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