigned int, len, subbuf->page_len);
700         if (this_len)
701                 _copy_from_pages(obj, subbuf->pages, subbuf->page_base, this_len);
702         len -= this_len;
703         obj += this_len;
704         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
705         memcpy(obj, subbuf->tail[0].iov_base, this_len);
706 }
707
708 /* obj is assumed to point to allocated memory of size at least len: */
709 int read_bytes_from_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
710 {
711         struct xdr_buf subbuf;
712         int status;
713
714         status = xdr_buf_subsegment(buf, &subbuf, base, len);
715         if (status != 0)
716                 return status;
717         __read_bytes_from_xdr_buf(&subbuf, obj, len);
718         return 0;
719 }
720
721 static void __write_bytes_to_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
722 {
723         unsigned int this_len;
724
725         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
726         memcpy(subbuf->head[0].iov_base, obj, this_len);
727         len -= this_len;
728         obj += this_len;
729         this_len = min_t(unsigned int, len, subbuf->page_len);
730         if (this_len)
731                 _copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
732         len -= this_len;
733         obj += this_len;
734         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
735         memcpy(subbuf->tail[0].iov_base, obj, this_len);
736 }
737
738 /* obj is assumed to point to allocated memory of size at least len: */
739 int write_bytes_to_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
740 {
741         struct xdr_buf subbuf;
742         int status;
743
744         status = xdr_buf_subsegment(buf, &subbuf, base, len);
745         if (status != 0)
746                 return status;
747         __write_bytes_to_xdr_buf(&subbuf, obj, len);
748         return 0;
749 }
750
751 int
752 xdr_decode_word(struct xdr_buf *buf, unsigned int base, u32 *obj)
753 {
754         __be32  raw;
755         int     status;
756
757         status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
758         if (status)
759                 return status;
760         *obj = ntohl(raw);
761         return 0;
762 }
763
764 int
765 xdr_encode_word(struct xdr_buf *buf, unsigned int base, u32 obj)
766 {
767         __be32  raw = htonl(obj);
768
769         return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
770 }
771
772 /* If the netobj starting offset bytes from the start of xdr_buf is contained
773  * entirely in the head or the tail, set object to point to it; otherwise
774  * try to find space for it at the end of the tail, copy it there, and
775  * set obj to point to it. */
776 int xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, unsigned int offset)
777 {
778         struct xdr_buf subbuf;
779
780         if (xdr_decode_word(buf, offset, &obj->len))
781                 return -EFAULT;
782         if (xdr_buf_subsegment(buf, &subbuf, offset + 4, obj->len))
783                 return -EFAULT;
784
785         /* Is the obj contained entirely in the head? */
786         obj->data = subbuf.head[0].iov_base;
787         if (subbuf.head[0].iov_len == obj->len)
788                 return 0;
789         /* ..or is the obj contained entirely in the tail? */
790         obj->data = subbuf.tail[0].iov_base;
791         if (subbuf.tail[0].iov_len == obj->len)
792                 return 0;
793
794         /* use end of tail as storage for obj:
795          * (We don't copy to the beginning because then we'd have
796          * to worry about doing a potentially overlapping copy.
