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/types.h>
  10 #include <linux/socket.h>
  11 #include <linux/string.h>
  12 #include <linux/kernel.h>
  13 #include <linux/pagemap.h>
  14 #include <linux/errno.h>
  15 #include <linux/in.h>
  16 #include <linux/net.h>
  17 #include <net/sock.h>
  18 #include <linux/sunrpc/xdr.h>
  19 #include <linux/sunrpc/msg_prot.h>
  20
  21 /*
  22  * XDR functions for basic NFS types
  23  */
  24 u32 *
  25 xdr_encode_netobj(u32 *p, const struct xdr_netobj *obj)
  26 {
  27         unsigned int    quadlen = XDR_QUADLEN(obj->len);
  28
  29         p[quadlen] = 0;         /* zero trailing bytes */
  30         *p++ = htonl(obj->len);
  31         memcpy(p, obj->data, obj->len);
  32         return p + XDR_QUADLEN(obj->len);
  33 }
  34
  35 u32 *
  36 xdr_decode_netobj(u32 *p, struct xdr_netobj *obj)
  37 {
  38         unsigned int    len;
  39
  40         if ((len = ntohl(*p++)) > XDR_MAX_NETOBJ)
  41                 return NULL;
  42         obj->len  = len;
  43         obj->data = (u8 *) p;
  44         return p + XDR_QUADLEN(len);
  45 }
  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 u32 *xdr_encode_opaque_fixed(u32 *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(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 u32 *xdr_encode_opaque(u32 *p, const void *ptr, unsigned int nbytes)
  86 {
  87         *p++ = htonl(nbytes);
  88         return xdr_encode_opaque_fixed(p, ptr, nbytes);
  89 }
  90 EXPORT_SYMBOL(xdr_encode_opaque);
  91
  92 u32 *
  93 xdr_encode_string(u32 *p, const char *string)
  94 {
  95         return xdr_encode_array(p, string, strlen(string));
  96 }
  97
  98 u32 *
  99 xdr_decode_string(u32 *p, char **sp, int *lenp, int maxlen)
 100 {
 101         unsigned int    len;
 102         char            *string;
 103
 104         if ((len = ntohl(*p++)) > maxlen)
 105                 return NULL;
 106         if (lenp)
 107                 *lenp = len;
 108         if ((len % 4) != 0) {
 109                 string = (char *) p;
 110         } else {
 111                 string = (char *) (p - 1);
 112                 memmove(string, p, len);
 113         }
 114         string[len] = '\0';
 115         *sp = string;
 116         return p + XDR_QUADLEN(len);
 117 }
 118
 119 u32 *
 120 xdr_decode_string_inplace(u32 *p, char **sp, int *lenp, int maxlen)
 121 {
 122         unsigned int    len;
 123
 124         if ((len = ntohl(*p++)) > maxlen)
 125                 return NULL;
 126         *lenp = len;
 127         *sp = (char *) p;
 128         return p + XDR_QUADLEN(len);
 129 }
 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
 158 void
 159 xdr_inline_pages(struct xdr_buf *xdr, unsigned int offset,
 160                  struct page **pages, unsigned int base, unsigned int len)
 161 {
 162         struct kvec *head = xdr->head;
 163         struct kvec *tail = xdr->tail;
 164         char *buf = (char *)head->iov_base;
 165         unsigned int buflen = head->iov_len;
 166
 167         head->iov_len  = offset;
 168
 169         xdr->pages = pages;
 170         xdr->page_base = base;
 171         xdr->page_len = len;
 172
 173         tail->iov_base = buf + offset;
 174         tail->iov_len = buflen - offset;
 175
 176         xdr->buflen += len;
 177 }
 178
 179
 180 int
 181 xdr_sendpages(struct socket *sock, struct sockaddr *addr, int addrlen,
 182                 struct xdr_buf *xdr, unsigned int base, int msgflags)
 183 {
 184         struct page **ppage = xdr->pages;
 185         unsigned int len, pglen = xdr->page_len;
 186         int err, ret = 0;
 187         ssize_t (*sendpage)(struct socket *, struct page *, int, size_t, int);
 188
 189         len = xdr->head[0].iov_len;
 190         if (base < len || (addr != NULL && base == 0)) {
 191                 struct kvec iov = {
 192                         .iov_base = xdr->head[0].iov_base + base,
 193                         .iov_len  = len - base,
 194                 };
 195                 struct msghdr msg = {
 196                         .msg_name    = addr,
 197                         .msg_namelen = addrlen,
 198                         .msg_flags   = msgflags,
 199                 };
 200                 if (xdr->len > len)
 201                         msg.msg_flags |= MSG_MORE;
 202
 203                 if (iov.iov_len != 0)
 204                         err = kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);
 205                 else
 206                         err = kernel_sendmsg(sock, &msg, NULL, 0, 0);
 207                 if (ret == 0)
 208                         ret = err;
 209                 else if (err > 0)
 210                         ret += err;
 211                 if (err != iov.iov_len)
 212                         goto out;
 213                 base = 0;
 214         } else
 215                 base -= len;
 216
 217         if (pglen == 0)
 218                 goto copy_tail;
