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/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 /**
 115  * xdr_terminate_string - '\0'-terminate a string residing in an xdr_buf
 116  * @buf: XDR buffer where string resides
 117  * @len: length of string, in bytes
 118  *
 119  */
 120 void
 121 xdr_terminate_string(struct xdr_buf *buf, const u32 len)
 122 {
 123         char *kaddr;
 124
 125         kaddr = kmap_atomic(buf->pages[0], KM_USER0);
 126         kaddr[buf->page_base + len] = '\0';
 127         kunmap_atomic(kaddr, KM_USER0);
 128 }
 129 EXPORT_SYMBOL(xdr_terminate_string);
 130
 131 void
 132 xdr_encode_pages(struct xdr_buf *xdr, struct page **pages, unsigned int base,
 133                  unsigned int len)
 134 {
 135         struct kvec *tail = xdr->tail;
 136         u32 *p;
 137
 138         xdr->pages = pages;
 139         xdr->page_base = base;
 140         xdr->page_len = len;
 141
 142         p = (u32 *)xdr->head[0].iov_base + XDR_QUADLEN(xdr->head[0].iov_len);
 143         tail->iov_base = p;
 144         tail->iov_len = 0;
 145
 146         if (len & 3) {
 147                 unsigned int pad = 4 - (len & 3);
 148
 149                 *p = 0;
 150                 tail->iov_base = (char *)p + (len & 3);
 151                 tail->iov_len  = pad;
 152                 len += pad;
 153         }
 154         xdr->buflen += len;
 155         xdr->len += len;
 156 }
 157 EXPORT_SYMBOL_GPL(xdr_encode_pages);
 158
 159 void
 160 xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
 161                  struct page **pages, unsigned int base, unsigned int len)
 162 {
 163         struct kvec *head = xdr->head;
 164         struct kvec *tail = xdr->tail;
 165         char *buf = (char *)head->iov_base;
 166         unsigned int buflen = head->iov_len;
 167
 168         head->iov_len  = offset;
 169
 170         xdr->pages = pages;
 171         xdr->page_base = base;
 172         xdr->page_len = len;
 173
 174         tail->iov_base = buf + offset;
 175         tail->iov_len = buflen - offset;
 176
 177         xdr->buflen += len;
 178 }
 179 EXPORT_SYMBOL_GPL(xdr_inline_pages);
 180
 181 /*
 182  * Helper routines for doing 'memmove' like operations on a struct xdr_buf
 183  *
 184  * _shift_data_right_pages
 185  * @pages: vector of pages containing both the source and dest memory area.
 186  * @pgto_base: page vector address of destination
 187  * @pgfrom_base: page vector address of source
 188  * @len: number of bytes to copy
 189  *
 190  * Note: the addresses pgto_base and pgfrom_base are both calculated in
 191  *       the same way:
 192  *            if a memory area starts at byte 'base' in page 'pages[i]',
 193  *            then its address is given as (i << PAGE_CACHE_SHIFT) + base
 194  * Also note: pgfrom_base must be < pgto_base, but the memory areas
 195  *      they point to may overlap.
 196  */
 197 static void
 198 _shift_data_right_pages(struct page **pages, size_t pgto_base,
 199                 size_t pgfrom_base, size_t len)
 200 {
 201         struct page **pgfrom, **pgto;
 202         char *vfrom, *vto;
 203         size_t copy;
 204
 205         BUG_ON(pgto_base <= pgfrom_base);
 206
 207         pgto_base += len;
 208         pgfrom_base += len;
 209
 210         pgto = pages + (pgto_base >> PAGE_CACHE_SHIFT);
 211         pgfrom = pages + (pgfrom_base >> PAGE_CACHE_SHIFT);
 212
 213         pgto_base &= ~PAGE_CACHE_MASK;
 214         pgfrom_base &= ~PAGE_CACHE_MASK;
 215
 216         do {
 217                 /* Are any pointers crossing a page boundary? */
 218                 if (pgto_base == 0) {
 219                         pgto_base = PAGE_CACHE_SIZE;
 220                         pgto--;
 221                 }
 222                 if (pgfrom_base == 0) {
 223                         pgfrom_base = PAGE_CACHE_SIZE;
 224                         pgfrom--;
 225                 }
 226
 227                 copy = len;
 228                 if (copy > pgto_base)
 229                         copy = pgto_base;
 230                 if (copy > pgfrom_base)
 231                         copy = pgfrom_base;
 232                 pgto_base -= copy;
 233                 pgfrom_base -= copy;
 234
 235                 vto = kmap_atomic(*pgto, KM_USER0);
 236                 vfrom = kmap_atomic(*pgfrom, KM_USER1);
 237                 memmove(vto + pgto_base, vfrom + pgfrom_base, copy);
 238                 flush_dcache_page(*pgto);
 239                 kunmap_atomic(vfrom, KM_USER1);
 240                 kunmap_atomic(vto, KM_USER0);
 241
 242         } while ((len -= copy) != 0);
 243 }
 244
 245 /*
 246  * _copy_to_pages
 247  * @pages: array of pages
 248  * @pgbase: page vector address of destination
 249  * @p: pointer to source data
 250  * @len: length
 251  *
 252  * Copies data from an arbitrary memory location into an array of pages
 253  * The copy is assumed to be non-overlapping.
