net/sunrpc/xdr.c

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