 219         if (base >= pglen) {
 220                 base -= pglen;
 221                 goto copy_tail;
 222         }
 223         if (base || xdr->page_base) {
 224                 pglen -= base;
 225                 base  += xdr->page_base;
 226                 ppage += base >> PAGE_CACHE_SHIFT;
 227                 base &= ~PAGE_CACHE_MASK;
 228         }
 229
 230         sendpage = sock->ops->sendpage ? : sock_no_sendpage;
 231         do {
 232                 int flags = msgflags;
 233
 234                 len = PAGE_CACHE_SIZE;
 235                 if (base)
 236                         len -= base;
 237                 if (pglen < len)
 238                         len = pglen;
 239
 240                 if (pglen != len || xdr->tail[0].iov_len != 0)
 241                         flags |= MSG_MORE;
 242
 243                 /* Hmm... We might be dealing with highmem pages */
 244                 if (PageHighMem(*ppage))
 245                         sendpage = sock_no_sendpage;
 246                 err = sendpage(sock, *ppage, base, len, flags);
 247                 if (ret == 0)
 248                         ret = err;
 249                 else if (err > 0)
 250                         ret += err;
 251                 if (err != len)
 252                         goto out;
 253                 base = 0;
 254                 ppage++;
 255         } while ((pglen -= len) != 0);
 256 copy_tail:
 257         len = xdr->tail[0].iov_len;
 258         if (base < len) {
 259                 struct kvec iov = {
 260                         .iov_base = xdr->tail[0].iov_base + base,
 261                         .iov_len  = len - base,
 262                 };
 263                 struct msghdr msg = {
 264                         .msg_flags   = msgflags,
 265                 };
 266                 err = kernel_sendmsg(sock, &msg, &iov, 1, iov.iov_len);
 267                 if (ret == 0)
 268                         ret = err;
 269                 else if (err > 0)
 270                         ret += err;
 271         }
 272 out:
 273         return ret;
 274 }
 275
 276
 277 /*
 278  * Helper routines for doing 'memmove' like operations on a struct xdr_buf
 279  *
 280  * _shift_data_right_pages
 281  * @pages: vector of pages containing both the source and dest memory area.
 282  * @pgto_base: page vector address of destination
 283  * @pgfrom_base: page vector address of source
 284  * @len: number of bytes to copy
 285  *
 286  * Note: the addresses pgto_base and pgfrom_base are both calculated in
 287  *       the same way:
 288  *            if a memory area starts at byte 'base' in page 'pages[i]',
 289  *            then its address is given as (i << PAGE_CACHE_SHIFT) + base
 290  * Also note: pgfrom_base must be < pgto_base, but the memory areas
 291  *      they point to may overlap.
 292  */
 293 static void
 294 _shift_data_right_pages(struct page **pages, size_t pgto_base,
 295                 size_t pgfrom_base, size_t len)
 296 {
 297         struct page **pgfrom, **pgto;
 298         char *vfrom, *vto;
 299         size_t copy;
 300
 301         BUG_ON(pgto_base <= pgfrom_base);
 302
 303         pgto_base += len;
 304         pgfrom_base += len;
 305
 306         pgto = pages + (pgto_base >> PAGE_CACHE_SHIFT);
 307         pgfrom = pages + (pgfrom_base >> PAGE_CACHE_SHIFT);
 308
 309         pgto_base &= ~PAGE_CACHE_MASK;
 310         pgfrom_base &= ~PAGE_CACHE_MASK;
 311
 312         do {
 313                 /* Are any pointers crossing a page boundary? */
 314                 if (pgto_base == 0) {
 315                         flush_dcache_page(*pgto);
 316                         pgto_base = PAGE_CACHE_SIZE;
 317                         pgto--;
 318                 }
 319                 if (pgfrom_base == 0) {
 320                         pgfrom_base = PAGE_CACHE_SIZE;
 321                         pgfrom--;
 322                 }
 323
 324                 copy = len;
 325                 if (copy > pgto_base)
 326                         copy = pgto_base;
 327                 if (copy > pgfrom_base)
 328                         copy = pgfrom_base;
 329                 pgto_base -= copy;
 330                 pgfrom_base -= copy;
 331
 332                 vto = kmap_atomic(*pgto, KM_USER0);
 333                 vfrom = kmap_atomic(*pgfrom, KM_USER1);
 334                 memmove(vto + pgto_base, vfrom + pgfrom_base, copy);
 335                 kunmap_atomic(vfrom, KM_USER1);
 336                 kunmap_atomic(vto, KM_USER0);
 337
 338         } while ((len -= copy) != 0);
 339         flush_dcache_page(*pgto);
 340 }
 341
 342 /*
 343  * _copy_to_pages
 344  * @pages: array of pages
 345  * @pgbase: page vector address of destination
 346  * @p: pointer to source data
 347  * @len: length
 348  *
 349  * Copies data from an arbitrary memory location into an array of pages
 350  * The copy is assumed to be non-overlapping.