 254  */
 255 static void
 256 _copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len)
 257 {
 258         struct page **pgto;
 259         char *vto;
 260         size_t copy;
 261
 262         pgto = pages + (pgbase >> PAGE_CACHE_SHIFT);
 263         pgbase &= ~PAGE_CACHE_MASK;
 264
 265         for (;;) {
 266                 copy = PAGE_CACHE_SIZE - pgbase;
 267                 if (copy > len)
 268                         copy = len;
 269
 270                 vto = kmap_atomic(*pgto, KM_USER0);
 271                 memcpy(vto + pgbase, p, copy);
 272                 kunmap_atomic(vto, KM_USER0);
 273
 274                 len -= copy;
 275                 if (len == 0)
 276                         break;
 277
 278                 pgbase += copy;
 279                 if (pgbase == PAGE_CACHE_SIZE) {
 280                         flush_dcache_page(*pgto);
 281                         pgbase = 0;
 282                         pgto++;
 283                 }
 284                 p += copy;
 285         }
 286         flush_dcache_page(*pgto);
 287 }
 288
 289 /*
 290  * _copy_from_pages
 291  * @p: pointer to destination
 292  * @pages: array of pages
 293  * @pgbase: offset of source data
 294  * @len: length
 295  *
 296  * Copies data into an arbitrary memory location from an array of pages
 297  * The copy is assumed to be non-overlapping.
 298  */
 299 static void
 300 _copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
 301 {
 302         struct page **pgfrom;
 303         char *vfrom;
 304         size_t copy;
 305
 306         pgfrom = pages + (pgbase >> PAGE_CACHE_SHIFT);
 307         pgbase &= ~PAGE_CACHE_MASK;
 308
 309         do {
 310                 copy = PAGE_CACHE_SIZE - pgbase;
 311                 if (copy > len)
 312                         copy = len;
 313
 314                 vfrom = kmap_atomic(*pgfrom, KM_USER0);
 315                 memcpy(p, vfrom + pgbase, copy);
 316                 kunmap_atomic(vfrom, KM_USER0);
 317
 318                 pgbase += copy;
 319                 if (pgbase == PAGE_CACHE_SIZE) {
 320                         pgbase = 0;
 321                         pgfrom++;
 322                 }
 323                 p += copy;
 324
 325         } while ((len -= copy) != 0);
 326 }
 327
 328 /*
 329  * xdr_shrink_bufhead
 330  * @buf: xdr_buf
 331  * @len: bytes to remove from buf->head[0]
 332  *
 333  * Shrinks XDR buffer's header kvec buf->head[0] by
 334  * 'len' bytes. The extra data is not lost, but is instead
 335  * moved into the inlined pages and/or the tail.
 336  */
 337 static void
 338 xdr_shrink_bufhead(struct xdr_buf *buf, size_t len)
 339 {
 340         struct kvec *head, *tail;
 341         size_t copy, offs;
 342         unsigned int pglen = buf->page_len;
 343
 344         tail = buf->tail;
 345         head = buf->head;
 346         BUG_ON (len > head->iov_len);
 347
 348         /* Shift the tail first */
 349         if (tail->iov_len != 0) {
 350                 if (tail->iov_len > len) {
 351                         copy = tail->iov_len - len;
 352                         memmove((char *)tail->iov_base + len,
 353                                         tail->iov_base, copy);
 354                 }
 355                 /* Copy from the inlined pages into the tail */
 356                 copy = len;
 357                 if (copy > pglen)
 358                         copy = pglen;
 359                 offs = len - copy;
 360                 if (offs >= tail->iov_len)
 361                         copy = 0;
 362                 else if (copy > tail->iov_len - offs)
 363                         copy = tail->iov_len - offs;
 364                 if (copy != 0)
 365                         _copy_from_pages((char *)tail->iov_base + offs,
 366                                         buf->pages,
 367                                         buf->page_base + pglen + offs - len,
 368                                         copy);
 369                 /* Do we also need to copy data from the head into the tail ? */
 370                 if (len > pglen) {
 371                         offs = copy = len - pglen;
 372                         if (copy > tail->iov_len)
 373                                 copy = tail->iov_len;
 374                         memcpy(tail->iov_base,
 375                                         (char *)head->iov_base +
 376                                         head->iov_len - offs,
 377                                         copy);
 378                 }
 379         }
 380         /* Now handle pages */
 381         if (pglen != 0) {
 382                 if (pglen > len)
 383                         _shift_data_right_pages(buf->pages,
 384                                         buf->page_base + len,
 385                                         buf->page_base,
 386                                         pglen - len);
 387                 copy = len;
 388                 if (len > pglen)
 389                         copy = pglen;
 390                 _copy_to_pages(buf->pages, buf->page_base,
 391                                 (char *)head->iov_base + head->iov_len - len,
 392                                 copy);
 393         }
 394         head->iov_len -= len;
 395         buf->buflen -= len;
 396         /* Have we truncated the message? */
 397         if (buf->len > buf->buflen)
 398                 buf->len = buf->buflen;
 399 }
 400
 401 /*
 402  * xdr_shrink_pagelen
 403  * @buf: xdr_buf
 404  * @len: bytes to remove from buf->pages
 405  *
 406  * Shrinks XDR buffer's page array buf->pages by
 407  * 'len' bytes. The extra data is not lost, but is instead
 408  * moved into the tail.
