net/sunrpc/xdr.c

   1 /*
   2  * linux/net/sunrpc/xdr.c
   3  *
   4  * Generic XDR support.
   5  *
   6  * Copyright (C) 1995, 1996 Olaf Kirch <[email protected]>
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/slab.h>
  11 #include <linux/types.h>
  12 #include <linux/string.h>
  13 #include <linux/kernel.h>
  14 #include <linux/pagemap.h>
  15 #include <linux/errno.h>
  16 #include <linux/sunrpc/xdr.h>
  17 #include <linux/sunrpc/msg_prot.h>
  18
  19 /*
  20  * XDR functions for basic NFS types
  21  */
  22 __be32 *
  23 xdr_encode_netobj(__be32 *p, const struct xdr_netobj *obj)
  24 {
  25         unsigned int    quadlen = XDR_QUADLEN(obj->len);
  26
  27         p[quadlen] = 0;         /* zero trailing bytes */
  28         *p++ = cpu_to_be32(obj->len);
  29         memcpy(p, obj->data, obj->len);
  30         return p + XDR_QUADLEN(obj->len);
  31 }
  32 EXPORT_SYMBOL_GPL(xdr_encode_netobj);
  33
  34 __be32 *
  35 xdr_decode_netobj(__be32 *p, struct xdr_netobj *obj)
  36 {
  37         unsigned int    len;
  38
  39         if ((len = be32_to_cpu(*p++)) > XDR_MAX_NETOBJ)
  40                 return NULL;
  41         obj->len  = len;
  42         obj->data = (u8 *) p;
  43         return p + XDR_QUADLEN(len);
  44 }
  45 EXPORT_SYMBOL_GPL(xdr_decode_netobj);
  46
  47 /**
  48  * xdr_encode_opaque_fixed - Encode fixed length opaque data
  49  * @p: pointer to current position in XDR buffer.
  50  * @ptr: pointer to data to encode (or NULL)
  51  * @nbytes: size of data.
  52  *
  53  * Copy the array of data of length nbytes at ptr to the XDR buffer
  54  * at position p, then align to the next 32-bit boundary by padding
  55  * with zero bytes (see RFC1832).
  56  * Note: if ptr is NULL, only the padding is performed.
  57  *
  58  * Returns the updated current XDR buffer position
  59  *
  60  */
  61 __be32 *xdr_encode_opaque_fixed(__be32 *p, const void *ptr, unsigned int nbytes)
  62 {
  63         if (likely(nbytes != 0)) {
  64                 unsigned int quadlen = XDR_QUADLEN(nbytes);
  65                 unsigned int padding = (quadlen << 2) - nbytes;
  66
  67                 if (ptr != NULL)
  68                         memcpy(p, ptr, nbytes);
  69                 if (padding != 0)
  70                         memset((char *)p + nbytes, 0, padding);
  71                 p += quadlen;
  72         }
  73         return p;
  74 }
  75 EXPORT_SYMBOL_GPL(xdr_encode_opaque_fixed);
  76
  77 /**
  78  * xdr_encode_opaque - Encode variable length opaque data
  79  * @p: pointer to current position in XDR buffer.
  80  * @ptr: pointer to data to encode (or NULL)
  81  * @nbytes: size of data.
  82  *
  83  * Returns the updated current XDR buffer position
  84  */
  85 __be32 *xdr_encode_opaque(__be32 *p, const void *ptr, unsigned int nbytes)
  86 {
  87         *p++ = cpu_to_be32(nbytes);
  88         return xdr_encode_opaque_fixed(p, ptr, nbytes);
  89 }
  90 EXPORT_SYMBOL_GPL(xdr_encode_opaque);
  91
  92 __be32 *
  93 xdr_encode_string(__be32 *p, const char *string)
  94 {
  95         return xdr_encode_array(p, string, strlen(string));
  96 }
  97 EXPORT_SYMBOL_GPL(xdr_encode_string);
  98
  99 __be32 *
 100 xdr_decode_string_inplace(__be32 *p, char **sp,
 101                           unsigned int *lenp, unsigned int maxlen)
 102 {
 103         u32 len;
 104
 105         len = be32_to_cpu(*p++);
 106         if (len > maxlen)
 107                 return NULL;
 108         *lenp = len;
 109         *sp = (char *) p;
 110         return p + XDR_QUADLEN(len);
 111 }
 112 EXPORT_SYMBOL_GPL(xdr_decode_string_inplace);
 113
 114 void
 115 xdr_encode_pages(struct xdr_buf *xdr, struct page **pages, unsigned int base,
 116                  unsigned int len)
 117 {
 118         struct kvec *tail = xdr->tail;
 119         u32 *p;
 120
 121         xdr->pages = pages;
 122         xdr->page_base = base;
 123         xdr->page_len = len;
 124
 125         p = (u32 *)xdr->head[0].iov_base + XDR_QUADLEN(xdr->head[0].iov_len);
 126         tail->iov_base = p;
 127         tail->iov_len = 0;
 128
 129         if (len & 3) {
 130                 unsigned int pad = 4 - (len & 3);
 131
 132                 *p = 0;
 133                 tail->iov_base = (char *)p + (len & 3);
 134                 tail->iov_len  = pad;
 135                 len += pad;
 136         }
 137         xdr->buflen += len;
 138         xdr->len += len;
 139 }
 140 EXPORT_SYMBOL_GPL(xdr_encode_pages);
 141
 142 void
 143 xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
 144                  struct page **pages, unsigned int base, unsigned int len)
 145 {
 146         struct kvec *head = xdr->head;
 147         struct kvec *tail = xdr->tail;
 148         char *buf = (char *)head->iov_base;
 149         unsigned int buflen = head->iov_len;
 150
 151         head->iov_len  = offset;
 152
 153         xdr->pages = pages;
 154         xdr->page_base = base;
 155         xdr->page_len = len;
 156
 157         tail->iov_base = buf + offset;
 158         tail->iov_len = buflen - offset;
 159
 160         xdr->buflen += len;
 161 }
 162 EXPORT_SYMBOL_GPL(xdr_inline_pages);
 163
 164 /*
 165  * Helper routines for doing 'memmove' like operations on a struct xdr_buf
 166  *
 167  * _shift_data_right_pages
 168  * @pages: vector of pages containing both the source and dest memory area.
