LXR linux-bk/include/linux/uio.h

   1#ifndef __LINUX_UIO_H
   2#define __LINUX_UIO_H
   3
   4#include <linux/compiler.h>
   5#include <linux/types.h>
   6
   7/*
   8 *      Berkeley style UIO structures   -       Alan Cox 1994.
   9 *
  10 *              This program is free software; you can redistribute it and/or
  11 *              modify it under the terms of the GNU General Public License
  12 *              as published by the Free Software Foundation; either version
  13 *              2 of the License, or (at your option) any later version.
  14 */
  15
  16
  17/* A word of warning: Our uio structure will clash with the C library one (which is now obsolete). Remove the C
  18   library one from sys/uio.h if you have a very old library set */
  19
  20struct iovec
  21{
  22        void __user *iov_base;  /* BSD uses caddr_t (1003.1g requires void *) */
  23        __kernel_size_t iov_len; /* Must be size_t (1003.1g) */
  24};
  25
  26#ifdef __KERNEL__
  27
  28struct kvec {
  29        void *iov_base; /* and that should *never* hold a userland pointer */
  30        size_t iov_len;
  31};
  32
  33#endif
  34
  35/*
  36 *      UIO_MAXIOV shall be at least 16 1003.1g (5.4.1.1)
  37 */
  38 
  39#define UIO_FASTIOV     8
  40#define UIO_MAXIOV      1024
  41#if 0
  42#define UIO_MAXIOV      16      /* Maximum iovec's in one operation 
  43                                   16 matches BSD */
  44                                /* Beg pardon: BSD has 1024 --ANK */
  45#endif
  46
  47/*
  48 * Total number of bytes covered by an iovec.
  49 *
  50 * NOTE that it is not safe to use this function until all the iovec's
  51 * segment lengths have been validated.  Because the individual lengths can
  52 * overflow a size_t when added together.
  53 */
  54static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
  55{
  56        unsigned long seg;
  57        size_t ret = 0;
  58
  59        for (seg = 0; seg < nr_segs; seg++)
  60                ret += iov[seg].iov_len;
  61        return ret;
  62}
  63
  64unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
  65
  66#endif
  67