 351  */
 352 static void
 353 _copy_to_pages(struct page **pages, size_t pgbase, const char *p, size_t len)
 354 {
 355         struct page **pgto;
 356         char *vto;
 357         size_t copy;
 358
 359         pgto = pages + (pgbase >> PAGE_CACHE_SHIFT);
 360         pgbase &= ~PAGE_CACHE_MASK;
 361
 362         do {
 363                 copy = PAGE_CACHE_SIZE - pgbase;
 364                 if (copy > len)
 365                         copy = len;
 366
 367                 vto = kmap_atomic(*pgto, KM_USER0);
 368                 memcpy(vto + pgbase, p, copy);
 369                 kunmap_atomic(vto, KM_USER0);
 370
 371                 pgbase += copy;
 372                 if (pgbase == PAGE_CACHE_SIZE) {
 373                         flush_dcache_page(*pgto);
 374                         pgbase = 0;
 375                         pgto++;
 376                 }
 377                 p += copy;
 378
 379         } while ((len -= copy) != 0);
 380         flush_dcache_page(*pgto);
 381 }
 382
 383 /*
 384  * _copy_from_pages
 385  * @p: pointer to destination
 386  * @pages: array of pages
 387  * @pgbase: offset of source data
 388  * @len: length
 389  *
 390  * Copies data into an arbitrary memory location from an array of pages
 391  * The copy is assumed to be non-overlapping.
 392  */
 393 static void
 394 _copy_from_pages(char *p, struct page **pages, size_t pgbase, size_t len)
 395 {
 396         struct page **pgfrom;
 397         char *vfrom;
 398         size_t copy;
 399
 400         pgfrom = pages + (pgbase >> PAGE_CACHE_SHIFT);
 401         pgbase &= ~PAGE_CACHE_MASK;
 402
 403         do {
 404                 copy = PAGE_CACHE_SIZE - pgbase;
 405                 if (copy > len)
 406                         copy = len;
 407
 408                 vfrom = kmap_atomic(*pgfrom, KM_USER0);
 409                 memcpy(p, vfrom + pgbase, copy);
 410                 kunmap_atomic(vfrom, KM_USER0);
 411
 412                 pgbase += copy;
 413                 if (pgbase == PAGE_CACHE_SIZE) {
 414                         pgbase = 0;
 415                         pgfrom++;
 416                 }
 417                 p += copy;
 418
 419         } while ((len -= copy) != 0);
 420 }
 421
 422 /*
 423  * xdr_shrink_bufhead
 424  * @buf: xdr_buf
 425  * @len: bytes to remove from buf->head[0]
 426  *
 427  * Shrinks XDR buffer's header kvec buf->head[0] by
 428  * 'len' bytes. The extra data is not lost, but is instead
 429  * moved into the inlined pages and/or the tail.
 430  */
 431 static void
 432 xdr_shrink_bufhead(struct xdr_buf *buf, size_t len)
 433 {
 434         struct kvec *head, *tail;
 435         size_t copy, offs;
 436         unsigned int pglen = buf->page_len;
 437
 438         tail = buf->tail;
 439         head = buf->head;
 440         BUG_ON (len > head->iov_len);
 441
 442         /* Shift the tail first */
 443         if (tail->iov_len != 0) {
 444                 if (tail->iov_len > len) {
 445                         copy = tail->iov_len - len;
 446                         memmove((char *)tail->iov_base + len,
 447                                         tail->iov_base, copy);
 448                 }
 449                 /* Copy from the inlined pages into the tail */
 450                 copy = len;
 451                 if (copy > pglen)
 452                         copy = pglen;
 453                 offs = len - copy;
 454                 if (offs >= tail->iov_len)
 455                         copy = 0;
 456                 else if (copy > tail->iov_len - offs)
 457                         copy = tail->iov_len - offs;
 458                 if (copy != 0)
 459                         _copy_from_pages((char *)tail->iov_base + offs,
 460                                         buf->pages,
 461                                         buf->page_base + pglen + offs - len,
 462                                         copy);
 463                 /* Do we also need to copy data from the head into the tail ? */
 464                 if (len > pglen) {
 465                         offs = copy = len - pglen;
 466                         if (copy > tail->iov_len)
 467                                 copy = tail->iov_len;
 468                         memcpy(tail->iov_base,
 469                                         (char *)head->iov_base +
 470                                         head->iov_len - offs,
 471                                         copy);
 472                 }
 473         }
 474         /* Now handle pages */
 475         if (pglen != 0) {
 476                 if (pglen > len)
 477                         _shift_data_right_pages(buf->pages,
 478                                         buf->page_base + len,
 479                                         buf->page_base,
 480                                         pglen - len);
 481                 copy = len;
 482                 if (len > pglen)
 483                         copy = pglen;
 484                 _copy_to_pages(buf->pages, buf->page_base,
 485                                 (char *)head->iov_base + head->iov_len - len,
 486                                 copy);
 487         }
 488         head->iov_len -= len;
 489         buf->buflen -= len;
 490         /* Have we truncated the message? */
 491         if (buf->len > buf->buflen)
 492                 buf->len = buf->buflen;
 493 }
 494
 495 /*
 496  * xdr_shrink_pagelen
 497  * @buf: xdr_buf
 498  * @len: bytes to remove from buf->pages
 499  *
 500  * Shrinks XDR buffer's page array buf->pages by
 501  * 'len' bytes. The extra data is not lost, but is instead
 502  * moved into the tail.