 169  * @pgto_base: page vector address of destination
 170  * @pgfrom_base: page vector address of source
 171  * @len: number of bytes to copy
 172  *
 173  * Note: the addresses pgto_base and pgfrom_base are both calculated in
 174  *       the same way:
 175  *            if a memory area starts at byte 'base' in page 'pages[i]',
 176  *            then its address is given as (i << PAGE_CACHE_SHIFT) + base
 177  * Also note: pgfrom_base must be < pgto_base, but the memory areas
 178  *      they point to may overlap.
 179  */
 180 static void
 181 _shift_data_right_pages(struct page **pages, size_t pgto_base,
 182                 size_t pgfrom_base, size_t len)
 183 {
 184         struct page **pgfrom, **pgto;
 185         char *vfrom, *vto;
 186         size_t copy;
 187
 188         BUG_ON(pgto_base <= pgfrom_base);
 189
 190         pgto_base += len;
 191         pgfrom_base += len;
 192
 193         pgto = pages + (pgto_base >> PAGE_CACHE_SHIFT);
 194         pgfrom = pages + (pgfrom_base >> PAGE_CACHE_SHIFT);
 195
 196         pgto_base &= ~PAGE_CACHE_MASK;
 197         pgfrom_base &= ~PAGE_CACHE_MASK;
 198
 199         do {
 200                 /* Are any pointers crossing a page boundary? */
 201                 if (pgto_base == 0) {
 202                         pgto_base = PAGE_CACHE_SIZE;
 203                         pgto--;
 204                 }
 205                 if (pgfrom_base == 0) {
 206                         pgfrom_base = PAGE_CACHE_SIZE;
 207                         pgfrom--;
 208                 }
 209
 210                 copy = len;
 211                 if (copy > pgto_base)
 212                         copy = pgto_base;
 213                 if (copy > pgfrom_base)
 214                         copy = pgfrom_base;
 215                 pgto_base -= copy;
 216                 pgfrom_base -= copy;
 217
 218                 vto = kmap_atomic(*pgto, KM_USER0);
 219                 vfrom = kmap_atomic(*pgfrom, KM_USER1);
 220                 memmove(vto + pgto_base, vfrom + pgfrom_base, copy);
 221                 flush_dcache_page(*pgto);
 222                 kunmap_atomic(vfrom, KM_USER1);
 223                 kunmap_atomic(vto, KM_USER0);
 224
 225         } while ((len -= copy) != 0);
 226 }
 227
 228 /*
 229  * _copy_to_pages
 230  * @pages: array of pages
 231  * @pgbase: page vector address of destination
 232  * @p: pointer to source data
 233  * @len: length
 234  *
 235  * Copies data from an arbitrary memory location into an array of pages
 236  * The copy is assumed to be non-overlapping.
 237  */
 238 static void
 239 _copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len)
 240 {
 241         struct page **pgto;
 242         char *vto;
 243         size_t copy;
 244
 245         pgto = pages + (pgbase >> PAGE_CACHE_SHIFT);
 246         pgbase &= ~PAGE_CACHE_MASK;
 247
 248         for (;;) {
 249                 copy = PAGE_CACHE_SIZE - pgbase;
 250                 if (copy > len)
 251                         copy = len;
 252
 253                 vto = kmap_atomic(*pgto, KM_USER0);
 254                 memcpy(vto + pgbase, p, copy);
 255                 kunmap_atomic(vto, KM_USER0);
 256
 257                 len -= copy;
 258                 if (len == 0)
 259                         break;
 260
 261                 pgbase += copy;
 262                 if (pgbase == PAGE_CACHE_SIZE) {
 263                         flush_dcache_page(*pgto);
 264                         pgbase = 0;
 265                         pgto++;
 266                 }
 267                 p += copy;
 268         }
 269         flush_dcache_page(*pgto);
 270 }
 271
 272 /*
 273  * _copy_from_pages
 274  * @p: pointer to destination
 275  * @pages: array of pages
 276  * @pgbase: offset of source data
 277  * @len: length
 278  *
 279  * Copies data into an arbitrary memory location from an array of pages
 280  * The copy is assumed to be non-overlapping.
