include/linux/uio.h

   1 /*
   2  *      Berkeley style UIO structures   -       Alan Cox 1994.
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  */
   9 #ifndef __LINUX_UIO_H
  10 #define __LINUX_UIO_H
  11
  12 #include <linux/kernel.h>
  13 #include <uapi/linux/uio.h>
  14
  15 struct page;
  16
  17 struct kvec {
  18         void *iov_base; /* and that should *never* hold a userland pointer */
  19         size_t iov_len;
  20 };
  21
  22 struct iov_iter {
  23         int type;
  24         const struct iovec *iov;
  25         unsigned long nr_segs;
  26         size_t iov_offset;
  27         size_t count;
  28 };
  29
  30 /*
  31  * Total number of bytes covered by an iovec.
  32  *
  33  * NOTE that it is not safe to use this function until all the iovec's
  34  * segment lengths have been validated.  Because the individual lengths can
  35  * overflow a size_t when added together.
  36  */
  37 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
  38 {
  39         unsigned long seg;
  40         size_t ret = 0;
  41
  42         for (seg = 0; seg < nr_segs; seg++)
  43                 ret += iov[seg].iov_len;
  44         return ret;
  45 }
  46
  47 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
  48 {
  49         return (struct iovec) {
  50                 .iov_base = iter->iov->iov_base + iter->iov_offset,
  51                 .iov_len = min(iter->count,
  52                                iter->iov->iov_len - iter->iov_offset),
  53         };
  54 }
  55
  56 #define iov_for_each(iov, iter, start)                          \
  57         for (iter = (start);                                    \
  58              (iter).count &&                                    \
  59              ((iov = iov_iter_iovec(&(iter))), 1);              \
  60              iov_iter_advance(&(iter), (iov).iov_len))
  61
  62 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
  63
  64 size_t iov_iter_copy_from_user_atomic(struct page *page,
  65                 struct iov_iter *i, unsigned long offset, size_t bytes);
  66 void iov_iter_advance(struct iov_iter *i, size_t bytes);
  67 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
  68 size_t iov_iter_single_seg_count(const struct iov_iter *i);
  69 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
  70                          struct iov_iter *i);
  71 unsigned long iov_iter_alignment(const struct iov_iter *i);
  72 void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
  73                         unsigned long nr_segs, size_t count);
  74 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
  75                         size_t maxsize, size_t *start);
  76 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
  77                         size_t maxsize, size_t *start);
  78 int iov_iter_npages(const struct iov_iter *i, int maxpages);
  79
  80 static inline size_t iov_iter_count(struct iov_iter *i)
  81 {
  82         return i->count;
  83 }
  84
  85 int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
  86 int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len);
  87
  88
  89 #endif