 503  */
 504 static void
 505 xdr_shrink_pagelen(struct xdr_buf *buf, size_t len)
 506 {
 507         struct kvec *tail;
 508         size_t copy;
 509         char *p;
 510         unsigned int pglen = buf->page_len;
 511
 512         tail = buf->tail;
 513         BUG_ON (len > pglen);
 514
 515         /* Shift the tail first */
 516         if (tail->iov_len != 0) {
 517                 p = (char *)tail->iov_base + len;
 518                 if (tail->iov_len > len) {
 519                         copy = tail->iov_len - len;
 520                         memmove(p, tail->iov_base, copy);
 521                 } else
 522                         buf->buflen -= len;
 523                 /* Copy from the inlined pages into the tail */
 524                 copy = len;
 525                 if (copy > tail->iov_len)
 526                         copy = tail->iov_len;
 527                 _copy_from_pages((char *)tail->iov_base,
 528                                 buf->pages, buf->page_base + pglen - len,
 529                                 copy);
 530         }
 531         buf->page_len -= len;
 532         buf->buflen -= len;
 533         /* Have we truncated the message? */
 534         if (buf->len > buf->buflen)
 535                 buf->len = buf->buflen;
 536 }
 537
 538 void
 539 xdr_shift_buf(struct xdr_buf *buf, size_t len)
 540 {
 541         xdr_shrink_bufhead(buf, len);
 542 }
 543
 544 /**
 545  * xdr_init_encode - Initialize a struct xdr_stream for sending data.
 546  * @xdr: pointer to xdr_stream struct
 547  * @buf: pointer to XDR buffer in which to encode data
 548  * @p: current pointer inside XDR buffer
 549  *
 550  * Note: at the moment the RPC client only passes the length of our
 551  *       scratch buffer in the xdr_buf's header kvec. Previously this
 552  *       meant we needed to call xdr_adjust_iovec() after encoding the
 553  *       data. With the new scheme, the xdr_stream manages the details
 554  *       of the buffer length, and takes care of adjusting the kvec
 555  *       length for us.
 556  */
 557 void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, uint32_t *p)
 558 {
 559         struct kvec *iov = buf->head;
 560         int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
 561
 562         BUG_ON(scratch_len < 0);
 563         xdr->buf = buf;
 564         xdr->iov = iov;
 565         xdr->p = (uint32_t *)((char *)iov->iov_base + iov->iov_len);
 566         xdr->end = (uint32_t *)((char *)iov->iov_base + scratch_len);
 567         BUG_ON(iov->iov_len > scratch_len);
 568
 569         if (p != xdr->p && p != NULL) {
 570                 size_t len;
 571
 572                 BUG_ON(p < xdr->p || p > xdr->end);
 573                 len = (char *)p - (char *)xdr->p;
 574                 xdr->p = p;
 575                 buf->len += len;
 576                 iov->iov_len += len;
 577         }
 578 }
 579 EXPORT_SYMBOL(xdr_init_encode);
 580
 581 /**
 582  * xdr_reserve_space - Reserve buffer space for sending
 583  * @xdr: pointer to xdr_stream
 584  * @nbytes: number of bytes to reserve
 585  *
 586  * Checks that we have enough buffer space to encode 'nbytes' more
 587  * bytes of data. If so, update the total xdr_buf length, and
 588  * adjust the length of the current kvec.