 281  */
 282 static void
 283 _copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
 284 {
 285         struct page **pgfrom;
 286         char *vfrom;
 287         size_t copy;
 288
 289         pgfrom = pages + (pgbase >> PAGE_CACHE_SHIFT);
 290         pgbase &= ~PAGE_CACHE_MASK;
 291
 292         do {
 293                 copy = PAGE_CACHE_SIZE - pgbase;
 294                 if (copy > len)
 295                         copy = len;
 296
 297                 vfrom = kmap_atomic(*pgfrom, KM_USER0);
 298                 memcpy(p, vfrom + pgbase, copy);
 299                 kunmap_atomic(vfrom, KM_USER0);
 300
 301                 pgbase += copy;
 302                 if (pgbase == PAGE_CACHE_SIZE) {
 303                         pgbase = 0;
 304                         pgfrom++;
 305                 }
 306                 p += copy;
 307
 308         } while ((len -= copy) != 0);
 309 }
 310
 311 /*
 312  * xdr_shrink_bufhead
 313  * @buf: xdr_buf
 314  * @len: bytes to remove from buf->head[0]
 315  *
 316  * Shrinks XDR buffer's header kvec buf->head[0] by
 317  * 'len' bytes. The extra data is not lost, but is instead
 318  * moved into the inlined pages and/or the tail.
 319  */
 320 static void
 321 xdr_shrink_bufhead(struct xdr_buf *buf, size_t len)
 322 {
 323         struct kvec *head, *tail;
 324         size_t copy, offs;
 325         unsigned int pglen = buf->page_len;
 326
 327         tail = buf->tail;
 328         head = buf->head;
 329         BUG_ON (len > head->iov_len);
 330
 331         /* Shift the tail first */
 332         if (tail->iov_len != 0) {
 333                 if (tail->iov_len > len) {
 334                         copy = tail->iov_len - len;
 335                         memmove((char *)tail->iov_base + len,
 336                                         tail->iov_base, copy);
 337                 }
 338                 /* Copy from the inlined pages into the tail */
 339                 copy = len;
 340                 if (copy > pglen)
 341                         copy = pglen;
 342                 offs = len - copy;
 343                 if (offs >= tail->iov_len)
 344                         copy = 0;
 345                 else if (copy > tail->iov_len - offs)
 346                         copy = tail->iov_len - offs;
 347                 if (copy != 0)
 348                         _copy_from_pages((char *)tail->iov_base + offs,
 349                                         buf->pages,
 350                                         buf->page_base + pglen + offs - len,
 351                                         copy);
 352                 /* Do we also need to copy data from the head into the tail ? */
 353                 if (len > pglen) {
 354                         offs = copy = len - pglen;
 355                         if (copy > tail->iov_len)
 356                                 copy = tail->iov_len;
 357                         memcpy(tail->iov_base,
 358                                         (char *)head->iov_base +
 359                                         head->iov_len - offs,
 360                                         copy);
 361                 }
 362         }
 363         /* Now handle pages */
 364         if (pglen != 0) {
 365                 if (pglen > len)
 366                         _shift_data_right_pages(buf->pages,
 367                                         buf->page_base + len,
 368                                         buf->page_base,
 369                                         pglen - len);
 370                 copy = len;
 371                 if (len > pglen)
 372                         copy = pglen;
 373                 _copy_to_pages(buf->pages, buf->page_base,
 374                                 (char *)head->iov_base + head->iov_len - len,
 375                                 copy);
 376         }
 377         head->iov_len -= len;
 378         buf->buflen -= len;
 379         /* Have we truncated the message? */
 380         if (buf->len > buf->buflen)
 381                 buf->len = buf->buflen;
 382 }
 383
 384 /*
 385  * xdr_shrink_pagelen
 386  * @buf: xdr_buf
 387  * @len: bytes to remove from buf->pages
 388  *
 389  * Shrinks XDR buffer's page array buf->pages by
 390  * 'len' bytes. The extra data is not lost, but is instead
 391  * moved into the tail.
 392  */
 393 static void
 394 xdr_shrink_pagelen(struct xdr_buf *buf, size_t len)
 395 {
 396         struct kvec *tail;
 397         size_t copy;
 398         char *p;
 399         unsigned int pglen = buf->page_len;
 400
 401         tail = buf->tail;
 402         BUG_ON (len > pglen);
 403
 404         /* Shift the tail first */
 405         if (tail->iov_len != 0) {
 406                 p = (char *)tail->iov_base + len;
 407                 if (tail->iov_len > len) {
 408                         copy = tail->iov_len - len;
 409                         memmove(p, tail->iov_base, copy);
 410                 } else
 411                         buf->buflen -= len;
 412                 /* Copy from the inlined pages into the tail */
 413                 copy = len;
 414                 if (copy > tail->iov_len)
 415                         copy = tail->iov_len;
 416                 _copy_from_pages((char *)tail->iov_base,
 417                                 buf->pages, buf->page_base + pglen - len,
 418                                 copy);
 419         }
 420         buf->page_len -= len;
 421         buf->buflen -= len;
 422         /* Have we truncated the message? */
 423         if (buf->len > buf->buflen)
 424                 buf->len = buf->buflen;
 425 }
 426
 427 void
 428 xdr_shift_buf(struct xdr_buf *buf, size_t len)
 429 {
 430         xdr_shrink_bufhead(buf, len);
 431 }
 432 EXPORT_SYMBOL_GPL(xdr_shift_buf);
 433
 434 /**
 435  * xdr_init_encode - Initialize a struct xdr_stream for sending data.