 409  */
 410 static void
 411 xdr_shrink_pagelen(struct xdr_buf *buf, size_t len)
 412 {
 413         struct kvec *tail;
 414         size_t copy;
 415         unsigned int pglen = buf->page_len;
 416         unsigned int tailbuf_len;
 417
 418         tail = buf->tail;
 419         BUG_ON (len > pglen);
 420
 421         tailbuf_len = buf->buflen - buf->head->iov_len - buf->page_len;
 422
 423         /* Shift the tail first */
 424         if (tailbuf_len != 0) {
 425                 unsigned int free_space = tailbuf_len - tail->iov_len;
 426
 427                 if (len < free_space)
 428                         free_space = len;
 429                 tail->iov_len += free_space;
 430
 431                 copy = len;
 432                 if (tail->iov_len > len) {
 433                         char *p = (char *)tail->iov_base + len;
 434                         memmove(p, tail->iov_base, tail->iov_len - len);
 435                 } else
 436                         copy = tail->iov_len;
 437                 /* Copy from the inlined pages into the tail */
 438                 _copy_from_pages((char *)tail->iov_base,
 439                                 buf->pages, buf->page_base + pglen - len,
 440                                 copy);
 441         }
 442         buf->page_len -= len;
 443         buf->buflen -= len;
 444         /* Have we truncated the message? */
 445         if (buf->len > buf->buflen)
 446                 buf->len = buf->buflen;
 447 }
 448
 449 void
 450 xdr_shift_buf(struct xdr_buf *buf, size_t len)
 451 {
 452         xdr_shrink_bufhead(buf, len);
 453 }
 454 EXPORT_SYMBOL_GPL(xdr_shift_buf);
 455
 456 /**
 457  * xdr_init_encode - Initialize a struct xdr_stream for sending data.
 458  * @xdr: pointer to xdr_stream struct
 459  * @buf: pointer to XDR buffer in which to encode data
 460  * @p: current pointer inside XDR buffer
 461  *
 462  * Note: at the moment the RPC client only passes the length of our
 463  *       scratch buffer in the xdr_buf's header kvec. Previously this
 464  *       meant we needed to call xdr_adjust_iovec() after encoding the
 465  *       data. With the new scheme, the xdr_stream manages the details
 466  *       of the buffer length, and takes care of adjusting the kvec
 467  *       length for us.
 468  */
 469 void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
 470 {
 471         struct kvec *iov = buf->head;
 472         int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
 473
 474         BUG_ON(scratch_len < 0);
 475         xdr->buf = buf;
 476         xdr->iov = iov;
 477         xdr->p = (__be32 *)((char *)iov->iov_base + iov->iov_len);
 478         xdr->end = (__be32 *)((char *)iov->iov_base + scratch_len);
 479         BUG_ON(iov->iov_len > scratch_len);
 480
 481         if (p != xdr->p && p != NULL) {
 482                 size_t len;
 483
 484                 BUG_ON(p < xdr->p || p > xdr->end);
 485                 len = (char *)p - (char *)xdr->p;
 486                 xdr->p = p;
 487                 buf->len += len;
 488                 iov->iov_len += len;
 489         }
 490 }
 491 EXPORT_SYMBOL_GPL(xdr_init_encode);
 492
 493 /**
 494  * xdr_reserve_space - Reserve buffer space for sending
 495  * @xdr: pointer to xdr_stream
 496  * @nbytes: number of bytes to reserve
 497  *
 498  * Checks that we have enough buffer space to encode 'nbytes' more
 499  * bytes of data. If so, update the total xdr_buf length, and
 500  * adjust the length of the current kvec.
