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 struct 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
  24 struct 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  */
  45 static 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
  55 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
  56
  57 #endif