 436  * @xdr: pointer to xdr_stream struct
 437  * @buf: pointer to XDR buffer in which to encode data
 438  * @p: current pointer inside XDR buffer
 439  *
 440  * Note: at the moment the RPC client only passes the length of our
 441  *       scratch buffer in the xdr_buf's header kvec. Previously this
 442  *       meant we needed to call xdr_adjust_iovec() after encoding the
 443  *       data. With the new scheme, the xdr_stream manages the details
 444  *       of the buffer length, and takes care of adjusting the kvec
 445  *       length for us.
 446  */
 447 void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
 448 {
 449         struct kvec *iov = buf->head;
 450         int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
 451
 452         BUG_ON(scratch_len < 0);
 453         xdr->buf = buf;
 454         xdr->iov = iov;
 455         xdr->p = (__be32 *)((char *)iov->iov_base + iov->iov_len);
 456         xdr->end = (__be32 *)((char *)iov->iov_base + scratch_len);
 457         BUG_ON(iov->iov_len > scratch_len);
 458
 459         if (p != xdr->p && p != NULL) {
 460                 size_t len;
 461
 462                 BUG_ON(p < xdr->p || p > xdr->end);
 463                 len = (char *)p - (char *)xdr->p;
 464                 xdr->p = p;
 465                 buf->len += len;
 466                 iov->iov_len += len;
 467         }
 468 }
 469 EXPORT_SYMBOL_GPL(xdr_init_encode);
 470
 471 /**
 472  * xdr_reserve_space - Reserve buffer space for sending
 473  * @xdr: pointer to xdr_stream
 474  * @nbytes: number of bytes to reserve
 475  *
 476  * Checks that we have enough buffer space to encode 'nbytes' more
 477  * bytes of data. If so, update the total xdr_buf length, and
 478  * adjust the length of the current kvec.
 479  */
 480 __be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
 481 {
 482         __be32 *p = xdr->p;
 483         __be32 *q;
 484
 485         /* align nbytes on the next 32-bit boundary */
 486         nbytes += 3;
 487         nbytes &= ~3;
 488         q = p + (nbytes >> 2);
 489         if (unlikely(q > xdr->end || q < p))
 490                 return NULL;
 491         xdr->p = q;
 492         xdr->iov->iov_len += nbytes;
 493         xdr->buf->len += nbytes;
 494         return p;
 495 }
 496 EXPORT_SYMBOL_GPL(xdr_reserve_space);
 497
 498 /**
 499  * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
 500  * @xdr: pointer to xdr_stream
 501  * @pages: list of pages
 502  * @base: offset of first byte
 503  * @len: length of data in bytes
 504  *
 505  */
 506 void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
 507                  unsigned int len)
 508 {
 509         struct xdr_buf *buf = xdr->buf;
 510         struct kvec *iov = buf->tail;
 511         buf->pages = pages;
 512         buf->page_base = base;
 513         buf->page_len = len;
 514
 515         iov->iov_base = (char *)xdr->p;
 516         iov->iov_len  = 0;
 517         xdr->iov = iov;
 518
 519         if (len & 3) {
 520                 unsigned int pad = 4 - (len & 3);
 521
 522                 BUG_ON(xdr->p >= xdr->end);
 523                 iov->iov_base = (char *)xdr->p + (len & 3);
 524                 iov->iov_len  += pad;
 525                 len += pad;
 526                 *xdr->p++ = 0;
 527         }
 528         buf->buflen += len;
 529         buf->len += len;
 530 }
 531 EXPORT_SYMBOL_GPL(xdr_write_pages);
 532
 533 /**
 534  * xdr_init_decode - Initialize an xdr_stream for decoding data.
 535  * @xdr: pointer to xdr_stream struct
 536  * @buf: pointer to XDR buffer from which to decode data
 537  * @p: current pointer inside XDR buffer
 538  */
 539 void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
 540 {
 541         struct kvec *iov = buf->head;
 542         unsigned int len = iov->iov_len;
 543
 544         if (len > buf->len)
 545                 len = buf->len;
 546         xdr->buf = buf;
 547         xdr->iov = iov;
 548         xdr->p = p;
 549         xdr->end = (__be32 *)((char *)iov->iov_base + len);
 550 }
 551 EXPORT_SYMBOL_GPL(xdr_init_decode);
 552
 553 /**
 554  * xdr_inline_decode - Retrieve non-page XDR data to decode
 555  * @xdr: pointer to xdr_stream struct
 556  * @nbytes: number of bytes of data to decode
 557  *
 558  * Check if the input buffer is long enough to enable us to decode
 559  * 'nbytes' more bytes of data starting at the current position.