 501  */
 502 __be32 * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
 503 {
 504         __be32 *p = xdr->p;
 505         __be32 *q;
 506
 507         /* align nbytes on the next 32-bit boundary */
 508         nbytes += 3;
 509         nbytes &= ~3;
 510         q = p + (nbytes >> 2);
 511         if (unlikely(q > xdr->end || q < p))
 512                 return NULL;
 513         xdr->p = q;
 514         xdr->iov->iov_len += nbytes;
 515         xdr->buf->len += nbytes;
 516         return p;
 517 }
 518 EXPORT_SYMBOL_GPL(xdr_reserve_space);
 519
 520 /**
 521  * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
 522  * @xdr: pointer to xdr_stream
 523  * @pages: list of pages
 524  * @base: offset of first byte
 525  * @len: length of data in bytes
 526  *
 527  */
 528 void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
 529                  unsigned int len)
 530 {
 531         struct xdr_buf *buf = xdr->buf;
 532         struct kvec *iov = buf->tail;
 533         buf->pages = pages;
 534         buf->page_base = base;
 535         buf->page_len = len;
 536
 537         iov->iov_base = (char *)xdr->p;
 538         iov->iov_len  = 0;
 539         xdr->iov = iov;
 540
 541         if (len & 3) {
 542                 unsigned int pad = 4 - (len & 3);
 543
 544                 BUG_ON(xdr->p >= xdr->end);
 545                 iov->iov_base = (char *)xdr->p + (len & 3);
 546                 iov->iov_len  += pad;
 547                 len += pad;
 548                 *xdr->p++ = 0;
 549         }
 550         buf->buflen += len;
 551         buf->len += len;
 552 }
 553 EXPORT_SYMBOL_GPL(xdr_write_pages);
 554
 555 /**
 556  * xdr_init_decode - Initialize an xdr_stream for decoding data.
 557  * @xdr: pointer to xdr_stream struct
 558  * @buf: pointer to XDR buffer from which to decode data
 559  * @p: current pointer inside XDR buffer
 560  */
 561 void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
 562 {
 563         struct kvec *iov = buf->head;
 564         unsigned int len = iov->iov_len;
 565
 566         if (len > buf->len)
 567                 len = buf->len;
 568         xdr->buf = buf;
 569         xdr->iov = iov;
 570         xdr->p = p;
 571         xdr->end = (__be32 *)((char *)iov->iov_base + len);
 572 }
 573 EXPORT_SYMBOL_GPL(xdr_init_decode);
 574
 575 /**
 576  * xdr_inline_peek - Allow read-ahead in the XDR data stream
 577  * @xdr: pointer to xdr_stream struct
 578  * @nbytes: number of bytes of data to decode
 579  *
 580  * Check if the input buffer is long enough to enable us to decode
 581  * 'nbytes' more bytes of data starting at the current position.
 582  * If so return the current pointer without updating the current
 583  * pointer position.
 584  */
 585 __be32 * xdr_inline_peek(struct xdr_stream *xdr, size_t nbytes)
 586 {
 587         __be32 *p = xdr->p;
 588         __be32 *q = p + XDR_QUADLEN(nbytes);
 589
 590         if (unlikely(q > xdr->end || q < p))
 591                 return NULL;
 592         return p;
 593 }
 594 EXPORT_SYMBOL_GPL(xdr_inline_peek);
 595
 596 /**
 597  * xdr_inline_decode - Retrieve non-page XDR data to decode
 598  * @xdr: pointer to xdr_stream struct
 599  * @nbytes: number of bytes of data to decode
 600  *
 601  * Check if the input buffer is long enough to enable us to decode
 602  * 'nbytes' more bytes of data starting at the current position.
 603  * If so return the current pointer, then update the current
 604  * pointer position.
 605  */
 606 __be32 * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
 607 {
 608         __be32 *p = xdr->p;
 609         __be32 *q = p + XDR_QUADLEN(nbytes);
 610
 611         if (unlikely(q > xdr->end || q < p))
 612                 return NULL;
 613         xdr->p = q;
 614         return p;
 615 }
 616 EXPORT_SYMBOL_GPL(xdr_inline_decode);
 617
 618 /**
 619  * xdr_read_pages - Ensure page-based XDR data to decode is aligned at current pointer position
 620  * @xdr: pointer to xdr_stream struct
 621  * @len: number of bytes of page data
 622  *
 623  * Moves data beyond the current pointer position from the XDR head[] buffer
 624  * into the page list. Any data that lies beyond current position + "len"
 625  * bytes is moved into the XDR tail[].
 626  */
 627 void xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
 628 {
 629         struct xdr_buf *buf = xdr->buf;
 630         struct kvec *iov;
 631         ssize_t shift;
 632         unsigned int end;
 633         int padding;
 634
 635         /* Realign pages to current pointer position */
 636         iov  = buf->head;
 637         shift = iov->iov_len + (char *)iov->iov_base - (char *)xdr->p;
 638         if (shift > 0)
 639                 xdr_shrink_bufhead(buf, shift);
 640
 641         /* Truncate page data and move it into the tail */
 642         if (buf->page_len > len)
 643                 xdr_shrink_pagelen(buf, buf->page_len - len);
 644         padding = (XDR_QUADLEN(len) << 2) - len;
 645         xdr->iov = iov = buf->tail;
 646         /* Compute remaining message length.  */
 647         end = iov->iov_len;
 648         shift = buf->buflen - buf->len;
 649         if (shift < end)
 650                 end -= shift;
 651         else if (shift > 0)
 652                 end = 0;
 653         /*
 654          * Position current pointer at beginning of tail, and
 655          * set remaining message length.