 589  */
 590 uint32_t * xdr_reserve_space(struct xdr_stream *xdr, size_t nbytes)
 591 {
 592         uint32_t *p = xdr->p;
 593         uint32_t *q;
 594
 595         /* align nbytes on the next 32-bit boundary */
 596         nbytes += 3;
 597         nbytes &= ~3;
 598         q = p + (nbytes >> 2);
 599         if (unlikely(q > xdr->end || q < p))
 600                 return NULL;
 601         xdr->p = q;
 602         xdr->iov->iov_len += nbytes;
 603         xdr->buf->len += nbytes;
 604         return p;
 605 }
 606 EXPORT_SYMBOL(xdr_reserve_space);
 607
 608 /**
 609  * xdr_write_pages - Insert a list of pages into an XDR buffer for sending
 610  * @xdr: pointer to xdr_stream
 611  * @pages: list of pages
 612  * @base: offset of first byte
 613  * @len: length of data in bytes
 614  *
 615  */
 616 void xdr_write_pages(struct xdr_stream *xdr, struct page **pages, unsigned int base,
 617                  unsigned int len)
 618 {
 619         struct xdr_buf *buf = xdr->buf;
 620         struct kvec *iov = buf->tail;
 621         buf->pages = pages;
 622         buf->page_base = base;
 623         buf->page_len = len;
 624
 625         iov->iov_base = (char *)xdr->p;
 626         iov->iov_len  = 0;
 627         xdr->iov = iov;
 628
 629         if (len & 3) {
 630                 unsigned int pad = 4 - (len & 3);
 631
 632                 BUG_ON(xdr->p >= xdr->end);
 633                 iov->iov_base = (char *)xdr->p + (len & 3);
 634                 iov->iov_len  += pad;
 635                 len += pad;
 636                 *xdr->p++ = 0;
 637         }
 638         buf->buflen += len;
 639         buf->len += len;
 640 }
 641 EXPORT_SYMBOL(xdr_write_pages);
 642
 643 /**
 644  * xdr_init_decode - Initialize an xdr_stream for decoding data.
 645  * @xdr: pointer to xdr_stream struct
 646  * @buf: pointer to XDR buffer from which to decode data
 647  * @p: current pointer inside XDR buffer
 648  */
 649 void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, uint32_t *p)
 650 {
 651         struct kvec *iov = buf->head;
 652         unsigned int len = iov->iov_len;
 653
 654         if (len > buf->len)
 655                 len = buf->len;
 656         xdr->buf = buf;
 657         xdr->iov = iov;
 658         xdr->p = p;
 659         xdr->end = (uint32_t *)((char *)iov->iov_base + len);
 660 }
 661 EXPORT_SYMBOL(xdr_init_decode);
 662
 663 /**
 664  * xdr_inline_decode - Retrieve non-page XDR data to decode
 665  * @xdr: pointer to xdr_stream struct
 666  * @nbytes: number of bytes of data to decode
 667  *
 668  * Check if the input buffer is long enough to enable us to decode
 669  * 'nbytes' more bytes of data starting at the current position.
 670  * If so return the current pointer, then update the current
 671  * pointer position.
 672  */
 673 uint32_t * xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
 674 {
 675         uint32_t *p = xdr->p;
 676         uint32_t *q = p + XDR_QUADLEN(nbytes);
 677
 678         if (unlikely(q > xdr->end || q < p))
 679                 return NULL;
 680         xdr->p = q;
 681         return p;
 682 }
 683 EXPORT_SYMBOL(xdr_inline_decode);
 684
 685 /**
 686  * xdr_read_pages - Ensure page-based XDR data to decode is aligned at current pointer position
 687  * @xdr: pointer to xdr_stream struct
 688  * @len: number of bytes of page data
 689  *
 690  * Moves data beyond the current pointer position from the XDR head[] buffer
 691  * into the page list. Any data that lies beyond current position + "len"
 692  * bytes is moved into the XDR tail[]. The current pointer is then
 693  * repositioned at the beginning of the XDR tail.
 694  */
 695 void xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
 696 {
 697         struct xdr_buf *buf = xdr->buf;
 698         struct kvec *iov;
 699         ssize_t shift;
 700         unsigned int end;
 701         int padding;
 702
 703         /* Realign pages to current pointer position */
 704         iov  = buf->head;
 705         shift = iov->iov_len + (char *)iov->iov_base - (char *)xdr->p;
 706         if (shift > 0)
 707                 xdr_shrink_bufhead(buf, shift);
 708
 709         /* Truncate page data and move it into the tail */
 710         if (buf->page_len > len)
 711                 xdr_shrink_pagelen(buf, buf->page_len - len);
 712         padding = (XDR_QUADLEN(len) << 2) - len;
 713         xdr->iov = iov = buf->tail;
 714         /* Compute remaining message length.  */
 715         end = iov->iov_len;
 716         shift = buf->buflen - buf->len;
 717         if (shift < end)
 718                 end -= shift;
 719         else if (shift > 0)
 720                 end = 0;
 721         /*
 722          * Position current pointer at beginning of tail, and
 723          * set remaining message length.