 560  * If so return the current pointer, then update the current
 561  * pointer position.
 562  */
 563 __be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
 564 {
 565         __be32 *p = xdr->p;
 566         __be32 *q = p + XDR_QUADLEN(nbytes);
 567
 568         if (unlikely(q > xdr->end || q < p))
 569                 return NULL;
 570         xdr->p = q;
 571         return p;
 572 }
 573 EXPORT_SYMBOL_GPL(xdr_inline_decode);
 574
 575 /**
 576  * xdr_read_pages - Ensure page-based XDR data to decode is aligned at current pointer position
 577  * @xdr: pointer to xdr_stream struct
 578  * @len: number of bytes of page data
 579  *
 580  * Moves data beyond the current pointer position from the XDR head[] buffer
 581  * into the page list. Any data that lies beyond current position + "len"
 582  * bytes is moved into the XDR tail[].
 583  */
 584 void xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
 585 {
 586         struct xdr_buf *buf = xdr->buf;
 587         struct kvec *iov;
 588         ssize_t shift;
 589         unsigned int end;
 590         int padding;
 591
 592         /* Realign pages to current pointer position */
 593         iov  = buf->head;
 594         shift = iov->iov_len + (char *)iov->iov_base - (char *)xdr->p;
 595         if (shift > 0)
 596                 xdr_shrink_bufhead(buf, shift);
 597
 598         /* Truncate page data and move it into the tail */
 599         if (buf->page_len > len)
 600                 xdr_shrink_pagelen(buf, buf->page_len - len);
 601         padding = (XDR_QUADLEN(len) << 2) - len;
 602         xdr->iov = iov = buf->tail;
 603         /* Compute remaining message length.  */
 604         end = iov->iov_len;
 605         shift = buf->buflen - buf->len;
 606         if (shift < end)
 607                 end -= shift;
 608         else if (shift > 0)
 609                 end = 0;
 610         /*
 611          * Position current pointer at beginning of tail, and
 612          * set remaining message length.
 613          */
 614         xdr->p = (__be32 *)((char *)iov->iov_base + padding);
 615         xdr->end = (__be32 *)((char *)iov->iov_base + end);
 616 }
 617 EXPORT_SYMBOL_GPL(xdr_read_pages);
 618
 619 /**
 620  * xdr_enter_page - decode data from the XDR page
 621  * @xdr: pointer to xdr_stream struct
 622  * @len: number of bytes of page data
 623  *
 624  * Moves data beyond the current pointer position from the XDR head[] buffer
 625  * into the page list. Any data that lies beyond current position + "len"
 626  * bytes is moved into the XDR tail[]. The current pointer is then
 627  * repositioned at the beginning of the first XDR page.
 628  */
 629 void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
 630 {
 631         char * kaddr = page_address(xdr->buf->pages[0]);
 632         xdr_read_pages(xdr, len);
 633         /*
 634          * Position current pointer at beginning of tail, and
 635          * set remaining message length.
 636          */
 637         if (len > PAGE_CACHE_SIZE - xdr->buf->page_base)
 638                 len = PAGE_CACHE_SIZE - xdr->buf->page_base;
 639         xdr->p = (__be32 *)(kaddr + xdr->buf->page_base);
 640         xdr->end = (__be32 *)((char *)xdr->p + len);
 641 }
 642 EXPORT_SYMBOL_GPL(xdr_enter_page);
 643
 644 static struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
 645
 646 void
 647 xdr_buf_from_iov(struct kvec *iov, struct xdr_buf *buf)
 648 {
 649         buf->head[0] = *iov;
 650         buf->tail[0] = empty_iov;
 651         buf->page_len = 0;
 652         buf->buflen = buf->len = iov->iov_len;
 653 }
 654 EXPORT_SYMBOL_GPL(xdr_buf_from_iov);
 655
 656 /* Sets subbuf to the portion of buf of length len beginning base bytes
 657  * from the start of buf. Returns -1 if base of length are out of bounds. */
 658 int
 659 xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
 660                         unsigned int base, unsigned int len)
 661 {
 662         subbuf->buflen = subbuf->len = len;
 663         if (base < buf->head[0].iov_len) {
 664                 subbuf->head[0].iov_base = buf->head[0].iov_base + base;
 665                 subbuf->head[0].iov_len = min_t(unsigned int, len,
 666                                                 buf->head[0].iov_len - base);
 667                 len -= subbuf->head[0].iov_len;
 668                 base = 0;
 669         } else {
 670                 subbuf->head[0].iov_base = NULL;
 671                 subbuf->head[0].iov_len = 0;
 672                 base -= buf->head[0].iov_len;
 673         }
 674
 675         if (base < buf->page_len) {
 676                 subbuf->page_len = min(buf->page_len - base, len);
 677                 base += buf->page_base;
 678                 subbuf->page_base = base & ~PAGE_CACHE_MASK;
 679                 subbuf->pages = &buf->pages[base >> PAGE_CACHE_SHIFT];
 680                 len -= subbuf->page_len;
 681                 base = 0;
 682         } else {
 683                 base -= buf->page_len;
 684                 subbuf->page_len = 0;