 656          */
 657         xdr->p = (__be32 *)((char *)iov->iov_base + padding);
 658         xdr->end = (__be32 *)((char *)iov->iov_base + end);
 659 }
 660 EXPORT_SYMBOL_GPL(xdr_read_pages);
 661
 662 /**
 663  * xdr_enter_page - decode data from the XDR page
 664  * @xdr: pointer to xdr_stream struct
 665  * @len: number of bytes of page data
 666  *
 667  * Moves data beyond the current pointer position from the XDR head[] buffer
 668  * into the page list. Any data that lies beyond current position + "len"
 669  * bytes is moved into the XDR tail[]. The current pointer is then
 670  * repositioned at the beginning of the first XDR page.
 671  */
 672 void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
 673 {
 674         char * kaddr = page_address(xdr->buf->pages[0]);
 675         xdr_read_pages(xdr, len);
 676         /*
 677          * Position current pointer at beginning of tail, and
 678          * set remaining message length.
 679          */
 680         if (len > PAGE_CACHE_SIZE - xdr->buf->page_base)
 681                 len = PAGE_CACHE_SIZE - xdr->buf->page_base;
 682         xdr->p = (__be32 *)(kaddr + xdr->buf->page_base);
 683         xdr->end = (__be32 *)((char *)xdr->p + len);
 684 }
 685 EXPORT_SYMBOL_GPL(xdr_enter_page);
 686
 687 static struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
 688
 689 void
 690 xdr_buf_from_iov(struct kvec *iov, struct xdr_buf *buf)
 691 {
 692         buf->head[0] = *iov;
 693         buf->tail[0] = empty_iov;
 694         buf->page_len = 0;
 695         buf->buflen = buf->len = iov->iov_len;
 696 }
 697 EXPORT_SYMBOL_GPL(xdr_buf_from_iov);
 698
 699 /* Sets subbuf to the portion of buf of length len beginning base bytes
 700  * from the start of buf. Returns -1 if base of length are out of bounds. */
 701 int
 702 xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
 703                         unsigned int base, unsigned int len)
 704 {
 705         subbuf->buflen = subbuf->len = len;
 706         if (base < buf->head[0].iov_len) {
 707                 subbuf->head[0].iov_base = buf->head[0].iov_base + base;
 708                 subbuf->head[0].iov_len = min_t(unsigned int, len,
 709                                                 buf->head[0].iov_len - base);
 710                 len -= subbuf->head[0].iov_len;
 711                 base = 0;
 712         } else {
 713                 subbuf->head[0].iov_base = NULL;
 714                 subbuf->head[0].iov_len = 0;
 715                 base -= buf->head[0].iov_len;
 716         }
 717
 718         if (base < buf->page_len) {
 719                 subbuf->page_len = min(buf->page_len - base, len);
 720                 base += buf->page_base;
 721                 subbuf->page_base = base & ~PAGE_CACHE_MASK;
 722                 subbuf->pages = &buf->pages[base >> PAGE_CACHE_SHIFT];
 723                 len -= subbuf->page_len;
 724                 base = 0;
 725         } else {
 726                 base -= buf->page_len;
 727                 subbuf->page_len = 0;
 728         }
 729
 730         if (base < buf->tail[0].iov_len) {
 731                 subbuf->tail[0].iov_base = buf->tail[0].iov_base + base;
 732                 subbuf->tail[0].iov_len = min_t(unsigned int, len,
 733                                                 buf->tail[0].iov_len - base);
 734                 len -= subbuf->tail[0].iov_len;
 735                 base = 0;
 736         } else {
 737                 subbuf->tail[0].iov_base = NULL;
 738                 subbuf->tail[0].iov_len = 0;
 739                 base -= buf->tail[0].iov_len;
 740         }
 741
 742         if (base || len)
 743                 return -1;
 744         return 0;
 745 }
 746 EXPORT_SYMBOL_GPL(xdr_buf_subsegment);
 747
 748 static void __read_bytes_from_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
 749 {
 750         unsigned int this_len;
 751
 752         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
 753         memcpy(obj, subbuf->head[0].iov_base, this_len);
 754         len -= this_len;
