LXR linux/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
  16struct iovec
  17{
  18        void __user *iov_base;  /* BSD uses caddr_t (1003.1g requires void *) */
  19        __kernel_size_t iov_len; /* Must be size_t (1003.1g) */
  20};
  21
  22#ifdef __KERNEL__
  23
  24struct kvec {
  25        void *iov_base; /* and that should *never* hold a userland pointer */
  26        size_t iov_len;
  27};
  28
  29#endif
  30
  31/*
  32 *      UIO_MAXIOV shall be at least 16 1003.1g (5.4.1.1)
  33 */
  34 
  35#define UIO_FASTIOV     8
  36#define UIO_MAXIOV      1024
  37
  38/*
  39 * Total number of bytes covered by an iovec.
  40 *
  41 * NOTE that it is not safe to use this function until all the iovec's
  42 * segment lengths have been validated.  Because the individual lengths can
  43 * overflow a size_t when added together.
  44 */
  45static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
  46{
  47        unsigned long seg;
  48        size_t ret = 0;
  49
  50        for (seg = 0; seg < nr_segs; seg++)
  51                ret += iov[seg].iov_len;
  52        return ret;
  53}
  54
  55unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
  56
  57#endif
  58