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 */
33 const struct iovec *iov;
34 const struct kvec *kvec;
35 const struct bio_vec *bvec;
37 unsigned long nr_segs;
41 * Total number of bytes covered by an iovec.
43 * NOTE that it is not safe to use this function until all the iovec's
44 * segment lengths have been validated. Because the individual lengths can
45 * overflow a size_t when added together.
47 static inline size_t iov_length(const struct iovec *iov, unsigned long nr_segs)
52 for (seg = 0; seg < nr_segs; seg++)
53 ret += iov[seg].iov_len;
57 static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
59 return (struct iovec) {
60 .iov_base = iter->iov->iov_base + iter->iov_offset,
61 .iov_len = min(iter->count,
62 iter->iov->iov_len - iter->iov_offset),
66 #define iov_for_each(iov, iter, start) \
67 if (!((start).type & ITER_BVEC)) \
68 for (iter = (start); \
70 ((iov = iov_iter_iovec(&(iter))), 1); \
71 iov_iter_advance(&(iter), (iov).iov_len))
73 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to);
75 size_t iov_iter_copy_from_user_atomic(struct page *page,
76 struct iov_iter *i, unsigned long offset, size_t bytes);
77 void iov_iter_advance(struct iov_iter *i, size_t bytes);
78 int iov_iter_fault_in_readable(struct iov_iter *i, size_t bytes);
79 int iov_iter_fault_in_multipages_readable(struct iov_iter *i, size_t bytes);
80 size_t iov_iter_single_seg_count(const struct iov_iter *i);
81 size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
83 size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
85 size_t copy_to_iter(void *addr, size_t bytes, struct iov_iter *i);
86 size_t copy_from_iter(void *addr, size_t bytes, struct iov_iter *i);
87 size_t copy_from_iter_nocache(void *addr, size_t bytes, struct iov_iter *i);
88 size_t iov_iter_zero(size_t bytes, struct iov_iter *);
89 unsigned long iov_iter_alignment(const struct iov_iter *i);
90 void iov_iter_init(struct iov_iter *i, int direction, const struct iovec *iov,
91 unsigned long nr_segs, size_t count);
92 void iov_iter_kvec(struct iov_iter *i, int direction, const struct kvec *kvec,
93 unsigned long nr_segs, size_t count);
94 void iov_iter_bvec(struct iov_iter *i, int direction, const struct bio_vec *bvec,
95 unsigned long nr_segs, size_t count);
96 ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
97 size_t maxsize, unsigned maxpages, size_t *start);
98 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i, struct page ***pages,
99 size_t maxsize, size_t *start);
100 int iov_iter_npages(const struct iov_iter *i, int maxpages);
102 const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags);
104 static inline size_t iov_iter_count(struct iov_iter *i)
109 static inline bool iter_is_iovec(struct iov_iter *i)
111 return !(i->type & (ITER_BVEC | ITER_KVEC));
115 * Cap the iov_iter by given limit; note that the second argument is
116 * *not* the new size - it's upper limit for such. Passing it a value
117 * greater than the amount of data in iov_iter is fine - it'll just do
118 * nothing in that case.
120 static inline void iov_iter_truncate(struct iov_iter *i, u64 count)
123 * count doesn't have to fit in size_t - comparison extends both
124 * operands to u64 here and any value that would be truncated by
125 * conversion in assignement is by definition greater than all
126 * values of size_t, including old i->count.
128 if (i->count > count)
133 * reexpand a previously truncated iterator; count must be no more than how much
136 static inline void iov_iter_reexpand(struct iov_iter *i, size_t count)
140 size_t csum_and_copy_to_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
141 size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);