 755         obj += this_len;
 756         this_len = min_t(unsigned int, len, subbuf->page_len);
 757         if (this_len)
 758                 _copy_from_pages(obj, subbuf->pages, subbuf->page_base, this_len);
 759         len -= this_len;
 760         obj += this_len;
 761         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
 762         memcpy(obj, subbuf->tail[0].iov_base, this_len);
 763 }
 764
 765 /* obj is assumed to point to allocated memory of size at least len: */
 766 int read_bytes_from_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
 767 {
 768         struct xdr_buf subbuf;
 769         int status;
 770
 771         status = xdr_buf_subsegment(buf, &subbuf, base, len);
 772         if (status != 0)
 773                 return status;
 774         __read_bytes_from_xdr_buf(&subbuf, obj, len);
 775         return 0;
 776 }
 777 EXPORT_SYMBOL_GPL(read_bytes_from_xdr_buf);
 778
 779 static void __write_bytes_to_xdr_buf(struct xdr_buf *subbuf, void *obj, unsigned int len)
 780 {
 781         unsigned int this_len;
 782
 783         this_len = min_t(unsigned int, len, subbuf->head[0].iov_len);
 784         memcpy(subbuf->head[0].iov_base, obj, this_len);
 785         len -= this_len;
 786         obj += this_len;
 787         this_len = min_t(unsigned int, len, subbuf->page_len);
 788         if (this_len)
 789                 _copy_to_pages(subbuf->pages, subbuf->page_base, obj, this_len);
 790         len -= this_len;
 791         obj += this_len;
 792         this_len = min_t(unsigned int, len, subbuf->tail[0].iov_len);
 793         memcpy(subbuf->tail[0].iov_base, obj, this_len);
 794 }
 795
 796 /* obj is assumed to point to allocated memory of size at least len: */
 797 int write_bytes_to_xdr_buf(struct xdr_buf *buf, unsigned int base, void *obj, unsigned int len)
 798 {
 799         struct xdr_buf subbuf;
 800         int status;
 801
 802         status = xdr_buf_subsegment(buf, &subbuf, base, len);
 803         if (status != 0)
 804                 return status;
 805         __write_bytes_to_xdr_buf(&subbuf, obj, len);
 806         return 0;
 807 }
 808 EXPORT_SYMBOL_GPL(write_bytes_to_xdr_buf);
 809
 810 int
 811 xdr_decode_word(struct xdr_buf *buf, unsigned int base, u32 *obj)
 812 {
 813         __be32  raw;
 814         int     status;
 815
 816         status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
 817         if (status)
 818                 return status;
 819         *obj = be32_to_cpu(raw);
 820         return 0;
 821 }
 822 EXPORT_SYMBOL_GPL(xdr_decode_word);
 823
 824 int
 825 xdr_encode_word(struct xdr_buf *buf, unsigned int base, u32 obj)
 826 {
 827         __be32  raw = cpu_to_be32(obj);
 828
 829         return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
 830 }
 831 EXPORT_SYMBOL_GPL(xdr_encode_word);
 832
 833 /* If the netobj starting offset bytes from the start of xdr_buf is contained
 834  * entirely in the head or the tail, set object to point to it; otherwise
 835  * try to find space for it at the end of the tail, copy it there, and
 836  * set obj to point to it. */
 837 int xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, unsigned int offset)
 838 {
 839         struct xdr_buf subbuf;
 840
 841         if (xdr_decode_word(buf, offset, &obj->len))
 842                 return -EFAULT;
 843         if (xdr_buf_subsegment(buf, &subbuf, offset + 4, obj->len))
 844                 return -EFAULT;
 845
 846         /* Is the obj contained entirely in the head? */
 847         obj->data = subbuf.head[0].iov_base;
 848         if (subbuf.head[0].iov_len == obj->len)
 849                 return 0;
 850         /* ..or is the obj contained entirely in the tail? */
 851         obj->data = subbuf.tail[0].iov_base;
 852         if (subbuf.tail[0].iov_len == obj->len)
 853                 return 0;
 854
 855         /* use end of tail as storage for obj:
 856          * (We don't copy to the beginning because then we'd have
 857          * to worry about doing a potentially overlapping copy.