797          * This assumes the object is at most half the length of the
798          * tail.) */
799         if (obj->len > buf->buflen - buf->len)
800                 return -ENOMEM;
801         if (buf->tail[0].iov_len != 0)
802                 obj->data = buf->tail[0].iov_base + buf->tail[0].iov_len;
803         else
804                 obj->data = buf->head[0].iov_base + buf->head[0].iov_len;
805         __read_bytes_from_xdr_buf(&subbuf, obj->data, obj->len);
806         return 0;
807 }
808
809 /* Returns 0 on success, or else a negative error code. */
810 static int
811 xdr_xcode_array2(struct xdr_buf *buf, unsigned int base,
812                  struct xdr_array2_desc *desc, int encode)
813 {
814         char *elem = NULL, *c;
815         unsigned int copied = 0, todo, avail_here;
816         struct page **ppages = NULL;
817         int err;
818
819         if (encode) {
820                 if (xdr_encode_word(buf, base, desc->array_len) != 0)
821                         return -EINVAL;
822         } else {
823                 if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
824                     desc->array_len > desc->array_maxlen ||
825                     (unsigned long) base + 4 + desc->array_len *
826                                     desc->elem_size > buf->len)
827                         return -EINVAL;
828         }
829         base += 4;
830
831         if (!desc->xcode)
832                 return 0;
833
834         todo = desc->array_len * desc->elem_size;
835
836         /* process head */
837         if (todo && base < buf->head->iov_len) {
838                 c = buf->head->iov_base + base;
839                 avail_here = min_t(unsigned int, todo,
840                                    buf->head->iov_len - base);
841                 todo -= avail_here;
842
843                 while (avail_here >= desc->elem_size) {
844                         err = desc->xcode(desc, c);
845                         if (err)
846                                 goto out;
847                         c += desc->elem_size;
848                         avail_here -= desc->elem_size;
849                 }
850                 if (avail_here) {
851                         if (!elem) {
852                                 elem = kmalloc(desc->elem_size, GFP_KERNEL);
853                                 err = -ENOMEM;
854                                 if (!elem)
855                                         goto out;
856                         }
857                         if (encode) {
858                                 err = desc->xcode(desc, elem);
859                                 if (err)
860                                         goto out;
861                                 memcpy(c, elem, avail_here);
862                         } else
863                                 memcpy(elem, c, avail_here);
864                         copied = avail_here;
865                 }
866                 base = buf->head->iov_len;  /* align to start of pages */
867         }
868
869         /* process pages array */
870         base -= buf->head->iov_len;
871         if (todo && base < buf->page_len) {
872                 unsigned int avail_page;
873
874                 avail_here = min(todo, buf->page_len - base);
875                 todo -= avail_here;
876
877                 base += buf->page_base;
878                 ppages = buf->pages + (base >> PAGE_CACHE_SHIFT);
879                 base &= ~PAGE_CACHE_MASK;
880                 avail_page = min_t(unsigned int, PAGE_CACHE_SIZE - base,
881                                         avail_here);
882                 c = kmap(*ppages) + base;
883
884                 while (avail_here) {
885                         avail_here -= avail_page;
886                         if (copied || avail_page < desc->elem_size) {
887                                 unsigned int l = min(avail_page,
888                                         desc->elem_size - copied);
889                                 if (!elem) {
890                                         elem = kmalloc(desc->elem_size,
891                                                        GFP_KERNEL);
892                                         err = -ENOMEM;
893                                         if (!elem)
894                                                 goto out;
895                                 }
896                                 if (encode) {
897                                         if (!copied) {
898                                                 err = desc->xcode(desc, elem);
899                                                 if (err)
900                                                         goto out;
901                                         }
902                                         memcpy(c, elem + copied, l);
903                                         copied += l;
904                                         if (copied == desc->elem_size)
905                                                 copied = 0;
906                                 } else {
907                                         memcpy(elem + copied, c, l);
908                                         copied += l;
909                                         if (copied == desc->elem_size) {
910                                                 err = desc->xcode(desc, elem);
911                                                 if (err)
912                                                         goto out;
913                                                 copied = 0;
914                                         }
915                                 }
916                                 avail_page -= l;
917                                 c += l;
918                         }
919                         while (avail_page >= desc->elem_size) {
920                                 err = desc->xcode(desc, c);
921                                 if (err)
922                                         goto out;
923                                 c += desc->elem_size;
924                                 avail_page -= desc->elem_size;
925                         }
926                         if (avail_page) {
927                                 unsigned int l = min(avail_page,
928                                             desc->elem_size - copied);
929                                 if (!elem) {
930                                         elem = kmalloc(desc->elem_size,
931                                                        GFP_KERNEL);