 724          */
 725         xdr->p = (uint32_t *)((char *)iov->iov_base + padding);
 726         xdr->end = (uint32_t *)((char *)iov->iov_base + end);
 727 }
 728 EXPORT_SYMBOL(xdr_read_pages);
 729
 730 static struct kvec empty_iov = {.iov_base = NULL, .iov_len = 0};
 731
 732 void
 733 xdr_buf_from_iov(struct kvec *iov, struct xdr_buf *buf)
 734 {
 735         buf->head[0] = *iov;
 736         buf->tail[0] = empty_iov;
 737         buf->page_len = 0;
 738         buf->buflen = buf->len = iov->iov_len;
 739 }
 740
 741 /* Sets subiov to the intersection of iov with the buffer of length len
 742  * starting base bytes after iov.  Indicates empty intersection by setting
 743  * length of subiov to zero.  Decrements len by length of subiov, sets base
 744  * to zero (or decrements it by length of iov if subiov is empty). */
 745 static void
 746 iov_subsegment(struct kvec *iov, struct kvec *subiov, int *base, int *len)
 747 {
 748         if (*base > iov->iov_len) {
 749                 subiov->iov_base = NULL;
 750                 subiov->iov_len = 0;
 751                 *base -= iov->iov_len;
 752         } else {
 753                 subiov->iov_base = iov->iov_base + *base;
 754                 subiov->iov_len = min(*len, (int)iov->iov_len - *base);
 755                 *base = 0;
 756         }
 757         *len -= subiov->iov_len;
 758 }
 759
 760 /* Sets subbuf to the portion of buf of length len beginning base bytes
 761  * from the start of buf. Returns -1 if base of length are out of bounds. */
 762 int
 763 xdr_buf_subsegment(struct xdr_buf *buf, struct xdr_buf *subbuf,
 764                         int base, int len)
 765 {
 766         int i;
 767
 768         subbuf->buflen = subbuf->len = len;
 769         iov_subsegment(buf->head, subbuf->head, &base, &len);
 770
 771         if (base < buf->page_len) {
 772                 i = (base + buf->page_base) >> PAGE_CACHE_SHIFT;
 773                 subbuf->pages = &buf->pages[i];
 774                 subbuf->page_base = (base + buf->page_base) & ~PAGE_CACHE_MASK;
 775                 subbuf->page_len = min((int)buf->page_len - base, len);
 776                 len -= subbuf->page_len;
 777                 base = 0;
 778         } else {
 779                 base -= buf->page_len;
 780                 subbuf->page_len = 0;
 781         }
 782
 783         iov_subsegment(buf->tail, subbuf->tail, &base, &len);
 784         if (base || len)
 785                 return -1;
 786         return 0;
 787 }
 788
 789 /* obj is assumed to point to allocated memory of size at least len: */
 790 int
 791 read_bytes_from_xdr_buf(struct xdr_buf *buf, int base, void *obj, int len)
 792 {
 793         struct xdr_buf subbuf;
 794         int this_len;
 795         int status;
 796
 797         status = xdr_buf_subsegment(buf, &subbuf, base, len);
 798         if (status)
 799                 goto out;
 800         this_len = min(len, (int)subbuf.head[0].iov_len);
 801         memcpy(obj, subbuf.head[0].iov_base, this_len);
 802         len -= this_len;
 803         obj += this_len;
 804         this_len = min(len, (int)subbuf.page_len);
 805         if (this_len)
 806                 _copy_from_pages(obj, subbuf.pages, subbuf.page_base, this_len);
 807         len -= this_len;
 808         obj += this_len;
 809         this_len = min(len, (int)subbuf.tail[0].iov_len);
 810         memcpy(obj, subbuf.tail[0].iov_base, this_len);
 811 out:
 812         return status;
 813 }
 814
 815 /* obj is assumed to point to allocated memory of size at least len: */
 816 int
 817 write_bytes_to_xdr_buf(struct xdr_buf *buf, int base, void *obj, int len)
 818 {
 819         struct xdr_buf subbuf;
 820         int this_len;
 821         int status;
 822
 823         status = xdr_buf_subsegment(buf, &subbuf, base, len);
 824         if (status)
 825                 goto out;
 826         this_len = min(len, (int)subbuf.head[0].iov_len);
 827         memcpy(subbuf.head[0].iov_base, obj, this_len);
 828         len -= this_len;
 829         obj += this_len;
 830         this_len = min(len, (int)subbuf.page_len);
 831         if (this_len)
 832                 _copy_to_pages(subbuf.pages, subbuf.page_base, obj, this_len);
 833         len -= this_len;
 834         obj += this_len;
 835         this_len = min(len, (int)subbuf.tail[0].iov_len);
 836         memcpy(subbuf.tail[0].iov_base, obj, this_len);
 837 out:
 838         return status;
 839 }
 840
 841 int
 842 xdr_decode_word(struct xdr_buf *buf, int base, u32 *obj)
 843 {
 844         u32     raw;
 845         int     status;
 846
 847         status = read_bytes_from_xdr_buf(buf, base, &raw, sizeof(*obj));
 848         if (status)
 849                 return status;
 850         *obj = ntohl(raw);
 851         return 0;
 852 }
 853
 854 int
 855 xdr_encode_word(struct xdr_buf *buf, int base, u32 obj)
 856 {
 857         u32     raw = htonl(obj);
 858
 859         return write_bytes_to_xdr_buf(buf, base, &raw, sizeof(obj));
 860 }
 861
 862 /* If the netobj starting offset bytes from the start of xdr_buf is contained
 863  * entirely in the head or the tail, set object to point to it; otherwise
 864  * try to find space for it at the end of the tail, copy it there, and
 865  * set obj to point to it. */
 866 int
 867 xdr_buf_read_netobj(struct xdr_buf *buf, struct xdr_netobj *obj, int offset)
 868 {
 869         u32     tail_offset = buf->head[0].iov_len + buf->page_len;
 870         u32     obj_end_offset;
 871
 872         if (xdr_decode_word(buf, offset, &obj->len))
 873                 goto out;
 874         obj_end_offset = offset + 4 + obj->len;
 875
 876         if (obj_end_offset <= buf->head[0].iov_len) {
