net/sunrpc/xdr.c

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