932                                         err = -ENOMEM;
933                                         if (!elem)
934                                                 goto out;
935                                 }
936                                 if (encode) {
937                                         if (!copied) {
938                                                 err = desc->xcode(desc, elem);
939                                                 if (err)
940                                                         goto out;
941                                         }
942                                         memcpy(c, elem + copied, l);
943                                         copied += l;
944                                         if (copied == desc->elem_size)
945                                                 copied = 0;
946                                 } else {
947                                         memcpy(elem + copied, c, l);
948                                         copied += l;
949                                         if (copied == desc->elem_size) {
950                                                 err = desc->xcode(desc, elem);
951                                                 if (err)
952                                                         goto out;
953                                                 copied = 0;
954                                         }
955                                 }
956                         }
957                         if (avail_here) {
958                                 kunmap(*ppages);
959                                 ppages++;
960                                 c = kmap(*ppages);
961                         }
962
963                         avail_page = min(avail_here,
964                                  (unsigned int) PAGE_CACHE_SIZE);
965                 }
966                 base = buf->page_len;  /* align to start of tail */
967         }
968
969         /* process tail */
970         base -= buf->page_len;
971         if (todo) {
972                 c = buf->tail->iov_base + base;
973                 if (copied) {
974                         unsigned int l = desc->elem_size - copied;
975
976                         if (encode)
977                                 memcpy(c, elem + copied, l);
978                         else {
979                                 memcpy(elem + copied, c, l);
980                                 err = desc->xcode(desc, elem);
981                                 if (err)
982                                         goto out;
983                         }
984                         todo -= l;
985                         c += l;
986                 }
987                 while (todo) {
988                         err = desc->xcode(desc, c);
989                         if (err)
990                                 goto out;
991                         c += desc->elem_size;
992                         todo -= desc->elem_size;
993                 }
994         }
995         err = 0;
996
997 out:
998         kfree(elem);
999         if (ppages)
1000                 kunmap(*ppages);
1001         return err;
1002 }
1003
1004 int
1005 xdr_decode_array2(struct xdr_buf *buf, unsigned int base,
1006                   struct xdr_array2_desc *desc)
1007 {
1008         if (base >= buf->len)
1009                 return -EINVAL;
1010
1011         return xdr_xcode_array2(buf, base, desc, 0);
1012 }
1013
1014 int
1015 xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
1016                   struct xdr_array2_desc *desc)
1017 {
1018         if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
1019             buf->head->iov_len + buf->page_len + buf->tail->iov_len)
1020                 return -EINVAL;
1021
1022         return xdr_xcode_array2(buf, base, desc, 1);
1023 }
1024
1025 int
1026 xdr_process_buf(struct xdr_buf *buf, unsigned int offset, unsigned int len,
1027                 int (*actor)(struct scatterlist *, void *), void *data)
1028 {
1029         int i, ret = 0;
1030         unsigned page_len, thislen, page_offset;
1031         struct scatterlist      sg[1];
1032
1033         if (offset >= buf->head[0].iov_len) {
1034                 offset -= buf->head[0].iov_len;
1035         } else {
1036                 thislen = buf->head[0].iov_len - offset;
1037                 if (thislen > len)
1038                         thislen = len;
1039                 sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
1040                 ret = actor(sg, data);
1041                 if (ret)
1042                         goto out;
1043                 offset = 0;
1044                 len -= thislen;
1045         }
1046         if (len == 0)
1047                 goto out;
1048
1049         if (offset >= buf->page_len) {
1050                 offset -= buf->page_len;
1051         } else {
1052                 page_len = buf->page_len - offset;
1053                 if (page_len > len)
1054                         page_len = len;
1055                 len -= page_len;
1056                 page_offset = (offset + buf->page_base) & (PAGE_CACHE_SIZE - 1);
1057                 i = (offset + buf->page_base) >> PAGE_CACHE_SHIFT;
1058                 thislen = PAGE_CACHE_SIZE - page_offset;
1059                 do {
1060                         if (thislen > page_len)
1061                                 thislen = page_len;
1062                         sg->page = buf->pages[i];
1063                         sg->offset = page_offset;
1064                         sg->length = thislen;
1065                         ret = actor(sg, data);
1066                         if (ret)
1067                                 goto out;
1068                         page_len -= thislen;
1069                         i++;
1070                         page_offset = 0;
1071                         thislen = PAGE_CACHE_SIZE;
1072                 } while (page_len != 0);
1073                 offset = 0;
1074         }
1075         if (len == 0)
1076                 goto out;
1077         if (offset < buf->tail[0].iov_len) {
1078                 thislen = buf->tail[0].iov_len - offset;
1079                 if (thislen > len)
1080                         thislen = len;
1081                 sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
1082                 ret = actor(sg, data);
1083                 len -= thislen;
1084         }
1085         if (len != 0)
1086                 ret = -EINVAL;
1087 out:
1088         return ret;
1089 }
1090 EXPORT_SYMBOL(xdr_process_buf);
1091