 877                 /* The obj is contained entirely in the head: */
 878                 obj->data = buf->head[0].iov_base + offset + 4;
 879         } else if (offset + 4 >= tail_offset) {
 880                 if (obj_end_offset - tail_offset
 881                                 > buf->tail[0].iov_len)
 882                         goto out;
 883                 /* The obj is contained entirely in the tail: */
 884                 obj->data = buf->tail[0].iov_base
 885                         + offset - tail_offset + 4;
 886         } else {
 887                 /* use end of tail as storage for obj:
 888                  * (We don't copy to the beginning because then we'd have
 889                  * to worry about doing a potentially overlapping copy.
 890                  * This assumes the object is at most half the length of the
 891                  * tail.) */
 892                 if (obj->len > buf->tail[0].iov_len)
 893                         goto out;
 894                 obj->data = buf->tail[0].iov_base + buf->tail[0].iov_len -
 895                                 obj->len;
 896                 if (read_bytes_from_xdr_buf(buf, offset + 4,
 897                                         obj->data, obj->len))
 898                         goto out;
 899
 900         }
 901         return 0;
 902 out:
 903         return -1;
 904 }
 905
 906 /* Returns 0 on success, or else a negative error code. */
 907 static int
 908 xdr_xcode_array2(struct xdr_buf *buf, unsigned int base,
 909                  struct xdr_array2_desc *desc, int encode)
 910 {
 911         char *elem = NULL, *c;
 912         unsigned int copied = 0, todo, avail_here;
 913         struct page **ppages = NULL;
 914         int err;
 915
 916         if (encode) {
 917                 if (xdr_encode_word(buf, base, desc->array_len) != 0)
 918                         return -EINVAL;
 919         } else {
 920                 if (xdr_decode_word(buf, base, &desc->array_len) != 0 ||
 921                     desc->array_len > desc->array_maxlen ||
 922                     (unsigned long) base + 4 + desc->array_len *
 923                                     desc->elem_size > buf->len)
 924                         return -EINVAL;
 925         }
 926         base += 4;
 927
 928         if (!desc->xcode)
 929                 return 0;
 930
 931         todo = desc->array_len * desc->elem_size;
 932
 933         /* process head */
 934         if (todo && base < buf->head->iov_len) {
 935                 c = buf->head->iov_base + base;
 936                 avail_here = min_t(unsigned int, todo,
 937                                    buf->head->iov_len - base);
 938                 todo -= avail_here;
 939
 940                 while (avail_here >= desc->elem_size) {
 941                         err = desc->xcode(desc, c);
 942                         if (err)
 943                                 goto out;
 944                         c += desc->elem_size;
 945                         avail_here -= desc->elem_size;
 946                 }
 947                 if (avail_here) {
 948                         if (!elem) {
 949                                 elem = kmalloc(desc->elem_size, GFP_KERNEL);
 950                                 err = -ENOMEM;
 951                                 if (!elem)
 952                                         goto out;
 953                         }
 954                         if (encode) {
 955                                 err = desc->xcode(desc, elem);
 956                                 if (err)
 957                                         goto out;
 958                                 memcpy(c, elem, avail_here);
 959                         } else
 960                                 memcpy(elem, c, avail_here);
 961                         copied = avail_here;
 962                 }
 963                 base = buf->head->iov_len;  /* align to start of pages */
 964         }
 965
 966         /* process pages array */
 967         base -= buf->head->iov_len;
 968         if (todo && base < buf->page_len) {
 969                 unsigned int avail_page;
 970
 971                 avail_here = min(todo, buf->page_len - base);
 972                 todo -= avail_here;
 973
 974                 base += buf->page_base;
 975                 ppages = buf->pages + (base >> PAGE_CACHE_SHIFT);
 976                 base &= ~PAGE_CACHE_MASK;
 977                 avail_page = min_t(unsigned int, PAGE_CACHE_SIZE - base,
 978                                         avail_here);
 979                 c = kmap(*ppages) + base;
 980
 981                 while (avail_here) {
 982                         avail_here -= avail_page;
 983                         if (copied || avail_page < desc->elem_size) {
 984                                 unsigned int l = min(avail_page,
 985                                         desc->elem_size - copied);
 986                                 if (!elem) {
 987                                         elem = kmalloc(desc->elem_size,
 988                                                        GFP_KERNEL);
 989                                         err = -ENOMEM;
 990                                         if (!elem)
 991                                                 goto out;
 992                                 }
 993                                 if (encode) {
 994                                         if (!copied) {
 995                                                 err = desc->xcode(desc, elem);
 996                                                 if (err)
 997                                                         goto out;
 998                                         }
 999                                         memcpy(c, elem + copied, l);
