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 */
24 const struct iovec *iov;
25 unsigned long nr_segs;
31 * Total number of bytes covered by an iovec.
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.
37 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
42 for (seg = 0; seg < nr_segs; seg++)
43 ret += iov[seg].iov_len;
47 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
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),
56 #define iov_for_each(iov, iter, start) \
57 for (iter = (start); \
59 ((iov = iov_iter_iovec(&(iter))), 1); \
60 iov_iter_advance(&(iter), (iov).iov_len))
62 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
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,
71 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
73 unsigned long iov_iter_alignment(const struct iov_iter *i);
74 void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
75 unsigned long nr_segs, size_t count);
76 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
77 size_t maxsize, size_t *start);
78 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
79 size_t maxsize, size_t *start);
80 int iov_iter_npages(const struct iov_iter *i, int maxpages);
82 static inline size_t iov_iter_count(struct iov_iter *i)
87 static inline void iov_iter_truncate(struct iov_iter *i, size_t count)
93 int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
94 int memcpy_toiovec(struct iovec *iov, unsigned char *kdata, int len);