2 * Berkeley style UIO structures - Alan Cox 1994.
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.
12 #include <linux/kernel.h>
13 #include <uapi/linux/uio.h>
18 void *iov_base; /* and that should *never* hold a userland pointer */
23 const struct iovec *iov;
24 unsigned long nr_segs;
30 * Total number of bytes covered by an iovec.
32 * NOTE that it is not safe to use this function until all the iovec's
33 * segment lengths have been validated. Because the individual lengths can
34 * overflow a size_t when added together.
36 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
41 for (seg = 0; seg < nr_segs; seg++)
42 ret += iov[seg].iov_len;
46 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
48 return (struct iovec) {
49 .iov_base = iter->iov->iov_base + iter->iov_offset,
50 .iov_len = min(iter->count,
51 iter->iov->iov_len - iter->iov_offset),
55 #define iov_for_each(iov, iter, start) \
56 for (iter = (start); \
58 ((iov = iov_iter_iovec(&(iter))), 1); \
59 iov_iter_advance(&(iter), (iov).iov_len))
61 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
63 size_t iov_iter_copy_from_user_atomic(struct page *page,
64 struct iov_iter *i, unsigned long offset, size_t bytes);
65 size_t iov_iter_copy_from_user(struct page *page,
66 struct iov_iter *i, unsigned long offset, size_t bytes);
67 void iov_iter_advance(struct iov_iter *i, size_t bytes);
68 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
69 size_t iov_iter_single_seg_count(const struct iov_iter *i);
70 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
73 static inline void iov_iter_init(struct iov_iter *i,
74 const struct iovec *iov, unsigned long nr_segs,
75 size_t count, size_t written)
80 i->count = count + written;
82 iov_iter_advance(i, written);
85 static inline size_t iov_iter_count(struct iov_iter *i)
90 int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
91 int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len);