 858          * This assumes the object is at most half the length of the
 859          * tail.) */
 860         if (obj->len > buf->buflen - buf->len)
 861                 return -ENOMEM;
 862         if (buf->tail[0].iov_len != 0)
 863                 obj->data = buf->tail[0].iov_base + buf->tail[0].iov_len;
 864         else
 865                 obj->data = buf->head[0].iov_base + buf->head[0].iov_len;
 866         __read_bytes_from_xdr_buf(&subbuf, obj->data, obj->len);
 867         return 0;
 868 }
 869 EXPORT_SYMBOL_GPL(xdr_buf_read_netobj);
 870
 871 /* Returns 0 on success, or else a negative error code. */
 872 static int
 873 xdr_xcode_array2(struct xdr_buf *buf, unsigned int base,
 874                  struct xdr_array2_desc *desc, int encode)
 875 {
 876         char *elem = NULL, *c;
 877         unsigned int copied = 0, todo, avail_here;
 878         struct page **ppages = NULL;
 879         int err;
 880
 881         if (encode) {
 882                 if (xdr_encode_word(buf, base, desc->array_len) != 0)
 883                         return -EINVAL;
 884         } else {
 885                 if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
 886                     desc->array_len > desc->array_maxlen ||
 887                     (unsigned long) base + 4 + desc->array_len *
 888                                     desc->elem_size > buf->len)
 889                         return -EINVAL;
 890         }
 891         base += 4;
 892
 893         if (!desc->xcode)
 894                 return 0;
 895
 896         todo = desc->array_len * desc->elem_size;
 897
 898         /* process head */
 899         if (todo && base < buf->head->iov_len) {
 900                 c = buf->head->iov_base + base;
 901                 avail_here = min_t(unsigned int, todo,
 902                                    buf->head->iov_len - base);
 903                 todo -= avail_here;
 904
 905                 while (avail_here >= desc->elem_size) {
 906                         err = desc->xcode(desc, c);
 907                         if (err)
 908                                 goto out;
 909                         c += desc->elem_size;
 910                         avail_here -= desc->elem_size;
 911                 }
 912                 if (avail_here) {
 913                         if (!elem) {
 914                                 elem = kmalloc(desc->elem_size, GFP_KERNEL);
 915                                 err = -ENOMEM;
 916                                 if (!elem)
 917                                         goto out;
 918                         }
 919                         if (encode) {
 920                                 err = desc->xcode(desc, elem);
 921                                 if (err)
 922                                         goto out;
 923                                 memcpy(c, elem, avail_here);
 924                         } else
 925                                 memcpy(elem, c, avail_here);
 926                         copied = avail_here;
 927                 }
 928                 base = buf->head->iov_len;  /* align to start of pages */
 929         }
 930
 931         /* process pages array */
 932         base -= buf->head->iov_len;
 933         if (todo && base < buf->page_len) {
 934                 unsigned int avail_page;
 935
 936                 avail_here = min(todo, buf->page_len - base);
 937                 todo -= avail_here;
 938
 939                 base += buf->page_base;
 940                 ppages = buf->pages + (base >> PAGE_CACHE_SHIFT);
 941                 base &= ~PAGE_CACHE_MASK;
 942                 avail_page = min_t(unsigned int, PAGE_CACHE_SIZE - base,
 943                                         avail_here);
 944                 c = kmap(*ppages) + base;
 945
 946                 while (avail_here) {
 947                         avail_here -= avail_page;
 948                         if (copied || avail_page < desc->elem_size) {
 949                                 unsigned int l = min(avail_page,
 950                                         desc->elem_size - copied);
 951                                 if (!elem) {
 952                                         elem = kmalloc(desc->elem_size,
 953                                                        GFP_KERNEL);
 954                                         err = -ENOMEM;
 955                                         if (!elem)
 956                                                 goto out;
 957                                 }
 958                                 if (encode) {
 959                                         if (!copied) {
 960                                                 err = desc->xcode(desc, elem);
 961                                                 if (err)
 962                                                         goto out;
 963                                         }
 964                                         memcpy(c, elem + copied, l);
 965                                         copied += l;
 966                                         if (copied == desc->elem_size)
 967                                                 copied = 0;
 968                                 } else {
 969                                         memcpy(elem + copied, c, l);
 970                                         copied += l;
 971                                         if (copied == desc->elem_size) {
 972                                                 err = desc->xcode(desc, elem);
 973                                                 if (err)
 974                                                         goto out;
 975                                                 copied = 0;
 976                                         }
 977                                 }
 978                                 avail_page -= l;
 979                                 c += l;
 980                         }
 981                         while (avail_page >= desc->elem_size) {
 982                                 err = desc->xcode(desc, c);
 983                                 if (err)
 984                                         goto out;
 985                                 c += desc->elem_size;
 986                                 avail_page -= desc->elem_size;
 987                         }
 988                         if (avail_page) {
 989                                 unsigned int l = min(avail_page,
 990                                             desc->elem_size - copied);
 991                                 if (!elem) {
 992                                         elem = kmalloc(desc->elem_size,
 993                                                        GFP_KERNEL);