 685         }
 686
 687         if (base < buf->tail[0].iov_len) {
 688                 subbuf->tail[0].iov_base = buf->tail[0].iov_base + base;
 689                 subbuf->tail[0].iov_len = min_t(unsigned int, len,
 690                                                 buf->tail[0].iov_len - base);
 691                 len -= subbuf->tail[0].iov_len;
 692                 base = 0;
 693         } else {
 694                 subbuf->tail[0].iov_base = NULL;
 695                 subbuf->tail[0].iov_len = 0;
 696                 base -= buf->tail[0].iov_len;
 697         }
 698
 699         if (base || len)
 700                 return -1;
 701         return 0;
 702 }
 703 EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
 704
 705 static void __read_bytes_from_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
 706 {
 707         unsigned int this_len;
 708
 709         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
 710         memcpy(obj, subbuf->head[0].iov_base, this_len);
 711         len -= this_len;
 712         obj += this_len;
 713         this_len = min_t(unsigned int, len, subbuf->page_len);
 714         if (this_len)
 715                 _copy_from_pages(obj, subbuf->pages, subbuf->page_base, this_len);
 716         len -= this_len;
 717         obj += this_len;
 718         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
 719         memcpy(obj, subbuf->tail[0].iov_base, this_len);
 720 }
 721
 722 /* obj is assumed to point to allocated memory of size at least len: */
 723 int read_bytes_from_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
 724 {
 725         struct xdr_buf subbuf;
 726         int status;
 727
 728         status = xdr_buf_subsegment(buf, &subbuf, base, len);
 729         if (status != 0)
 730                 return status;
 731         __read_bytes_from_xdr_buf(&subbuf, obj, len);
 732         return 0;
 733 }
 734 EXPORT_SYMBOL_GPL(read_bytes_from_xdr_buf);
 735
 736 static void __write_bytes_to_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
 737 {
 738         unsigned int this_len;
 739
 740         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
 741         memcpy(subbuf->head[0].iov_base, obj, this_len);
 742         len -= this_len;
 743         obj += this_len;
 744         this_len = min_t(unsigned int, len, subbuf->page_len);
 745         if (this_len)
 746                 _copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
 747         len -= this_len;
 748         obj += this_len;
 749         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
 750         memcpy(subbuf->tail[0].iov_base, obj, this_len);
 751 }
 752
 753 /* obj is assumed to point to allocated memory of size at least len: */
 754 int write_bytes_to_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
 755 {
 756         struct xdr_buf subbuf;
 757         int status;
 758
 759         status = xdr_buf_subsegment(buf, &subbuf, base, len);
 760         if (status != 0)
 761                 return status;
 762         __write_bytes_to_xdr_buf(&subbuf, obj, len);
 763         return 0;
 764 }
 765 EXPORT_SYMBOL_GPL(write_bytes_to_xdr_buf);
 766
 767 int
 768 xdr_decode_word(struct xdr_buf *buf, unsigned int base, u32 *obj)
 769 {
 770         __be32  raw;
 771         int     status;
 772
 773         status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
 774         if (status)
 775                 return status;
 776         *obj = be32_to_cpu(raw);
 777         return 0;
 778 }
 779 EXPORT_SYMBOL_GPL(xdr_decode_word);
 780
 781 int
 782 xdr_encode_word(struct xdr_buf *buf, unsigned int base, u32 obj)
 783 {
 784         __be32  raw = cpu_to_be32(obj);
 785
 786         return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
 787 }
 788 EXPORT_SYMBOL_GPL(xdr_encode_word);
 789
 790 /* If the netobj starting offset bytes from the start of xdr_buf is contained
 791  * entirely in the head or the tail, set object to point to it; otherwise
 792  * try to find space for it at the end of the tail, copy it there, and
 793  * set obj to point to it. */
 794 int xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, unsigned int offset)
 795 {
 796         struct xdr_buf subbuf;
 797
 798         if (xdr_decode_word(buf, offset, &obj->len))
 799                 return -EFAULT;
 800         if (xdr_buf_subsegment(buf, &subbuf, offset + 4, obj->len))
 801                 return -EFAULT;
 802
 803         /* Is the obj contained entirely in the head? */
 804         obj->data = subbuf.head[0].iov_base;
 805         if (subbuf.head[0].iov_len == obj->len)
 806                 return 0;
 807         /* ..or is the obj contained entirely in the tail? */
 808         obj->data = subbuf.tail[0].iov_base;
 809         if (subbuf.tail[0].iov_len == obj->len)
 810                 return 0;
 811
 812         /* use end of tail as storage for obj:
 813          * (We don't copy to the beginning because then we'd have
 814          * to worry about doing a potentially overlapping copy.