1000                                         copied += l;
1001                                         if (copied == desc->elem_size)
1002                                                 copied = 0;
1003                                 } else {
1004                                         memcpy(elem + copied, c, l);
1005                                         copied += l;
1006                                         if (copied == desc->elem_size) {
1007                                                 err = desc->xcode(desc, elem);
1008                                                 if (err)
1009                                                         goto out;
1010                                                 copied = 0;
1011                                         }
1012                                 }
1013                                 avail_page -= l;
1014                                 c += l;
1015                         }
1016                         while (avail_page >= desc->elem_size) {
1017                                 err = desc->xcode(desc, c);
1018                                 if (err)
1019                                         goto out;
1020                                 c += desc->elem_size;
1021                                 avail_page -= desc->elem_size;
1022                         }
1023                         if (avail_page) {
1024                                 unsigned int l = min(avail_page,
1025                                             desc->elem_size - copied);
1026                                 if (!elem) {
1027                                         elem = kmalloc(desc->elem_size,
1028                                                        GFP_KERNEL);
1029                                         err = -ENOMEM;
1030                                         if (!elem)
1031                                                 goto out;
1032                                 }
1033                                 if (encode) {
1034                                         if (!copied) {
1035                                                 err = desc->xcode(desc, elem);
1036                                                 if (err)
1037                                                         goto out;
1038                                         }
1039                                         memcpy(c, elem + copied, l);
1040                                         copied += l;
1041                                         if (copied == desc->elem_size)
1042                                                 copied = 0;
1043                                 } else {
1044                                         memcpy(elem + copied, c, l);
1045                                         copied += l;
1046                                         if (copied == desc->elem_size) {
1047                                                 err = desc->xcode(desc, elem);
1048                                                 if (err)
1049                                                         goto out;
1050                                                 copied = 0;
1051                                         }
1052                                 }
1053                         }
1054                         if (avail_here) {
1055                                 kunmap(*ppages);
1056                                 ppages++;
1057                                 c = kmap(*ppages);
1058                         }
1059
1060                         avail_page = min(avail_here,
1061                                  (unsigned int) PAGE_CACHE_SIZE);
1062                 }
1063                 base = buf->page_len;  /* align to start of tail */
1064         }
1065
1066         /* process tail */
1067         base -= buf->page_len;
1068         if (todo) {
1069                 c = buf->tail->iov_base + base;
1070                 if (copied) {
1071                         unsigned int l = desc->elem_size - copied;
1072
1073                         if (encode)
1074                                 memcpy(c, elem + copied, l);
1075                         else {
1076                                 memcpy(elem + copied, c, l);
1077                                 err = desc->xcode(desc, elem);
1078                                 if (err)
1079                                         goto out;
1080                         }
1081                         todo -= l;
1082                         c += l;
1083                 }
1084                 while (todo) {
1085                         err = desc->xcode(desc, c);
1086                         if (err)
1087                                 goto out;
1088                         c += desc->elem_size;
1089                         todo -= desc->elem_size;
1090                 }
1091         }
1092         err = 0;
1093
1094 out:
1095         if (elem)
1096                 kfree(elem);
1097         if (ppages)
1098                 kunmap(*ppages);
1099         return err;
1100 }
1101
1102 int
1103 xdr_decode_array2(struct xdr_buf *buf, unsigned int base,
1104                   struct xdr_array2_desc *desc)
1105 {
1106         if (base >= buf->len)
1107                 return -EINVAL;
1108
1109         return xdr_xcode_array2(buf, base, desc, 0);
1110 }
1111
1112 int
1113 xdr_encode_array2(struct xdr_buf *buf, unsigned int base,
1114                   struct xdr_array2_desc *desc)
1115 {
1116         if ((unsigned long) base + 4 + desc->array_len * desc->elem_size >
1117             buf->head->iov_len + buf->page_len + buf->tail->iov_len)
1118                 return -EINVAL;
1119
1120         return xdr_xcode_array2(buf, base, desc, 1);
1121 }