 994                                         err = -ENOMEM;
 995                                         if (!elem)
 996                                                 goto out;
 997                                 }
 998                                 if (encode) {
 999                                         if (!copied) {
1000                                                 err = desc->xcode(desc, elem);
1001                                                 if (err)
1002                                                         goto out;
1003                                         }
1004                                         memcpy(c, elem + copied, l);
1005                                         copied += l;
1006                                         if (copied == desc->elem_size)
1007                                                 copied = 0;
1008                                 } else {
1009                                         memcpy(elem + copied, c, l);
1010                                         copied += l;
1011                                         if (copied == desc->elem_size) {
1012                                                 err = desc->xcode(desc, elem);
1013                                                 if (err)
1014                                                         goto out;
1015                                                 copied = 0;
1016                                         }
1017                                 }
1018                         }
1019                         if (avail_here) {
1020                                 kunmap(*ppages);
1021                                 ppages++;
1022                                 c = kmap(*ppages);
1023                         }
1024
1025                         avail_page = min(avail_here,
1026                                  (unsigned int) PAGE_CACHE_SIZE);
1027                 }
1028                 base = buf->page_len;  /* align to start of tail */
1029         }
1030
1031         /* process tail */
1032         base -= buf->page_len;
1033         if (todo) {
1034                 c = buf->tail->iov_base + base;
1035                 if (copied) {
1036                         unsigned int l = desc->elem_size - copied;
1037
1038                         if (encode)
1039                                 memcpy(c, elem + copied, l);
1040                         else {
1041                                 memcpy(elem + copied, c, l);
1042                                 err = desc->xcode(desc, elem);
1043                                 if (err)
1044                                         goto out;
1045                         }
1046                         todo -= l;
1047                         c += l;
1048                 }
1049                 while (todo) {
1050                         err = desc->xcode(desc, c);
1051                         if (err)
1052                                 goto out;
1053                         c += desc->elem_size;
1054                         todo -= desc->elem_size;
1055                 }
1056         }
1057         err = 0;
1058
1059 out:
1060         kfree(elem);
1061         if (ppages)
1062                 kunmap(*ppages);
1063         return err;
1064 }
1065
1066 int
1067 xdr_decode_array2(struct xdr_buf *buf, unsigned int base,
1068                   struct xdr_array2_desc *desc)
1069 {
1070         if (base >= buf->len)
1071                 return -EINVAL;
1072
1073         return xdr_xcode_array2(buf, base, desc, 0);
1074 }
1075 EXPORT_SYMBOL_GPL(xdr_decode_array2);
1076
1077 int
1078 xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
1079                   struct xdr_array2_desc *desc)
1080 {
1081         if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
1082             buf->head->iov_len + buf->page_len + buf->tail->iov_len)
1083                 return -EINVAL;
1084
1085         return xdr_xcode_array2(buf, base, desc, 1);
1086 }
1087 EXPORT_SYMBOL_GPL(xdr_encode_array2);
1088
1089 int
1090 xdr_process_buf(struct xdr_buf *buf, unsigned int offset, unsigned int len,
1091                 int (*actor)(struct scatterlist *, void *), void *data)
1092 {
1093         int i, ret = 0;
1094         unsigned page_len, thislen, page_offset;
1095         struct scatterlist      sg[1];
1096
1097         sg_init_table(sg, 1);
1098
1099         if (offset >= buf->head[0].iov_len) {
1100                 offset -= buf->head[0].iov_len;
1101         } else {
1102                 thislen = buf->head[0].iov_len - offset;
1103                 if (thislen > len)
1104                         thislen = len;
1105                 sg_set_buf(sg, buf->head[0].iov_base + offset, thislen);
1106                 ret = actor(sg, data);
1107                 if (ret)
1108                         goto out;
1109                 offset = 0;
1110                 len -= thislen;
1111         }
1112         if (len == 0)
1113                 goto out;
1114
1115         if (offset >= buf->page_len) {
1116                 offset -= buf->page_len;
1117         } else {
1118                 page_len = buf->page_len - offset;
1119                 if (page_len > len)
1120                         page_len = len;
1121                 len -= page_len;
1122                 page_offset = (offset + buf->page_base) & (PAGE_CACHE_SIZE - 1);
1123                 i = (offset + buf->page_base) >> PAGE_CACHE_SHIFT;
1124                 thislen = PAGE_CACHE_SIZE - page_offset;
1125                 do {
1126                         if (thislen > page_len)
1127                                 thislen = page_len;
1128                         sg_set_page(sg, buf->pages[i], thislen, page_offset);
1129                         ret = actor(sg, data);
1130                         if (ret)
1131                                 goto out;
1132                         page_len -= thislen;
1133                         i++;
1134                         page_offset = 0;
1135                         thislen = PAGE_CACHE_SIZE;
1136                 } while (page_len != 0);
1137                 offset = 0;
1138         }
1139         if (len == 0)
1140                 goto out;
1141         if (offset < buf->tail[0].iov_len) {
1142                 thislen = buf->tail[0].iov_len - offset;
1143                 if (thislen > len)
1144                         thislen = len;
1145                 sg_set_buf(sg, buf->tail[0].iov_base + offset, thislen);
1146                 ret = actor(sg, data);
1147                 len -= thislen;
1148         }
1149         if (len != 0)
1150                 ret = -EINVAL;
1151 out:
1152         return ret;
1153 }
1154 EXPORT_SYMBOL_GPL(xdr_process_buf);
1155