 815          * This assumes the object is at most half the length of the
 816          * tail.) */
 817         if (obj->len > buf->buflen - buf->len)
 818                 return -ENOMEM;
 819         if (buf->tail[0].iov_len != 0)
 820                 obj->data = buf->tail[0].iov_base + buf->tail[0].iov_len;
 821         else
 822                 obj->data = buf->head[0].iov_base + buf->head[0].iov_len;
 823         __read_bytes_from_xdr_buf(&subbuf, obj->data, obj->len);
 824         return 0;
 825 }
 826 EXPORT_SYMBOL_GPL(xdr_buf_read_netobj);
 827
 828 /* Returns 0 on success, or else a negative error code. */
 829 static int
 830 xdr_xcode_array2(struct xdr_buf *buf, unsigned int base,
 831                  struct xdr_array2_desc *desc, int encode)
 832 {
 833         char *elem = NULL, *c;
 834         unsigned int copied = 0, todo, avail_here;
 835         struct page **ppages = NULL;
 836         int err;
 837
 838         if (encode) {
 839                 if (xdr_encode_word(buf, base, desc->array_len) != 0)
 840                         return -EINVAL;
 841         } else {
 842                 if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
 843                     desc->array_len > desc->array_maxlen ||
 844                     (unsigned long) base + 4 + desc->array_len *
 845                                     desc->elem_size > buf->len)
 846                         return -EINVAL;
 847         }
 848         base += 4;
 849
 850         if (!desc->xcode)
 851                 return 0;
 852
 853         todo = desc->array_len * desc->elem_size;
 854
 855         /* process head */
 856         if (todo && base < buf->head->iov_len) {
 857                 c = buf->head->iov_base + base;
 858                 avail_here = min_t(unsigned int, todo,
 859                                    buf->head->iov_len - base);
 860                 todo -= avail_here;
 861
 862                 while (avail_here >= desc->elem_size) {
 863                         err = desc->xcode(desc, c);
 864                         if (err)
 865                                 goto out;
 866                         c += desc->elem_size;
 867                         avail_here -= desc->elem_size;
 868                 }
 869                 if (avail_here) {
 870                         if (!elem) {
 871                                 elem = kmalloc(desc->elem_size, GFP_KERNEL);
 872                                 err = -ENOMEM;
 873                                 if (!elem)
 874                                         goto out;
 875                         }
 876                         if (encode) {
 877                                 err = desc->xcode(desc, elem);
 878                                 if (err)
 879                                         goto out;
 880                                 memcpy(c, elem, avail_here);
 881                         } else
 882                                 memcpy(elem, c, avail_here);
 883                         copied = avail_here;
 884                 }
 885                 base = buf->head->iov_len;  /* align to start of pages */
 886         }
 887
 888         /* process pages array */
 889         base -= buf->head->iov_len;
 890         if (todo && base < buf->page_len) {
 891                 unsigned int avail_page;
 892
 893                 avail_here = min(todo, buf->page_len - base);
 894                 todo -= avail_here;
 895
 896                 base += buf->page_base;
 897                 ppages = buf->pages + (base >> PAGE_CACHE_SHIFT);
 898                 base &= ~PAGE_CACHE_MASK;
 899                 avail_page = min_t(unsigned int, PAGE_CACHE_SIZE - base,
 900                                         avail_here);
 901                 c = kmap(*ppages) + base;
 902
 903                 while (avail_here) {
 904                         avail_here -= avail_page;
 905                         if (copied || avail_page < desc->elem_size) {
 906                                 unsigned int l = min(avail_page,
 907                                         desc->elem_size - copied);
 908                                 if (!elem) {
 909                                         elem = kmalloc(desc->elem_size,
 910                                                        GFP_KERNEL);
 911                                         err = -ENOMEM;
 912                                         if (!elem)
 913                                                 goto out;
 914                                 }
 915                                 if (encode) {
 916                                         if (!copied) {
 917                                                 err = desc->xcode(desc, elem);
 918                                                 if (err)
 919                                                         goto out;
 920                                         }
 921                                         memcpy(c, elem + copied, l);
 922                                         copied += l;
 923                                         if (copied == desc->elem_size)
 924                                                 copied = 0;
 925                                 } else {
 926                                         memcpy(elem + copied, c, l);
 927                                         copied += l;
 928                                         if (copied == desc->elem_size) {
 929                                                 err = desc->xcode(desc, elem);
 930                                                 if (err)
 931                                                         goto out;
 932                                                 copied = 0;
 933                                         }
 934                                 }
 935                                 avail_page -= l;
 936                                 c += l;
 937                         }
 938                         while (avail_page >= desc->elem_size) {
 939                                 err = desc->xcode(desc, c);
 940                                 if (err)
 941                                         goto out;
 942                                 c += desc->elem_size;
 943                                 avail_page -= desc->elem_size;
 944                         }
 945                         if (avail_page) {
 946                                 unsigned int l = min(avail_page,
 947                                             desc->elem_size - copied);
 948                                 if (!elem) {
 949                                         elem = kmalloc(desc->elem_size,
 950                                                        GFP_KERNEL);
 951                                         err = -ENOMEM;
 952                                         if (!elem)
 953                                                 goto out;
 954                                 }
 955                                 if (encode) {
 956                                         if (!copied) {
 957                                                 err = desc->xcode(desc, elem);
 958                                                 if (err)
 959                                                         goto out;
 960                                         }
 961                                         memcpy(c, elem + copied, l);
 962                                         copied += l;
 963                                         if (copied == desc->elem_size)
 964                                                 copied = 0;
 965                                 } else {
 966                                         memcpy(elem + copied, c, l);
 967                                         copied += l;
 968                                         if (copied == desc->elem_size) {
 969                                                 err = desc->xcode(desc, elem);
 970                                                 if (err)
 971                                                         goto out;
 972                                                 copied = 0;
 973                                         }
 974                                 }
 975                         }
 976                         if (avail_here) {
 977                                 kunmap(*ppages);
 978                                 ppages++;
 979                                 c = kmap(*ppages);
 980                         }
 981
 982                         avail_page = min(avail_here,
 983                                  (unsigned int) PAGE_CACHE_SIZE);
 984                 }
 985                 base = buf->page_len;  /* align to start of tail */
 986         }
 987
 988         /* process tail */
 989         base -= buf->page_len;
 990         if (todo) {
 991                 c = buf->tail->iov_base + base;
 992                 if (copied) {
 993                         unsigned int l = desc->elem_size - copied;
 994
 995                         if (encode)
 996                                 memcpy(c, elem + copied, l);
 997                         else {
 998                                 memcpy(elem + copied, c, l);
 999                                 err = desc->xcode(desc, elem);
1000                                 if (err)
1001                                         goto out;
1002                         }
1003                         todo -= l;
1004                         c += l;
1005                 }
1006                 while (todo) {
1007                         err = desc->xcode(desc, c);
1008                         if (err)
1009                                 goto out;
1010                         c += desc->elem_size;
1011                         todo -= desc->elem_size;
1012                 }
1013         }
1014         err = 0;
1015
1016 out:
1017         kfree(elem);
1018         if (ppages)
1019                 kunmap(*ppages);
1020         return err;
1021 }
1022
1023 int
1024 xdr_decode_array2(struct xdr_buf *buf, unsigned int base,
1025                   struct xdr_array2_desc *desc)
1026 {
1027         if (base >= buf->len)
1028                 return -EINVAL;
1029
1030         return xdr_xcode_array2(buf, base, desc, 0);
1031 }
1032 EXPORT_SYMBOL_GPL(xdr_decode_array2);
1033
1034 int
1035 xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
1036                   struct xdr_array2_desc *desc)
1037 {
1038         if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
1039             buf->head->iov_len + buf->page_len + buf->tail->iov_len)
1040                 return -EINVAL;
1041
1042         return xdr_xcode_array2(buf, base, desc, 1);
1043 }
1044 EXPORT_SYMBOL_GPL(xdr_encode_array2);
1045
1046 int
1047 xdr_process_buf(struct xdr_buf *buf, unsigned int offset, unsigned int len,
1048                 int (*actor)(struct scatterlist *, void *), void *data)
1049 {
1050         int i, ret = 0;
1051         unsigned page_len, thislen, page_offset;
1052         struct scatterlist      sg[1];
1053
1054         sg_init_table(sg, 1);
1055
1056         if (offset >= buf->head[0].iov_len) {
1057                 offset -= buf->head[0].iov_len;
1058         } else {
1059                 thislen = buf->head[0].iov_len - offset;
1060                 if (thislen > len)
1061                         thislen = len;
1062                 sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
1063                 ret = actor(sg, data);
1064                 if (ret)
1065                         goto out;
1066                 offset = 0;
1067                 len -= thislen;
1068         }
1069         if (len == 0)
1070                 goto out;
1071
1072         if (offset >= buf->page_len) {
1073                 offset -= buf->page_len;
1074         } else {
1075                 page_len = buf->page_len - offset;
1076                 if (page_len > len)
1077                         page_len = len;
1078                 len -= page_len;
1079                 page_offset = (offset + buf->page_base) & (PAGE_CACHE_SIZE - 1);
1080                 i = (offset + buf->page_base) >> PAGE_CACHE_SHIFT;
1081                 thislen = PAGE_CACHE_SIZE - page_offset;
1082                 do {
1083                         if (thislen > page_len)
1084                                 thislen = page_len;
1085                         sg_set_page(sg, buf->pages[i], thislen, page_offset);
1086                         ret = actor(sg, data);
1087                         if (ret)
1088                                 goto out;
1089                         page_len -= thislen;
1090                         i++;
1091                         page_offset = 0;
1092                         thislen = PAGE_CACHE_SIZE;
1093                 } while (page_len != 0);
1094                 offset = 0;
1095         }
1096         if (len == 0)
1097                 goto out;
1098         if (offset < buf->tail[0].iov_len) {
1099                 thislen = buf->tail[0].iov_len - offset;
1100                 if (thislen > len)
1101                         thislen = len;
1102                 sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
1103                 ret = actor(sg, data);
1104                 len -= thislen;
1105         }
1106         if (len != 0)
1107                 ret = -EINVAL;
1108 out:
1109         return ret;
1110 }
1111 EXPORT_SYMBOL_GPL(xdr_process_buf);
1112